Repair of polycrystalline layers

Abstract

Additive manufacturing of single crystal materials results in polycrystalline layers or grains, which may be reduced or eliminated by treatment with Al or optionally Pt. The thinning of the polycrystalline layer may be performed without mechanical or chemical removal of the polycrystalline material. A workpiece formed by the process may include a single crystal substrate; an interdiffusion region on the substrate; and a thermal barrier coating over the interdiffusion region, and the interdiffusion region diffuses the polycrystalline layer such that post-processing required to remove the polycrystalline layer is not required.

Description

[0001] This application claims priority to U.S. Provisional Application 63 / 539,929, filed September 22, 2023, entitled “Repair of Polymer Layers,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The implementation generally involves the repair of polycrystalline (PX) layers generated during additive manufacturing of objects formed from superalloys or steel. Background Technology

[0003] Traditionally, the Bridgman process has been used to produce high-strength and heat-resistant single-crystal (SX) workpieces, such as turbine blades for aerospace applications. The Bridgman technique involves slowly cooling molten material by moving a container of molten material from a hot zone to a cold zone. To promote crystal growth, the end of the container where crystal growth begins can be elongated, and a seed crystal can be placed at that end. The presence of the seed crystal requires precise temperature control at the interface, and in many cases, crystal growth occurs without a seed crystal. In the original Bridgman technique, the cold zone was outside the furnace, so the temperature gradient was not well defined.

[0004] Bridgman technology uses "hot" and "cold" zones to create a temperature difference within the furnace, such as... Figure 1 As shown. Hot zone 10 is maintained at a temperature above the melting point of material 20. For superalloys, the metal is melted in a separate crucible (not shown). Once the metal is at the correct temperature and the mold 30 is at the correct temperature, the molten metal is poured into the mold. The mold has a predetermined shape, which is the desired shape of the end-use part. The precursor material is a melt in hot zone 10 and is transferred to cold zone 50 by movement. The material solidifies 40 as it moves through the temperature gradient in the furnace. The Bridgman method can be performed in a vertical configuration.

[0005] The improved Bridgman method, known as the Bridgman-Stockbarger technique, features two well-controlled temperature zones, achieved by employing two separate furnaces with baffles between them. Some variations of the Bridgman and Bridgman-Stockbarger techniques include rotating containers and horizontal arrangements of one or more furnaces. Important considerations during crystal growth are the mold material, the temperature of the hot zones, the temperature gradient, and the cooling rate. The container should have minimal reactivity with the sample and withstand the temperature and ambient conditions during growth.

[0006] In recent years, there has been widespread interest in using additive manufacturing (AM) (a modified form of 3D printing) to manufacture SX parts (such as turbine blades). Figure 2The diagram shows the additive manufacturing process.

[0007] exist Figure 2 In this process, powder feeder 110 deposits powder 112 to create a powder layer 105 in powder bed 108. The first deposited powder layer may be located directly on the powder bed or on a substrate placed in the powder bed before powder layer deposition. Beam scanner 101 may move beam source 102 or manipulate energy beam 111 generated by the beam source. The energy beam may be a laser beam, electron beam, etc. Energy beam 111 creates a molten pool 104 in which some of the powder in powder bed 108 is melted. Molten pool 104 has a molten pool depth 103. Molten pool depth 103 is shown to be large enough to also melt some patterned layers 106 directly below powder layer 105. Beam scanner moves molten pool 104 in a path through the topmost powder layer to selectively melt some of the powder, thereby creating patterned layers. The first deposited powder layer becomes the bottom patterned layer 107. Patterned layers are created by iteratively depositing powder layers and using an energy beam to melt patterns into the powder layers to print 3D objects.

