Turbines having silicide-strengthened niobium-based alloys and turbine components formed therefrom - Patents.com

Abstract

A niobium silicide-based alloy and a turbine having a turbine component formed from at least the niobium silicide-based alloy are provided, the niobium silicide-based alloy comprising about 14 atomic percent to about 24 atomic percent titanium (Ti), about 11 atomic percent to about 19 atomic percent silicon (Si), about 4 atomic percent to about 8 atomic percent chromium (Cr), about 2 atomic percent to about 6 atomic percent hafnium (Hf), up to about 4 atomic percent aluminum (Al), about 0.5 atomic percent to about 1 atomic percent tin (Sn), about 5 atomic percent to about 15 atomic percent tantalum (Ta), about 1 atomic percent to about 5 atomic percent tungsten (W), up to about 5 atomic percent rhenium (Re), up to about 5 atomic percent zirconium (Zr), up to about 6 atomic percent yttrium (Y), and the balance niobium (Nb).

Description

[Technical Field]

[0001] The present disclosure relates generally to silicide-strengthened niobium (Nb)-based alloys (also referred to as "niobium (Nb) silicide-based alloys" or "Nb-Si-based alloys," which are used interchangeably throughout this disclosure). More particularly, the present disclosure relates to Nb-Si-based alloys having high-temperature strength and environmental resistance suitable for applications including turbine components, and turbines having at least turbine components formed from such Nb-Si-based alloys. [Background technology]

[0002] Turbines (and components thereof), including, but not limited to, aviation turbines, land-based turbines, and marine turbines, are typically formed from superalloys, often based on nickel (Ni). Turbine components formed from Ni-based superalloys generally exhibit desirable chemical and physical properties under the high temperature, high stress, and high pressure conditions typically encountered during turbine operation. For example, turbine components, such as the airfoils of modern jet engines, can reach temperatures as high as approximately 1050°C, which is above the melting temperature (T) of many Ni-based superalloys. m ) can be approximately 85% higher than the

[0003] Because Ni-base superalloys have provided the desired level of performance in such applications, the development of such Ni-base superalloys has been widely considered. As a result, this field has matured, and few significant improvements have been realized in this area in recent years. Meanwhile, efforts have been made to develop alternative turbine component materials. These alternative materials include Nb-based refractory metal intermetallic composites (hereinafter "RMICs"). Most RMICs have melting temperatures of approximately 1700°C. If RMICs could be used at approximately 80% of their melting temperature, they could potentially be used in applications where temperatures exceed the current service limits of Ni-base superalloys.

[0004] RMICs containing at least niobium (Nb), silicon (Si), titanium (Ti), hafnium (Hf), chromium (Cr), and aluminum (Al) have been investigated for turbine component applications. Some known Nb-silicide-based RMICs exhibit high-temperature properties that exceed those of current Ni-base superalloys. Some known Nb-silicide-based RMICs have oxidation resistance properties sufficient for turbine applications. Other known Nb-silicide-based alloys have fracture toughness sufficient for turbine component applications.

[0005] Although the above-mentioned Nb-silicide-based alloys have beneficial mechanical and chemical properties, they do not provide a sufficient balance of mechanical properties, such as high-temperature strength and environmental resistance, including oxidation resistance, for application in high-temperature section engine components such as airfoils, rotors, nozzles, shrouds, and exhaust components. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] US Patent Application Publication No. 2003 / 0066578 Summary of the Invention

[0007] All aspects, examples, and features described below can be combined in any technically possible manner.

[0008] One embodiment of the present disclosure provides a niobium silicide-based alloy comprising about 14 atomic percent to about 24 atomic percent titanium (Ti), about 11 atomic percent to about 19 atomic percent silicon (Si), about 4 atomic percent to about 8 atomic percent chromium (Cr), about 2 atomic percent to about 6 atomic percent hafnium (Hf), up to about 4 atomic percent aluminum (Al), about 0.5 atomic percent to about 1 atomic percent tin (Sn), about 5 atomic percent to about 15 atomic percent tantalum (Ta), about 1 atomic percent to about 5 atomic percent tungsten (W), up to about 5 atomic percent rhenium (Re), up to about 5 atomic percent zirconium (Zr), up to about 6 atomic percent yttrium (Y), and the balance niobium (Nb).

[0009] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the sum of the atomic percentage of zirconium (Zr) and the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

[0010] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the atomic percent of zirconium (Zr) is from about 0.1 atomic percent to about 5 atomic percent.

[0011] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the atomic percent of yttrium (Y) is from about 0.1 atomic percent to about 6 atomic percent.

[0012] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the sum of the atomic percentage of tantalum (Ta) and the atomic percentage of tungsten (W) present in the niobium silicide-based alloy is between about 5 atomic percent and about 20 atomic percent.

[0013] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the atomic percent of tantalum (Ta) is between about 5 atomic percent and about 10 atomic percent.

[0014] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the atomic percent of tungsten (W) is from about 2.5 atomic percent to about 5 atomic percent.

[0015] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the atomic percent of rhenium (Re) is from about 0.1 atomic percent to about 5 atomic percent.

[0016] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the niobium silicide-based alloy further includes up to about 5 atomic percent boron (B), or up to about 5 atomic percent carbon (C), or both.

[0017] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the niobium silicide-based alloy includes at least one metal phase, the metal phase comprising at least 40 volume percent of the niobium silicide-based alloy.

[0018] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the metallic phase includes between about 40 volume percent and about 60 volume percent of a niobium silicide-based alloy.

