Method of providing braze reservoir in metal component or coupon therefor

Abstract

To provide a method of providing a braze reservoir in metal component or coupon therefor.SOLUTION: Provided is a method comprising: additively manufacturing a metal coupon (200) for inserting into a coupon opening (204) in a body (206) of a component (202); inserting a first braze material (328) in a first cavity (320); sealing the first cavity (320) from the exterior of the AM metal member (290); positioning the metal coupon (200) in the coupon opening (204); and heating the AM metal member (290) to a predetermined temperature exceeding a melting temperature of the first braze material (328), causing the first braze material (328) to liquefy and the blocking member (332) to open and the liquefied first braze material (328) to flow through the first conduit (324) to infiltrate the braze region (294).SELECTED DRAWING: Figure 7A

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to repairing parts, and more particularly to repairing parts through the use of metal coupons having braze reservoirs or braze reservoirs within the part. [Background technology]

[0002] Industrial components may require repair from time to time. For example, hot gas path components used in turbomachinery to channel a working fluid for energy production may require repair. Hot gas path components may take a variety of forms, such as turbine rotor blades or stationary vanes that include airfoils that channel the working fluid for energy production. The rotor blades are coupled to the turbine rotor and act to rotate the turbine rotor, and the stationary vanes are coupled to the turbomachine casing and channel the working fluid toward the rotor blades.

[0003] Additive manufacturing, such as direct metal laser melting (DMLM) or selective laser melting (SLM), has emerged as a reliable manufacturing method for producing industrial parts. The advent of additive manufacturing techniques also allows for the replacement of portions of components, such as portions of the leading or trailing edge of a turbomachine blade. For example, a portion of the leading edge of a turbomachine blade may be removed, leaving a cutout in the blade, and a new section (referred to herein as a “coupon”) may be bonded to the cutout. The coupon is additively manufactured to have a shape that at least generally matches the shape of the cutout. This coupon can replace worn portions of used turbomachine blades or can be added as part of a new turbomachine blade. The coupon can simply replace the internal cooling structure of the turbomachine blade or can provide additional or improved cooling structure (e.g., near-wall cooling passages) not present in the original turbomachine blade.

[0004] However, replacement coupons are made from the same material and exterior construction as the removed portion of the part. As a result, replacement coupons exhibit some of the same shortcomings as the original part and / or notch and do not offer improved overall performance characteristics, such as overall strength, stress / strain resistance, ductility, wear resistance, thermal or electrical conductivity, and / or mass reduction. Bonding a replacement coupon to a part using a single brazing filler metal negates the above-mentioned overall performance characteristics, as well as additional joint-related performance characteristics, such as improved joint bond strength and reliability and reduced post-braze machining / blending operations. Furthermore, using a coupon made of substantially the same material as the removed notch negates the high material cost of the replacement coupon. Furthermore, current brazing processes only allow brazing filler metal to be introduced from the outside of the metal coupon and / or part, limiting the ability to introduce brazing filler metal into the interior of the coupon and / or part, for example, to repair internal damage, ensure brazing filler infiltration, and / or otherwise improve brazing performance. Summary of the Invention

[0005] All aspects, embodiments and features listed below may be combined in any technically possible manner.

[0006] One aspect of the disclosure is a method comprising additively manufacturing a metal coupon for insertion into a coupon opening in a body of a part, the metal coupon including an additively manufactured (AM) metal part having a braze reservoir, the braze reservoir comprising: a first cavity defined in the AM metal part; a second conduit defined in the AM metal part fluidly connecting the first cavity to an outer surface of the AM metal part; a first conduit defined in the AM metal part fluidly connecting the first cavity to a braze region; and a fluid conduit between the first cavity and the braze region. the first brazing material being a brazing material, the brazing material including a blocking member across the first conduit to block fluid communication between the first and second cavities; inserting a first brazing material into the first cavity through a second conduit and sealing the second conduit from the exterior of the AM metal part; placing a metal coupon in the coupon opening; and heating the AM metal part to a predetermined temperature above the melting temperature of the first brazing material, causing the first brazing material to liquefy and opening the blocking member, allowing the liquefied first brazing material to flow down the first conduit and infiltrate the brazing area.

[0007] Another aspect of the present disclosure includes any of the above aspects, wherein the AM metal component includes a porous region having porosity, and further includes applying a second brazing filler metal, different from the first brazing filler metal, to at least the AM metal component, wherein upon heating, the second brazing filler metal infiltrates at least the porous region based on the porosity characteristics of the at least porous region to bond the AM metal component within the coupon opening.

[0008] Another aspect of the present disclosure includes any of the above aspects, wherein the obstruction member includes a eutectic mixture of the AM metallic material and the metallic material of the first brazing material, and the predetermined temperature exceeds a melting temperature of the first brazing material.

[0009] Another aspect of the present disclosure includes any of the above aspects, wherein the additive manufacturing further includes additively manufacturing a second cavity in the AM metal part and a first conduit between the first cavity and the brazing area, and filling the second cavity with a second brazing material, wherein the liquefied first brazing material flows through the first conduit and liquefies the second brazing material, and the liquefied first and second brazing materials infiltrate the brazing area.

[0010] Another aspect of the present disclosure includes any of the above aspects, wherein the brazing region includes at least one of a porous region of the AM metal component, a contact interface between the metal coupon and a coupon opening in a body of a component on which the metal coupon is placed, and a portion or an outer surface of a body of a component on which the metal coupon is placed.

[0011] Another embodiment of the present disclosure includes any of the above embodiments, wherein the porous region has variable porosity, having two or more porous subregions with different porosity.

[0012] Another aspect of the present disclosure includes any of the above aspects and further includes removing the braze reservoir from the metal coupon after heating.

[0013] Another aspect of the present disclosure includes a method including additively manufacturing a body of a part, the body including a brazing filler metal reservoir, the brazing filler metal reservoir including a first cavity defined in the body, a second conduit defined in the body fluidly connecting the first cavity to an outer surface of the body, a first conduit defined in the body fluidly connecting the first cavity to a brazing area, and a blocking member across the first conduit to block fluid communication between the first cavity and the brazing area; inserting a first brazing filler metal into the first cavity through the second conduit; sealing the first cavity from an exterior of the body; and heating the body to a predetermined temperature above a melting temperature of the first brazing filler metal, causing the first brazing filler metal to liquefy and opening the blocking member to allow the liquefied first brazing filler metal to flow through the first conduit and infiltrate the brazing area.

[0014] Another aspect of the present disclosure includes any of the above aspects, wherein the closure member includes a eutectic mixture of the metallic material of the body and the first brazing material, and the predetermined temperature exceeds a melting temperature of the first brazing material.

[0015] Another aspect of the present disclosure includes any of the above-described aspects, wherein the additive manufacturing further includes additively manufacturing a second cavity in the body and a first conduit between the first cavity and the brazing area, and filling the second cavity with a second brazing material, wherein the liquefied first brazing material flows through the first conduit and liquefies the second brazing material, and the liquefied first and second brazing materials infiltrate the brazing area.

[0016] Another aspect of the present disclosure includes any of the above aspects, wherein the brazing region includes at least one of a porous region within the body, a contact interface between the body and the metal coupon within the coupon opening of the body, at least one of a portion and an outer surface of the body, and a damaged region of the body.

[0017] Another embodiment of the present disclosure includes any of the above embodiments, wherein the porous region has variable porosity, having two or more porous subregions with different porosity.

[0018] Another aspect of the present disclosure includes any of the above aspects and further includes removing the braze reservoir from the body after heating.

[0019] Another aspect of the present disclosure includes any of the above aspects, wherein the heating occurs during use of the component.

[0020] Two or more aspects described in this disclosure, including those described in the Summary of the Invention, may be combined to form embodiments not specifically described herein, i.e., all embodiments described in this application may be combined with each other.

[0021] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. [Brief explanation of the drawings]

[0022] These and other features of the present disclosure may be better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, which set forth various embodiments of the present disclosure. [Figure 1] 1 is a schematic diagram of an exemplary industrial machine in the form of a gas turbine system including components according to embodiments of the present disclosure; [Figure 2] 2 is a cross-sectional view of an exemplary gas turbine assembly that may be used in the gas turbine system of FIG. 1 including components according to embodiments of the present disclosure. [Figure 3] 1 is a perspective view of a component in the form of a turbine rotating blade including a metal coupon according to an embodiment of the present disclosure; [Figure 4] 1 is a perspective view of a component in the form of a turbine nozzle including a metal coupon according to an embodiment of the present disclosure; [Figure 5] FIG. 1 is a schematic block diagram of an exemplary additive manufacturing system for additive manufacturing metal coupons according to embodiments of the present disclosure. [Figure 6A] FIG. 1B is a top view of a sample metal coupon having multiple porous regions with different porosities according to an embodiment of the present disclosure. [Figure 6B] FIG. 1B is a top view of a sample metal coupon having multiple porous regions with different porosities according to an embodiment of the present disclosure. [Figure 6C] FIG. 1B is a top view of a sample metal coupon having multiple porous regions with different porosities according to an embodiment of the present disclosure. [Figure 6D] FIG. 1B is a top view of a sample metal coupon having multiple porous regions with different porosities according to an embodiment of the present disclosure. [Figure 7A] 1A and 1B are cross-sectional views of a braze reservoir in a metal coupon or body of a component according to various embodiments of the present disclosure. [Figure 7B] 1A and 1B are cross-sectional views of a braze reservoir in a metal coupon or body of a component according to various embodiments of the present disclosure. [Figure 7C] 1A and 1B are cross-sectional views of a braze reservoir in a metal coupon or body of a component according to various embodiments of the present disclosure. [Figure 7D] 1A and 1B are cross-sectional views of a braze reservoir in a metal coupon or body of a component according to various embodiments of the present disclosure. [Figure 8A] 1 is a perspective view of a metal coupon including a braze reservoir according to various embodiments of the present disclosure; [Figure 8B] 1 is a perspective view of a metal coupon including a braze reservoir according to various embodiments of the present disclosure; [Figure 8C] 1 is a perspective view of a metal coupon including a braze reservoir according to various embodiments of the present disclosure; [Figure 8D] 1 is a perspective view of a metal coupon including a braze reservoir according to various embodiments of the present disclosure; [Figure 8E] 1 is a perspective view of a metal coupon including a braze reservoir according to various embodiments of the present disclosure; [Figure 9A] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9B] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9C] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9D] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9E] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9F] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 9G] 1A-1C are perspective or cross-sectional views of methods according to various embodiments of the present disclosure. [Figure 10A] 10A-10C are enlarged cross-sectional views of a metal coupon at an opening in the body of a component according to various embodiments of the present disclosure. [Figure 10B] 10A-10C are enlarged cross-sectional views of a metal coupon at an opening in the body of a component according to various embodiments of the present disclosure. [Figure 10C] 10A-10C are enlarged cross-sectional views of a metal coupon at an opening in the body of a component according to various embodiments of the present disclosure. [Figure 10D] 10A-10C are enlarged cross-sectional views of a metal coupon at an opening in the body of a component according to various embodiments of the present disclosure. [Figure 10E]10A-10C are enlarged cross-sectional views of a metal coupon at an opening in the body of a component according to various embodiments of the present disclosure. [Figure 11] 1 is a perspective view of a component including a braze reservoir therein according to various embodiments of the present disclosure;

[0023] The drawings of the present disclosure are not necessarily to scale. The drawings are intended to illustrate exemplary aspects of the present disclosure only and are not intended to limit the scope of the present disclosure. In the drawings, like reference numerals represent like elements between the drawings. DETAILED DESCRIPTION OF THE INVENTION

[0024] First, to clearly explain the technical content of this disclosure, it is necessary to select terminology when referring to and describing relevant machine components in an exemplary turbomachinery application. Wherever possible, terms common in the art will be used consistent with their ordinary meaning. Unless otherwise noted, such terms should be interpreted broadly within the context of this application and the accompanying claims. Those skilled in the art will recognize that a component will often be referred to using several different or overlapping terms. What is described as a single element in this specification may be described as consisting of multiple components in another context. Alternatively, what is described as including multiple components in one place in this specification may be described as a single element in another place.