[0008] Figure 3 This is a high-level concept diagram illustrating a scan pattern 200 having a melt pool 104 and a shadow distance 203 according to some aspects. The scan pattern 200 may include a large number of scan lines 201 that can be parallel to each other, such as... Figure 3 As shown. The shadow distance 203 is the distance between scan lines 201. The shadow direction is the direction from the previous scan line to the subsequent scan line in the scan pattern. The shadow direction 204 can be perpendicular to the scan line 201. The beam scanner moves the molten pool 104 along the scan pattern. For simplicity, the molten pool is shown as circular, where the energy beam 111 contacts the powder layer and melts the powder at that location. In practice, the molten pool is much longer because the energy beam melts the material in a pattern, and the molten material remains molten for a short time.

[0009] In other words, laser powder bed melting (AM) of metals (such as steel and nickel superalloys) is carried out in a protective chamber with a dynamic inert gas flow (e.g., argon or nitrogen) to prevent oxidation or gas dissolution and to remove welding byproducts such as soot and spatter. To melt specific locations, a laser or electron beam is scanned across the top of the powder bed with different focal sizes and powers. Absorption of the laser beam leads to melting of the powder in the i-th layer and some remelting of the (i-1)-th solid layer. The kinetics of the melt and the shape of the molten pool are determined by the scanning strategy in the xy-plane. With a predetermined geometric cross-section in the z-direction, the evolution of porosity, cracks, solidification grain structure, solid-state transformation, and plastic deformation can be observed. Furthermore, all of the above physical phenomena lead to spatial variations in microstructure and properties. Moreover, the resulting workpiece may not have a uniform single crystallinity and may contain polycrystalline grains or even polycrystalline boundary layers.

[0010] Therefore, there is a need in the art for additive manufacturing of single-crystal metal products with reduced defects (including polycrystalline defects). Summary of the Invention

[0011] The following summary is provided to facilitate understanding of some innovative features specific to the disclosed embodiments and is not intended to be an exhaustive description. A full understanding of the various aspects of the embodiments can be obtained by considering the entire specification, claims, drawings, and abstract as a whole.

[0012] Therefore, one aspect of the disclosed embodiments is to minimize or eliminate polycrystalline shells, which are byproducts of additive manufacturing of single-crystal (SX) metal components.

[0013] In this disclosure, the workpiece formed by additive manufacturing may include a single crystal substrate and an interdiffusion zone (IDZ) above the substrate, the interdiffusion zone comprising the same material as the single crystal substrate plus a certain amount of at least one of Al or Pt.

[0014] The thickness of the interdiffusion region is approximately 1 μm to 200 μm or 1 μm to 20 μm. The interdiffusion region may include a β phase (body-centered cubic). The workpiece may include a thermal barrier coating formed of ceramic. The thermal barrier coating may be a ceramic containing yttria-stabilized zirconia. The yttria-stabilized zirconia may contain approximately 4-7% by weight of yttria. The substrate may be a nickel alloy.

[0015] In this disclosure, the process of manufacturing the workpiece may include forming a single-crystal substrate by additive manufacturing, and treating the polycrystalline layer with at least one of Al or Pt to form interdiffusion regions.

[0016] The polycrystalline layer can be treated by vapor phase aluminide (VPA) to form a nickel aluminum compound containing at least one of Ni3Al, NiAl, or NiAl3. The polycrystalline layer is treated by vapor phase aluminide to produce an interdiffusion region thickness of about 1 to 200 μm or about 1 to 20 μm. The interdiffusion region may include a β phase.

[0017] In this disclosure, the single-crystal substrate is formed by the following sequential steps: depositing a metal powder coating, and then molten powder coating. The polycrystalline layer can be thinned without mechanical polishing or chemical treatment. Alternatively, the polycrystalline layer can be thinned without mechanical polishing or chemical treatment before or after treatment with at least one of Al or Pt.

[0018] The method disclosed herein may further include forming a thermally adhesive coating over the interdiffusion region, the thermally adhesive coating comprising at least one material selected from titanium dioxide, zirconium oxide, alumina, ceramic, mullite, pyrochlore, garnet, monazite, perovskite, or lanthanum magnesium hexaaluminate. Attached Figure Description

[0019] The accompanying drawings further illustrate embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein. In the drawings, the same reference numerals refer to the same or functionally similar elements throughout the individual views, and the drawings are incorporated in and form a part of the specification.