[0019] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the niobium silicide-based alloy further includes a tetragonal Nb5Si3 phase comprising at least 40 volume percent of the niobium silicide-based alloy.

[0020] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the niobium silicide-based alloy includes a tetragonal Nb5Si3 phase and a hexagonal Nb5Si3 phase, and the total volume percent of the tetragonal and hexagonal Nb5Si3 phases is about 40 volume percent to about 60 volume percent of the niobium silicide-based alloy.

[0021] Another aspect of the present disclosure includes any of the preceding aspects, wherein the niobium silicide-based alloy is resistant to oxidation at temperatures of about 1300°C.

[0022] One aspect of the present disclosure provides a turbine having at least a turbine component formed from a niobium silicide-based alloy, the niobium silicide-based alloy comprising: about 14 atomic percent to about 24 atomic percent titanium (Ti), about 11 atomic percent to about 19 atomic percent silicon (Si), about 4 atomic percent to about 8 atomic percent chromium (Cr), about 2 atomic percent to about 6 atomic percent hafnium (Hf), up to about 4 atomic percent aluminum (Al), about 0.5 atomic percent to about 1 atomic percent tin (Sn), about 5 atomic percent to about 15 atomic percent tantalum (Ta), about 1 atomic percent to about 5 atomic percent tungsten (W), up to about 5 atomic percent rhenium (Re), up to about 5 atomic percent zirconium (Zr), up to about 6 atomic percent yttrium (Y), and the balance niobium (Nb).

[0023] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the sum of the atomic percentage of zirconium (Zr) and the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

[0024] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the niobium silicide-based alloy further includes a tetragonal Nb5Si3 phase comprising at least 40 volume percent of the niobium silicide-based alloy.

[0025] Another embodiment of the present disclosure includes any of the preceding embodiments, wherein the sum of the atomic percentage of tantalum (Ta) and the atomic percentage of tungsten (W) present in the niobium silicide-based alloy is between about 5 atomic percent and about 20 atomic percent.

[0026] Another aspect of the present disclosure includes any of the preceding aspects, wherein the turbine component is one or more of a blade, a rotor, or a nozzle.

[0027] Another aspect of the present disclosure includes any of the preceding aspects, wherein the turbine is selected from the group consisting of a land-based turbine, a marine turbine, an aero turbine, and a power generation turbine.

[0028] Two or more aspects described in this disclosure, including those described in this Summary section, may be combined to form an embodiment not specifically described herein.

[0029] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description and drawings, and from the claims.

[0030] These and other features of the present disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure, taken in conjunction with the accompanying drawings which illustrate various embodiments of the disclosure. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a table of non-limiting examples of various Nb—Si-based alloys (Alloys A-K) with each composition listed in atomic percent (at%) for each respective Nb—Si-based alloy and baseline alloy, according to embodiments of the present disclosure. [Figure 2A] 2 is a scanning electron micrograph (SEM) of the microstructure of Nb—Si-based alloy A of the table of FIG. 1 according to an embodiment of the present disclosure. [Figure 2B] 2 is a scanning electron micrograph of the microstructure of Nb—Si-based alloy C of the table of FIG. 1 according to an embodiment of the present disclosure. [Figure 2C] 2 is a scanning electron micrograph of the microstructure of Nb—Si-based alloy D of the table of FIG. 1 according to an embodiment of the present disclosure. [Figure 3] 2 is a graph showing yield strength (megapascals, MPa) in compression at 1300° C. for alloys listed in the table of FIG. 1 according to an embodiment of the present disclosure. [Figure 4]2 is a graph showing metal loss (microns, μm) after cyclic oxidation at 1300° C. for 20 cycles (1 hour per cycle) for the alloys listed in the table of FIG. 1 according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0032] It should be noted that the drawings of the present disclosure are not necessarily to scale. The drawings are intended to illustrate only typical aspects of the present disclosure and therefore should not be considered as limiting the scope of the present disclosure. In the drawings, like numbers represent like elements between the drawings.

[0033] As an initial matter, a clear explanation of the subject matter of this disclosure requires the selection of certain terminology when referring to and describing the relevant mechanical components within this disclosure. Wherever possible, common industry terminology is used and employed in a manner consistent with its accepted meaning. Unless otherwise noted, such terminology should be given a broad interpretation consistent with the context of this application and the scope of the appended claims. Those skilled in the art will recognize that in many cases, a particular component may be referred to using several different or overlapping terms. What may be described herein as a single component may include and be referred to in other contexts as consisting of multiple components. Alternatively, what may be described herein as including multiple components may be referred to elsewhere as a single component.

[0034] The terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to denote the location or importance of the individual components.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. It will be further understood that the terms "comprise" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. "Optional" or "optionally" means that a described event or circumstance may or may not occur, or that a described component or element may or may not be present, and that the description includes instances in which the event occurs or the component is present as well as instances in which the event does not occur or the component is absent.

[0036] When an element or layer is referred to as "on," "engaged," "connected," or "coupled" to another element or layer, it can be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers may be present. Conversely, when an element is referred to as "directly on," "directly engaged," "directly connected," or "directly coupled" to another element or layer, there may not be intervening elements or layers. Other terms used to describe relationships between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent to" versus "directly adjacent to," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] As discussed above, the present disclosure provides Nb—Si-based alloys that have high temperature strength and environmental resistance.

[0038] While the oxidation performance and creep rupture resistance of known RMICs for turbine component applications are desirable, there remains a need for materials better suited for turbine / turbine component applications. For example, in applications where turbine components are subject to high stresses at temperatures ranging from about 1300°C to about 1700°C for extended periods of time, materials are needed that have both enhanced high temperature yield strength and oxidation resistance.

