Method for producing a composite metal component and composite metal component

Abstract

The application relates to the technical field of alloy preparation, in particular to a composite metal component preparation method and a composite metal component. The composite metal component preparation method sequentially forms a titanium alloy layer, a niobium metal intermediate layer and a nickel-titanium shape memory alloy layer on a base through laser directional energy deposition. By introducing the niobium intermediate layer with a specific thickness, the generation of brittle Ti-Ni intermetallic compounds is effectively inhibited, and the interface thermal stress is relieved, so that dense metallurgical bonding between the titanium alloy and the nickel-titanium alloy without macroscopic cracks is realized, and a reliable scheme is provided for the preparation of structure-function integrated composite components.

Description

Technical Field

[0001] This invention relates to the technical field of alloy preparation, and more particularly to a method for preparing composite metal components and the composite metal components themselves. Background Technology

[0002] Titanium alloys (such as TC4) and nickel-titanium shape memory alloys (NiTi) are two types of advanced metallic materials with vastly different properties. TC4 alloys, due to their high strength, low density, and good biocompatibility, are widely used in aerospace structural components and biomedical implants. NiTi alloys, with their unique shape memory effect and superelasticity, demonstrate significant value in intelligent drive structures and medical devices. Integrating these two materials into a single component to form a "structure-function integrated" heterogeneous composite structure holds promise for enabling a single component to simultaneously bear mechanical loads and sensing / drive functions. This could be used to manufacture aerospace intelligent structures with self-deploying and self-adjusting capabilities, or composite implants that combine excellent mechanical support and biofunctionality, showing significant engineering application potential.

[0003] To achieve the composite of such dissimilar materials, additive manufacturing technologies such as laser-directed energy deposition (L-DED) are considered effective potential methods due to their high energy density and ability to precisely shape localized materials. When joining two metals with significantly different properties, existing technologies often employ the addition of an intermediate layer to mitigate the mismatch between metallurgical and physical properties. For example, when attempting to join TC4 and NiTi, technicians might choose common metals such as iron (Fe), copper (Cu), or nickel (Ni) as intermediate transition materials, hoping to improve the bonding quality through their plasticity or partial compatibility with the base material. The joining process typically includes steps such as pretreating the substrate and sequentially or simultaneously depositing different material layers under a protective atmosphere.

[0004] However, due to the lack of a key intermediate layer material that can simultaneously buffer thermal stress and effectively suppress the formation of the brittle Ti-Ni phase, the interface of the TC4-NiTi heterostructure is prone to macroscopic cracks during laser additive manufacturing, making it difficult to achieve reliable bonding. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing composite metal components and the composite metal components themselves, in order to solve the technical problem in the prior art that the lack of a key intermediate layer material that can simultaneously buffer thermal stress and effectively suppress the formation of the Ti-Ni brittle phase leads to the easy generation of macroscopic cracks at the interface of TC4-NiTi heterostructures during laser additive manufacturing, making it difficult to achieve reliable bonding.

[0006] In a first aspect, the present invention provides a method for preparing a composite metal component, comprising the following steps: S1. A titanium alloy layer is formed on the substrate surface by laser-directed energy deposition; S2. A niobium metal intermediate layer is formed on the surface of the titanium alloy layer by laser directional energy deposition. S3. A nickel-titanium shape memory alloy layer is formed on the surface of the niobium metal intermediate layer by laser directional energy deposition.

[0007] Furthermore, the niobium metal interlayer has a thickness of 0.5-1 mm, which is used to suppress the formation of brittle intermetallic compounds between the titanium alloy layer and the nickel-titanium shape memory alloy layer, and to alleviate the thermal stress between the two.

[0008] Furthermore, the titanium alloy layer is a TC4 alloy, and the nickel-titanium shape memory alloy layer is a NiTi alloy.

[0009] Furthermore, the process parameters for depositing the titanium alloy layer include: laser power 750-850W, scanning speed 200-400mm / min, and powder feeding speed 0.5-1.5r / min; The process parameters for depositing the niobium metal intermediate layer include: laser power 700-800W, scanning speed 200-400mm / min, and powder feeding speed 1-2r / min.

