High-strength wear-resistant and oxidation-resistant titanium-based composite material and preparation method thereof

Abstract

The present application aims at the problems of poor wear resistance and insufficient oxidation resistance of titanium alloy, and provides a high-strength wear-resistant and oxidation-resistant titanium-based composite material and a preparation method thereof.The titanium-based composite material is composed of a matrix and a reinforcing phase, the matrix is commercial pure titanium and titanium alloy (such as TA15, TB7, TC4, etc.), and the reinforcing phase is a double reinforcing phase, i.e., TiN and rare earth oxides (such as Y2O3, Nd2O3, La2O3, etc.) generated by in-situ reaction of nitrogen and the matrix molten pool under laser action.The preparation method comprises ball milling, pretreatment of the substrate and the powder, laser melting deposition, hot isostatic pressing, forging and heat treatment, and surface shot peening.

Description

Technical Field

[0001] This invention belongs to the field of metal material forming technology, specifically relating to a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material and its preparation method. Background Technology

[0002] Titanium alloys are widely used in aerospace, petrochemical, and other fields due to their low density, good comprehensive mechanical properties, and high corrosion resistance. However, their low hardness, poor wear resistance, insufficient oxidation resistance in high-temperature environments, and low mechanical strength severely limit their application under harsh conditions such as high loads, friction and wear, and high temperature and pressure. To address the problems of poor wear resistance and insufficient oxidation resistance of titanium alloys, researchers have developed different types of titanium matrix composites (TMCs). Compared to titanium alloys, titanium matrix composites exhibit superior comprehensive mechanical properties, better wear resistance, and higher oxidation resistance due to the introduction of reinforcing phases, effectively promoting the application of titanium alloys under harsh conditions.

[0003] Commonly used reinforcing phases in titanium-based composites can be categorized by type, including ceramic powders (such as TiB, TiC, and TiN), metal oxide powders (such as Al2O3 and TiO2), and rare earth oxide powders (such as Y2O3, Nd2O3, and La2O3). Studies have shown that TiN, with its high melting point and hardness, good thermal and chemical stability, excellent corrosion resistance, and good interfacial bonding with the titanium matrix, is one of the ideal reinforcing phases for titanium alloys. Meanwhile, rare earth oxides can significantly refine the grain size of titanium alloys. Their uniform dispersion within the titanium matrix effectively hinders dislocation movement, thereby improving the strength, hardness, and wear resistance of titanium alloys. Furthermore, their high melting point and good thermal stability help promote the formation of a dense and stable passivation film on the titanium alloy surface, thus improving its oxidation resistance. In practice, by adding two different types of reinforcing phases, utilizing their respective excellent properties and the synergistic effect caused by their differences in physical properties, the overall performance of the matrix material can be effectively improved. Therefore, by using TiN and rare earth oxides as reinforcing phases in titanium alloys and employing appropriate forming methods, it is expected to prepare high-strength, wear-resistant, and oxidation-resistant titanium-based composite materials.

[0004] Traditional forming methods (such as casting) for preparing titanium-based composites suffer from problems such as coarse grains, agglomeration of reinforcing phases, and low interfacial bonding strength. While powder metallurgy can produce composites with fine grains and uniform microstructure, it suffers from long process flows, high energy consumption, and limitations on part size. Laser Melting Deposition (LMD), as an advanced additive manufacturing technology, uses a high-energy laser beam to melt and rapidly solidify raw material powder in an extremely short time, effectively avoiding defect formation. The resulting parts have the advantages of fine grains and uniform microstructure. By changing process parameters such as laser power and powder feed rate, the chemical composition of the components can be precisely controlled, making it an effective means of preparing high-performance titanium-based composites.

[0005] Achieving uniform distribution of the reinforcing phase and suppressing the formation of internal defects are key to preparing high-performance titanium-based composite materials. To this end, a preparation approach based on in-situ gas-liquid reaction to generate the reinforcing phase has emerged: during laser melting deposition, a mixture of nitrogen and argon is introduced as a protective gas. Under the action of a high-energy laser beam, nitrogen decomposes near the high-temperature molten pool to form nitrogen atoms (N2→N+N). These nitrogen atoms diffuse within the molten pool and react in situ to generate the TiN reinforcing phase (Ti+N→TiN). Due to the good dispersibility and diffusion of the gas, and the convection effect of the molten pool, the generated TiN exhibits smaller size and a more dispersed distribution. Furthermore, the fine and dispersed TiN can also promote the uniform distribution of rare earth oxides. In summary, laser melting deposition technology holds promise for preparing high-performance titanium-based composite materials containing both TiN and rare earth oxides as dual reinforcing phases. Based on the modification effects of TiN and rare earth oxides, excellent comprehensive properties such as high strength, wear resistance, and oxidation resistance can be obtained. Summary of the Invention

[0006] This invention addresses the problems of poor wear resistance and insufficient oxidation resistance of titanium alloys by proposing a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material and its preparation method. The titanium-based composite material consists of a matrix and a reinforcing phase. The matrix is ​​commercially available pure titanium and titanium alloys (such as TA15, TB7, TC4, etc.), and the reinforcing phase is a dual-reinforcing phase, namely TiN and rare earth oxides (such as Y2O3, Nd2O3, La2O3, etc.) generated by the in-situ reaction of nitrogen gas with the matrix molten pool under laser irradiation. The preparation method includes ball milling and powder mixing, substrate and powder pretreatment, laser melting deposition, hot isostatic pressing, forging and heat treatment, and surface shot peening.