[0039] The present disclosure provides Nb-silicide-based alloys that balance mechanical properties such as high-temperature strength with environmental resistance, including oxidation resistance, making them suitable for a variety of applications, including, but not limited to, turbine components that are subject to high stresses at high temperatures for extended periods of time.

[0040] FIG. 1 is a table containing non-limiting examples of various Nb—Si-based alloys embodied by the present disclosure, listing the composition of each respective Nb—Si-based alloy in atomic percent (at%) of the elements. If an element is not present in an alloy sample listed in FIG. 1, a line is marked in the respective cell in the table of FIG. 1 for that element. Each alloy is identified by a sample ID (e.g., Alloy A, Alloy B, Alloy C, etc.). FIG. 1 further includes a baseline alloy, which is used as a reference alloy in all studies described in this disclosure. As shown in the table of FIG. 1, the baseline alloy does not contain Ta, Zr, Y, C, B, C, or Re. The baseline alloy is one type of alloy described in U.S. Pat. No. 6,419,765, where the atomic percentage of each element (Ti, Si, Cr, Hf, Al, Sn, and W) present in the baseline alloy is within the respective range of the atomic percentage of each respective element (Ti, Si, Cr, Hf, Al, Sn, and W) described in U.S. Pat. No. 6,419,765, and is generally represented herein as "X" for simplicity. The baseline alloy may be labeled "Baseline (US6419765)" in the drawings.

[0041] It is emphasized that the table in Figure 1 depicts non-limiting embodiments for illustrative purposes only, and that the examples depicted in Figure 1 are not intended to limit the present disclosure. For example, while specific atomic percentages of elements are included in each example alloy for illustrative purposes, the atomic percentages of each element are not limited to the specific values ​​listed in the table in Figure 1. Rather, the atomic percentages of each element in each alloy composition can be within their respective ranges described throughout this disclosure and embodied in the claims presented herein, including any value or subrange not specifically listed but within the respective ranges of each element described in this disclosure.

[0042] In embodiments, the niobium silicide-based alloys of the present disclosure include about 14 atomic percent to about 24 atomic percent titanium (Ti), about 11 atomic percent to about 19 atomic percent silicon (Si), about 4 atomic percent to about 8 atomic percent chromium (Cr), about 2 atomic percent to about 6 atomic percent hafnium (Hf), up to about 4 atomic percent aluminum (Al), about 0.5 atomic percent to about 1 atomic percent tin (Sn), about 5 atomic percent to about 15 atomic percent tantalum (Ta), about 1 atomic percent to about 5 atomic percent tungsten (W), up to about 5 atomic percent rhenium (Re), up to about 5 atomic percent zirconium (Zr), up to about 6 atomic percent yttrium (Y), and the balance niobium (Nb).

[0043] In embodiments, the atomic percent of titanium (Ti) in the niobium silicide-based alloys of the present disclosure can be from about 14 to about 24, e.g., about 14, about 15, about 16, about 17, about 18, about 19, about 20, about 21, about 22, about 23, about 24, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of titanium (Ti) in the niobium silicide-based alloy can be present in a range from about 14 to about 24 atomic percent, or from about 14 to about 20 atomic percent, or from about 20 to about 24 atomic percent, or from about 18 to about 22 atomic percent, or from about 19 to about 21 atomic percent.

[0044] In embodiments, the atomic percent of silicon (Si) in the niobium silicide-based alloys of the present disclosure can be from about 11 to about 19, e.g., about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of silicon (Si) in the niobium silicide-based alloy can be present in a range from about 11 to about 19 atomic percent, or from about 11 to about 15 atomic percent, or from about 15 to about 19 atomic percent, or from about 17 to about 19 atomic percent.

[0045] In embodiments, the atomic percent of chromium (Cr) in the niobium silicide-based alloys of the present disclosure can be from about 4 to about 8, e.g., about 4, about 5, about 6, about 7, about 8, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of chromium (Cr) in the niobium silicide-based alloy can be present in a range from about 4 to about 8 atomic percent, or from about 4 to about 6 atomic percent, or from about 6 to about 8 atomic percent, or from about 5 to about 7 atomic percent.

[0046] In embodiments, the atomic percent of hafnium (Hf) in the niobium silicide-based alloys of the present disclosure can be from about 2 to about 6, e.g., about 2, about 3, about 4, about 5, about 6, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of hafnium (Hf) in the niobium silicide-based alloy can be present in a range from about 2 to about 6 atomic percent, or from about 2 to about 4 atomic percent, or from about 4 to about 6 atomic percent, or from about 3 to about 5 atomic percent.

[0047] In embodiments, the atomic percent of aluminum (Al) in the niobium silicide-based alloys of the present disclosure can be from about 0 to about 4, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of aluminum (Al) in the niobium silicide-based alloy can be present in the range of about 0 to about 4 atomic percent, or about 0.1 to about 4 atomic percent, or about 0.5 to about 4 atomic percent, or about 1 to about 3 atomic percent, or about 1.5 to about 2.5 atomic percent.

[0048] In embodiments, the atomic percent of tin (Sn) in the niobium silicide-based alloys of the present disclosure can be from about 0.5 to about 1, e.g., about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, about 1, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of tin (Sn) in the niobium silicide-based alloy can be present in a range from about 0.5 to about 1 atomic percent, or from about 0.5 to about 0.75 atomic percent, or from about 0.75 to about 1 atomic percent, or from about 0.7 to about 0.8 atomic percent.