[0010] Furthermore, the process parameters for depositing the nickel-titanium shape memory alloy layer include: laser power 600-800W, scanning speed 200-400mm / min, and powder feeding speed 1-3r / min.

[0011] Furthermore, before forming the titanium alloy layer, the substrate surface is pretreated, including polishing and cleaning.

[0012] Furthermore, the laser-directed energy deposition is performed in a protective atmosphere, which is argon with an oxygen content of less than 300 ppm.

[0013] Furthermore, the material of the niobium metal interlayer is pure niobium or a niobium alloy.

[0014] Secondly, the present invention also provides a composite metal component prepared by the above method. The component comprises, in sequence, a titanium alloy layer, a niobium metal intermediate layer, and a nickel-titanium shape memory alloy layer. The thickness of the niobium metal intermediate layer is 0.5-1 mm, and there are no macroscopic cracks at the interface between the titanium alloy layer and the nickel-titanium shape memory alloy layer.

[0015] Furthermore, the titanium alloy layer is a TC4 alloy, and the nickel-titanium shape memory alloy layer is a NiTi alloy.

[0016] Compared with the prior art, the present invention provides a method for preparing a composite metal component, comprising the following steps: S1. A titanium alloy layer is formed on the substrate surface by laser-directed energy deposition; S2. A niobium metal intermediate layer is formed on the surface of the titanium alloy layer by laser-directed energy deposition. S3. A nickel-titanium shape memory alloy layer is formed on the surface of the niobium metal intermediate layer by laser-directed energy deposition; Addressing the technical challenge of easily generating interfacial cracks in TC4 and NiTi heterostructures during laser additive manufacturing due to thermal stress concentration and the formation of brittle intermetallic compounds, this study creatively introduced niobium (Nb) metal as an interlayer. A titanium alloy layer, a niobium interlayer, and a nickel-titanium shape memory alloy layer were sequentially deposited using laser-directed energy deposition (EDD). The niobium interlayer, with its excellent solid solution ability with titanium and nickel, effectively blocked the direct diffusion reaction between titanium and nickel, significantly suppressing the formation of brittle Ti-Ni intermetallic compounds (such as Ti2Ni and TiNi3). Furthermore, the niobium interlayer buffered and alleviated thermal stress during the solidification process of the molten pool. Thus, a continuous and dense bonding of the interfacial structure between TC4 and NiTi was successfully achieved, fundamentally avoiding the generation of macroscopic cracks. This process exhibits high stability and provides a reliable technical solution for the fabrication of high-performance structural-functional integrated composite metal components. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is an overall flowchart of the composite metal component preparation method provided in the embodiments of the present invention; Figure 2 This is a cross-sectional view of the composite metal component sample provided in Embodiment 2 of the present invention; Figure 3 This is a cross-sectional view of the sample provided in Embodiment 2 of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] Example 1 This embodiment describes a method for preparing a composite metal component.

[0027] Step S1: Matrix pretreatment and TC4 layer deposition A TC4 titanium alloy substrate with dimensions of 100mm × 100mm × 10mm was selected. First, the substrate surface was pretreated: it was sanded sequentially using 600# to 2000# sandpaper, and then cleaned with anhydrous ethanol in an ultrasonic cleaner for 10 minutes to thoroughly remove surface oxides, oil, and impurities, ensuring a good bonding foundation for subsequent deposition layers. The pretreated substrate was fixed on the worktable of the laser-directed energy deposition (LDED) equipment. The processing chamber was sealed, and high-purity argon gas was introduced for purging until the oxygen content inside the chamber stabilized below 300ppm. Subsequently, a TC4 alloy layer was deposited on the substrate surface using LDED. Specific process parameters were set as follows: laser power 800W, scanning speed 300mm / min, powder feed rate 1.0r / min. The chemical composition of the TC4 powder used had to meet the following mass percentage requirements: Al: 5.5-6.5%, V: 3.5-4.5%, Fe≤0.25%, C≤0.08%, O≤0.20%, with the balance being Ti. The total thickness of the deposition layer is controlled at 10-15 mm, which is achieved through multi-layer reciprocating scanning.

