A powder metallurgy and additive manufacturing method for preparing a Cu and TiB synergistically reinforced titanium matrix composite

Abstract

The application discloses a powder metallurgy and additive manufacturing preparation method of a Cu and TiB synergistically reinforced titanium matrix composite. The method comprises the following steps: (1) mixing copper source powder, boron source powder and titanium source powder to obtain mixed powder, wherein the mass of copper is 0.01% to 10% of the mass of a target component; the mass of boron is 0.01% to 4% of the mass of the target component; (2) performing ball milling treatment on the mixed powder; and (3) adopting a forming process to obtain a block-shaped titanium matrix composite from the mixed powder after ball milling. The application can significantly improve the strength of the material under the premise of hardly losing the elongation of the material.

Description

Technical Field

[0001] This invention relates to a powder metallurgy and additive manufacturing method for preparing a Cu-modified interface TiB whisker-reinforced titanium matrix composite, belonging to the field of metal matrix composite material preparation technology. Background Technology

[0002] Titanium is an important new structural material developed in the mid-20th century. Titanium has a density 40% lower than steel, while its strength is comparable. Replacing steel with titanium can effectively improve structural efficiency. Titanium also possesses high hardness, high modulus, and good heat resistance, corrosion resistance, formability, and biocompatibility. It has become an important material in high-end manufacturing fields such as aerospace, marine, and medical devices. However, titanium's Young's modulus, wear resistance, and heat resistance are inferior to steel and nickel-based alloys, making it difficult to apply in fields such as high-temperature compressors in engines to achieve overall weight reduction. Titanium-based composite materials (TMCs) compensate for the shortcomings of titanium alloys by introducing reinforcements with high strength, high hardness, high modulus, and high thermal stability, enabling wider applications of titanium materials.

[0003] TiB whiskers, due to their high aspect ratio and excellent mechanical properties, have become a key development direction for discontinuously reinforced TMCs. While the strength of uniformly distributed TiB-reinforced TMCs increases with increasing reinforcement content, significant losses in ductility and toughness severely limit their applications. Currently, the mainstream approach to address this issue is to prepare non-uniformly distributed TiB-reinforced TMCs, such as three-dimensional network structures and island structures. Their main characteristic is the presence of numerous tiny TiB whisker-rich regions and TiB whisker-poor regions. The enriched regions provide high strength, while the high ductility of the poor regions dulls cracks and delays fracture caused by crack propagation, thus solving the problem of low ductility in uniformly distributed TiB-reinforced TMCs. Fracture in metallic materials originates from crack initiation and propagation. Crack initiation in TiB-reinforced TMCs stems from whisker debonding and whisker fracture, both closely related to interfacial bonding strength. The design philosophy of non-uniform configurations is to suppress crack propagation; therefore, theoretically, suppressing crack initiation can also improve the ductility of the composite material. Summary of the Invention

[0004] The purpose of this invention is to address the limitations of current technologies by providing a Cu-modified TiB whisker-reinforced titanium matrix composite material and its preparation method. This method introduces copper into the TiB-reinforced titanium matrix composite material, utilizing the synergistic effect of Cu and TiB to achieve strengthening and toughening. Specifically, a Cu segregation layer is formed at the TiB / Ti interface through elemental diffusion, improving the interfacial bonding strength and suppressing crack initiation induced by interfacial debonding and whisker fracture in the composite material. This solves the problem of significantly reduced plasticity despite increased strength in TiB-reinforced TMCs. This invention can increase the strength of the material by up to 36% with almost no loss of elongation.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A powder metallurgy and additive manufacturing method for preparing Cu and TiB synergistically reinforced titanium-based composites includes the following steps:

[0007] (1) Preparation of mixed powder

[0008] A mixed powder was obtained by mixing copper source powder, boron source powder, and titanium source powder.

[0009] In this target composition, the sum of the masses of Cu, B, and Ti in the mixed powder is taken as the mass of the target composition. The mass of copper is 0.01% to 10% of the target composition mass; the mass of boron is 0.01% to 4% of the target composition mass; and the balance is Ti.

[0010] The boron source is pure boron, TiB2, B4C, or BN;

[0011] The titanium source is pure titanium or a titanium alloy; specifically, the titanium alloy is an α titanium alloy (such as TA7), a β titanium alloy (such as Ti1023), or an α+β titanium alloy (such as TC4).

[0012] The copper source is pure copper or a copper master alloy, wherein the copper master alloy is a copper-titanium alloy (CuTix) or a copper-boron alloy (CuBx);

[0013] (2) The mixed powder was ball-milled.