[0049] In embodiments, the atomic percent of tantalum (Ta) in the niobium silicide-based alloys of the present disclosure can be about 5 to about 15, e.g., about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of tantalum (Ta) in the niobium silicide-based alloy can be present in a range from about 5 to about 15 atomic percent, or from about 5 to about 10 atomic percent, or from about 10 to about 15 atomic percent, or from about 6.5 to about 8.5 atomic percent, or from about 7 to about 8 atomic percent, or from about 5 to about 8 atomic percent.

[0050] In embodiments, the atomic percent of tungsten (W) in the niobium silicide-based alloys of the present disclosure can be from about 1 to about 5, e.g., about 1, about 2, about 3, about 4, about 5, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of tungsten (W) in the niobium silicide-based alloy can be present in the range of about 1 to about 5 atomic percent, or about 1 to about 3 atomic percent, or about 2 to about 5 atomic percent, or about 2 to about 3 atomic percent, or about 2.5 to about 5 atomic percent, or about 3 to about 4 atomic percent.

[0051] In embodiments, the atomic percent of rhenium (Re) in the niobium silicide-based alloys of the present disclosure can be from about 0 to about 5, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of rhenium (Re) in the niobium silicide-based alloy can be present in a range from about 0 to about 5 atomic percent, or from about 0.1 to about 5 atomic percent, or from about 0.1 to about 2 atomic percent, or from about 0.5 to about 2.5 atomic percent.

[0052] In embodiments, the atomic percent of zirconium (Zr) in the niobium silicide-based alloys of the present disclosure can be from about 0 to about 5, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of zirconium (Zr) in the niobium silicide-based alloy can be present in a range from about 0.1 to about 5 atomic percent, or from about 0.1 to about 3 atomic percent, or from about 0.1 to about 2 atomic percent, or from about 0.1 to about 1.5 atomic percent, or from about 1.5 to about 5 atomic percent, or from about 1 to about 3 atomic percent, or from about 3 to about 5 atomic percent.

[0053] In embodiments, the atomic percent of yttrium (Y) in the niobium silicide-based alloys of the present disclosure can be from about 0 to about 6, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, about 6, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of yttrium (Y) in the niobium silicide-based alloy can be present in a range from about 0.1 to about 6 atomic percent, or from about 0.1 to about 5 atomic percent, or from about 0.1 to about 4 atomic percent, or from about 0.1 to about 3 atomic percent, or from about 0.1 to about 2 atomic percent, or from about 0.1 to about 1 atomic percent, or from about 0.2 to about 0.8 atomic percent.

[0054] In embodiments, the atomic percentage of zirconium (Zr) plus the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy can be from about 0.1 to about 11, e.g., about 0.1, about 0.2, about 0.5, about 1, about 1.5, about 2, about 2.5, about 3, about 3.5, about 4, about 4.5, about 5, about 5.5, about 6, about 7, about 8, about 9, about 10, about 11, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the sum of the atomic percentages of zirconium (Zr) and yttrium (Y) present in the niobium silicide-based alloy is in the range of about 0.1 atomic percent to about 11 atomic percent, about 0.2 atomic percent to about 11 atomic percent, or about 0.5 atomic percent to about 11 atomic percent, or about 0.5 atomic percent to about 6 atomic percent, or about 0.5 atomic percent to about 4 atomic percent, or about 0.5 atomic percent to about 2 atomic percent, or about 2 atomic percent to about 11 atomic percent, or about 2 atomic percent to about 6 atomic percent, or about 2.5 atomic percent to about 5.5 atomic percent, or about 3 atomic percent to about 11 atomic percent, or about 3 atomic percent to about 6 atomic percent.

[0055] In an embodiment, the sum of the atomic percentage of zirconium (Zr) and the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

[0056] In embodiments, the sum of the atomic percent of tantalum (Ta) and the atomic percent of tungsten (W) present in the niobium silicide-based alloy can be about 5 to about 20, e.g., about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, about 16, about 17, about 18, about 19, about 20, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the sum of the atomic percent of tantalum (Ta) and the atomic percent of tungsten (W) present in the niobium silicide-based alloy is within the range of about 5 atomic percent to about 20 atomic percent, about 5 atomic percent to about 15 atomic percent, about 7 atomic percent to about 15 atomic percent, about 10 atomic percent to about 18 atomic percent, about 10 atomic percent to about 15 atomic percent, about 12 atomic percent to about 16 atomic percent, or about 13 atomic percent to about 15 atomic percent.

[0057] In some embodiments, the niobium silicide-based alloy includes up to about 5 atomic percent boron (B), or up to about 5 atomic percent carbon (C), or both.

[0058] In embodiments, the niobium silicide-based alloys of the present disclosure may include up to about 5 atomic percent boron (B). The atomic percent of boron (B) can be from about 0 to about 5, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of boron (B) in the niobium silicide-based alloy may be present in a range from about 0 to about 5 atomic percent, or from about 0.1 to about 5 atomic percent, or from about 0.1 to about 4 atomic percent, or from about 0.1 to about 3 atomic percent, or from about 2 to about 4 atomic percent. In embodiments, the niobium silicide-based alloys of the present disclosure may include up to about 5 atomic percent carbon (C). The atomic percent of carbon (C) can be from about 0 to about 5, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the atomic percent of carbon (C) in the niobium silicide-based alloy can be present in a range from about 0 to about 5 atomic percent, or from about 0.1 to about 5 atomic percent, or from about 0.1 to about 4 atomic percent, or from about 0.1 to about 3 atomic percent, or from about 2 to about 4 atomic percent.