[0007] The roles of each component in the reinforcing phase are as follows: TiN, generated by the in-situ reaction of nitrogen with the matrix molten pool under laser irradiation, is small in size. On one hand, it can act as a heterogeneous nucleation site to hinder matrix grain growth, thus playing a role in grain refinement strengthening; on the other hand, its dispersed distribution can play a role in precipitation strengthening and sedimentation strengthening. Furthermore, the interface between the in-situ generated TiN and the matrix is ​​generally coherent or semi-coherent, with high bonding strength, which strengthens the interface and allows for better load transfer. Generally, rare earth oxides (such as Y₂O₃, Nd₂O₃, La₂O₃, etc.) have high hardness and high strength, as well as excellent heat resistance and chemical stability. They can promote the formation of a dense passivation film on the matrix surface and enhance the bonding strength between the passivation film and the matrix, thereby improving the oxidation resistance of the matrix. Rare earth oxides added to the matrix in the form of fine powder can also play a role in dispersion strengthening. The dual reinforcing phases formed by TiN and rare earth oxides have excellent individual properties and can form a synergistic effect with the matrix, effectively improving the wear resistance and oxidation resistance of titanium alloys.

[0008] The roles of each process in the preparation method are as follows: ball milling is used to fully mix pure titanium and titanium alloy powders with different size mismatches with rare earth oxide powders to obtain mixed powders with specific component ratios, ensuring that the laser melting deposition components have uniform chemical composition; substrate and powder pretreatment is used to remove surface oil, impurities and adsorbed moisture from the materials to reduce forming defects; laser melting deposition is used to prepare titanium-based composite materials containing TiN and rare earth oxide dual reinforcing phases. Reasonable control of process parameters can optimize the forming quality of the components and is the key process of this invention; hot isostatic pressing treats the components under high temperature and high pressure to reduce their porosity and increase their density, thereby improving their comprehensive performance; forging and heat treatment cause the components to undergo large plastic deformation at high temperature to break the grains, and recrystallize at a relatively low temperature to refine the grains. This process can reduce defects such as pores and cracks in the components and further improve their strength and toughness; surface shot peening is used to generate compressive stress on the surface of the components, refine the surface grains, obtain a dense structure, generate a hardened layer of a certain depth, and at the same time improve its surface strength, hardness and corrosion resistance.

[0009] The technical solution of this invention is as follows:

[0010] A high-strength, wear-resistant, and oxidation-resistant titanium-based composite material, wherein the titanium-based composite material is composed of a matrix and a reinforcing phase. The matrix is ​​commercially available pure titanium and titanium alloys (such as TA15, TB7, TC4, etc.), and the reinforcing phase is a dual reinforcing phase, namely TiN and rare earth oxides (such as Y2O3, Nd2O3, La2O3, etc.) generated by the in-situ reaction of nitrogen gas with the matrix molten pool under laser irradiation.

[0011] A method for preparing a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material includes the following steps:

[0012] Step 1: Ball milling and powder mixing

[0013] Commercially available pure titanium and titanium alloy powders with a particle size of 22–45 μm and rare earth oxide powders with a particle size of 43–68 μm were selected as raw materials. Pure titanium and titanium alloy powders with different mass fractions and rare earth oxide powders were mixed and placed in a low-temperature ball mill jar. The mass fraction of rare earth oxide powder was 1–7 wt.%. Ball milling media were added to the ball mill jar at a ball-to-material ratio of 5:1. Argon gas was introduced for 120 seconds and then released for 20 seconds. Ball milling was carried out by a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed was 40–80 rpm, and the left-and-right rotation speed was 250–370 rpm. The ball milling time was 15–20 hours to obtain mixed powder.

[0014] Preferably, the rare earth oxide powder has a mass fraction of 3-5 wt.%, the vertical rotation speed is 60-70 rpm, the horizontal rotation speed is 280-330 rpm, and the ball milling time is 17-19 h.

[0015] Step 2: Substrate and Powder Pretreatment

[0016] The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with wet sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment at a temperature of 70°C for 5 hours.