[0014] The prepared mixed powder was ball-milled under argon protection. The ball milling parameters were: ball-to-powder ratio 2:1 to 15:1, rotation speed 100 to 500 rpm, and ball milling time 0.5 to 6 hours.

[0015] (3) Molding process

[0016] The ball-milled mixed powder is then subjected to a molding process to obtain a blocky titanium-based composite material.

[0017] The forming process is vacuum hot pressing sintering, spark plasma sintering, hot isostatic pressing sintering, or laser additive manufacturing.

[0018] When the process is spark plasma sintering, the following steps are included: the ball-milled powder is placed into a spark plasma sintering mold, the sintering pressure is 10-100 MPa, the sintering temperature is 800-1400℃, the vacuum degree is <5 Pa, and the sintering time is 0.2-1.5 hours.

[0019] When using direct laser deposition technology, the following steps are included: laser power of 600-1500W, single-pass width of 1.5-3mm, pass spacing of 0.9-1.8, scanning speed of 5-15mm / s, and alternation of layers at 0-90°.

[0020] The essential features of this invention are:

[0021] Since uniformly distributed TiB-reinforced titanium matrix composites improve strength but suffer severe plasticity loss, the current mainstream solution is to design non-uniform configurations. This involves creating whisker-rich and whisker-deficient regions at the microscale, i.e., hard and soft regions. The hard regions provide strength while the soft regions suppress crack propagation (provide plasticity). Essentially, the soft regions control crack propagation.

[0022] The fracture of TiB-reinforced titanium matrix composites originates from whisker debonding and whisker fracture. This invention addresses this by simultaneously introducing copper and TiB into titanium, specifically by introducing copper into the TiB-reinforced titanium matrix composite. At high temperatures, copper has a certain solid solubility in titanium, and the TiB / Ti interface itself is a defect. Copper will spontaneously diffuse towards the interface, thereby reducing the system's free energy. Therefore, a copper segregation layer will form at the interface. Figure 5 The effect is increased strength without decreasing elongation. The mechanism is that copper segregation improves interfacial bonding strength and inhibits crack initiation. Therefore, the design concept of this invention is to control crack initiation.

[0023] The beneficial effects of this invention are as follows:

[0024] Ideal metallic structural materials maintain good ductility and toughness while achieving high strength. However, the strength and ductility of materials exhibit a significant inverse relationship, meaning that as strength increases, ductility and toughness decrease. This invention can significantly improve the strength of materials with almost no loss of elongation. Example 1: Cu-modified TiB-reinforced TMCs prepared by spark plasma sintering showed a 36% increase in strength (190 MPa) compared to a control sample prepared using the same process, without a decrease in elongation. Figure 2 Example 3: Cu-modified TiB-reinforced TMCs prepared by direct laser deposition showed a 9% increase in strength (65 MPa) compared to the control sample, without a decrease in elongation. Figure 4 ). Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the titanium-based composite material from Example 1.

[0026] Figure 2 The stress-strain curves are shown for the titanium-based composite material of Example 1 and Ti-3wt%Cu prepared by the same process.

[0027] Figure 3This is a scanning electron microscope (SEM) image of the titanium-based composite material from Example 3.

[0028] Figure 4 The stress-strain curves are shown for the composite material of Example 3 and Ti-3wt%TiB-1wt%Cu prepared by the same process.

[0029] Figure 5 The image shows the energy dispersive spectroscopy (EDS) elemental analysis diagram of the interface between the TiB whiskers and the Ti matrix in Example 1.

[0030] Figure 6 This is a physical image of the titanium-based composite material from Example 1.

[0031] Figure 7 This is a physical image of the titanium-based composite material from Example 3. Detailed Implementation

[0032] The present invention will be further described below with reference to embodiments.

[0033] The preparation process of the copper-modified TiB interface titanium-based composite material of the present invention is as follows: Figure 1 As shown, we designed a method for preparing a copper-modified TiB interface by ball milling titanium powder, boron powder, and copper powder, followed by a subsequent preparation process. This improves the interfacial bonding strength between TiB whiskers and the matrix, suppresses whisker stress concentration, and prevents interfacial debonding. This invention provides a method for preparing a copper-modified TiB interface using powder metallurgy or additive manufacturing processes. The technical approach of this invention will be explained first.

[0034] (1) Preparation of mixed powder

[0035] Copper powder, boron source powder (boron powder, TiB2 powder, B4C, BN, etc.), and titanium powder (or titanium alloy powder) are mixed in a certain proportion to form a mixed powder (wherein, the sum of the masses of Cu, B, and Ti in the mixed powder is the target component mass, the mass of copper is 0.01% to 10% of the target component mass, the mass of boron is 0.01% to 4% of the target component mass, and the balance is titanium). Here, the mass of boron source powder is calculated based on equivalent boron powder, and copper can also be introduced in the form of an intermediate alloy.