[0020] Figure 1 The formation of single-crystal workpieces via the Bridgman process is depicted.

[0021] Figure 2 It describes the formation of single-crystal workpieces through additive manufacturing.

[0022] Figure 3 This is a conceptual diagram showing a scanned pattern with a molten pool.

[0023] Figure 4 This is a diagram of creep fracture in Rene alloy.

[0024] Figure 5 An electron micrograph of a single-crystal workpiece is shown.

[0025] Figure 6 An electron micrograph of a single-crystal workpiece with polycrystalline layers is shown.

[0026] Figure 7 An electron micrograph of the expected cross-section of the workpiece according to this disclosure is shown. Detailed Implementation

[0027] The specific values ​​and configurations discussed in the following non-limiting examples may vary and are cited only to illustrate one or more implementations and are not intended to limit their scope.

[0028] Example embodiments will now be described more fully below with reference to the accompanying drawings, in which illustrative embodiments are shown. The embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to those set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. The same reference numerals throughout denote the same elements.

[0029] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that, when used in this specification, the terms “comprising” and / or “including” specify the presence of the 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.

[0030] Throughout the specification and claims, terms may have subtle meanings beyond those explicitly stated, implied or suggested in the context. Similarly, the phrase "in one embodiment" as used herein does not necessarily refer to the same embodiment, and the phrase "in another embodiment" as used herein does not necessarily refer to different embodiments. For example, the claimed subject matter is intended to include combinations of all or some of the exemplary embodiments.

[0031] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which the exemplary embodiments pertain. It will also be understood that terms such as those defined in common dictionaries shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field, and shall not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0032] It is anticipated that any embodiments discussed in this specification can be implemented with respect to any method, kit, reagent, or composition of the present invention, and vice versa. Furthermore, the compositions of the present invention can be used to implement the methods of the present invention.

[0033] It should be understood that the specific embodiments described herein are illustrated by way of illustration and not intended to limit the invention. The main features of the invention may be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize or be able to determine many equivalents of the specific procedures described herein using only conventional experimentation. Such equivalents are considered to be within the scope of the invention and are covered by the claims.

[0034] When used in conjunction with the term “comprising” in the claims and / or description, the use of the words “a” or “an” can mean “one”, but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more.” The term “or” is used in the claims to mean “and / or” unless it is explicitly stated that it refers only to alternatives or that the alternatives are mutually exclusive, although this disclosure supports the definition of “and / or” throughout this application. The term “about” is used to indicate values ​​including inherent variations in the error of the apparatus, variations in the method used to determine the value, or variations that exist between study subjects.

[0035] As used in this specification and claims, the words “comprising” (and any form of inclusion, such as “comprising” and “including”), “having” (and any form of having, such as “having” and “having”), “containing” (and any form of inclusion, such as “containing” and “containing”), or “containing” (and any form of containing, such as “containing” and “containing”) are inclusive or open-ended and do not exclude additional, unlisted elements or method steps.

[0036] As used herein, the term "or a combination thereof" refers to all permutations and combinations of the items listed preceding the term. For example, "A, B, C, or a combination thereof" is intended to include at least one of the following: A, B, C, AB, AC, BC, or ABC, and also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB if the order is significant in the particular context. Continuing with this embodiment, explicitly included are combinations containing repetitions of one or more items or terms, such as BB, AAA, AB, BBC, AAABCC, CBBAAA, CABABB, etc. Those skilled in the art will understand that there is generally no limitation on the number of items or terms in any combination unless obvious from the context.

[0037] All compositions and / or methods disclosed and claimed herein can be prepared and performed without excessive experimentation based on this disclosure. While the compositions and methods of the invention have been described according to preferred embodiments, it will be apparent to those skilled in the art that variations may be made to the compositions and / or methods described herein, as well as the steps or order of steps of the methods, without departing from the concept, spirit, and scope of the invention. All such similar substitutions and modifications that are apparent to those skilled in the art are considered to be within the spirit, scope, and concept of the invention as defined by the appended claims.