[0017] Step 3: Laser melting deposition

[0018] The mixed powder obtained in the second step is placed into the powder tank of a laser melting deposition equipment. The mixed powder is melted by a high-energy laser according to a preset scanning path. The scanning method is a multi-pass, multi-layer, short-side reciprocating method. The protective gas is a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%). The volume fraction of high-purity nitrogen is 10% to 30%, the gas flow rate is 2 to 6 L / min, the laser power is 500 to 1000 W, the scanning speed is 500 to 800 mm / min, the powder feeding speed is 8 to 14 g / min, the melt width is 3 to 7 mm, the overlap rate is 35% to 65%, and the single-pass layer height is 0.4 to 0.8 mm, resulting in a titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases.

[0019] Preferably, the volume fraction of high-purity nitrogen is 15% to 25%, the gas flow rate is 3 to 5 L / min, the laser power is 700 to 900 W, the scanning speed is 600 to 700 mm / min, the powder feeding speed is 10 to 12 g / min, the melt width is 4 to 6 mm, the overlap rate is 50% to 60%, and the single-pass layer height is 0.5 to 0.7 mm.

[0020] Step 4: Hot isostatic pressing

[0021] The titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon (99.999%) was used as the protective atmosphere. The treatment pressure was 80–130 MPa, the treatment temperature was 1300–1700 °C, and the treatment time was 30–90 min to obtain the HIP composite material.

[0022] Preferably, the treatment pressure is 90–120 MPa, the treatment temperature is 1450–1650 °C, and the treatment time is 50–70 min.

[0023] Step 5: Forging and Heat Treatment

[0024] The hot isostatically pressed composite material obtained in step four is forged and heat-treated. For forging: the forging temperature is 950-980℃, the deformation is 40%-60%, and the deformation speed is 8-12 mm / s. For heat treatment: the heat treatment temperature is 400-700℃, the heat treatment time is 30-90 min, and air cooling is used. The forged and heat-treated composite material is obtained.

[0025] Preferably, the forging temperature is 960–970℃, the deformation amount is 50%–60%, and the deformation speed is 9–11 mm / s; the heat treatment temperature is 500–650℃, and the heat treatment time is 40–80 min.

[0026] Step 6: Surface shot peening

[0027] The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot (average diameter 0.6 mm), the air pressure was 0.2–0.5 MPa, the shot peening flow rate was 1.0–1.5 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.2–0.6 mm, the shot peening time was 20–30 min, the incident angle was 45°–90°, and the shot peening coverage was 100%, thus obtaining the surface shot-peened composite material.

[0028] Preferably, the air pressure is 0.3-0.4 MPa, the shot peening flow rate is 1.2-1.4 kg / min, the shot peening intensity measured using an N-type Almen test piece is 0.3-0.5 mm, the shot peening time is 22-27 min, and the incident angle is 60°-90°.

[0029] The high-strength, wear-resistant, and oxidation-resistant titanium-based composite material prepared by the above method consists of a matrix and a reinforcing phase. The material system is novel in design and ingenious in composition: TiN and rare earth oxides are dual reinforcing phases. They are uniformly fine and evenly dispersed in the matrix and have a good bonding interface with the matrix. With the help of their respective excellent properties and the synergistic effect formed between them and the matrix, the wear resistance and oxidation resistance of titanium alloys can be effectively improved. The preparation method described is rationally designed and feasible, with each process closely integrated: ball milling and powder mixing can obtain powder with a specific component ratio and uniform mixing; substrate and powder pretreatment can remove oil, impurities, and adsorbed moisture from the material surface, thereby improving the forming quality of laser melting deposition; laser melting deposition can prepare titanium-based composite materials containing TiN and rare earth oxide dual reinforcing phases, and the microstructure and service performance of the components can be optimized by adjusting the process parameters; hot isostatic pressing can improve the density of the composite material and further improve its comprehensive performance; forging and heat treatment can refine the grains and reduce defects, thereby improving the strength and toughness of the composite material; surface shot peening can generate compressive stress on the surface of the composite material and form a hardened layer of a certain depth, while improving its strength, hardness, and corrosion resistance.

[0030] The beneficial effects of this invention are as follows:

[0031] (1) The inventors, through a comprehensive approach utilizing ball milling and powder mixing, substrate and powder pretreatment, laser melting deposition, hot isostatic pressing, forging and heat treatment, and surface shot peening, prepared a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material after extensive experimentation. The optimal process parameter ranges were summarized as follows: For ball milling and powder mixing, the mass fraction of rare earth oxide powder was 3–5 wt.%, the rotation speed for vertical tumbling was 60–70 rpm, the rotation speed for horizontal rotation was 280–330 rpm, and the ball milling time was 17–19 h; for laser melting deposition, the volume fraction of high-purity nitrogen was 15%–25%, the gas flow rate was 3–5 L / min, the laser power was 700–900 W, the scanning speed was 600–700 mm / min, the powder feeding speed was 10–12 g / min, and the melt width was 4–6 mm / min. The process parameters are as follows: mm, overlap rate 50%–60%, single-pass layer height 0.5–0.7 mm; for hot isostatic pressing, treatment pressure 90–120 MPa, treatment temperature 1450–1650℃, treatment time 50–70 min; for forging and heat treatment, forging temperature 960–970℃, deformation amount 50%–60%, deformation speed 9–11 mm / s, heat treatment temperature 500–650℃, heat treatment time 40–80 min; for surface shot peening, air pressure 0.3–0.4 MPa, shot peening flow rate 1.2–1.4 kg / min, shot peening intensity measured using N-type Almen specimens 0.3–0.5 mm, shot peening time 22–27 min, incident angle 60°–90°. Using these process parameters, high-strength, wear-resistant, and oxidation-resistant titanium-based composite materials can be prepared.