[0059] The niobium silicide-based alloys of the present disclosure may further include molybdenum (Mo) to tailor the alloy's properties for specific applications. In embodiments, the niobium silicide-based alloys may further include up to about 5 atomic percent of molybdenum (Mo). The atomic percent of molybdenum (Mo) can be about 0 to about 5, e.g., about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, or a range between any two of the above values. For example, in non-limiting embodiments, the atomic percent of molybdenum (Mo) in the niobium silicide-based alloy may be present in a range of about 0 to about 5 atomic percent, or about 0.1 to about 5 atomic percent, or about 0.1 to about 4 atomic percent, or about 0.1 to about 3 atomic percent, or about 0.1 to about 2 atomic percent, or about 0.1 to about 1.5 atomic percent.

[0060] Figure 2A is a scanning electron micrograph (SEM) of the microstructure of Nb—Si-based alloy A from the table in Figure 1, Figure 2B is a scanning electron micrograph of the microstructure of Nb—Si-based alloy C from the table in Figure 1, and Figure 2C is a scanning electron micrograph of the microstructure of Nb—Si-based alloy D from the table in Figure 1 according to an embodiment of the present disclosure. The materials used for the SEM images were prepared by arc-melting the respective alloys followed by heat treatment at 1400°C for 6 hours.

[0061] The Nb—Si-based alloys of the present disclosure include at least one metallic phase (e.g., "Nb-bcc" as shown in FIGS. 2A-2C). In embodiments, the metallic phase comprises at least 40 volume percent of the Nb—Si-based alloy. In some embodiments, the metallic phase comprises between about 40 volume percent and about 60 volume percent of the Nb—Si-based alloy.

[0062] Nb silicide in Nb-Si-based alloys can exist in two phases: the tetragonal Nb5Si3 phase (e.g., "Nb5Si3(tI32)") and / or the hexagonal Nb5Si3 phase ("Nb5Si3(hP16)"), as shown in Figures 2A-2C. The tetragonal Nb5Si3 phase is desirable for certain mechanical properties of Nb-Si-based alloys, such as increased creep strength, while the hexagonal Nb5Si3 phase is generally undesirable due to reduced creep strength.

[0063] In certain embodiments, the Nb—Si-based alloy includes a tetragonal Nb5Si3 phase with at least 40 volume percent of the Nb—Si-based alloy. In some embodiments, the Nb—Si-based alloy includes a tetragonal Nb5Si3 phase and a hexagonal Nb5Si3 phase, and the total volume percent of the tetragonal and hexagonal Nb5Si3 phases is about 40 volume percent to about 60 volume percent of the Nb—Si-based alloy.

[0064] The compositions of alloys A, C, and D used in Figures 2A, 2B, and 2C, respectively, are the same as alloys A, C, and D in the table of Figure 1 and are listed below.

[0065] [Table 1]

[0066] As noted above, the main difference between alloys A, C, and D is the atomic percentage of W and Ta in the Nb-Si based alloys. Alloy A contains 5 at% Ta, while alloy C contains an additional 5 at% W compared to alloy A, and alloy D contains an even higher 10 at% Ta and 3.5 at% W.

[0067] As shown in FIG. 2A, in Alloy A, the majority of the Nb silicide exists in the tetragonal phase, while only a small portion of the Nb silicide exists in the hexagonal phase. The microstructure shown in FIG. 2B for Alloy C indicates that the addition of 5 at.% W to Alloy A significantly increases the proportion of the hexagonal phase, with the tetragonal and hexagonal phases in a ratio of approximately 1:1 based on the volume percent of each phase. However, with a higher Ta addition (10 at.% Ta), as shown in FIG. 2C, Nb silicide exists almost exclusively in the tetragonal phase in Alloy D, while allowing for a certain atomic percent of W (e.g., 3.5 at.% in Alloy D) to be accommodated in the alloy. Having the ability to add a moderate amount of W is beneficial because the addition of W can contribute to a high yield strength (MPa) in compression at 1300°C, as discussed in more detail below with respect to FIG. 3.

[0068] In summary, a comparison of the SEM results for alloys A, C, and D shows that (1) in the W-free alloys, the majority of Nb silicide exists in the tetragonal phase, (2) the addition of 5 at% W increases the proportion of the undesirable hexagonal phase, and (3) the addition of large amounts of Ta offers a surprising advantage, significantly stabilizing the proportion of the desirable tetragonal phase and eliminating the undesirable hexagonal phase while allowing a moderate amount of W to be present in the alloy. This further demonstrates that the delicate balance between alloy elements (e.g., Ta, W) can play a critical role in the alloy microstructure, which in turn can affect the alloy's mechanical properties and environmental resistance.

[0069] FIG. 3 is a graph showing yield strength (MPa) in compression at 1300° C. for the baseline alloy and alloys A-K listed in the table of FIG. 1 according to an embodiment of the present disclosure.

[0070] As shown in Figure 3, all alloys A-K exhibit significantly higher yield strengths (MPa) in compression at 1300°C compared to the baseline alloy. Importantly, the presence of Ta and W contributes significantly to the high yield strength of Nb-Si-based alloys. For example, comparing the baseline alloy with alloys A-F, the contribution of Ta to the high yield strengths (MPa) in compression at 1300°C was calculated to be approximately 7-10 MPa / at%, while the contribution of W to the high yield strengths (MPa) in compression at 1300°C was calculated to be approximately 40-60 MPa / at%. The addition of Ta and W is beneficial to the high yield strength of Nb-Si-based alloys.