[0025] Additionally, several descriptive terms are used repeatedly in this specification, and it may be helpful to define these terms at the beginning of this section. These terms and their definitions are as follows, unless otherwise specified: As used herein, the terms "downstream" and "upstream" refer to directions with respect to fluid flow (e.g., the flow of working fluid through a turbine engine, or the flow of air through a combustor or coolant through one of the turbine's subsystems). The term "downstream" corresponds to the direction in which the fluid is flowing, and the term "upstream" refers to the direction opposite to the flow (i.e., the direction from which it is flowing). The terms "forward" and "aft" refer to directions not further specified, with "forward" referring to the forward or compressor end of the turbomachine and "aft" referring to the aft or turbine end of the turbomachine.

[0026] Furthermore, certain descriptive terms are used repeatedly in this specification, as described below: The terms "first," "second," and "third" are used interchangeably to distinguish one component from another, and do not denote the location or importance of the individual components.

[0027] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used herein, the singular "a," "an," or "an" includes the plural unless the context clearly dictates otherwise. As used herein, the terms "comprise," "include," and / or "have" refer to the presence of stated features, integers, steps, operations, components, and / or parts, and do not exclude the presence or addition of one or more other features, integers, steps, operations, components, parts, and / or groups thereof. The terms "optional" or "optionally" mean that the event described following the term may or may not occur, or the feature described following the term may or may not be present, and such descriptions encompass both the occurrence of the event or the presence of the feature and the absence of the event or the absence of the feature.

[0028] When a component or layer is referred to as being "on," "engaged with," "connected to," "coupled to," or "attached to" another component or layer, it may be directly on, directly engaged with, connected to, coupled to, or attached to that other component or layer, or there may be intervening components or layers. In contrast, when a component is referred to as being "directly on," "directly engaged with," "directly connected to," or "directly coupled to" another component or layer, there are no intervening components or layers. Other terms used to describe relationships between components (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.) are to be interpreted similarly. As used herein, the term "and / or" encompasses any and all combinations of one or more of the listed items. The terms "coupled" and "attached" may be used interchangeably herein.

[0029] As described above, the present disclosure provides a metal coupon for insertion into a component. As used herein, "coupon" encompasses a component that is placed into a coupon opening in the body of a component, either as part of the original manufactured component or to repair a portion of the component (e.g., after removal of a damaged portion). The metal coupon includes an additively manufactured (AM) metal component including a braze reservoir. The braze reservoir includes a first cavity within the AM metal component, a first conduit fluidly connecting the first cavity to an outer surface of the AM metal component, a first conduit fluidly connecting the first cavity to a brazing region, a closure member blocking fluid communication through the first conduit between the first cavity and the brazing region, a braze material within the first cavity, and a sealing member sealing the second conduit from the exterior of the AM metal component. In another embodiment, a component may include a body including a braze reservoir similar to that described above. In either case, the braze reservoir is thermally activated when the metal coupon and / or component body reaches a predetermined temperature above the melting temperature of the braze material, potentially causing the closure member to open (e.g., melt, dissolve, or rupture) along with the pressure generated at the predetermined temperature. The braze region receiving the liquefied braze material can take various forms, such as, but not limited to, a porous region within the AM metal member of the metal coupon, the interface between the metal coupon and the component body, or a crack within the component body. The use of porous regions in the metal coupon allows for customization of the brazing process and resulting structure, while also reducing material costs. When used for repairs, the customized metal coupon does not exhibit the same shortcomings as the original component and / or notch, and can be customized with one or more porous regions and / or one or more braze materials to alter, for example, joint bond strength, stress / strain resistance, ductility, wear resistance, oxidation resistance, thermal conductivity, electrical conductivity, surface roughness, hardness, and / or mass. One or more brazing filler metals can be used not only to bond the replacement coupon to the part, but also to improve joint-related performance characteristics such as joint bond strength and reliability, and to reduce post-braze machining / blending operations. The brazing filler metal reservoir also provides the ability to deliver liquid brazing filler metal to hard-to-reach areas and provide driving force to various brazing areas (e.g., porous areas, cracks, and the interface between the coupon and the part body).The pressurized liquefied brazing material from the brazing reservoir (pressurized by heat in the first cavity) can infiltrate various brazing areas that may not normally receive the liquefied brazing material by gravity and / or capillary action. When used within the body of the part, the brazing reservoir provides self-healing (e.g., for internal cracks) without additional treatment during use or heat treatment of the part.

[0030] FIG. 1 illustrates a schematic diagram of an exemplary industrial machine that may include components consistent with the teachings of the present disclosure. In this example, the machine includes a turbomachine 100 in the form of a combustion or gas turbine (GT) system. The turbomachine 100 includes a compressor 102 and a combustor 104. The combustor 104 includes a combustion section 106 and a fuel nozzle assembly 108. The turbomachine 100 also includes a turbine assembly 110 and a common compressor / turbine shaft (i.e., rotor) 112. In one embodiment, the turbomachine 100 is a 7HA.03 engine commercially available from GE Vernoa. The present disclosure is not limited to any particular GT system and may be implemented with other engines, including, for example, other GE Vernoa HA, F, B, LM, GT, TM, and E-class engine models, as well as engine models from other manufacturers. The present disclosure is also not limited to any particular turbomachine and may be applicable to, for example, steam turbines, jet engines, compressors, turbofans, etc. Furthermore, the present disclosure is not limited to any particular turbomachinery component, but may be applied to any industrial component that uses coupons during manufacture or repair.

[0031] During operation, air flows through the compressor 102, providing compressed air to the combustors 104. Specifically, the compressed air is provided to a fuel nozzle assembly 108 housed within the combustors 104. The assembly 108 is in fluid communication with the combustion zone 106. The fuel nozzle assembly 108 is also in fluid communication with a fuel source (not shown in FIG. 2 ) and directs fuel and air to the combustion zone 106. The combustors 104 ignite and burn the fuel. The combustors 104 are in fluid communication with a turbine assembly 110 for converting thermal energy of the gas stream into mechanical, rotational energy. The turbine assembly 110 includes a turbine 111 rotatably coupled to and driving a rotor 112. The compressor 102 is also rotatably coupled to the rotor 112. In the exemplary embodiment, there are multiple combustors 104 and fuel nozzle assemblies 108.

[0032] FIG. 2 illustrates a cross-sectional view of an exemplary turbine assembly 110 of the turbomachine 100 (FIG. 1) that may be used in the gas turbine system of FIG. 1. The turbine 111 of the turbine assembly 110 includes a row of nozzles or vanes 120 coupled to a stationary casing 122 of the turbomachine 100 and an axially adjacent row of blades 124. The stationary vanes or nozzles 126 may be retained within the turbine assembly 110 by a radially outer platform 128 and a radially inner platform 130. The row of blades 124 of the turbine assembly 110 includes rotating blades 132 coupled to the rotor 112 and rotating therewith. The rotating blades 132 may include a radially inner platform 148 (blade root, FIG. 3) coupled to the rotor 112 and, optionally, a radially outer tip 136 (blade tip). As used herein, the term "component" refers collectively to the stationary nozzles 126, the rotating blades 132, and other structures that may utilize metal coupons including one or more porous regions according to the present disclosure.

[0033] 3 and 4 illustrate example components, such as hot gas path components of a turbomachine, that may employ the teachings of the present disclosure. FIG. 3 illustrates a perspective view of a turbine rotor blade 132 of a type that may employ embodiments of the present disclosure. The turbine rotor blade 132 includes a root 140 by which the rotor blade 132 is attached to the rotor 112 ( FIG. 2 ). The root 140 may include a dovetail 142 configured to fit into a corresponding dovetail slot on the outer periphery of a rotor wheel 144 ( FIG. 2 ) of the rotor 112 ( FIG. 2 ). The root 140 may further include a shank 146 extending between the dovetail 142 and a platform 148, which is disposed at the junction of the airfoil 150 and the root 140 and defines a portion of the inner boundary of the flowpath through the turbine assembly 110. Airfoil 150 is the active component of rotor blade 132 that receives the flow of working fluid 151 (i.e., hot combustion gases) (FIG. 2) and induces rotor disk rotation. Airfoil 150 of rotor blade 132 includes a concave pressure side (PS) outer wall 152 and a circumferentially or laterally opposite convex suction side (SS) outer wall 154, extending axially between a leading edge 156 and a trailing edge 158. Side outer walls 152 and 154 extend radially from platform 148 to an outer tip 160, which may or may not include tip shroud 136 (FIG. 2).

[0034] FIG. 4 is a perspective view of a static nozzle 126 of a type that may be used in embodiments of the present disclosure. The static nozzle 126 includes an outer platform 170 by which the static nozzle 126 is mounted to a stationary casing 122 ( FIG. 2 ) of a turbomachine. The outer platform 170 may include any now known or later developed mounting configuration for mounting to a corresponding mount on the casing. The static nozzle 126 may further include an inner platform 174 disposed between adjacent turbine rotor blades 132 ( FIG. 3 ) and platform 148 ( FIG. 3 ). The platforms 170, 174 define respective portions of the outer and inner boundaries of the flowpath through the turbine assembly 110. The airfoils 176 are the active components of the static nozzle 126 that receive and direct the working fluid flow toward the turbine rotor blades 132 ( FIG. 3 ). Airfoil 176 of static nozzle 126 includes a concave pressure side (PS) outer wall 178 and a circumferentially or laterally opposite convex suction side (SS) outer wall 180, extending axially between a leading edge 182 and a trailing edge 184. Side outer walls 178 and 180 also extend radially from platform 170 to platform 174.

[0035] The blades 132 or nozzles 126 may include internal cooling structures, such as passages, conduits, or other structures, that include a source of coolant, such as air from the compressor 102, to deliver the coolant to their surfaces for film cooling.

[0036] The embodiments of the present disclosure described herein encompass aspects applicable to a stationary nozzle 126, a turbine rotor blade 132, and / or any other industrial component in which a coupon is used. Also shown in FIGS. 3 and 4 is an exemplary additively manufactured (AM) metal coupon 200 (hereinafter, "metal coupon 200" or "AM metal coupon 200") in a part 202. More specifically, the metal coupon 200 resides within a coupon opening 204 in a body 206 of the part 202. The "coupon opening 204 in the body 206" may be any void size within the body 206, including a removed portion of the body 206 (e.g., a tip shroud). For example, the metal coupon 200 may be disposed within the opening 204 in the trailing edge 158, 184 of the blade 132 or nozzle 126, respectively. Alternatively, the metal coupon 200 may be disposed within the opening 204 in the leading edge 156, 182 of the blade 132 or nozzle 126, respectively. The metal coupon 200 may also be present on the tip of the blade 132 or on the platform 170, 174 (shown in FIG. 4) of the nozzle 126. However, the metal coupon 200 may be used in any coupon opening 204 in the body 206 of the part 202. The body 206 may be any portion of the part 202 or may be the entire part.

[0037] Additively manufactured (AM) metal coupons 200 and / or AM parts 202 containing brazing filler reservoirs and / or one or more porous regions may be fabricated using any currently known or future-developed technology capable of forming porous regions. Figure 5 shows a schematic / block diagram of an exemplary computerized metal powder additive manufacturing system 210 (hereinafter, "AM system 210") for producing a metal coupon 200, a part 202, multiple metal coupons 200A, 200B (as shown), or multiple parts 202 (only one layer of which is shown). While this disclosure describes building a metal coupon 200 or part 202 using multiple melt beam sources 212, 214, 216, and 218, it should be apparent that the teachings of this disclosure are equally applicable to building multiple coupons 200A, 200B and / or parts 202 using any number of melt beam sources. In this example, the AM system 210 is configured for direct metal laser melting (DMLM). The general teachings of this disclosure are equally applicable to other forms of metal powder additive manufacturing (i.e., other than metal powder applications), such as powder bed fusion, direct metal laser sintering (DMLS), electron beam melting (EBM), selective laser sintering (SLS), selective laser melting (SLM), etc. Although coupons 200A, 200B are shown as rectangular components, the additive manufacturing process can be readily adapted to produce coupons or parts of any shape, a wide variety of different coupons or parts, and large numbers of coupons or parts on build platform 220.