[0032] (2) The inventors prepared a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material. The microstructure and performance analysis showed that the titanium matrix has dual reinforcing phases of TiN and rare earth oxides. The reinforcing phases are uniformly dispersed in the titanium matrix, and there are no obvious defects at the interface between the reinforcing phases and the titanium matrix. The titanium-based composite material exhibits a tensile strength of 1530–1824 MPa, a microhardness of 453–524 HV, a surface friction coefficient of 0.19–0.25, and a high-temperature oxidation weight gain of 1.49–2.87 mg. For the corresponding titanium alloy, the tensile strength is 756–884 MPa, the microhardness is 356–374 HV, the surface friction coefficient is 0.35–0.42, and the high-temperature oxidation weight gain is 9.12–15.83 mg. In comparison, the added reinforcing phase and the adopted preparation method increased the tensile strength of the titanium alloy by 102.38%–106.33%, increased the microhardness by 27.25%–40.11%, decreased the surface friction coefficient by 40.48%–45.71%, and reduced the high-temperature oxidation weight gain by 81.87%–83.66%. Attached Figure Description

[0033] Figure 1This is a comparison of the microstructures of pure titanium and titanium-based composite materials in Example 1.

[0034] Figure 2 This is a comparison of the tensile strength of pure titanium and titanium-based composite materials in Example 1.

[0035] Figure 3 The microhardness and surface friction coefficient of pure titanium and titanium-based composite material in Example 1 are compared.

[0036] Figure 4 This is a comparison of the weight gain from high-temperature oxidation of pure titanium and titanium-based composite materials in Example 1. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0038] The present invention discloses a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material, wherein the titanium-based composite material is composed of a matrix and a reinforcing phase. The matrix is ​​commercially available pure titanium and titanium alloys (such as TA15, TB7, TC4, etc.), and the reinforcing phase is a dual reinforcing phase, namely TiN and rare earth oxides (such as Y2O3, Nd2O3, La2O3, etc.) generated by the in-situ reaction of nitrogen gas with the matrix molten pool under laser irradiation.

[0039] The preparation method of a high-strength, wear-resistant, and oxidation-resistant titanium-based composite material according to the present invention includes the following steps:

[0040] Step 1: Ball milling and powder mixing

[0041] Commercially available pure titanium and titanium alloy powder with a particle size of 22–45 μm and rare earth oxide powder with a particle size of 43–68 μm were selected as raw materials. Pure titanium and titanium alloy powder with different mass fractions and rare earth oxide powder were mixed and placed in a low-temperature ball mill jar. The mass fraction of rare earth oxide powder was 1–7 wt.%, preferably 3–5 wt.%. Ball milling media were added to the ball mill jar at a ball-to-material ratio of 5:1. Argon gas was introduced for 120 s and then released for 20 s. Ball milling was carried out by a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed was 40–80 rpm, preferably 60–70 rpm, and the left-and-right rotation speed was 250–370 rpm, preferably 280–330 rpm. The ball milling time was 15–20 h, preferably 17–19 h, to obtain mixed powder.

[0042] Step 2: Substrate and Powder Pretreatment

[0043] The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with wet sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment at a temperature of 70°C for 5 hours.

[0044] Step 3: Laser melting deposition

[0045] The mixed powder obtained in the second step is placed into the powder tank of a laser melting deposition apparatus. A high-energy laser is used to melt the mixed powder according to a preset scanning path. The scanning method is a multi-channel, multi-layer, short-side reciprocating motion. The protective gas is a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%), with the volume fraction of high-purity nitrogen being 10%–30%, preferably 15%–25%. The gas flow rate is 2–6 L / min, preferably 3–5 L / min, and the laser power is 500–1000 kW. A titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases is obtained by using a scanning speed of 500-800 mm / min (preferably 600-700 mm / min), a powder feeding speed of 8-14 g / min (preferably 10-12 g / min), a melt width of 3-7 mm (preferably 4-6 mm), an overlap rate of 35%-65% (preferably 50%-60%), and a single-pass layer height of 0.4-0.8 mm (preferably 0.5-0.7 mm).