[0038] Therefore, one aspect of the disclosed embodiments is to minimize or eliminate polycrystalline shells as a byproduct of additive manufacturing (AM) of single-crystal (SX) metal parts.

[0039] The materials used in AM (Advanced Metallurgy) are single-crystal nickel superalloys due to their high-temperature properties and tendency to form a heat-resistant β phase when treated with Al or optionally Pt. In nickel superalloys, the β crystal structure is typically body-centered cubic (BCC) austenite. Examples of such alloys include Hastelloy, Inconel, Waspaloy, René, Incoloy, MP98T, TMS, and CMSX single-crystal alloys.

[0040] Conventional nickel superalloys are represented by Rene alloys such as Rene N5 or Rene 125. Typical formulations for these types of alloys are listed in Table 1.

[0041] Table 1. Typical alloy composition

[0042] In Hastelloy, Hastelloy C22 has a composition (wt%) of 56% Ni, 22% Cr, and 13% Mo, with added iron, tungsten, and cobalt. Hastelloy C-276 has a composition (wt%) of 57% Ni, 15-17% Mo, 14.5-16.5% Cr, 4-7% Fe, 3-4.5% W, 1% max Mn, 2.5% max Co, 0.35% max V, and 0.08% max Si. In Inconel, Inconel 600 has 72% Ni, 14-17% Cr, 6-10% Fe, and 1% Mn, as well as trace amounts of Cu, Si, C, and S.

[0043] During the AM process, after depositing the i-th layer of powder, the i-th layer can be melted by an electron beam or a laser beam. If an electron beam is used to melt the i-th layer, the median particle size of the nickel alloy is in the range of approximately 40 μm to 105 μm. If a laser beam is used to melt the i-th layer, the median particle size can be in the range of approximately 15 μm to 55 μm. The i-1-th layer is used as a seed crystal to make the i-th layer the SX layer.

[0044] The body-centered cubic β phase or face-centered cubic γ phase is formed by Ni3(Al, Ti). In the absence of significant Ti presence, the γ' phase is formed by Ni3Al. The properties of the alloy are highly dependent on either the β or γ' phase. Figure 4 This is a graph showing the creep rupture of Rene-type alloys as a function of the volume fraction of the γ' phase. It can be seen that the creep rupture life reaches its maximum at approximately 60% to 70% γ' phase. Even a 10% increase or decrease in the γ' phase from this maximum will result in a one-order-of-magnitude reduction in the creep rupture life on a logarithmic scale. The γ' phase is a major determinant of the material's high-temperature strength and its superior resistance to creep deformation.

[0045] The additive manufacturing process for producing single-crystal (SX) metallic materials can generate polycrystalline (PX) shells. PX shells are undesirable and need to be removed to continue processing the single crystals. Figure 5 Electron micrographs of a single SX nickel alloy formed by additive manufacturing are shown, which have been post-processed to remove or reduce the PX shell. The PX domains (vertical lines in the electron micrograph on the right) were mechanically or chemically reduced before the application of a thermal barrier coating (TBC).

[0046] exist Figure 6 The electron micrographs shown reveal residual PX shells. It can be seen that the PX shells form at both edges of the workpiece body, and these shells are undesirable artifacts resulting from the fusion process using electron beams or laser beams. The width of the PX shells ranges from approximately 0 mm to 2 mm (up to 2000 μm) or approximately 0.1 mm to 2 mm (100 μm to 2000 μm), and can even be in the range of approximately 1 mm to 2 mm (1000 μm to 2000 μm). The faint stripes at the center of the SX are deformations caused by the AM delamination process.