[0038] The AM system 210 generally includes an additive manufacturing control system 230 ("control system") and an AM printer 232. As described below, the control system 230 executes a set of computer-executable instructions or code 234 to generate the coupon 200 or part 202 using multiple melt beam sources 212, 214, 216, and 218. In the illustrated example, the four melt beam sources include four lasers. However, the teachings of this disclosure are applicable to any melt beam source, such as an electron beam, laser, etc. The control system 230 is shown implemented as computer program code on a computer 236. In this regard, the computer 236 is shown to include a memory 238 and / or storage system 240, a processor unit (PU) 244, an input / output (I / O) interface 246, and a bus 248. The computer 236 is also shown in communication with an external I / O device / resource 250. Generally, processor unit (PU) 244 executes computer program code 234 stored in memory 238 and / or storage system 240. While executing computer program code 234, processor unit (PU) 244 can read and write data from memory 238, storage system 240, I / O devices 250, and / or AM printer 232. Bus 248 provides a communication link between objects within computer 236, and I / O devices 250 may comprise any device (e.g., keyboard, pointing device, display, etc.) that allows a user to interact with computer 236. Computer 236 is merely representative of various possible combinations of hardware and software. For example, processor unit (PU) 244 may comprise a single processing unit or may be distributed across one or more processing units on one or more locations, e.g., a client and a server. Similarly, memory 238 and / or storage system 240 may reside in one or more physical locations.Memory 238 and / or storage system 240 may comprise any combination of various types of non-transitory computer-readable storage media including magnetic media, optical media, random access memory (RAM), read-only memory (ROM), etc. Computer 236 may include any type of computing device, such as an industrial controller, a network server, a desktop computer, a laptop, a handheld device, etc.

[0039] As described above, the AM system 210, and particularly the control system 230, executes code 234 to produce one or more metal coupons 200 or parts 202. The code 234 may include, among other things, a set of computer-executable instructions 234S (also referred to herein as “code 234S”) for operating the AM printer 232 and a set of computer-executable instructions 234O (also referred to herein as “code 234O”) that define the one or more metal coupons 200 or parts 202 to be physically produced by the AM printer 232. As described herein, the additive manufacturing process begins with a non-transitory computer-readable storage medium (e.g., memory 238, storage system 240, etc.) that stores the code 234. The set of computer-executable instructions 234S for operating the AM printer 232 may include any now known or later developed software code capable of operating the AM printer 232.

[0040] The set of computer-executable instructions 234O defining one or more metal coupons 200 or parts 202 may include a precisely defined 3D model of the coupon 200 and may be generated from a well-known computer-aided design (CAD) software system such as AutoCAD®, TurboCAD®, or DesignCAD3DMax. In this regard, the code 234O may include any file format now known or later developed. Furthermore, the code 234O representing the metal coupon 200 or part 202 may be converted between different formats. For example, the code 234O may include a Standard Tessellation Language (STL) file created for a 3D Systems stereolithography CAD program, or an Additive Manufacturing File (AMF), an American Society of Mechanical Engineers (ASME) standard that is an extensible markup language (XML)-based format designed to allow any CAD software to describe any three-dimensional shape and composition to be manufactured on any AM printer. The code 234O representing the metal coupon 200 or part 202 may be converted into a set of data signals and transmitted, or received as a set of data signals, converted into code, and stored, as desired. The code 234O may be configured to form boundaries and interior sections in overlapping field regions, as described below, in accordance with embodiments of the present disclosure. In either case, the code 234O may be input to the AM system 210 or may originate from a part designer, intellectual property (IP) provider, design firm, operator or owner of the AM system 210, or other source. In either case, the control system 230 executes the codes 234S and 234O to divide one or more metal coupons 200 or parts 202 into a series of thin slices that are laminated into successive layers of material using the AM printer 232.

[0041] The AM printer 232 may include an enclosed processing chamber 260 to provide a controlled atmosphere for printing the metal coupon 200 or part 202. The build platform 220 on which the metal coupon 200 or part 202 is built is disposed within the processing chamber 260. Multiple melting beam sources 212, 214, 216, and 218 are configured to melt a layer of metal powder on the build platform 220 to produce the coupon 200. While four melting beam sources 212, 214, 216, and 218 are illustrated, the teachings of this disclosure are applicable to systems using any number of beam sources (e.g., one, two, three, or five or more). Each melting beam source 212, 214, 216, and 218 may have a field that includes a non-overlapping field region capable of exclusively melting the metal powder, or may include one or more overlapping field regions capable of melting the metal powder with two or more beam sources. In this regard, each melt beam source 212, 214, 216, and 218 can generate a melt beam that fuses particles for each slice defined by code 234O. For example, FIG. 5 shows melt beam source 212 creating a layer of metal coupon 200 or part 202 in one area using melt beam 262, while melt beam source 216 creating a layer of metal coupon 200 or part 202 in another area using melt beam 262'. Each melt beam source 212, 214, 216, and 218 is calibrated by any now known or later developed method. That is, each melt beam source 212, 214, 216, and 218 provides individual positional corrections (not shown) to ensure its individual accuracy, thereby correlating the expected position of the laser beam or electron beam with its actual position relative to the build platform 220. In one embodiment, each of the multiple melt beam sources 212, 214, 216, 218 may produce a melt beam (eg, 262, 262') having the same cross-sectional dimensions (eg, operational shape and size), power, and scan speed.

[0042] 5 , the applicator (or recoater blade) 270 can create a thin layer of feedstock 272, laid out as a blank canvas, upon which each successive slice of the final metal coupon 200 is created. Various parts of the AM printer 232 can be moved to accommodate each new layer being added, such as lowering the build platform 220 and / or raising the chamber 260 and / or applicator 270 after each layer. The process can use various feedstocks in the form of fine metal powders, and a stock of feedstock can be held in the chamber 260 accessible to the applicator 270. In this instance, the coupon 200 or part 202 can be made from a metal, which can include a pure metal or an alloy. In one example, the metal may be substantially any non-reactive metal powder, i.e., non-explosive or non-conductive, including, but not limited to, cobalt chromium molybdenum (CoCrMo) alloy, stainless steel, austenitic nickel-chromium based alloys such as nickel-chromium-molybdenum-niobium alloy (NiCrMoNb) (e.g., Inconel 625 or Inconel 718), nickel-chromium-iron-molybdenum alloy (NiCrFeMo) (e.g., Hastelloy® X available from Haynes International), or nickel-chromium-cobalt-molybdenum alloy (NiCrCoMo) (e.g., Haynes 282 available from Haynes International), etc. Other possibilities include precipitation-hardened (PH) nickel-based alloys such as Rene 108, CM247LC, MarM247, and other precipitation-hardened (PH) nickel-based alloys.

[0043] The process chamber 260 is filled with an inert gas, such as argon or nitrogen, and is controlled to minimize or completely eliminate oxygen. The control system 230 is configured to control the flow of a gas mixture 274 within the process chamber 260 from a source of inert gas 276. In this case, the control system 230 may control a pump 280 and / or a flow valve system 282 for the inert gas to control the content of the gas mixture 274. The flow valve system 282 may include one or more computer-controllable valves, flow sensors, temperature sensors, pressure sensors, etc., that can precisely control the flow of specific gases. The pump 280 can be provided with or without the valve system 282. If the pump 280 is omitted, the inert gas can simply enter a conduit or manifold prior to introduction into the process chamber 260. The source of the inert gas 276 can take the form of any conventional source for the material contained therein, such as a tank, reservoir, or other source. Any sensors (not shown) necessary to measure the gas mixture 274 may be provided. The gas mixture 274 may be filtered using a filter 286 in a conventional manner.

[0044] During operation, the process chamber 260 contains the build platform 220 loaded with metal powder, and the control system 230 controls the flow of a gas mixture 274 from a source of inert gas 276 within the process chamber 260. The control system 230 also controls the AM printer 232, particularly the applicator 270 and melt beam sources 212, 214, 216, and 218, to sequentially melt layers of metal powder on the build platform 220 to produce a metal coupon 200 or part 202 according to embodiments of the present disclosure.

[0045] Although a particular AM system 210 has been described herein, the teachings of this disclosure are not limited to any particular additive manufacturing system or method. Additionally, while the teachings of this disclosure relate to additively manufactured metal coupons 200 or parts 202, if the part 202 does not include a braze reservoir or porous region, the part 202 may be manufactured by any method now known or later developed, such as casting or other methods. The part 202 may include any of the materials listed herein for the metal coupon 200.

[0046] As mentioned above, in one embodiment of the present disclosure, the metal coupon 200 includes an additively manufactured (AM) metal part 290 that includes a braze reservoir 292 within the AM metal part 290. In another embodiment of the present disclosure, the part 202 includes a body 206 that includes the braze reservoir 292. As described further below, the braze reservoir 292 can provide a liquefied braze material to a brazing region 294, which may, in one example, include a porous region 300 within the body 206 of the metal coupon 200 and / or part 202.

[0047] As used herein, "porosity" refers to the ratio of the volume of open space to the total volume of the subject structure (e.g., porous region, metal coupon, etc.). Typically, in this regard, porosity is described as the percentage of the volume of open space relative to the total or aggregate volume of the subject structure. Void space is an empty area within a solid material, referred to herein as "pores" 302, and may include interconnected passages within the material of the subject structure. Thus, a "porous region" of the metal coupon 200 is less than 100% solid and includes open space in the form of pores 302 and / or interconnected passages. The porous metal coupon 200 may include solid regions, but also includes one or more porous regions (as part of the braze region 294) that are less than 100% solid. As used herein, the three-dimensional boundaries of a porous region or sub-region for purposes of determining its "total volume" can be identified by the locations within the metal coupon 200 where a porosity change of greater than 2% occurs relative to adjacent regions or sub-regions and / or where the edges of the metal coupon 200 are present. "Void space volume" collectively refers to the three-dimensional space within a region or sub-region that is empty (i.e., not filled with voids, gaps, empty spaces, and / or material). As used herein, "differential porosity" or "porosity difference" generally refers to variations in various characteristics, such as the percentage of void space volume relative to the total volume, the number of pores 302 within a given volume, the volume (i.e., size) of the pores 302, the shape of the pores 302, and variations in interconnected openings between the pores 302 that may not be recognizable as actual discrete pores (referred to herein as "pore interconnected passages"). Pore diameters range, for example, from 0.025 to 0.381 mm. 3(0.0001 to 0.015 cubic inches). It will be apparent that differences in porosity are not based solely on the percentage of void volume relative to the total volume, for example, due to differences in pore shape or pore-connecting pathways. However, when comparing porosity differences by degree (e.g., high or low), the difference being referred to is solely a volumetric property, i.e., the difference in void volume relative to the total volume. Although different porous regions or subregions are typically shown in the drawings as being continuous or adjacent to one another, they may also be separated from one another (e.g., by solid regions between them). That is, a single metal coupon may include one or more isolated, non-contacting porous regions.

[0048] The porous metal coupon 200 can be formed with different porous regions with different porosities (which may or may not include one or more porous subregions with different porosities) using the AM system 210 described herein or other metal additive manufacturing systems or methods capable of forming porous metal. With respect to the operation of the AM system 210, the melting beam sources 212, 214, 216, and 218 can be intermittently programmed to not sinter the metal, leaving metal powder rather than solid material. This process may include varying amounts of overlap of the laser field areas and / or design of the pores 302 in the build file (i.e., code 234O). Less overlap between each laser scan results in higher porosity, while more laser overlap between successive scans results in lower porosity. Laser spot size, scan speed, focus, and power can also be controlled to tailor the porosity. When the unmelted metal powder is removed from the metal coupon 200, pores 302 remain, along with interconnected passages between the pores 302, forming one or more porous regions in the metal coupon 200. In any event, the layer-by-layer manufacturing of the metal coupons 200 can be controlled to produce the desired porosity for any number, shape, and / or size of porous regions within the desired layers of one or more metal coupons 200 .