[0071] Furthermore, when comparing Alloy B with Alloys G and H (compositions listed in the table in Figure 1 and transcribed below), it can be seen that the primary difference between Alloys B, G, and H is the atomic percentage of Zr and Y in each respective Nb-Si based alloy.

[0072] [Table 2]

[0073] As shown in Figure 3, both alloys G and H have higher yield strength (MPa) under compression at 1300°C than alloy B. The combined addition of Zr and Y contributes to improving the yield strength of Nb-Si based alloys.

[0074] It should be noted that the alloy sample used in Figure 3 is a non-limiting embodiment. In certain embodiments, the sum of the atomic percent of zirconium (Zr) and the atomic percent of yttrium (Y) present in the niobium silicide-based alloy can be from about 0.1 to about 11, such as about 0.1, about 0.2, about 0.5, about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, or a range between any two of the foregoing values. For example, in non-limiting embodiments, the sum of the atomic percentages of zirconium (Zr) and yttrium (Y) present in the niobium silicide-based alloy is in the range of about 0.1 atomic percent to about 11 atomic percent, about 0.2 atomic percent to about 11 atomic percent, or about 0.5 atomic percent to about 11 atomic percent, or about 0.5 atomic percent to about 6 atomic percent, or about 0.5 atomic percent to about 4 atomic percent, or about 0.5 atomic percent to about 2 atomic percent, or about 2 atomic percent to about 11 atomic percent, or about 2 atomic percent to about 6 atomic percent, or about 3 atomic percent to about 11 atomic percent, or about 3 atomic percent to about 6 atomic percent.

[0075] In an embodiment, the sum of the atomic percentage of zirconium (Zr) and the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

[0076] FIG. 4 shows the results of 20 cycles at 1300°C ( 1 hour per cycle 1 is a graph showing metal loss (microns, μm) after cyclic oxidation of t0 and t1. Each respective alloy was heated at 1300°C for 1 hour for each of 20 cycles. Metal loss was calculated by measuring the initial thickness (μm) of the coupon (t0) and measuring the thickness (μm) of the remaining metal thickness (t1) after exposure. In this case, metal loss (μm) is defined / calculated by (t0-t1) / 2.

[0077] The results in FIG. 4 (based on alloys A-J listed in the table in FIG. 1) and other previous results show the following:

[0078] (1) The addition of Ta or W affects metal thinning.

[0079] The primary difference between Alloys A, E, and F is their respective atomic percentages of Ta and / or W. Alloy A contains 5 at% Ta, Alloy E contains 5 at% W, and Alloy F contains 10 at% W. Alloys A, E, and F are listed in the table in Figure 1 and transcribed below.

[0080] [Table 3]

[0081] Compared to Ta, W appears to have a less detrimental effect on increasing metal loss. For example, Alloy E, containing 5 at% W, has a less detrimental effect on increasing metal loss than Alloy A, containing 5 at% Ta. As shown in Figure 3, moderate amounts of W (e.g., 5 at%) can be incorporated into the alloy without significantly affecting the alloy's oxidation profile. However, as can be seen from a comparison of Alloy F (10 at% W) and Alloy E (5 at% W), higher W additions result in much greater metal loss. This further demonstrates the delicate balancing effect of selecting the desired elements and values / ranges in Nb-Si-based alloys. While W has been shown to significantly contribute to the desired high yield strength (as discussed with respect to Figure 3), higher W additions can adversely affect the microstructure (as discussed with respect to Figures 2A-2C), potentially resulting in much greater metal loss. Additionally, Ta (e.g., 5 at% and 10 at% Ta as described with respect to FIGS. 2A-2C) has been shown to help stabilize the desired tetragonal Nb5Si3 phase, but 5 at% Ta has been shown to increase metal loss in the alloy and adversely affect oxidation.

[0082] (2) Alloys with both Ta and W (Alloys B, C, and D) exhibit much reduced metal loss than alloys containing only either Ta (Alloy A) or W (Alloys E and F).

[0083] Surprisingly, the inventors of the present disclosure have discovered that a synergistic effect of the combined addition of Ta and W exists in the Nb—Si alloys embodied in the present disclosure. Alloys A through F are listed in the table of FIG. 1 and are reproduced below.

[0084] [Table 4]

[0085] As shown above, alloys B and C contain an additional 2.5 at% and 5 at% W, respectively, compared to alloy A. As shown in Figure 4, both alloys B and C have much reduced metal loss compared to alloy A. Furthermore, alloy D, which has a higher total atomic percentage of Ta and W, exhibits the most reduced metal loss compared to alloys A, B, and C. Furthermore, surprisingly, as the sum of the atomic percentages of Ta and W present in the Nb-Si-based alloy increases (e.g., from A (Ta+W at%=5) to B (Ta+W at%)=7.5), to C (Ta+W at%)=10, to D (Ta+W at%)=13.5), the metal loss decreases significantly. ) , the metal loss of each alloy is reduced.

[0086] The above observations (1) and (2) indicate that both the individual atomic percentages of Ta and W, as well as the total atomic percentage of Ta and W, play important roles in developing Nb-Si-based alloys with desirable microstructures, high mechanical strength, and robust oxidation resistance. The combined addition of Ta and W in Nb-Si alloys results in unexpected advantageous synergistic effects.

[0087] It should be noted that the alloy samples used in Figure 4 and the total atomic percentage of Ta and W present in each alloy sample are non-limiting examples. The total atomic percentage of Ta and W present in the niobium silicide-based alloys can be any value or range described in previous sections of this disclosure and are omitted here for brevity.