[0028] Step S2: Deposition of Nb metal interlayer On the surface of the deposited TC4 layer, a Nb metal interlayer is deposited. Before deposition, the powder feed chamber is replaced with Nb metal powder. The purity of the Nb powder must be higher than 99.9%, or niobium alloy powder with the following composition can be used: Ni≤0.03%, C≤0.003%, Mo≤0.003%, O≤0.03%, with the balance being Nb. The optimized process parameters for depositing the Nb interlayer are: laser power 750W, scanning speed 300mm / min, and powder feed speed 1.0r / min. By controlling the number of deposition passes, the final thickness of the Nb interlayer is precisely controlled to 1.0mm. This thickness range (0.5-1mm) is one of the key aspects of this invention, as it effectively blocks Ti / Ni diffusion and inhibits the formation of brittle Ti-Ni intermetallic compounds (such as Ti2Ni, TiNi3), while also utilizing its thermal expansion coefficient, which is between that of TC4 and NiTi (Nb is approximately 7.3×10⁻⁶). -6 / K, TC4 approximately 9.0 × 10 -6 / K, NiTi approximately 11.0 × 10 -6 / K), effectively buffering and mitigating the thermal stress generated in the interface area during rapid solidification.

[0029] Step S3: Deposition of NiTi shape memory alloy layer After completing the Nb interlayer deposition, the powder feeder was replaced with NiTi alloy powder. The chemical composition of the NiTi powder needed to meet the following mass percentage requirements: Ni: 55.0-56.0%, C≤0.05%, O≤0.05%, Fe≤0.05%, with the balance being Ti. Laser-guided energy deposition of the NiTi layer was then performed on the Nb interlayer surface. The process parameters were set as follows: laser power 700W, scanning speed 350mm / min, and powder feed rate 2.0r / min. During the deposition process, argon gas was continuously introduced for protection, maintaining the oxygen content below 300ppm. After depositing a certain thickness, the NiTi functional layer was obtained.

[0030] Step S4: Post-processing After all deposition steps are completed, the component is kept in the equipment's working chamber and allowed to cool naturally to room temperature (approximately 25°C) under continuous argon gas protection. This slow cooling process helps to further release residual stress. After cooling, the component is removed, yielding a composite metal component consisting of a TC4 structural layer, an Nb intermediate transition layer, and a NiTi functional layer.

[0031] The method in this embodiment systematically solves the metallurgical incompatibility and thermophysical mismatch problems encountered when directly bonding TC4 and NiTi by introducing a Nb interlayer of specific thickness and optimizing the L-DED process parameters of each layer. This ultimately yields a high-quality component with no macroscopic cracks in the interfacial bonding zone. The process parameters are optimized windows verified through extensive experiments, ensuring the density of each layer and the quality of the interfacial metallurgical bonding. Control of the protective atmosphere is a fundamental condition for the successful implementation of the entire process. Pure niobium or niobium alloy materials are the core material guarantee for the proper functioning of the interlayer.

[0032] Example 2 like Figure 1 and Figure 2 As shown, this embodiment provides a composite metal component prepared according to the method of Embodiment 1.

[0033] The composite metal component is a block sample, and its macroscopic structure consists of the following layers: a lower TC4 alloy layer (approximately 12 mm thick), a middle Nb metal interlayer (1.0 mm thick), and an upper NiTi shape memory alloy layer (approximately 12 mm thick). A sample containing the complete interface was cut from the deposited block using wire cutting.

[0034] Interface microstructure and performance characterization: Macroscopic and microscopic morphology: Observation with the naked eye and optical microscope showed that the two interfaces between the TC4 layer and the Nb layer, and between the Nb layer and the NiTi layer, were continuous and smooth, with no visible macroscopic cracks, pores, or incomplete fusion defects. Observation under a scanning electron microscope showed that the interface regions had a smooth transition, and no large-area continuous brittle Ti-Ni intermetallic compound phase was found.

[0035] Mechanical properties: Room temperature tensile tests were conducted on specimens containing a complete TC4 / Nb / NiTi interface. The test results showed that the tensile strength of the composite component reached 652.1 MPa, and the elongation after fracture was 6.93%. Tensile fracture surface analysis showed that fracture mainly occurred at the Nb-NiTi interface, exhibiting ductile fracture characteristics, while the TC4 / Nb and Nb / NiTi interfaces themselves did not debond, proving that the interfacial bonding strength was higher than that of the Nb or NiTi parent material, achieving a strong metallurgical bond.