[0049] 6A-6D show top-view schematic views of sample metal coupons 200 with varying porosities. Pores 302 are shown in the figures as dark void spaces. FIG. 6A shows a sample metal coupon 200 with a first porosity of about 40% void space volume relative to the total sample volume (generally having a low amount of void space and many or large pores 302), FIG. 6B shows a sample metal coupon 200 with a first porosity of about 30% void space volume relative to the total sample volume, FIG. 6C shows a sample metal coupon 200 with a first porosity of about 20% void space volume relative to the total sample volume, and FIG. 6D shows a sample metal coupon 200 with a first porosity of about 10% void space volume relative to the total sample volume (generally having a small amount of void space). Each porous region can have a void space volume of 2% to 50% of the total volume of the porous region (i.e., 2% to 50% void space and the remaining 50% to 98% solid). In other embodiments, each porosity can have a void space volume of 10% to 40% of the total volume of the porous region (i.e., 10% to 40% void space and the remaining 60% to 90% solid). In other embodiments, the porous region can have a void space volume of less than 10%, less than 15%, less than 20%, less than 25%, less than 30%, less than 35%, less than 40%, less than 45%, 2% to 45%, 2% to 40%, 2% to 35%, 2% to 30%, 2% to 25%, 2% to 20%, 5% to 45%, 5% to 40%, 5% to 35%, 5% to 30%, 5% to 25%, 5% to 20%, 10% to 40%, or 10% to 40%. Porosity ranges of 5%, 10%-40%, 10%-35%, 10%-30%, 10%-25%, 10%-20%, 15%-45%, 15%-40%, 15%-35%, 15%-30%, 15%-25%, 15%-20%, 10%-50%, 20%-50%, 25%-50%, 30%-50%, 35%-50%, or 40%-50% are possible, as described herein.

[0050] 7A-7D illustrate schematic cross-sectional views of an exemplary braze reservoir 292 in a metal coupon 200 or component 202 according to embodiments of the present disclosure. The metal coupon 200 includes an AM metal component 290 having a braze reservoir 292 therein. The braze reservoir 292 is located within the AM metal component 290. The component 202 includes a body 206 with the braze reservoir 292 therein. The braze reservoir 292 is located within the body 206.

[0051] 7A-7D , for the first metal coupon 200, the braze reservoir 292 includes a first cavity 320 in the AM metal member 290, a second conduit 322 fluidly connecting the first cavity 320 to the outer surface 306 of the AM metal member 290, and a first conduit 324 fluidly connecting the first cavity 320 to the brazing region 294. As used herein, the conduits 322, 324 are elongated passages or open spaces configured to channel unmelted braze metal powder or molten braze material therethrough. Additionally, the cavity 320 is a non-elongated or not-so-elongated open space configured to hold or store unmelted first braze material 328 (but permitting molten braze material to exit via the conduit in fluid communication therewith). The cavities and conduits can be formed by programming the melt beam sources 212, 214, 216, and 218 of the AM system 210 to unsinter metal in certain areas of the metal coupon 200 or part 202, leaving metal powder rather than solid material. Once the metal coupon 200 or part 202 is completed, the unmelted metal powder can be removed, leaving behind the cavities and / or conduits. The braze reservoir 292 also contains a first braze material 328 in the first cavity 320 and a sealing member 330 that seals the second conduit 322 from the exterior of the AM metal part 290. The first braze material 328 is introduced (inserted) into the first cavity 320 through the second conduit 322 after additive manufacturing of the metal coupon 200. As described further herein, the first brazing filler metal 328 can be introduced into the first cavity 320 in a controlled atmosphere, e.g., a non-reactive gas such as argon and / or nitrogen. The first brazing filler metal 328 can be in powder form or in non-powder form, e.g., a paste consisting of a powder and a binder, e.g., Braz-BinderGel available from Vitta. The brazing filler metal 328 (or any brazing filler metal described herein, e.g., 360) can include any currently known or future developed brazing filler composition, such as GE (Alstom) B1P, AmdryTMD15, DF4B, or BRB, some of which are listed in the table below along with other brazing filler metal compositions.

[0052] [Table 1]

[0053] Once the first braze material 328 enters the first cavity 320, a sealing member 330 is formed, sealing the second conduit 322. The sealing member 330 may include any structure at or near the outer surface 306 of the AM metal member 290 that is capable of occluding the second conduit 322 after the first braze material 328 has been introduced into the first cavity 320 through the second conduit 322. For example, the sealing member 330 may include a plug or weld in the second conduit 322 at or near the outer surface 306 of the AM metal member 290.

[0054] The braze reservoir 292 may include a blocking member 332 that blocks fluid communication between the first cavity 320 and the brazing region 294 via the first conduit 324. The blocking member 332 blocks fluid communication between the first cavity 320 and the brazing region 294 via the first conduit 324 before the blocking member 332 is exposed to a predetermined temperature that exceeds the melting temperature of the first braze material 328. The blocking member 332 may include any material that has a melting temperature that is lower than that of the material of the AM metal member 290 and equal to or higher than that of the material of the first braze material 328. In some embodiments, the blocking member 332 may include a eutectic mixture of the metal material of the AM metal member 290 and at least one element of the first braze material 328. In this case, the closure member 332 is formed by additive manufacturing using the same material as the AM metal member 290, i.e., the AM metal member 290, and then, due to absorption of elements of the first brazing filler metal 328 (when the first brazing filler metal 328 is introduced into the first cavity 320), its melting temperature changes compared to the rest of the AM metal member 290.

[0055] In one example, the AM metal member 290 (coupon 200) and the plugging member 332 may comprise a superalloy such as In-738, In-738LC, MAR-M-247, Rene-108, GTD-111, or a variant designed for additive manufacturing, or any other superalloy common to turbomachinery components, and the first braze filler metal 328 may comprise any of the braze filler metals listed herein. The plugging member 332 is a relatively thin layer of material compared to the remainder of the AM metal member 290 and therefore absorbs a relatively large volume of elements, such as boron, of the first braze filler metal 328, lowering its melting temperature, compared to the remainder of the AM metal member 290 (e.g., the first cavity 320 or the surrounding conduits 322, 324). That is, when the metallic material surrounding the first cavity 320 or conduits 322, 324 absorbs the elements of the first braze filler metal 328, they are too thick for the elements to change their physical properties. In contrast, the occlusion member 332 may be a eutectic, i.e., a mixture of materials that melts at a temperature lower than the melting points of its individual components. More specifically, the first braze filler metal 328 comprises a "low melting point" braze filler metal typically used in repairing superalloy components that contains elements such as boron and / or silicon in amounts greater than would otherwise be found in the superalloy to lower the melting temperature of the first braze filler metal 328. When the first braze filler metal 328 is held at an elevated temperature (e.g., near or above its melting temperature), the melt-suppressing elements diffuse into the surrounding area. This elevated temperature may result from the braze filler metal 328 being inserted into the first cavity 320, or a separate heat treatment may be performed to induce diffusion. In either case, the diffusion reduces the local concentrations of elements around the first braze material 328 in the first cavity 320 and increases their concentrations in the surrounding superalloy, including the plugging member 332. This diffusion zone may be, for example, 50 to 254 microns (approximately 0.002 to 0.010 inches) into the superalloy, i.e., the plugging member 332, which significantly increases the temperature at which the plugging member 332 melts and melts the first braze material 328 in a subsequent thermal cycle.

[0056] As a result of the above-described configuration, the closure member 332 can function as a single-use (possibly eutectic) valve that can be opened or closed (i.e., melted, dissolved, or broken to allow the liquefied braze material 328 to flow therethrough) at a predetermined temperature above the melting temperature of the first braze material 328. More specifically, the braze reservoir 292 is thermally activated, i.e., activated, by the metal coupon 200 and / or the component body 206 reaching a predetermined temperature higher than the melting temperature of the first braze material 328. The predetermined temperature need not be higher than the melting temperature of the closure member 332 for the closure member 332 to open. For example, the liquefied first braze material 328 can open the closure member 332, e.g., melt or forcefully break the closure member 332, in response to an increase in pressure caused by the predetermined temperature within the first cavity 320. Alternatively, the liquefied first braze material 328 may simply melt the closure member 332 in such a way that the liquefied first braze material 328 can flow into the first conduit 324. In another alternative, the predetermined temperature may be higher than the melting temperature of the closure member 332 to melt it open. In either case, the closure member 332 may be opened by either melting, dissolving, and / or breaking open.

[0057] The blocking member 332 can have any shape and / or profile to block the first conduit 324. The thickness of the blocking member 332 may depend, for example, on the materials of the first braze material 328 and the metal coupon 200. In one non-limiting example, the blocking member 332 may have a thickness of less than 1270 microns (approximately 0.050 inches), and in another example, a thickness of 50 to 254 microns (approximately 0.002 to 0.010 inches). The blocking member 332 may be of constant or variable thickness and / or surface finish.

[0058] 7A-7D and the part 202, the braze reservoir 292 of the part 202 is substantially similar to that described with respect to the metal coupon 200. FIGS. 3, 4, and 11 illustrate the braze reservoir 292 in the part 202. In this case, the braze reservoir includes a first cavity 320 (not the AM metal member 290) in the body 206, a second conduit 322 fluidly connecting the first cavity 320 to the exterior surface 334 of the body 206, and a first conduit 324 fluidly connecting the first cavity 320 to the braze region 294. As described above, the cavities and conduits can be formed by programming the melt beam sources 212, 214, 216, and 218 of the AM system 210 to not sinter metal in certain areas of the part 202, leaving metal powder rather than solid material. Once the part 202 is completed, the unmelted metal powder can be removed, leaving behind the cavity and / or conduit. The braze reservoir 292 also contains a first braze material 328 in the first cavity 320 and a sealing member 330 that seals the second conduit 320 from the exterior of the body 206. The first braze material 328 is introduced (inserted) into the first cavity 320 through the second conduit 322 after additive manufacturing of the part 202. As mentioned above, the first braze material 328 can be inserted into the first cavity 320 in a controlled atmosphere, e.g., a non-reactive gas such as argon and / or nitrogen. As mentioned above, the first braze material 328 can be in powder form or non-powder form, e.g., a paste consisting of a powder and a binder, e.g., Braz-BinderGel available from Vitta. Once the first brazing material 328 enters the first cavity 320, a sealing member 330 is formed, sealing the second conduit 322. The sealing member 330 may include any structure at or near the exterior surface 334 of the body 206 that is capable of occluding the second conduit 322 after the first brazing material 328 has been introduced into the first cavity 320 through the second conduit 322. For example, the sealing member 330 may include a plug or weld in the second conduit 322 at or near the exterior surface 334 of the body 206.

[0059] The brazing filler metal reservoir 292 in the part 202, prior to where the metal coupon 200 or part body 206 is located, may include a blocking member 332 that blocks fluid communication between the first cavity 320 and the brazing region 294 via the first conduit 324. The blocking member 332 may include any material having a melting temperature lower than that of the material of the body 206 and equal to or higher than that of the material first brazing filler metal 328. In some embodiments, the blocking member 332 is a eutectic mixture of the metallic material of the body 206 and at least one element of the first brazing filler metal 328. In this case, the blocking member 332 is formed by additive manufacturing with the body 206, i.e., made of the same material as the body 206, and then, due to absorption of elements of the first brazing filler metal 328, the melting temperature of the blocking member 332 changes compared to the rest of the body 206 when the first brazing filler metal 328 is introduced into the first cavity 320 (and optionally heat treated). As described above, the closure member 332 is a relatively thin layer of material compared to the rest of the body 206 and, therefore, absorbs a relatively large volume of certain elements of the first brazing filler metal 328, such as boron, compared to the rest of the body 206 (e.g., the area surrounding the first cavity 320 or the conduits 322, 324), which lowers its melting temperature. That is, when the metallic material surrounding the first cavity 320 or the conduits 322, 324 absorbs the elements of the first brazing filler metal 328, such as boron, it is too thick for the elements to change their physical properties. In contrast, the closure member 332 becomes eutectic. In this manner, the closure member 332 can function as a single-use eutectic valve that can be opened and closed (i.e., melted, dissolved, or broken in a manner that allows the flow of liquefied brazing filler metal 328) at a predetermined temperature above the melting temperature of the first brazing filler metal 328.