[0047] Workpiece processing can include a range of techniques. These techniques are, but are not limited to, vapor phase aluminizing (VPA), platinum aluminizing (PtAl), thermal barrier coating (TBC), chemical vapor deposition (CVD) aluminizing, other CVD processes, hydrogen reduction of vapor-phase mixtures of NiCl2 and AlCl3, electron beam physical vapor deposition (EB-PVD), sputtering (of Al, Ni-rich alloys, or other materials), molecular beam epitaxy (MBE), thermal annealing, laser annealing, mechanical polishing, chemical polishing, passivation (i.e., anodizing), acid etching, etc., which are used to increase the temperature capacity of materials.

[0048] For example, after a VPA or PtAl process, the resulting IDZ thickness is approximately 1 μm to 200 μm, and can be 0 μm to 20 μm or 1 μm to 20 μm. This reduced thickness eliminates the need to remove the PX layer by mechanical or chemical methods, thus removing this step before further processing.

[0049] VPA, or Above-the-Pack, is a method of placing a component in a heated, inert atmosphere surrounded by a CrAl donor material. The donor material does not directly contact the component. During heat treatment, aluminum in the donor material and halide activator evaporates and condenses onto the target component in the presence of a carrier gas. It then diffuses further into the substrate and bonds with nickel to form nickel aluminum compounds (Ni3Al, NiAl, or NiAl3). The resulting coating comprises both a diffusion layer and an additive layer. In hot service environments, a durable oxide scale forms, protecting the component from further oxidation. This VPA process can also be used to coat internal passages of components such as turbine blades. Additionally, VPA can be combined with platinum plating to form platinum aluminum compounds, or variations in the donor material can be used for vapor phase chromizing (VPC), both for heat corrosion resistance.

[0050] VPA is a cost-effective solution for increasing the thermal oxidation and corrosion resistance of superalloys. It is relatively thin, ranging from approximately 25 μm to 80 μm, and allows for the coating of internal channels. VPA can be combined with other thermal barrier coating processes to further enhance protection and can be used on a variety of superalloys. Another advantage of VPA is the formation of a high-temperature resistant β phase. The β phase can be formed, for example, from Ni(Al,Ti) with an ordered BCC structure.

[0051] Micrographs of the coating application method show the interdiffusion zone (IDZ) between the TBC coating and the substrate. The additional treatment of the workpiece results in... Figure 6 As shown, the PX shell ranges from 0 mm to 2 mm.

[0052] In this disclosure, the PX shell thickness is effectively reduced directly through VPA. The PX shell becomes part of the adhesive coating and IDZ, thus eliminating the need for post-processing for removal, resulting in a more economical process. In other words, the PX shell produced by the additive process is an "adhesive coating" for VPA / PtAI process applications. However, additional processes can be performed to further reduce the PX shell thickness.

[0053] During heat treatment, aluminum from the donor material and halide activator evaporates and condenses onto the target component in the presence of a carrier gas. It then diffuses further into the substrate and bonds with nickel to form nickel aluminide. The resulting coating comprises both a diffusion layer and an additive layer. In hot service environments, a durable oxide scale forms, protecting the component from further oxidation. This VPA process can also be used to coat internal channels of components such as turbine blades. Additionally, VPA can be combined with platinum plating to form platinum aluminum oxide, or variations in the donor material can be used for vapor phase chromizing (VPC), both for heat corrosion resistance.

[0054] In the VPA method, components are processed in batches within large, circular tanks surrounded by donor material and an activator. The donor material is kept in separate baskets and does not directly contact the components. These tanks are then loaded into a distiller and placed in a furnace. An inert gas is passed through the tanks and distiller while heating to a temperature suitable for evaporating the donor material. The donor vapor condenses on the target portion and diffuses into the substrate material. The components are then subjected to vacuum heat treatment to further enhance their properties.

[0055] The crack closure mechanism disclosed herein utilizes AM to generate single crystals. Polycrystalline (PX) shells or edge grains are generated as part of these processes. The PX shell thickness is controlled to be thin enough to directly apply VPA or PtAl.