[0046] Step 4: Hot isostatic pressing

[0047] The titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon (99.999%) was used as the protective atmosphere. The treatment pressure was 80–130 MPa, preferably 90–120 MPa, the treatment temperature was 1300–1700 °C, preferably 1450–1650 °C, and the treatment time was 30–90 min, preferably 50–70 min, to obtain the HIP composite material.

[0048] Step 5: Forging and Heat Treatment

[0049] The hot isostatically pressed composite material obtained in step four is forged and heat-treated. For forging: the forging temperature is 950–980℃, preferably 960–970℃, the deformation is 40%–60%, preferably 50%–60%, and the deformation speed is 8–12 mm / s, preferably 9–11 mm / s. For heat treatment: the heat treatment temperature is 400–700℃, preferably 500–650℃, and the heat treatment time is 30–90 min, preferably 40–80 min, using air cooling. The forged and heat-treated composite material is obtained.

[0050] Step 6: Surface shot peening

[0051] The forged and heat-treated composite material obtained in step 5 is subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material is S230 steel shot (average diameter 0.6 mm), the air pressure is 0.2–0.5 MPa, preferably 0.3–0.4 MPa, the shot peening flow rate is 1.0–1.5 kg / min, preferably 1.2–1.4 kg / min, the shot peening intensity measured using an N-type Alman test piece is 0.2–0.6 mm, preferably 0.3–0.5 mm, the shot peening time is 20–30 min, preferably 22–27 min, the incident angle is 45°–90°, preferably 60°–90°, and the shot peening coverage is 100%, thus obtaining the surface shot-peened composite material.

[0052] Microstructure and performance analysis of the titanium-based composite material prepared by the method described in this invention revealed that a uniform, fine, and dispersed dual reinforcing phase of TiN and rare earth oxides was formed in the titanium matrix, and the interface between the reinforcing phase and the titanium matrix was well bonded. Under the preferred preparation process parameters, the addition of the reinforcing phase effectively improved the comprehensive performance of the titanium alloy, giving it superior wear resistance and oxidation resistance.

[0053] The following detailed description is provided through specific embodiments.

[0054] Example 1:

[0055] Step 1: Ball milling and powder mixing

[0056] Commercially available pure titanium powder with a particle size of 22–45 μm and Y2O3 rare earth oxide powder with a particle size of 43–68 μm were selected as raw materials. Commercially available pure titanium powder and Y2O3 rare earth oxide powder with different mass fractions were mixed and placed in a low-temperature ball mill jar. The mass fraction of Y2O3 rare earth oxide powder was 3 wt.%. Ball milling media were added to the ball mill jar at a ball-to-material ratio of 5:1. Argon gas was introduced for 120 s and then released for 20 s. Ball milling was carried out by a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed was 60 rpm and the left-and-right rotation speed was 280 rpm. The ball milling time was 17 h to obtain mixed powder.

[0057] Step 2: Substrate and Powder Pretreatment

[0058] The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with wet sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment at a temperature of 70°C for 5 hours.

[0059] Step 3: Laser melting deposition

[0060] The mixed powder obtained in the second step was placed into the powder tank of a laser melting deposition equipment. The mixed powder was melted by a high-energy laser according to a preset scanning path. The scanning method was a multi-pass, multi-layer, short-side reciprocating method. The protective gas was a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%), with a volume fraction of 15% for high-purity nitrogen, a gas flow rate of 3 L / min, a laser power of 700 W, a scanning speed of 600 mm / min, a powder feeding speed of 10 g / min, a melt width of 4 mm, an overlap rate of 50%, and a single-pass layer height of 0.5 mm, resulting in a titanium-based composite material containing dual reinforcing phases of TiN and Y2O3 rare earth oxides.

[0061] Step 4: Hot isostatic pressing

[0062] The titanium-based composite material containing TiN and Y2O3 rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon (99.999%) was used as the protective atmosphere. The treatment pressure was 90 MPa, the treatment temperature was 1450 °C, and the treatment time was 50 min to obtain the HIP composite material.

[0063] Step 5: Forging and Heat Treatment

[0064] The hot isostatically pressed composite material obtained in step four was forged and heat-treated. For forging: the forging temperature was 960℃, the deformation amount was 50%, and the deformation speed was 9mm / s. For heat treatment: the heat treatment temperature was 500℃, the heat treatment time was 40min, and air cooling was used. The forged and heat-treated composite material was obtained.

[0065] Step 6: Surface shot peening

[0066] The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot (average diameter 0.6 mm), the air pressure was 0.3 MPa, the shot peening flow rate was 1.2 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.3 mm, the shot peening time was 22 min, the incident angle was 60°, and the shot peening coverage was 100%, thus obtaining the surface shot-peened composite material.

[0067] The tissue structure and performance of the samples in Example 1 were analyzed:

[0068] (A) Microstructure

[0069] The microstructure of the sample was observed using a scanning electron microscope, as shown in the attached figure. Figure 1 As shown, the TiN and Y2O3 reinforcing phases are uniformly dispersed in the matrix, effectively refining the grain size of the matrix.