[0060] 7D , in an alternative embodiment applicable to the metal coupon 200 or component 202 with the braze reservoir 292, a second cavity 340 can be defined in the AM metal member 290 or body 206. The second cavity 340 can be an enlarged region of the first conduit 324 between the first cavity 320 and the brazing region 294. The second cavity 340 has a second braze material 342 therein that is different from the first braze material 328. In some embodiments, the second braze material 342 can have a higher melting temperature than the first braze material 328, but low enough that the liquefied first braze material 328 can conduct the second braze material 342 in solid or molten form to the brazing region 294. The second braze material 342 can include the unmelted metal powder, i.e., superalloy metal powder, used to form the metal coupon 200 or component 202. The unfused metal powder is not removed, but remains on the metal coupon 200 or part 202 after its additive manufacturing.

[0061] The brazing area 294 can take a variety of forms depending on the intended application of the metal coupon 200, the part 202, and / or the brazing material reservoir 292. In particular, the brazing area 294 can be any area or location where additional brazing material is desired, for example, to ensure all of the area to be brazed is filled with brazing material, such as joints 384 between parts (FIGS. 10A-10E) or porous areas 300 used to direct the liquid brazing material in a desired manner, and / or to ensure that potential damaged areas, such as cracks or other high-stress damage, are filled / repaired. For example, the braze region 294 may include a porous region 300 within the AM metal member 290 or body 206, as shown in Figures 7B and 7D, or a contact interface 346 between the AM metal member 290 or body 206 and another element, as shown in Figure 7A, or a damaged region 348, such as a crack, in the AM metal member 290 or a portion of the body 206 of the part 202, as shown in Figure 7C, or at least one of a portion (e.g., coupon opening 204) of the body 206 of the part 202 in which the AM metal member 290 (metal coupon 200) is located, as shown in Figure 7A. The braze region 294 may be an outer surface 306 of the AM metal member 290 of the metal coupon 200, as shown in Figure 7A, or an outer surface 334 of the body 206 of the part 202. As will be further explained, the porous region 300 may have two or more porous subregions 314 (FIG. 7B) with different porosities and variable porosity, for example, by directing brazing filler metals 328, 342, among other brazing filler metals, in a desired manner.

[0062] Note that the damaged area 348 may be an area where damage is more likely, but not guaranteed, to occur, such as a high-stress area in the metal coupon 200, the body 206 of the part 202, or an area in between. For example, the damaged area 348 may be a corner within the metal coupon 200, the body 206 of the part 202, or an area in between that is subject to high stress and may be repaired by filling with brazing material 328 and / or 342. The contact interface 346 may be located between any portions where a brazed joint 384 (FIGS. 10A-10E) is desired. For example, as shown in FIG. 10B, the contact interface 346 may be between the AM metal member 290 of the metal coupon 200 and the coupon opening 204 in the body 206 of the part 202 where the AM metal member 290 is located. The braze reservoir 292 may provide additional braze to the brazing region 294 in the form of a joint between the metal coupon 200 and the coupon opening 204 in the body 206, for example, where the braze normally applied to the outer surfaces 306, 334 of the metal coupon 200 and the body 206, respectively, does not sufficiently infiltrate the contact interface 346 to ensure a proper braze joint. The braze reservoir 292 can be positioned to supply braze material 328, 342 to the brazing region 294 in any form upon application of a predetermined temperature. Heat applied to the first cavity 320 increases the pressure therein, forcing the liquefied braze material 328 into the first conduit 324. Although each braze reservoir 292 is shown with a single first conduit 324 for delivering liquefied braze material 328 to a single brazing region 294, it will be appreciated that, as shown in Figures 7C and 8D, multiple first conduits 324 may be provided in any of the illustrated embodiments, thereby providing multiple brazing regions 294 with liquefied braze material 328. In Figures 7C and 8D, the second brazing region 294X is shown as a porous region 300, but it may be a brazing region of any form described herein.

[0063] 8A-8E show perspective views of an exemplary additive manufacturing (AM) metal coupon 200 including an AM part 290 having one or more porous regions 300 (with pores 302). The porous regions 300 are infiltrated with a brazing material. The liquefied brazing material 328 (and possibly 342) for the porous regions 300 may be supplied by a brazing material reservoir 292 (making these porous regions 300 "brazing regions" 294 of the brazing material reservoir 292). Alternatively, the porous regions 300 may be supplied with another (third) brazing material 360 in a manner other than from the brazing material reservoir 292, for example, by applying the brazing material 360 to the outside of the metal coupon 200 and heating to induce flow via gravity and / or capillary action. In another embodiment, the porous regions 300 may be supplied with the first brazing material 328 (and possibly the second brazing material 342) from the brazing material reservoir 292 and the third brazing material 360.

[0064] As shown in FIG. 8A, the metal coupon 200 may have a first porous region 300 having a first porosity. In FIG. 8A, the metal coupon 200 includes a single porous region 300 having a first porosity. In FIG. 8A, the entire metal coupon 200 includes the first porosity. Thus, each layer of the metal coupon 200 has the same porosity. In FIGS. 8B and 8E, the metal coupon 200 includes two porous regions 300A-B, each having a different porosity. In FIG. 8B, the two different porous regions 300A, 300B are layered in the interior and exterior regions, one further inward than the other, and in FIG. 8E, the two different porous regions 300A, 300B are on different sides of the metal coupon 200. The regions within the layers of the metal coupon 200 defining regions 300A-B can be formed to include pores 302. In FIG. 8C , the metal coupon 200 includes one or more porous regions 300C, each possibly having the same or different porosity, and a solid region 304. The regions within the layer of the metal coupon 200 defining regions 300A-B can be formed to include pores 302, while the region within the layer of the metal coupon 200 defining solid region 304 is formed without pores 302. In FIG. 8D , the metal coupon 200 includes a variable porosity region 312 between (and possibly including a portion of) the first porous region 300A and the second porous region 300B. The regions 300A-B or the region within the layer of the metal coupon 200 defining the variable porosity region 312 can be formed to include pores 302 of different sizes or numbers, creating different porosities. The variable porosity region 312 can have any varying porosity, for example, increasing, decreasing, and / or both increasing and decreasing porosity. The porosity change can be gradual, stepped, or incremental, while the variable porosity region 312 between the inner and outer porosity regions 300A, 300B shown in Figure 8D can also be applied to the Figure 8E version.Each porous region 300 may have a porosity of between 2-50% open space volume relative to the total volume of the porous region 300, i.e., between 2-50% open space and the other 50-98% solids. In other embodiments, each porosity may be between 10%-40% open space volume relative to the total volume of the porous region 300, i.e., between 10%-40% open space and the other 60-90% solids. Other ranges of porosity are possible. For example, the porous region 300 can have any of the porosities described herein.

[0065] The metal coupon 200 in FIGS. 8A-8E illustrates a shape configured to be positioned in an opening 204 in the trailing edge 158 or 184 of the blade 132 or nozzle 126, respectively, or in the leading edge 156 or 182 of the blade 132 or nozzle 126, respectively, as shown in FIGS. 3 and 4. The metal coupon 200 may also be present at any tip (not shown) of the blade 132 or platform 170 (shown), 174 of the nozzle 126. However, it is emphasized that the metal coupon 200 may be used in any opening 204 in any portion of the body 206 of any part 202. As noted above, the "coupon opening 204 in the body 206" may be any size void within the body 206 up to and including a removed portion of the body 206, such as a tip shroud.

[0066] 8A-8E, the braze reservoir 292 can be positioned anywhere within the metal coupon 200 to deliver the braze material 328, 342 where desired. When the braze reservoir 292 is defined by a porous metal, as shown in FIG. 8A, the cavities 320, 340 and / or conduits 322, 324 can be formed by a denser layer 364, e.g., a braze barrier permeation layer, within the porous region 300, surrounding the respective cavities 320, 340 and / or conduits 322, 324. Alternatively, a dense region, e.g., a solid region, may be defined within the porous metal to allow for the definition of the cavities and conduits of the braze reservoir 292 therein.

[0067] 8E shows an example of another embodiment in which the braze reservoir 292 is removable from the AM metal member 290. In this case, the braze reservoir 292 may be formed in a section 370 of the AM metal member 290 of the metal coupon 200, which can be later removed once the braze reservoir 292 is used. That is, the section 370 is provided primarily for the purpose of providing the braze reservoir 292 but is not otherwise required by the part 202 or the metal coupon 200. Once the braze reservoir 292 is used, the section 370 of the AM metal member 290 in which it is located can be removed, for example, by grinding, electrical discharge machining, etc. The remaining section 372 of the AM metal member 290 should not include any portion of the braze reservoir 292. A similar approach can be used with part 202, for example, by forming a braze reservoir 292 in a section of part 202 that is not needed in the finished part 202, and removing that section after the braze reservoir 292 is used.

[0068] As further described herein, as shown in Figures 3, 4, 9C-9G, and 10A-10E, the brazing material 360 (outside the brazing reservoir 292) penetrates the porous region 300 of the metal coupon 200 and bonds the metal coupon 200 to the coupon opening 204 in the body 206 of the part 202. The different porosities and / or variable subregions differ from one another in at least one of the following: void volume to total volume ratio, pore shape, pore size, pore number, and pore connectivity. Each porous region 300 or porous subregion may have a porosity as described above herein. The different porosities allow for controlled uptake of the brazing material 360, i.e., via capillary action, into the metal coupon 200. 8D, the porous region 300 includes an outer porous region 300A adjacent the outer surface 306 of the AM metal member 290, which has a higher porosity than the inner porous region 300B. Thus, the outer porous region 300A is configured to receive more brazing material 360 therein than the inner porous region 300B.

[0069] 3, 4, 8A-8E, 9A-9G, and 10A-10E, an embodiment of a method according to the disclosure will be described. The method may include repair of part 202. Figures 9A-9G are perspective views of a method according to an embodiment of the disclosure.

[0070] FIG. 9A shows a coupon opening 204 being created in the body 206 of the part 202. The coupon opening 204 will ultimately receive the metal coupon 200. The coupon opening 204 may have any shape. In certain applications, the coupon opening 204 is created by removing a damaged portion of the body 206 of the part 202, but the coupon opening 204 may also be in a location that would be difficult to manufacture in the original version of the part 202, such as the remainder of the part 202. In the non-limiting example shown, the coupon opening 204 is at the trailing edge 184 of the nozzle 126. FIG. 9A also shows the creation of a model of the coupon opening 204. The model creation may include using any now known or later developed three-dimensional scanner (not shown, see arrow) to scan and create a digitized representation of the coupon opening 204 relative to the body 206 of the part 202. Because the process of scanning and modeling parts is well known in the art, further details are omitted to allow the reader to focus on the salient aspects of the disclosure.

[0071] 5, 7A-7D, and 8A-8E illustrate an additively manufactured metal coupon 200 for insertion into the coupon opening 204 in the body 206 of the part 202. The additive manufacturing process includes forming an AM metal part 290 having a braze reservoir 292 therein, as described herein. Briefly, the braze reservoir 292 includes a first cavity 320 within the AM metal part 290, a second conduit 322 fluidly connecting the first cavity 320 to the outer surface 306 of the AM metal part 290, and a first conduit 324 fluidly connecting the first cavity 320 to the brazing region 294. The braze reservoir 292 may include a closure member 332 that blocks fluid communication between the first cavity 320 and the brazing region 294 via the first conduit 324. The blocking member 332 blocks fluid communication between the first cavity 320 and the brazing region 294 via the first conduit 324 before the blocking member 332 is exposed to a predetermined temperature above the melting temperature of the first brazing material 328.

[0072] Additive manufacturing may include any of the AM processes described herein for fabricating the porous metal coupon 200 (or component 202), for example, using a porous or dense metal, and fabricating the braze reservoir 292. Additive manufacturing may include fabricating the metal coupon 200 to generally match that of the coupon opening 204 or to have a near-net shape of the coupon opening 204 based on a model of the coupon opening 204. As used herein, "near-net shape" indicates that the metal coupon 200, when positioned in the coupon opening 204, closely approximates the surface of the body 206 required to bond the metal coupon 200 within the coupon opening 204, e.g., closely approximates the surface of the body 206 required to bond with a selected braze material and minimal required finishing methods, such as machining or grinding. However, the use of a porous region 300 in the metal coupon 200 accommodates larger joint gap dimensional variations compared to a solid coupon with a narrow gap for the braze material because the porous region improves grip and retention of the braze material despite the larger gap. Metal coupon 200 is shown in Figures 9C-9G as being additively manufactured using, for example, the shape from the embodiment of Figures 8A-8E, but may take any of the forms described herein.