[0088] (3) The combined addition of Zr and Y reduces metal loss.

[0089] For example, alloys B, G, and H are listed in the table in Figure 1 and are reproduced below.

[0090] [Table 5]

[0091] The main difference between alloys B, G, and H is the atomic percentage of Zr and Y in the Nb-Si-based alloys. As shown in Figure 4, both alloys G and H have much reduced metal loss at 1300°C than alloy B. The combined addition of Zr and Y contributes to the significantly improved oxidation resistance of the Nb-Si-based alloys.

[0092] It should be noted that the alloy samples used in Figure 4 are non-limiting embodiments. In certain embodiments, the atomic percentage of zirconium (Zr) plus the atomic percentage of yttrium (Y) present in the niobium silicide-based alloy can be any value or range described in previous sections of this disclosure and will be omitted here for brevity.

[0093] With reference to both FIG. 3 and FIG. 4, it can be further seen that:

[0094] (4) Adding carbon (C) to Nb-Si based alloys improves the yield strength and reduces metal loss in Nb-Si based alloys.

[0095] For example, alloys B, G, H, and K are listed in the table in Figure 1 and have compositions reproduced below.

[0096] [Table 6]

[0097] As shown in Figure 3, alloys G, H, and K all have increased yield strength and reduced metal loss at 1300°C compared to alloy B. In addition, alloy K has yield strength and metal loss at 1300°C that are comparable to those of alloys G and H. The addition of carbon (C) contributes to improved mechanical strength and oxidation resistance in Nb-Si based alloys.

[0098] In certain embodiments, the atomic percentage of carbon (C) present in the niobium silicide-based alloy can be any value or range described in previous sections of this disclosure and will be omitted here for the sake of brevity.

[0099] (5) The addition of rhenium (Re) to Nb-Si based alloys is acceptable and does not adversely affect the metal loss of Nb-Si based alloys.

[0100] For example, alloy J (listed in the table in Figure 1) containing about 1.5 at% Re has both high yield strength (>300 MPa) and low metal loss (similar to alloys G and H) at 1300°C.

[0101] The Nb—Si-based alloys of the present disclosure can be used in high-temperature applications requiring high temperatures (e.g., above about 1300°C) and are resistant to oxidation at such high temperatures. In embodiments, the Nb—Si-based alloys of the present disclosure are resistant to oxidation at temperatures of about 1300°C. The Nb—Si-based alloys of the present disclosure may find potential use in applications where temperatures range from about 1300°C to about 1700°C. The Nb—Si-based alloys of the present disclosure successfully achieve balanced mechanical properties and environmental resistance by controlling the balancing effects of various compositions in the alloy. For example, by utilizing the various interactive effects of the atomic percentages of Ta, W, Zr, Y, B, C, and Re, the combined total of Ta and W additions, and the combined total of Zr and Y, alloys with desirable mechanical properties and environmental resistance can be developed for applications including, but not limited to, turbines or turbine components that are subject to high stress at high temperatures for extended periods of time.

[0102] The Nb-Si-based alloys of the present disclosure can be used in turbines or turbine components. In embodiments, the turbine has at least a turbine component formed from a niobium silicide-based alloy containing about 14 atomic percent to about 24 atomic percent titanium (Ti), about 11 atomic percent to about 19 atomic percent silicon (Si), about 4 atomic percent to about 8 atomic percent chromium (Cr), about 2 atomic percent to about 6 atomic percent hafnium (Hf), up to about 4 atomic percent aluminum (Al), about 0.5 atomic percent to about 1 atomic percent tin (Sn), about 5 atomic percent to about 15 atomic percent tantalum (Ta), about 1 atomic percent to about 5 atomic percent tungsten (W), up to about 5 atomic percent rhenium (Re), up to about 5 atomic percent zirconium (Zr), up to about 6 atomic percent yttrium (Y), and the balance niobium (Nb).

[0103] In an embodiment, the sum of the atomic percentage of zirconium (Zr) and the atomic percentage of yttrium (Y) present in the Nb—Si based alloy in the turbine component is between about 0.2 atomic percent and about 11 atomic percent.

[0104] In an embodiment, the Nb-Si based alloy in the turbine component further comprises a tetragonal Nb5Si3 phase comprising at least 40 volume percent of the niobium silicide based alloy.

[0105] In an embodiment, the turbine component is one or more of a blade, a rotor, or a nozzle.

[0106] In an embodiment, the turbine is selected from the group consisting of a land-based turbine, a marine turbine, an aero turbine, and a power generation turbine.

[0107] The above figures illustrate some of the processes involved in some embodiments of the present disclosure. In this regard, each figure or block within the flow diagrams of the figures represents a process associated with the described method embodiment. It should also be noted that in some alternative implementations, the actions shown in the figures or blocks may occur out of the order shown in the figures, or may actually be performed substantially simultaneously or in reverse order, depending on the actions involved, for example. Those skilled in the art will also recognize that additional blocks describing the processes may be added.

[0108] As used herein throughout the present specification and claims, approximation language may be applied to modify any quantitative expression that can reasonably vary without resulting in a change in the relevant basic function. Thus, values ​​modified by one or more terms such as "about," "approximately," and "substantially" are not limited to the exact value specified. In at least some cases, approximation language may correspond to the precision of the instrument used to measure the value. Here, and throughout the present specification and claims, range limitations may be combined and / or substituted, and unless the context or language dictates otherwise, such ranges are identified and include all subranges encompassed therein. "Approximately," as applied to a particular value in a range, applies to both endpoints and may indicate + / - 10% of the stated value(s), unless specifically reliant on the precision of the instrument used to measure the value.