[0070] (B) Tensile strength

[0071] The tensile strength of the sample was determined by performing a tensile test on it using a universal testing machine at room temperature, as shown in the attached figure. Figure 2 As shown, the tensile strength of the titanium-based composite material in Example 1 reached 1530 MPa, which is 102.38% higher than that of the matrix (756 MPa).

[0072] (C) Microhardness and surface friction coefficient

[0073] The microhardness of the samples was determined using a microhardness tester at room temperature, and the surface friction coefficient was determined using a multifunctional tribometer. Generally, higher microhardness and lower surface friction coefficient correspond to better wear resistance. (See attached image.) Figure 3 As shown, the microhardness of the titanium-based composite material in Example 1 is 453 HV and the surface friction coefficient is 0.25. Compared with the matrix (microhardness is 356 HV and surface friction coefficient is 0.42), the microhardness is increased by 27.25% and the surface friction coefficient is reduced by 40.48%.

[0074] (D) Weight gain from high-temperature oxidation

[0075] Thermal cycling oxidation tests were conducted on the samples in an air atmosphere using a box furnace at 800℃ for 50 hours. The weight gain from oxidation was measured. (See attached image) Figure 4 As shown, the weight gain of the titanium-based composite material in Example 1 was 2.87 mg, which was 81.87% lower than that of the matrix (15.83 mg).

[0076] Example 2:

[0077] Step 1: Ball milling and powder mixing

[0078] Commercial TB7 titanium alloy powder with a particle size of 22–45 μm and Nd2O3 rare earth oxide powder with a particle size of 43–68 μm were selected as raw materials. Commercial TB7 titanium alloy powder and Nd2O3 rare earth oxide powder with different mass fractions were mixed and placed in a low-temperature ball mill jar. The mass fraction of Nd2O3 rare earth oxide powder was 4 wt.%. Ball milling media were added to the ball mill jar, and the ball-to-material ratio was 5:1. Argon gas was introduced for 120 s and then released for 20 s. Ball milling was carried out by a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed was 65 rpm and the left-and-right rotation speed was 305 rpm. The ball milling time was 18 h to obtain mixed powder.

[0079] Step 2: Substrate and Powder Pretreatment

[0080] The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with wet sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment at a temperature of 70°C for 5 hours.

[0081] Step 3: Laser melting deposition

[0082] The mixed powder obtained in the second step was placed into the powder tank of a laser melting deposition equipment. The mixed powder was melted by a high-energy laser according to a preset scanning path. The scanning method was a multi-pass, multi-layer, short-side reciprocating method. The protective gas was a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%), with a volume fraction of 20% for high-purity nitrogen, a gas flow rate of 4 L / min, a laser power of 800 W, a scanning speed of 650 mm / min, a powder feeding speed of 11 g / min, a melt width of 5 mm, an overlap rate of 55%, and a single-pass layer height of 0.6 mm, resulting in a titanium-based composite material containing dual reinforcing phases of TiN and Nd2O3 rare earth oxides.

[0083] Step 4: Hot isostatic pressing

[0084] The titanium-based composite material containing TiN and Nd2O3 rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon (99.999%) was used as the protective atmosphere. The treatment pressure was 105 MPa, the treatment temperature was 1550 °C, and the treatment time was 60 min to obtain the HIP composite material.

[0085] Step 5: Forging and Heat Treatment

[0086] The hot isostatically pressed composite material obtained in step four was forged and heat-treated. For forging: the forging temperature was 965℃, the deformation amount was 55%, and the deformation speed was 10mm / s. For heat treatment: the heat treatment temperature was 575℃, the heat treatment time was 60min, and air cooling was used. The forged and heat-treated composite material was obtained.

[0087] Step 6: Surface shot peening

[0088] The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot (average diameter 0.6 mm), the air pressure was 0.35 MPa, the shot peening flow rate was 1.3 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.4 mm, the shot peening time was 24.5 min, the incident angle was 75°, and the shot peening coverage was 100%, resulting in a surface shot-peened composite material.

[0089] Organizational and performance analysis showed that no defects such as cracks or pores were observed in the titanium-based composite material of Example 2, and the uniformly dispersed TiN and Nd2O3 reinforcing phases were well bonded to the matrix. The tensile strength of the titanium-based composite material was 1680 MPa, which was 102.89% higher than that of the matrix (828 MPa); the microhardness of the titanium-based composite material was 511 HV, which was 36.63% higher than that of the matrix (374 HV); the surface friction coefficient of the titanium-based composite material was 0.22, which was 43.59% lower than that of the matrix (0.39); and the oxidation weight gain of the titanium-based composite material was 2.12 mg, which was 82.79% lower than that of the matrix (12.32 mg).