[0073] According to embodiments of the present disclosure, the porosity of the porous regions 300 or subregions thereof in the metal coupon 200 is controlled, i.e., customized, to control the flow of brazing material 360 therein during a subsequent brazing process when the metal coupon 200 is bonded to the coupon openings 204 (FIGS. 3-4, 9E-9G) in the body 206 (FIGS. 3-4, 9E-9G) of the part 202 (FIGS. 3-4, 9E-9G). Each porous region 300 or subregion may be customized with respect to any of the above-mentioned characteristics that affect porosity. The shape and / or location of the porous regions 300 or subregions thereof can be arranged to braze materials as desired. For example, in FIGS. 8A-8B, the entire metal coupon 200 includes uniformly porous regions 300 such that the brazing material 360 is uniformly distributed therein. 8D , the metal coupon 200 includes an outermost porous region 300A near the edge 308 of the metal coupon 200, where it mates with the coupon opening 204 ( FIGS. 3-4 ), and a different inner porous region 300B having a different porosity, e.g., distal from the edge 308. In this manner, the braze material 360 is distributed differently in each porous region, resulting in different physical properties of the metal coupon 200 in those different regions. More specifically, any number of different porous regions and / or subregions can be used to create at least one different physical property in the part 202 including the metal coupon 200, such as joint adhesive bond strength, stress / strain resistance, ductility, wear resistance, oxidation resistance, thermal conductivity, electrical conductivity, surface roughness, hardness, and mass. In a non-exhaustive list of possibilities, the metal coupon 200 may include higher porosity in one porous region compared to other solid regions of the metal coupon 200 to direct more braze material therein through capillary action, thereby controlling at least one physical property of the part 202. In another embodiment, the metal coupon 200 may include lower porosity in one porous region compared to other solid regions of the metal coupon 200 to direct less braze material therein through capillary action, thereby controlling at least one physical property of the part 202.In other embodiments, the metal coupon 200 may include two or more porous regions that collectively make up the entire metal coupon 200. Any arrangement of porous regions and / or sub-regions is possible to create the desired braze material 360 flow and infiltration.

[0074] In some embodiments, additive manufacturing may also include forming any of a variety of modifications to the part 202, including, for example, structures not previously present in the removed, damaged part. For example, as shown in FIG. 8B , additive manufacturing may optionally include forming cooling passages 380 in the metal coupon 200. The cooling passages 380 may extend in any manner in the metal coupon 200, such as in a serpentine path therein or through the outer surface 306 of the metal coupon 200. In another example, as shown in FIG. 8B , additive manufacturing may optionally include forming one or more support and / or cooling structures 382 (e.g., pins / fins) in the metal coupon 200, possibly with cooling passages (not shown) therein. Any advantageous internal structural modifications may be made to the metal coupon 200. Currently known or future developed post-additive manufacturing finishing processes may optionally be performed on the metal coupon 200, such as using abrasives to smooth and blend its surface. Advantageously, the teachings of the present disclosure can eliminate the need for other finishing processes typically used to address residual stresses present in materials after additive manufacturing, such as peening, heat treatment, and hot isostatic pressing (HIP). FIG. 9B illustrates the insertion of a first brazing filler metal 328 into the first cavity 320 through a second conduit 322. The first brazing filler metal 328 may be introduced into the first cavity 320 via the second conduit 322 (after additive manufacturing of the metal coupon 200) by any method now known or later developed, such as forced gas flow, gravity feed, vibration feed, etc. The first brazing filler metal 328 may include any of the brazing filler metals listed below. The first brazing filler metal 328 may be introduced into the first cavity 320 in a controlled atmosphere, such as a non-reactive gas such as argon and / or nitrogen. As mentioned above, the first brazing filler material 328 can be in powder form or in non-powder form, such as a paste consisting of a powder and a binder, such as Braz-BinderGel available from Vitta. In either case, the closure member 332 holds the brazing filler material 328 in the first cavity 320. Insertion may also include heat treatment, as described herein, to diffuse the melting temperature-reducing elements of the brazing filler material 328 into the closure member 332.

[0075] 9C illustrates sealing the second conduit 322 from the exterior of the AM metal member 290. That is, once the first braze material 328 enters the first cavity 320, a sealing member 330 is formed that seals the second conduit 322. As discussed above, the sealing member 330 may include any structure capable of occluding the second conduit 322 at or near the exterior surface 306 of the AM metal member 290, that is, after the first braze material 328 has been introduced into the first cavity 320 through the second conduit 322. For example, the sealing member 330 may include a plug or weld in the second conduit 322 at or near the exterior surface 306 of the AM metal member 290.

[0076] FIGS. 9D and 9E illustrate positioning a metal coupon 200 in a coupon opening 204 of a body 206 of a part 202. The metal coupon 200 can be placed in the coupon opening 204 of the body 206 by any method now known or later developed, for example, using a robotic arm or manually. If desired, the metal coupon 200 can be held in place by any desired method, such as adhesive, a male-female connector 354 ( FIG. 7B ), a clamp, etc. FIGS. 9E-9G also illustrate the infiltration of the metal coupon 200 and brazing material 360 into the coupon opening 204 of the body 206, i.e., by a brazing process. FIGS. 10A-10E illustrate enlarged cross-sectional views of the metal coupon 200 in the coupon opening 204 of the body 206 of a part 202, including various (used) braze reservoirs 292, according to disclosed embodiments. The brazing material 328 and / or 360 may comprise any now known or later developed braze composition, as described herein. Infiltration may include any now known or later developed brazing process, such as using a vacuum brazing system, an induction brazing system, and / or an inert gas atmosphere heating system and related techniques. In one non-limiting example, brazing may include, for example, applying a brazing material 360 (FIG. 9D) and applying heat (FIG. 9E) to cause it to flow into, through, and around the metal coupon 200 via capillary action.

[0077] Infiltration of the braze material 360 is based at least on the porosity or porosity characteristics of the porous region 300. For example, as shown in FIGS. 8B and 10A, infiltration may include moving the braze material 360 to infiltrate the porous region 300. The porosity of the porous region 300 determines how the braze material 360 flows. For example, as shown in FIGS. 8B and 10B, infiltration may include moving the braze material 360 to infiltrate the outer porous region 300A based on its first porosity characteristics and penetrating through the second, outer porous region 300B based on its second porosity characteristics. As shown in FIG. 8D and FIG. 10B, when a variable porosity subregion 312 is present with two or more porous regions 300A, 300B having different porosities, the braze material 360 may penetrate through the variable porosity region 312 based on the characteristics of the variable porosity subregion 312 (e.g., porosity gradient, step porosity, etc.). As shown in FIG. 8D and as shown in FIG. 10B , when the variable porosity subregion 312 includes and is interposed between inner and outer porous regions 300A-B, infiltration may include moving the brazing material 360 through and infiltrating the outer porous region 300A based on its first porosity characteristic, moving between the regions 300A-B to penetrate and infiltrate the variable porosity subregion 312 based on its second porosity characteristic (e.g., its porosity gradient, stepped porosity, etc.), and moving through and infiltrating the inner porous region 300B based on its second porosity characteristic.

[0078] Different porosity options in the porous region 300 result in different braze material 360 flow and infiltration. As a result of the brazing process, the porous region 300, or subregions with different porosity having the braze material 360 therein, can have at least one different physical property. In one example, as shown in FIGS. 8D and 10B, the porosity of the first, outer porous region 300A can be higher (i.e., lower density) than the porosity of the second, inner porous region 300B. In this case, infiltration involves infiltration of the first, outer porous region 300A, and the second, inner porous region 300B, which are more braze material 360-rich. Depending on the braze material 360 used, among other factors, different porosities allow customization of at least one physical property of the part 202, such as joint adhesive strength, stress / strain resistance, ductility, wear resistance, oxidation resistance, thermal conductivity, electrical conductivity, surface roughness, hardness, and / or mass. Additionally, the multiple flow paths of the brazing material using the porous region 300 may reduce the likelihood of lack of filling and / or voids along the brazing joint compared to conventional narrow gap filling brazing processes and due to the tight manufacturing tolerances required for narrow gap brazing.

[0079] In some embodiments, different braze filler metals 360 may be used on different portions of the metal coupon 200 to further customize the bonding of the metal coupon 200 in the component 202. For example, with reference to FIG. 10C , a braze filler metal 360A may be used on a first metal component or side 326 of the component 202, and another braze filler metal 360B may be used on a different component or side 327 of the component 202 than the braze filler metal 360A. In one example, with reference to FIGS. 3 , 4 and 10A-10D , the first metal component or side 326 of the component 202 may be the first (concave, pressure) side outer wall 152, 178 of the airfoil 150, 176 and the second or side 327 of the component 202, or the second (convex, suction) side outer wall 154, 180 of the airfoil 150, 176. Different brazing filler metals 360A, 360B can be customized for different porous regions 300 as well as different portions or sides 326, 327 to suit the expected environment of the part 202 at those locations. In this way, there are numerous variations in brazing filler metals and porous regions / partial regions, allowing for compatibility with a variety of difficult-to-cut materials.

[0080] In addition to infusing the braze material 360 described above into the mating metal coupon 200, embodiments of the present disclosure advantageously employ a braze reservoir 292 to provide additional braze material 328 (342) in the braze region 294. As discussed above, FIGS. 10A-10E illustrate several examples of braze reservoirs 292 in the metal coupon 200. FIG. 11 illustrates a partial perspective view of an exemplary component 202, e.g., an airfoil as shown in FIGS. 3-4, including a braze reservoir 292. The braze reservoir 292 may be used to bond the metal coupon 200 to the coupon opening 204 simultaneously with the infusion of the braze material 360 described above, or may be used thereafter during use of the component 202 with the metal coupon 200 attached thereto, for example, to heal a damaged region 348. When the braze reservoir 292 is used by heating the AM metal member 290 to a predetermined temperature above the melting temperature of the first braze material 328, the first braze material 328 liquefies, opening the barrier material 332 and allowing the liquefied first braze material 328 to flow through the first conduit 324 and infiltrate the brazing region 294. The liquefied first braze material 328 flows under pressure due to the increased pressure in the first cavity 320 caused by heating. Thus, the pressurized liquefied first braze material 328 can infiltrate various braze regions 294 that may not normally receive liquefied braze material 360 entering through gravity and / or capillary action.

[0081] 10A-10E and 11 show the liquefied first brazing filler metal 328 flowing through the first conduit 324 (or partially solidifying in the first conduit 324). Some of the first brazing filler metal 328 may remain within the first cavity 322, i.e., after solidification. However, the first cavity 320 becomes at least partially empty in response to the metal coupon 200 or body 206 exceeding a predetermined temperature. Note that, if a second brazing filler metal 342 is used, the predetermined temperature may exceed its melting temperature. The predetermined temperature may be selected to be within the range of heat used during the infiltration step to bond the metal coupon 200 to the coupon opening 204 or within the range experienced during use of the part 202, e.g., within the range in which the damaged region 348 is expected to occur. This predetermined temperature can be controlled by controlling the composition of the first braze material 328 and / or the plugging member 332, and the physical configuration of the plugging member 332, e.g., thickness, width, chemical composition, etc. When the predetermined temperature of the metal coupon 200 or the part 202 exceeds the melting temperature of the first braze material 328, whichever braze reservoir 292 is located in, the plugging member 332 opens fluid communication via the first conduit 324. For example, as shown in FIG. 11 , in response to the body 206 exceeding the predetermined temperature, the first braze material 328 liquefies, and the liquefied first braze material 328 (and possibly a portion of the barrier material 332 therein) flows through the first conduit 324 and infiltrates the braze region 294, shown in FIG. 11 as damaged region 348. When used in the body 206 of the part 202, the braze reservoir 292 can provide self-repair, for example, for internal cracks, during use of the part or during heat treatment without additional processing. 7D , a second cavity 340 is defined in the metal coupon 200 or body 206 (i.e., the first conduit 324 between the first cavity 320 and the brazing region 294), and the second brazing material 342 therein is different from the first brazing material 328. The liquefied first brazing material 328 flows through the first conduit 324 and through the second brazing material 344, mixing with at least a portion of the second brazing material 342, and the liquefied first brazing material 328 and second brazing material 342 infiltrate the brazing region 294.Note that the second brazing filler metal 342 may have a melting temperature higher than that of the first brazing filler metal 328, and a temperature higher than a predetermined temperature is required to melt it. In such a case, part of the second brazing filler metal 342 liquefies, and part of the second brazing filler metal 342 is caught in the flow to the brazing region 294 (mixed with the liquefied first brazing filler metal 328), and part of the second brazing filler metal 342 is left behind.