[0109] The corresponding structure, material, acts, and equivalents of all means-plus-function or step-plus-function elements in the following claims are intended to include any structure, material, or acts for performing that function in combination with other specifically claimed elements. The description of the present disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The embodiments were chosen and described to best explain the principles and practical applications of the disclosure and to enable others skilled in the art to understand the disclosure in various embodiments with various modifications suitable for the particular uses envisioned.

Claims

1. about 14 atomic percent to about 24 atomic percent titanium (Ti); about 11 atomic percent to about 19 atomic percent silicon (Si); about 4 atomic percent to about 8 atomic percent chromium (Cr); about 2 atomic percent to about 6 atomic percent hafnium (Hf); up to about 4 atomic percent aluminum (Al); about 0.5 atomic percent to about 1 atomic percent tin (Sn); about 5 atomic percent to about 15 atomic percent tantalum (Ta); about 1 atomic percent to about 5 atomic percent tungsten (W); up to about 5 atomic percent rhenium (Re); up to about 5 atomic percent zirconium (Zr); up to about 6 atomic percent yttrium (Y), and The balance is niobium (Nb).

1. A niobium silicide-based alloy comprising:

2. 2. The niobium silicide-based alloy of claim 1, wherein the sum of the atomic percent of said zirconium (Zr) and the atomic percent of said yttrium (Y) present in said niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

3. The niobium silicide-based alloy of claim 1, wherein the atomic percent of zirconium (Zr) is between about 0.1 atomic percent and about 5 atomic percent.

4. 2. The niobium silicide-based alloy of claim 1, wherein the atomic percent of yttrium (Y) is between about 0.1 atomic percent and about 6 atomic percent.

5. 2. The niobium silicide-based alloy of claim 1, wherein the sum of the atomic percent of tantalum (Ta) and the atomic percent of tungsten (W) present in the niobium silicide-based alloy is between about 5 atomic percent and about 20 atomic percent.

6. The niobium silicide-based alloy of claim 1, wherein the atomic percent of tantalum (Ta) is between about 5 atomic percent and about 10 atomic percent.

7. The niobium silicide-based alloy of claim 1, wherein the atomic percent of tungsten (W) is between about 2.5 atomic percent and about 5 atomic percent.

8. The niobium silicide-based alloy of claim 1, wherein the atomic percent of rhenium (Re) is between about 0.1 atomic percent and about 5 atomic percent.

9. 10. The niobium silicide-based alloy of claim 1, further comprising up to about 5 atomic percent boron (B), or up to about 5 atomic percent carbon (C), or both.

10. 2. The niobium silicide-based alloy of claim 1, wherein said niobium silicide-based alloy includes at least one metallic phase, said metallic phase comprising at least 40 volume percent of said niobium silicide-based alloy.

11. The niobium silicide-based alloy of claim 10, wherein the metallic phase comprises between about 40 volume percent and about 60 volume percent of the niobium silicide-based alloy.

12. The niobium silicide-based alloy contains tetragonal Nb 2 O 3 comprising at least 40 volume percent of the niobium silicide-based alloy. ５ Si ３ The niobium silicide-based alloy of claim 10 further comprising a phase.

13. The niobium silicide-based alloy is a tetragonal Nb ５ Si ３ phase and hexagonal Nb ５ Si ３ phase, and the tetragonal and hexagonal Nb ５ Si ３ The niobium silicide-based alloy of claim 1, wherein the total volume percent of phases is between about 40 volume percent and about 60 volume percent of the niobium silicide-based alloy.

14. The niobium silicide-based alloy of claim 1 , wherein the niobium silicide-based alloy is resistant to oxidation at temperatures of about 1300° C.

15. 1. A turbine having at least a turbine component formed from a niobium silicide-based alloy, the niobium silicide-based alloy comprising: about 14 atomic percent to about 24 atomic percent titanium (Ti); about 11 atomic percent to about 19 atomic percent silicon (Si); about 4 atomic percent to about 8 atomic percent chromium (Cr); about 2 atomic percent to about 6 atomic percent hafnium (Hf); up to about 4 atomic percent aluminum (Al); about 0.5 atomic percent to about 1 atomic percent tin (Sn); about 5 atomic percent to about 15 atomic percent tantalum (Ta); about 1 atomic percent to about 5 atomic percent tungsten (W); up to about 5 atomic percent rhenium (Re); up to about 5 atomic percent zirconium (Zr); up to about 6 atomic percent yttrium (Y), and The balance is niobium (Nb), Turbine.

16. The turbine of claim 15, wherein the sum of the atomic percent of the zirconium (Zr) and the atomic percent of the yttrium (Y) present in the niobium silicide-based alloy is between about 0.2 atomic percent and about 11 atomic percent.

17. The turbine of claim 15, wherein the atomic percent of the tantalum (Ta) plus the atomic percent of the tungsten (W) present in the niobium silicide-based alloy is between about 5 atomic percent and about 20 atomic percent.

18. The niobium silicide-based alloy contains tetragonal Nb 2 O 3 comprising at least 40 volume percent of the niobium silicide-based alloy. ５ Si ３ The turbine of claim 15 further comprising a phase.

19. The turbine of claim 15 , wherein the turbine component is one or more of a blade, a rotor, or a nozzle.

20. The turbine of claim 15 , wherein the turbine is selected from the group consisting of a land-based turbine, a marine turbine, an aero turbine, and a power generation turbine.

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