[0056] In this disclosure, the PX shell thickness is directly controlled by the VPA during AM, so that the remaining PX shell is directly bonded to the IDZ, thereby eliminating or reducing the need for otherwise complete removal of the PX shell.

[0057] Alternatively, other methods can be used before or after the VPA step to reduce the PX shell thickness. These methods may include mechanical polishing of the PX layer or chemical treatment to dissolve a portion of the PX layer.

[0058] The workpiece is optionally covered with a thermally bonded or barrier coating (TBC), which is typically ceramic.

[0059] Further processing of the workpiece can include vapor phase aluminizing (VPA), platinum aluminizing-aluminum (PtAl), and thermal barrier coating (TBC), which are used to improve the temperature capacity of the material. Micrographs of the coating application process show the interdiffusion zone (IDZ) between the coating and the substrate. The expected results of additional workpiece processing are... Figure 7 As shown in the electron micrograph.

[0060] exist Figure 7 In the cross-sectional view, the top adhesive coating is approximately 22 μm to 55 μm thick. The IDZ between the substrate and the adhesive coating is approximately 20 μm thick. This thickness range of 20 μm or less (down to 1 μm) allows for the direct processing of PX materials via VPA or PtAl to produce the IDZ.

[0061] The structure is optionally covered with a thermally bonded coating or a thermal barrier coating (TBC), such as in Figure 7 As can be seen, it is typically a ceramic suitable for performing well in corrosive thermal environments and handling thermal expansion stresses during heating and cooling, requiring sufficient porosity and a proper match between the coefficient of thermal expansion and the metal surface to which the TBC is being coated. Phase stability is required to prevent significant volume changes (which occur during phase transitions) that would lead to coating cracking or peeling. In air-breathing engines, oxidation resistance and good mechanical properties of rotating / moving or contact parts are essential.

[0062] In thermal barrier (TBC) applications, effective thermal barrier materials should exhibit properties such as low thermal diffusivity, phase stability and thermal shock resistance during thermal cycling, strong adhesion to the substrate, and resistance to oxidation and corrosion of both the metal bonding coating and the substrate. Commonly used materials include titanium dioxide, zirconium oxide, alumina, ceramics, mullite, and pyrochlore (A2). 3+ B2 4+ O7), Garnet (Y3Al) x Fe 5-x O 12 Monazite (LaPO4), perovskite (ABO3), lanthanum magnesium hexaaluminate (LaMgA) 11 O 19 Materials such as (and even diamond) have been measured to have low thermal conductivity and can therefore be considered potential TBC materials.

[0063] Yttrium-stabilized zirconia (YSZ) is a widely used ceramic material in transition toughening (TBC) due to its excellent overall properties (e.g., relatively low thermal conductivity, high dielectric constant, excessive fracture toughness, and chemical inertness at high temperatures). Notably, YSZ exhibits greater thermal shock resistance than other ceramic overcoats. The yttrium oxide stabilizer in the YSZ coating helps maintain the tetragonal phase of zirconia at room temperature, which undergoes a monoclinic phase transformation under applied external stress. This phase transformation leads to volume expansion and thus the accumulation of compressive stress near the crack, thereby promoting transformation toughening through crack propagation. Typically, approximately 4% to 7% yttrium oxide is present.

[0064] Under peak operating conditions found in gas turbine engines exceeding 700°C, oxidation of the binder coating leads to the formation of a thermally grown oxide (TGO) layer. TGO layer formation is unavoidable for many high-temperature applications; therefore, thermal barrier coatings are typically designed to allow the TGO layer to grow slowly and uniformly. This TGO will have a structure with low oxygen diffusivity, allowing further growth to be controlled by diffusion of metal from the binder coating rather than diffusion of oxygen from the topcoat.

[0065] This technology is not limited to conventional powder AM processes. It can also be used for directional solidification (DS), powder bed melting (PBF), electron beam melting (EBM), laser powder bed melting (L-PBF), directional energy distribution (DED), and selective laser melting (SLM). These technologies can be used to produce components for high-pressure turbines (HPT) and low-pressure turbines (LPT).