[0082] As mentioned above, the braze region 294 can take a variety of forms. Figures 10A-10E and 11 show some examples of the braze region 294. For example, in the case of the part 202, the braze region 294 can include at least one of the contact interface 346 between the coupon opening 204 in the body 206 and the metal coupon 200 in the coupon opening 204, the porous region 300 in at least one of the body 206 and the metal coupon 200, and the portion and outer surface 334 of the body 206. In the case of the metal coupon 200, for example, the braze region 294 can include at least one of the porous region 300 in the AM metal member 290, the contact interface 346 between the metal coupon 200 and the coupon opening 204 in the body 206 of the part 202 in which the metal coupon 200 is located, and the portion or outer surface 334 of the body 206 of the part 202 in which the metal coupon 200 is located. If the brazing region 294 includes a porous region 300, the porous region may be the same as the one infiltrated with the brazing material 360, or it may be a separate porous region 300 from the one infiltrated with the brazing material 360. FIG. 10A shows an example where the porous region 300 is the same for both brazing processes. In this example, a brazing material reservoir 292 may be used to provide additional brazing material 328 (and possibly 342) to the porous region 300 that may not be reached by the brazing material 360. FIG. 10D shows an embodiment where a brazing material reservoir 292 is used to provide brazing material 328 to a porous region 300E that is different from the porous regions 300A, 300B used to bond the metal coupon 200 to the coupon opening 204. The porous region 300E may be in a location where high stresses may occur, for example, resulting from a predetermined temperature or other cause. Once the predetermined temperature is reached, the first brazing material 328 may provide additional strength and / or stability during use of the part 202. Any porous region 300 supplied by the braze reservoir 294 may have variable porosity, with two or more porous regions or sub-regions having different porosities (see, for example, FIG. 8D). It is recognized that porous region 300E, as shown in FIG. 10D, may instead be a solid region where high stresses may cause cracking, which may be filled and stabilized by the first braze material 328.10B shows an example where the braze region 294 is a contact interface 346 (joint 384) between the metal coupon 200 and the coupon opening 204 of the body 206 of the component 202. The first braze material 328 is within the joint 384. FIG. 10C shows the braze region 294 as a damaged region 348, e.g., a crack, inside the solid region of the metal coupon 200. It is emphasized that while a particular braze region 294 is illustrated herein, the braze region 294 may include other structures and / or features not described herein.

[0083] Certain embodiments of this method may include removing the braze reservoir 292 from the metal coupon 200 or the body 206 of the part 202 after heating, i.e., after its use. Referring to FIGS. 8E and 10E, in some embodiments, the braze reservoir 292 may be provided in a removable section 370 of the metal coupon 200 or the body 206 of the part 202. FIGS. 8E and 10E illustrate the metal coupon 200 including a section 370 of the AM metal member 290 of the metal coupon 200 that can be removed after the braze reservoir 292 has been used. That is, the section 370 is provided primarily for the purpose of providing the braze reservoir 292 but is not otherwise required by the part 202 or metal coupon 200. As shown in FIG. 10E, once the braze reservoir 292 has been used, the section 370 of the AM metal member 290 in which it is located can be removed, for example, by grinding, electrical discharge machining, etc. In FIG. 10E, the section 370 above the dashed horizontal line is removed. The remaining section 372 of the AM metal part 290 must not include any portion of the braze reservoir 292. A similar approach can be used with the part 202, for example, by forming the braze reservoir 292 in a section of the part 202 that is not needed in the finished part 202, and removing that section after the braze reservoir 292 is used.

[0084] Other embodiments of methods according to the present disclosure may include simply forming one or more metal coupons 200 for repairing a part 202. In this case, as shown in FIG. 9A , the method includes creating a model of a coupon opening 204 in a body 206 of the part 202 and additively manufacturing the metal coupon 200 as described herein.

[0085] Any now known or future developed post-manufacturing finishing process can be performed on the metal coupon 200 as appropriate, such as peening, heat treating, hot isostatic pressing (HIP), among others. FIG. 9G illustrates optional finishing steps for the part 202, such as, but not limited to, machining to create a seamless transition in the surface of the part 202 where the metal coupon 200 was added. However, as discussed above, the disclosed teachings may eliminate the need for other finishing processes, such as peening, heat treating, and hot isostatic pressing (HIP), that are typically used to address residual stresses present in materials post-additive manufacturing.

[0086] Embodiments of the present disclosure also include methods of using a braze reservoir 292 in a part 202. The methods may include additively manufacturing the body 206 of the part 202 to include the braze reservoir 292 therein. FIGS. 3, 4, and 11 illustrate an exemplary part 202, e.g., an airfoil like those in FIGS. 3-4, including the braze reservoir 292. The braze reservoir 292 may include the same structure as described herein for the metal coupon 200. That is, the braze reservoir 292 may include a first cavity 320 in the body 206 (not the AM metal member 290), a second conduit 322 fluidly connecting the first cavity 320 to the outer surface 334 of the body 206, and a first conduit 324 fluidly connecting the first cavity 320 to the brazing region 294. The braze region 294 may include a porous region 300 in the body 206 (which may optionally include a variable porosity region having two or more porous subregions with different porosities), a contact interface 346 between the body 206 and the metal coupon 200 within the coupon opening 204 in the body 206, a portion of the body 206, and / or an outer surface 334. A damaged region 348 of the body 206. The braze reservoir 292 also includes a first braze material 328 in the first cavity 320 and a sealing member 330 that seals the second conduit 320 from the exterior of the body 206. The first braze material 328 is introduced into the first cavity 320 through the second conduit 322 after additive manufacturing of the part 202. As the first braze material 328 enters the first cavity 320, the sealing member 330 is formed, sealing the second conduit 322. The braze reservoir 292 in the part 202 may also include a plug 332 that blocks fluid communication between the first cavity 320 and the brazing region 294 through the first conduit 324 before the plug 332 is exposed to a predetermined temperature that exceeds the melting temperature of the first braze material 328. As described herein, the plug 332 includes a eutectic mixture of the metallic material of the body 206 and the first braze material 328. The predetermined temperature of the heating step, as described below, exceeds the melting temperature of the first braze material 328.The additive manufacturing may also optionally include forming a second cavity 340 (FIG. 7D) in the body 206 and the first conduit 324 between the first cavity 320 and the brazing region 294, and filling the second cavity 340 with a second brazing material 342.

[0087] The body 206 of the component 202 may be heated to a predetermined temperature above the melting temperature of the first braze material 328, causing the first braze material 328 to liquefy, opening the obstruction member 332 and allowing the liquefied first braze material 328 (and any remnants of the obstruction member 332) to flow through the first conduit 324 and infiltrate the braze region 294. The heating may occur during manufacture of the component 202, for example, to provide the first braze material 328 to the porous region 300 to provide customized physical properties at that location, as described herein. In this case, as shown in FIGS. 8E and 10E , the braze reservoir 292 may be removed from the body 206 after heating, i.e., after being used to supply braze material to the braze region 294 during manufacture. In other embodiments, the heating occurs during use of the component 202, for example, during use of the nozzle 126 or blade 132 in the turbomachine 100 ( FIG. 1 ). The brazing filler metal reservoir 292 may be used to address potential damage areas 348, such as areas of high stress, oxidation, etc., that may occur during use. When the first brazing filler metal 328 infiltrates the brazing area 294, it can extend the life of the component 202. Here, the second cavity 340 contains a second brazing filler metal 342, and as the liquefied first brazing filler metal 328 flows through the first conduit 324, it at least partially mixes with the second brazing filler metal 342 and infiltrates the brazing area 294 where the liquefied first brazing filler metal 328 and second brazing filler metal 342 are mixed. As described above, the second brazing filler metal 342 may have a higher melting temperature than the first brazing filler metal 328 and require a higher temperature to melt. In such a case, a portion of the second brazing filler metal 342 will liquefy, and a portion of the second brazing filler metal 342 will be caught in the flow to the brazing region 294 (mixed with the liquefied first brazing filler metal 328), and a portion of the second brazing filler metal 342 will be left behind.

[0088] 3, 4, 10A-10E, and 11 illustrate an embodiment of an additively manufactured (AM) part 202 including a spent braze reservoir 292 according to embodiments of the disclosure. In this case, the part 202 includes a solidified first braze material 328 in the braze region 294, regardless of the form the braze region 294 takes. FIGS. 10A-10E and 11 illustrate the liquefied first braze material 328 flowing through (or partially solidifying in) the first conduit 324. A portion of the first braze material 328 may remain within the first cavity 322, i.e., after solidification. However, in response to the metal coupon 200 or body 206 exceeding a predetermined temperature, the first cavity 320 is at least partially empty space, i.e., space within the coupon opening 204 or body 206 of the metal coupon 200.

[0089] 10A-10E, part 202 includes body 206. As discussed herein, body 206 can have any configuration for the particular industrial application in which part 202 is used. In the examples used herein, body 206 is for a turbine rotor blade 132 (FIG. 3) or a turbine static nozzle 126 (FIG. 4). While metal coupon 200 is shown in FIGS. 3 and 4 on the airfoils 150, 176 of blade 132 and nozzle 126, respectively, metal coupon 200 can be present in any portion of body 206 of part 202. Part 202 also includes additively manufactured (AM) metal coupon 200 using braze reservoir 292. Braze material 360 bonds metal coupon 200 to coupon opening 204 in body 206 and may infiltrate porous region 300.

[0090] As shown in FIG. 10A , the braze material 360 includes a first section 390 that infiltrates the porous region 300 based on at least the first porosity characteristic of the braze material. As shown in FIG. 10B , the braze material 360 includes the first section 390 that infiltrates the first porous region 300A, and the metal coupon 200 further includes a second (inner) porous region 300B having a second porosity that differs from the first porosity. The first porosity may differ from the second porosity in at least one of the following: void space volume to total volume ratio, void shape, pore size, pore number, and pore connectivity. The “at least characteristic” porosity indicates that the porosity may result in different infiltration characteristics, such as the braze material volume, intraporosity pattern, crystallization, chemical gradient, composition, and other characteristics. However, as understood in the art, other factors can also affect infiltration characteristics, such as the type of braze material and characteristics of the brazing process, such as temperature, pressure, location of the component 202, and the format and configuration of the metal coupon 200. The body 206 may have a third porosity that is different from both the first and second porosities. For example, the body 206 may have a third porosity that is denser than both the first and second porosities, e.g., 100% solid. Optionally, the metal coupon 200 may include a variable porosity region 312 having two or more porous subregions (only the portions shown by the dashed box in FIG. 10B for clarity) between (and possibly including portions of) the first outer porous region 300A and the second outer porous region 300B. The variable porosity region 312 may gradually change porosity between the first and second porosities, e.g., in a stepped or gradual manner. 8D , the porosity of the porous region 300 may increase in defined steps from the inner region toward the outer surface 306 (through the porous subregion) of the metal coupon 200. As described herein, in certain cases, the porosity of the porous region 300 may increase toward the outer surface 306 of the metal coupon 200, e.g., more braze material 360 is in the outer porous region, e.g., 300A, of the metal coupon 200 of the part 202.