[0036] (2) The mixed powder was ball-milled.

[0037] The prepared mixed powder was ball-milled under argon protection. The ball milling parameters were: ball-to-powder ratio 2:1 to 15:1, rotation speed 100 to 500 rpm, and ball milling time 0.5 to 6 hours.

[0038] (3) Molding process

[0039] The forming process of mixed powders can employ technologies such as vacuum hot pressing sintering, spark plasma sintering, hot isostatic pressing sintering, and additive manufacturing. Here, we will focus on spark plasma sintering (SPS), a traditional powder forming process, and direct laser deposition (DLD), a technology used in additive manufacturing. Spark Plasma Sintering: The ball-milled powder is placed in a spark plasma sintering mold. The sintering pressure is 10–100 MPa, the sintering temperature is 800–1400℃, the vacuum degree is <5 Pa, and the sintering time is 0.2–1.5 hours. Direct Laser Deposition (DLD): The laser power is 600–1500 W, the single-pass width is 1.5–3 mm, the pass spacing is 0.9–1.8 mm, the scanning speed is 5–15 mm / s, and the layers alternate at 0–90°.

[0040] The present invention will be further described below with reference to embodiments.

[0041] Example 1

[0042] 6 g of copper powder (5 μm, analytical grade), 1.086 g of boron powder (1 μm, analytical grade), and 192.914 g of titanium powder (53–150 μm, analytical grade) were weighed and placed in a 500 mL stainless steel ball mill jar, which was then filled with argon gas. The mixture was milled for 3 hours at 300 rpm using a planetary ball mill, with a ball-to-powder ratio of 3:1 (6 mm diameter tungsten carbide balls). The milled powder mixture was then removed and subjected to spark plasma sintering using a 45 mm diameter mold. The sintering temperature was 1100 °C, the sintering pressure was 50 MPa, the vacuum degree was less than 5 Pa, and the sintering time was 0.5 hours. A TiB whisker-reinforced titanium matrix composite sample with a diameter of 45 mm and a thickness of approximately 20 mm was obtained.

[0043] Example 2

[0044] 4g of copper powder, 0.724g of boron powder, and 195.276g of TC4 titanium alloy powder were weighed and placed in a 500ml stainless steel ball mill jar, which was then filled with argon gas. The mixture was ball-milled for 2 hours at 250 rpm using a planetary ball mill with a ball-to-powder ratio of 2.5:1. The milled powder mixture was then removed and subjected to spark plasma sintering using a 45mm diameter mold. The sintering temperature was 1100℃, the sintering pressure was 50MPa, the vacuum degree was less than 5Pa, and the sintering time was 0.5 hours. A TiB whisker-reinforced titanium matrix composite sample with a diameter of 45mm and a thickness of approximately 20mm was obtained.

[0045] Example 3

[0046] 4g of copper powder, 1.086g of boron powder, and 194.914g of titanium powder were weighed and placed in a 500ml stainless steel ball mill jar, which was then filled with argon gas. The mixture was ball-milled for 2 hours at 350 rpm using a planetary ball mill with a ball-to-powder ratio of 2.5:1. The milled powder mixture was then removed and sample preparation was performed using laser deposition. The laser power was 800W, the scanning speed was 10mm / s, the layers alternated at 90° intervals, and the powder feed rate was 3g / min. A TiB whisker-reinforced titanium matrix composite sample with a length of 80mm, a width of 30mm, and a height of 20mm was obtained.

[0047] Example 4

[0048] 2g of copper powder, 0.724g of boron powder, and 197.276g of TC4 titanium alloy powder were weighed and placed in a 500ml stainless steel ball mill jar, which was then filled with argon gas. The mixture was ball-milled for 2 hours at 350 rpm using a planetary ball mill with a ball-to-powder ratio of 2.5:1. The milled powder mixture was then removed and sample preparation was performed using laser deposition. The laser power was 800W, the scanning speed was 10mm / s, the layers alternated at 90° intervals, and the powder feed rate was 3g / min. A TiB whisker-reinforced titanium matrix composite sample with a length of 80mm, a width of 30mm, and a height of 20mm was obtained. The properties were similar to those in Example 1.