[0066] Thermal barrier coatings typically consist of four layers: a metal substrate, a metal binder coating, a thermally grown oxide (TGO), and a ceramic topcoat. The ceramic topcoat is usually composed of yttria-stabilized zirconia (YSZ), which has very low thermal conductivity and remains stable at the nominal operating temperatures common in TBC applications. This ceramic layer generates the maximum thermal gradient in the TBC and keeps the underlying layers at a lower temperature than the surface.

[0067] All compositions and / or methods disclosed and claimed herein can be prepared and performed without excessive experimentation based on this disclosure. While the compositions and methods of the invention have been described according to preferred embodiments, it will be apparent to those skilled in the art that variations may be made to the compositions and / or methods described herein, as well as the steps or order of steps of the methods, without departing from the concept, spirit, and scope of the invention. All such similar substitutions and modifications that are apparent to those skilled in the art are considered to be within the spirit, scope, and concept of the invention as defined by the appended claims.

Claims

1. A workpiece formed by additive manufacturing, comprising: Single-crystal substrate; and The interdiffusion region on the substrate comprises the same material as the single-crystal substrate and a certain amount of at least one of Al or Pt.

2. The workpiece according to claim 1, wherein the thickness of the interdiffusion zone is about 1 μm to 200 μm.

3. The workpiece according to claim 1, wherein the thickness of the interdiffusion zone is about 1 μm to 20 μm.

4. The workpiece according to claim 1, wherein the interdiffusion region comprises a β phase.

5. The workpiece according to claim 1, further comprising a thermal barrier coating formed of ceramic.

6. The workpiece according to claim 1, further comprising a thermal barrier coating formed of a ceramic comprising yttrium-stabilized zirconium oxide.

7. The workpiece according to claim 6, wherein the yttrium-stabilized zirconium oxide contains about 4% to 7% by weight of yttrium oxide.

8. The workpiece according to claim 1, wherein the substrate comprises a nickel alloy.

9. A method for manufacturing a workpiece, comprising: A single-crystal substrate is formed by additive manufacturing, wherein the single-crystal substrate has polycrystalline layers; and The polycrystalline layer is treated with at least one of Al or Pt to form a cross-diffusion region.

10. The method of claim 9, wherein the treatment of the polycrystalline layer is performed by vapor-phase aluminizing.

11. The method of claim 9, wherein the treatment of the polycrystalline layer is performed by vapor-phase aluminizing to form a nickel aluminum compound comprising at least one of Ni3Al, NiAl, or NiAl3.

12. The method of claim 9, wherein the treatment of the polycrystalline layer is performed by vapor-phase aluminizing to produce a thickness of the interdiffusion region of about 1 μm to 200 μm.

13. The method of claim 9, wherein the treatment of the polycrystalline layer is performed by vapor-phase aluminizing to produce a thickness of the interdiffusion region of about 1 μm to 20 μm.

14. The method of claim 9, wherein the interdiffusion region comprises a β phase.

15. The method of claim 9, wherein the single-crystal substrate is formed by the following sequential steps: Powder coatings for deposited metals; and The powder coating is melted.

16. The method of claim 9, wherein the polycrystalline layer is not thinned by mechanical polishing.

17. The method of claim 9, wherein the polycrystalline layer is not thinned by chemical treatment.

18. The method of claim 9, wherein the polycrystalline layer is treated by mechanical polishing or chemical treatment before or after treatment with at least one of Al or Pt.

19. The method of claim 9, further comprising: A thermally adhesive coating is formed on the interdiffusion zone.

20. The method of claim 9, further comprising: A thermally adhesive coating is formed on the interdiffusion region, the thermally adhesive coating comprising at least one material selected from titanium dioxide, zirconium oxide, alumina, ceramic, mullite, pyrochlore, garnet, monazite, perovskite, and lanthanum magnesium hexaaluminate.

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