[0091] In FIG. 10B , the braze material 360B includes a second section 392 that infiltrates the second porous region 300B based on at least a second porosity characteristic. The result of the different porosities is that the first porous region 300A and the second porous region 300B including the braze material 360 have at least one different physical characteristic. The porosity can be customized to select those physical characteristics, to the extent that the porosity can affect those physical characteristics. In one example, the first porosity of the first porous region 300A can be higher (i.e., less dense) than the second porosity of the second porous region 300B, such that the first porous region 300A contains more braze material 360 (328, 342) therein than the second porous region 300B. As shown in FIG. 10B , the first porous region 300A may be the adjacent outer surface 306 of the metal coupon 200 that has a higher porosity than the second (inner) porous region 300B, and the porous region 300A has more braze material therein than the porous region 300B. In another example, the first porous region 300A shown in FIG. 10B is on at least a portion of the edge 308 of the metal coupon 200 configured for bonding to the body 206. This configuration may be advantageous to place more braze material 360 (328, 342) near the braze joint 384 to enhance the bond bond strength of the metal coupon 200, or to reduce oxidation at the braze joint 384, or to increase thermal conductivity at the braze joint 384, as shown in FIG. 10B . Any of the physical properties described herein may also be customized based on different porosities and / or different braze materials. As mentioned above, depending on the braze material 360 (328, 342) used, different porosity may allow customization of the physical property(ies) of the part 202: joint adhesive bond strength, stress / strain resistance, ductility, wear resistance, oxidation resistance, thermal conductivity, electrical conductivity, surface roughness, hardness, and / or mass. As mentioned above, the metallic coupon 200 may have a near-net shape of the coupon opening 204 in the body 206 of the part 202. 10B, the braze material 360B includes a second section 392 that infiltrates the second porous region 300B based on at least a second porosity characteristic. The various porous regions 300 and / or various subregions 314 within a given porous region 300 have one or more different physical properties in the part 202. Porosity can be customized to select those physical properties, as long as the porosity can affect those physical properties. In one example, as shown in FIG. 9B , a first porous subregion 314A can have a higher first porosity (i.e., lower density) than a second porous subregion 314B, with the first porous subregion 314A containing more braze material 310 therein than the second porous subregion 314B. As shown in FIGS. 7E and 7G , the porous region 300B can include an outer porous subregion 314B adjacent the outer surface 306 of the metal coupon 200 (i.e., distal from the barrier 304) and having a higher porosity than the inner porous subregion 314A of the porous region 300A near the barrier 304. In this case, the outer porous portion region 314B includes more braze material 310 therein than the inner porous portion region 314A. In another example, the outer porous portion region 314A shown in FIG. 9B is located on at least a portion of the edge 308 of the metal coupon 200 configured to bond to the body 206. The porous regions 300A and 300B may be adjacent edges 308. Alternatively, the porous portion regions 314A and 314B may be adjacent to the barrier 304. This arrangement shown in FIG. 9B may be beneficial for enhancing the joint bond strength of the metal coupon 200 within the coupon opening 204 of the body 206, or for reducing oxidation at the braze joint 374 or increasing the thermal conductivity of the braze joint 374, since more braze material 310 is located near the braze joint 374. In other examples, an increase in braze material 310 may lead to increased joint bond strength, improved ductility, increased thermal or electrical conductivity, or increased oxidation resistance, while a decrease in braze material 310 may lead to decreased surface roughness, decreased hardness, decreased joint bond strength, decreased ductility, decreased thermal or electrical conductivity, or decreased oxidation resistance. Any of the physical properties described herein may also be customized based on different porosities and / or different braze materials.As mentioned above, depending on the braze material 310 used, different porosities may allow customization of one or more physical properties of the part 202, such as joint bond strength, stress / strain resistance, ductility, wear resistance, oxidation resistance, thermal conductivity, electrical conductivity, surface roughness, hardness, and / or mass. As mentioned above, the metal coupon 200 may have a near-net shape of the coupon opening 204 in the body 206 of the part 202.

[0092] Although specific locations for the various porous regions 300 and / or subregions are illustrated herein, the various porous regions or subregions may be positioned in any manner to provide different brazing filler infiltration characteristics and different physical properties of the component 202.

[0093] Embodiments of the present disclosure may include a turbomachine 100 including a turbine assembly 110 as shown in Figures 1-2, as well as one or more components 202 as described herein. The components 202 may take the form of a turbine stationary nozzle 126, a turbine rotating blade 132, or other components of the turbomachine 100. The metal coupons 200 may be used for new or repair parts.

[0094] The present disclosure provides various technical and commercial advantages, examples of which are described below. Regarding repairs, additive manufacturing can cost-effectively create custom-shaped metal coupons, requiring only the damaged material to be removed. Porous regions or subregions can increase the percentage of base metal alloy (e.g., >60%) in specific areas, potentially resulting in improved physical properties compared to, for example, pre-sintered preforms. Porous regions or subregions can also provide a welded / fused particle matrix (e.g., a superalloy metal matrix) with stronger braze fill compared to traditional braze-surrounded metal particles. Multiple braze flow paths using multiple porous regions or subregions can reduce the risk of underfill and / or voids along the brazed joint compared to traditional narrow-gap brazing processes. Porous regions or subregions can be formed with varying porosity / density across the metal coupon, allowing for a high degree of customization of braze flow. Porous regions or subregions can also accommodate greater variations in joint gap dimensions compared to machined solid coupons with narrow gaps for braze filler metal. The braze reservoir also provides the ability to provide liquefied braze material in hard-to-reach areas and provide a driving force to various brazing areas (e.g., porous areas, cracks, and the interface between the coupon and the component body). Pressurized liquefied braze material from the braze reservoir can infiltrate various brazing areas that may not normally receive liquefied braze material through gravity and / or capillary action. When used within the component body, the braze reservoir provides self-healing (e.g., for internal cracks) without additional treatment during component use or heat treatment.

[0095] Approximate expressions used in this specification and claims are used to describe quantitative modifiers that can vary within acceptable limits without causing a change in the basic function to which the quantity relates. Thus, values ​​modified by terms such as "about," "approximately," and "substantially" are not limited to their exact numerical values. In at least some instances, approximate expressions correspond to the precision of the instrument used to measure the value. In some cases, approximate expressions correspond to the precision of the instrument used to measure the value. In this specification and claims, ranges of numerical limitations are combinable and / or interchangeable with each other. Such ranges specify and encompass all subranges within the range, unless otherwise clear from the context. The term "about" used in connection with a particular value in a range applies to both the upper and lower limits and may indicate ±10% of the stated numerical value, except where the precision of the instrument used to measure the value is dependent.

[0096] Corresponding structures, materials, acts, and equivalents of elements identified by functional descriptions in the following claims encompass any structures, materials, or acts that perform the function in combination with other elements specifically recited in the claims. The description of the present disclosure has been provided for purposes of illustration and description and is not intended to be exhaustive or limited to the disclosed form. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The embodiments of the present disclosure have been selected and described to best explain the principles and practical applications of the present disclosure and to enable those skilled in the art to understand the disclosure regarding various embodiments and various modifications suitable for particular applications. [Explanation of symbols]

[0097] 200 Metal Coupons 202 parts 290 Additive Manufacturing (AM) Metal Components 292 Wax Storage Unit 320 First Cavity 322 Second Conduit 324 First Conduit 328 First brazing filler metal 330 Sealing member 332 Closure element 340 Second Cavity 342 Second brazing filler metal

Claims

1. 1. A method comprising: Additive manufacturing a metal coupon (200) for insertion into a coupon opening (204) in a body (206) of a part (202), the metal coupon (200) comprising an additively manufactured (AM) metal member (290) having a braze reservoir (292), the braze reservoir (292) comprising: a first cavity (320) defined within said AM metal member (290); a first conduit (324) defined within the AM metal member (290), the first conduit (324) fluidly connecting the first cavity (320) to the braze region (294); and a blocking member (332) across the first conduit (324) to block fluid communication between the first cavity (320) and said brazing region (294); and Inserting a first brazing material (328) into the first cavity (320); sealing the first cavity (320) from the exterior of the AM metal member (290); placing the metal coupon (200) in the coupon opening (204); heating the AM metal member (290) to a predetermined temperature above the melting temperature of a first brazing filler metal (328), causing the first brazing filler metal (328) to liquefy and opening the closure member (332) so that the liquefied first brazing filler metal (328) flows through a first conduit (324) and infiltrates the brazing area (294); A method comprising:

2. 2. The method of claim 1, wherein the AM metal component includes a porous region having a porosity, the method including applying a second brazing filler metal to at least the AM metal component, the second brazing filler metal being different from the first brazing filler metal, and wherein the heating causes the second brazing filler metal to infiltrate at least the porous region based on the porosity characteristics of the at least porous region to bond the AM metal component within the coupon opening.

3. 2. The method of claim 1, wherein the plugging member (332) comprises a eutectic mixture of a metallic material of the AM metal member (290) and a first brazing filler metal (328), and the predetermined temperature exceeds a melting temperature of the first brazing filler metal (328).

4. 2. The method of claim 1, wherein the additive manufacturing step further comprises additively manufacturing a second cavity (340) in the AM metal member (290) and a first conduit (324) between the first cavity (320) and the brazing region (294), and filling the second cavity (340) with a second brazing material (342), wherein the liquefied first brazing material (328) flows through the first conduit (324) to liquefy the second brazing material (342), and the liquefied first and second brazing materials (328, 342) infiltrate the brazing region (294).

5. 2. The method of claim 1, wherein the brazing region (294) comprises at least one of a porous region (300, 312) within the AM metal member (290), a contact interface (346) between the metal coupon (200) and a coupon opening (204) in a body (206) of the component (202) on which the metal coupon (200) is disposed, and a portion or an outer surface (306, 334) of the body (206) of the component (202) on which the metal coupon (200) is disposed.

6. The method of claim 5, wherein the porous region (300, 312) has variable porosity having two or more porous subregions of different porosity.

7. The method of claim 1, further comprising removing the braze reservoir (292) from the metal coupon (200) after heating.

8. 2. The method of claim 1, wherein the additive manufacturing step includes forming a second conduit (322) defined within the AM metal member (290) and fluidly connecting the first cavity (320) to an outer surface (306, 334) of the AM metal member (290), and wherein sealing the first cavity (320) from an exterior of the AM metal member (290) includes sealing the second conduit (322).

9. 1. A method comprising: Additive manufacturing a body (206) of a part (202), the body (206) including a wax reservoir (292), the wax reservoir (292) comprising: a first cavity (320) defined within said body (206); a first conduit (324) defined within the body (206), the first conduit (324) fluidly connecting the first cavity (320) to the braze region (294); and a blocking member (332) across the first conduit (324) to block fluid communication between the first cavity (320) and the brazing area (294); and Inserting a first brazing material (328) into the first cavity (320); sealing the first cavity (320) from the exterior of the body (206); heating the body (206) to a predetermined temperature above the melting temperature of a first brazing filler metal (328), causing the first brazing filler metal (328) to liquefy and opening the closure member (332), allowing the liquefied first brazing filler metal (328) to flow through a first conduit (324) and infiltrate the brazing area (294); A method comprising:

10. 10. The method of claim 9, wherein the closure member (332) comprises a eutectic mixture of the metallic material of the body (206) and a first braze material (328), and the predetermined temperature exceeds a melting temperature of the first braze material (328).

11. 10. The method of claim 9, wherein the additive manufacturing step includes additively manufacturing a second cavity (340) in the body (206) and a first conduit (324) between the first cavity (320) and the brazing region (294), and filling the second cavity (340) with a second brazing material (342), wherein the liquefied first brazing material (328) flows through the first conduit (324) and mixes with at least a portion of the second brazing material (342), and the liquefied and mixed first brazing material (328) and second brazing material (342) infiltrate the brazing region (294).

12. 10. The method of claim 9, wherein the brazing region includes at least one of a porous region within the body, a contact interface between the body and a metal coupon within a coupon opening in the body, a portion and an outer surface of the body, and a damaged region within the body.

13. The method of claim 12, wherein the porous region (300, 312) has variable porosity having two or more porous subregions of different porosity.

14. The method of claim 9, wherein the heating occurs while the component (202) is in use.

15. 10. The method of claim 9, wherein the additive manufacturing step includes forming a second conduit (322) defined within the body (206) and fluidly connecting the first cavity (320) to an outer surface (306, 334) of the body (206), and wherein sealing the first cavity (320) from the exterior of the body (206) includes sealing the second conduit (322).

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