[0049] Example 5

[0050] 14g of copper powder, 1.388g of boron powder, and 184.612g of titanium powder were weighed and placed in a 500ml stainless steel ball mill jar, which was then filled with argon gas. The mixture was ball-milled for 3 hours at 200 rpm using a planetary ball mill with a ball-to-powder ratio of 3:1. The milled powder mixture was then removed and sample preparation was performed using laser deposition. The laser power was 800W, the scanning speed was 10mm / s, the layers alternated at 90° intervals, and the powder feed rate was 3g / min. A TiB whisker-reinforced titanium matrix composite sample with a length of 80mm, a width of 30mm, and a height of 20mm was obtained. The properties were similar to those in Example 1.

[0051] The low-magnification scanning electron microscope (SEM) results of the titanium-based composite material prepared by spark plasma sintering in Example 1 are as follows: Figure 1 As shown, TiB still exhibits a whisker morphology, indicating that copper does not alter the whisker morphology of TiB.

[0052] The tensile test results of Example 1 are as follows: Figure 2As shown in the figure (tests were conducted based on GB / T228.1-2021), the composite material exhibits significantly improved strength compared to the Ti+3wt%Cu alloy prepared using the same process, while maintaining the same elongation. The Ti+3wt%Cu alloy prepared using the same process lacks the reinforcing effect of TiB compared to the sample in Example 1, resulting in lower strength. The sample in Example 1, due to the synergistic strengthening effect of TiB and Cu, possesses higher strength without reducing elongation.

[0053] The tensile test results in Example 3 are as follows: Figure 4 As shown (tests were conducted based on GB / T228.1-2021), compared with the Ti-3wt%TiB-1wt%Cu composite material prepared with the same process parameters, the copper content of the sample in Example 3 was increased to 2wt%, and the strength of the composite material was improved without a decrease in elongation.

[0054] Figure 5 The energy dispersive spectroscopy (EDS) pattern of the interface between TiB whiskers and Ti matrix in the titanium-based composite material of Example 1 shows that copper segregation exists at the interface, which strengthens the interface and inhibits crack initiation caused by whisker debonding and whisker fracture. This is the reason why the strength of the composite material is improved while the elongation remains unchanged.

[0055] While increasing the content of reinforcements in titanium-based composites increases strength, it also leads to significant loss of plasticity. Developing metal matrix composites that combine both strength and toughness has been a persistent pursuit for researchers. This invention presents a Cu-modified TiB whisker-reinforced titanium-based composite material and its preparation method, effectively addressing the problem of increased strength but severe plasticity loss due to reinforcement introduction. This method achieves improved strength while maintaining unchanged plasticity. This invention provides support for my country's high-end manufacturing, industrial upgrading, and national defense modernization from the perspective of new material development.

[0056] Matters not covered in this invention are common knowledge.

Claims

1. A powder metallurgy and additive manufacturing method for preparing Cu and TiB synergistically reinforced titanium-based composites, characterized in that the method includes the following steps: (1) Preparation of mixed powder A mixed powder was obtained by mixing copper source powder, boron source powder, and titanium source powder. Specifically, based on the sum of the masses of Cu, B, and Ti in the mixed powder as the target component mass, the mass of copper is 0.01% to 10% of the target component mass; and the mass of boron is 0.01% to 4% of the target component mass. The boron source is pure boron or TiB2; The titanium source is pure titanium or a titanium alloy; the copper source is pure copper or a copper master alloy. (2) The mixed powder was ball-milled. The prepared mixed powder was ball-milled under argon protection. The ball milling parameters were: ball-to-powder ratio 2:1 to 15:1, rotation speed 100 to 500 rpm, and ball milling time 0.5 to 6 hours. (3) Molding process The ball-milled mixed powder is then subjected to a molding process to obtain a bulk titanium-based composite material. The titanium alloys mentioned are specifically α-titanium alloys, β-titanium alloys, or α+β-titanium alloys; The copper master alloy is a copper-titanium alloy or a copper-boron alloy; The forming process is vacuum hot pressing sintering, spark plasma sintering, hot isostatic pressing sintering, or laser additive manufacturing.

2. The powder metallurgy and additive manufacturing method for preparing Cu and TiB synergistically reinforced titanium-based composites as described in claim 1, characterized in that when spark plasma sintering is performed, it includes the following steps: the ball-milled powder is placed in a spark plasma sintering mold, the sintering pressure is 10-100 MPa, the sintering temperature is 800-1400℃, the vacuum degree is <5 Pa, and the sintering time is 0.2-1.5 hours; When laser additive manufacturing is a direct laser deposition technology, it includes the following steps: laser power of 600-1500 W, single-pass width of 1.5-3 mm, pass spacing of 0.9-1.8, scanning speed of 5-15 mm / s, and alternation of layers from 0 to 90°.

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