[0036] Functional performance verification: Differential scanning calorimetry (DSC) analysis of the NiTi functional layer revealed a distinct martensitic phase transformation peak, indicating that the NiTi alloy retained its shape memory properties after composite manufacturing. Upon bending deformation followed by heating, the NiTi layer recovered its original shape, verifying the component's integrated structural-functional characteristics.

[0037] Comparison and explanation: like Figure 3 As shown, as a comparative example, the same process parameters as in Example 1 were used, but the intermediate layer material was replaced with 1 mm thick Fe. The prepared TC4 / Fe / NiTi component showed numerous macroscopic cracks along the Fe layer and interface after cooling, making effective mechanical testing impossible. This demonstrates the irreplaceable nature of Nb as the intermediate layer material: Fe cannot effectively suppress the brittle Ti-Ni phase, and its coefficient of thermal expansion differs more significantly from TC4 and NiTi, leading to more severe stress concentration.

[0038] The composite metal component prepared in this embodiment successfully combines high-strength TC4 titanium alloy with functional NiTi shape memory alloy through a unique TC4 / Nb / NiTi three-layer structure design, particularly the introduction of a 0.5-1mm thick Nb intermediate layer. This component not only achieves a crack-free metallurgical bond at the interface, ensuring overall mechanical load-bearing capacity, but also allows the NiTi layer to retain its core shape memory / superelasticity function, perfectly meeting the urgent needs of aerospace, biomedical, and other fields for structural-functional integrated heterogeneous components.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite metal component, characterized in that, Includes the following steps: S1. A titanium alloy layer is formed on the substrate surface by laser-directed energy deposition; S2. A niobium metal intermediate layer is formed on the surface of the titanium alloy layer by laser directional energy deposition. S3. A nickel-titanium shape memory alloy layer is formed on the surface of the niobium metal intermediate layer by laser directional energy deposition.

2. The method for preparing composite metal components according to claim 1, characterized in that, The niobium metal interlayer has a thickness of 0.5-1 mm and is used to suppress the formation of brittle intermetallic compounds between the titanium alloy layer and the nickel-titanium shape memory alloy layer, and to alleviate the thermal stress between the two.

3. The method for preparing composite metal components according to claim 1 or 2, characterized in that, The titanium alloy layer is TC4 alloy, and the nickel-titanium shape memory alloy layer is NiTi alloy.

4. The method for preparing composite metal components according to claim 1 or 2, characterized in that, The process parameters for depositing the titanium alloy layer include: laser power 750-850W, scanning speed 200-400mm / min, and powder feeding speed 0.5-1.5r / min; The process parameters for depositing the niobium metal intermediate layer include: laser power 700-800W, scanning speed 200-400mm / min, and powder feeding speed 1-2r / min.

5. The method for preparing composite metal components according to claim 1 or 2, characterized in that, The process parameters for depositing the nickel-titanium shape memory alloy layer include: laser power 600-800W, scanning speed 200-400mm / min, and powder feeding speed 1-3r / min.

6. The method for preparing composite metal components according to claim 1, characterized in that, Before forming the titanium alloy layer, the substrate surface is pretreated, including polishing and cleaning.

7. The method for preparing composite metal components according to claim 1, characterized in that, The laser-directed energy deposition is performed in a protective atmosphere, which is argon with an oxygen content of less than 300 ppm.

8. The method for preparing composite metal components according to claim 1, characterized in that, The material of the niobium metal interlayer is pure niobium or a niobium alloy.

9. A composite metal component, prepared according to the method of any one of claims 1 to 8, characterized in that, The component comprises, in sequence, a titanium alloy layer, a niobium metal intermediate layer, and a nickel-titanium shape memory alloy layer. The thickness of the niobium metal intermediate layer is 0.5-1 mm, and there are no macroscopic cracks at the interface between the titanium alloy layer and the nickel-titanium shape memory alloy layer.

10. The composite metal component according to claim 9, characterized in that, The titanium alloy layer is TC4 alloy, and the nickel-titanium shape memory alloy layer is NiTi alloy.

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