[0090] Example 3:

[0091] Step 1: Ball milling and powder mixing

[0092] Commercial TC4 titanium alloy powder with a particle size of 22–45 μm and La2O3 rare earth oxide powder with a particle size of 43–68 μm were selected as raw materials. Commercial TC4 titanium alloy powder and La2O3 rare earth oxide powder with different mass fractions were mixed and placed in a low-temperature ball mill jar. The mass fraction of La2O3 rare earth oxide powder was 5 wt.%. Ball milling media were added to the ball mill jar, and the ball-to-material ratio was 5:1. Argon gas was introduced for 120 s and then released for 20 s. Ball milling was carried out by a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed was 70 rpm and the left-and-right rotation speed was 330 rpm. The ball milling time was 19 h to obtain mixed powder.

[0093] Step 2: Substrate and Powder Pretreatment

[0094] The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with wet sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment at a temperature of 70°C for 5 hours.

[0095] Step 3: Laser melting deposition

[0096] The mixed powder obtained in the second step was placed into the powder tank of a laser melting deposition equipment. The mixed powder was melted by a high-energy laser according to a preset scanning path. The scanning method was a multi-pass, multi-layer, short-side reciprocating method. The protective gas was a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%), with a volume fraction of 25% for high-purity nitrogen, a gas flow rate of 5 L / min, a laser power of 900 W, a scanning speed of 700 mm / min, a powder feeding speed of 12 g / min, a melt width of 6 mm, an overlap rate of 60%, and a single-pass layer height of 0.7 mm, resulting in a titanium-based composite material containing dual reinforcing phases of TiN and La2O3 rare earth oxides.

[0097] Step 4: Hot isostatic pressing

[0098] The titanium-based composite material containing TiN and La2O3 rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon (99.999%) was used as the protective atmosphere. The treatment pressure was 120 MPa, the treatment temperature was 1650 °C, and the treatment time was 70 min to obtain the HIP composite material.

[0099] Step 5: Forging and Heat Treatment

[0100] The hot isostatically pressed composite material obtained in step four was forged and heat-treated. For forging: the forging temperature was 970℃, the deformation amount was 60%, and the deformation speed was 11mm / s. For heat treatment: the heat treatment temperature was 650℃, the heat treatment time was 80min, and air cooling was used. The forged and heat-treated composite material was obtained.

[0101] Step 6: Surface shot peening

[0102] The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot (average diameter 0.6 mm), the air pressure was 0.4 MPa, the shot peening flow rate was 1.4 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.5 mm, the shot peening time was 27 min, the incident angle was 90°, and the shot peening coverage was 100%, thus obtaining the surface shot-peened composite material.

[0103] Organizational and performance analysis showed that no defects such as cracks or pores were observed in the titanium-based composite material of Example 3, and the uniformly dispersed TiN and La2O3 reinforcing phases were well bonded to the matrix. The tensile strength of the titanium-based composite material was 1824 MPa, which was 106.33% higher than that of the matrix (884 MPa), and also higher than that of the titanium-based composite materials of Examples 1 and 2; the microhardness of the titanium-based composite material was 524 HV, which was 40.11% higher than that of the matrix (374 HV); the surface friction coefficient of the titanium-based composite material was 0.19, which was 45.71% lower than that of the matrix (0.35), and also lower than that of the titanium-based composite materials of Examples 1 and 2; the oxidation weight gain of the titanium-based composite material was 1.49 mg, which was 83.66% lower than that of the matrix (9.12 mg), and also lower than that of the titanium-based composite materials of Examples 1 and 2.

[0104] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

[0105] Matters not covered in this invention are common knowledge.

Claims

1. A high-strength, wear-resistant, and oxidation-resistant titanium-based composite material, characterized in that, The titanium-based composite material consists of a matrix and dual reinforcing phases. The matrix is ​​commercially available pure titanium or a titanium alloy, specifically TA15, TB7, or TC4. The dual reinforcing phases consist of TiN and rare earth oxides. The TiN is generated by the in-situ reaction of nitrogen with the molten matrix under laser irradiation. The rare earth oxides are Y2O3, Nd2O3, or La2O3. The titanium-based composite material has a tensile strength of 1530–1824 MPa, a microhardness of 453–524 HV, a surface friction coefficient of 0.19–0.25, and a high-temperature oxidation weight gain of 1.49–2.87 mg. The preparation method includes the following steps: Step 1: Ball milling and powder mixing Commercially available pure titanium powder or titanium alloy powder with a particle size of 22–45 μm and rare earth oxide powder with a particle size of 43–68 μm are selected as raw materials. The titanium alloy is selected as TA15, TB7, or TC4, and the rare earth oxide is selected as Y2O3, Nd2O3, or La2O3. The commercially available pure titanium powder or titanium alloy powder and the rare earth oxide powder are mixed and placed in a low-temperature ball mill jar. The mass fraction of the rare earth oxide powder is 3–5 wt.%. Ball milling media are added to the ball mill jar at a ball-to-material ratio of 5:

1. Argon gas is introduced for 120 seconds and then released for 20 seconds. Ball milling is performed using a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed is 60–70 rpm, and the left-and-right rotation speed is 280–330 rpm. The ball milling time is 17–19 hours to obtain a mixed powder. Step 2: Substrate and Powder Pretreatment The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with water sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes respectively and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment for 5 hours at a temperature of 70°C. Step 3: Laser melting deposition The mixed powder obtained in the second step is placed into the powder tank of a laser melting deposition equipment. The mixed powder is melted by a high-energy laser according to a preset scanning path. The scanning method is a multi-pass, multi-layer, short-side reciprocating method. The protective gas is a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%). The volume fraction of high-purity nitrogen is 10% to 30%, the gas flow rate is 2 to 6 L / min, the laser power is 500 to 1000 W, the scanning speed is 500 to 800 mm / min, the powder feeding speed is 8 to 14 g / min, the melt width is 3 to 7 mm, the overlap rate is 35% to 65%, and the single-pass layer height is 0.4 to 0.8 mm. Under the action of the laser, the nitrogen reacts in situ with the matrix melt pool to generate TiN, thus obtaining a titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases. Step 4: Hot isostatic pressing The titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon gas with a purity of 99.999% was used as the protective atmosphere. The treatment pressure was 80–130 MPa, the treatment temperature was 1300–1700 °C, and the treatment time was 30–90 min to obtain the HIP composite material. Step 5: Forging and Heat Treatment The hot isostatically pressed composite material obtained in step four is forged and heat-treated. The forging temperature is 950–980℃, the deformation is 40%–60%, and the deformation speed is 8–12 mm / s. The heat treatment temperature is 400–700℃, and the heat treatment time is 30–90 min. Air cooling is used to obtain the forged and heat-treated composite material. Step 6: Surface shot peening The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot with an average diameter of 0.6 mm, the air pressure was 0.2–0.5 MPa, the shot peening flow rate was 1.0–1.5 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.2–0.6 mm, the shot peening time was 20–30 min, the incident angle was 45°–90°, and the shot peening coverage was 100%, thus obtaining the surface shot-peened composite material.

2. A method for preparing the high-strength, wear-resistant, and oxidation-resistant titanium-based composite material as described in claim 1, characterized in that, Includes the following steps: Step 1: Ball milling and powder mixing Commercially available pure titanium powder or titanium alloy powder with a particle size of 22–45 μm and rare earth oxide powder with a particle size of 43–68 μm are selected as raw materials. The titanium alloy is selected as TA15, TB7, or TC4, and the rare earth oxide is selected as Y2O3, Nd2O3, or La2O3. The commercially available pure titanium powder or titanium alloy powder and the rare earth oxide powder are mixed and placed in a low-temperature ball mill jar. The mass fraction of the rare earth oxide powder is 3–5 wt.%. Ball milling media are added to the ball mill jar at a ball-to-material ratio of 5:

1. Argon gas is introduced for 120 seconds and then released for 20 seconds. Ball milling is performed using a combination of up-and-down tumbling and left-and-right rotation. The up-and-down tumbling speed is 60–70 rpm, and the left-and-right rotation speed is 280–330 rpm. The ball milling time is 17–19 hours to obtain a mixed powder. Step 2: Substrate and Powder Pretreatment The substrate used for laser melting deposition and the mixed powder obtained in the first step were pretreated. The substrate was made of pure titanium. The surface of the substrate was polished with water sandpaper to remove surface oxides and impurities. It was then ultrasonically cleaned in acetone and anhydrous ethanol for 15 minutes respectively and dried with cold air. The mixed powder obtained in the first step was dried in a vacuum environment for 5 hours at a temperature of 70°C. Step 3: Laser melting deposition The mixed powder obtained in the second step is placed into the powder tank of a laser melting deposition equipment. The mixed powder is melted by a high-energy laser according to a preset scanning path. The scanning method is a multi-pass, multi-layer, short-side reciprocating method. The protective gas is a mixture of high-purity nitrogen (99.999%) and high-purity argon (99.999%). The volume fraction of high-purity nitrogen is 10% to 30%, the gas flow rate is 2 to 6 L / min, the laser power is 500 to 1000 W, the scanning speed is 500 to 800 mm / min, the powder feeding speed is 8 to 14 g / min, the melt width is 3 to 7 mm, the overlap rate is 35% to 65%, and the single-pass layer height is 0.4 to 0.8 mm. Under the action of the laser, the nitrogen reacts in situ with the matrix melt pool to generate TiN, thus obtaining a titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases. Step 4: Hot isostatic pressing The titanium-based composite material containing TiN and rare earth oxide dual reinforcing phases obtained in the third step was subjected to hot isostatic pressing (HIP) treatment. High-purity argon gas with a purity of 99.999% was used as the protective atmosphere. The treatment pressure was 80–130 MPa, the treatment temperature was 1300–1700 °C, and the treatment time was 30–90 min to obtain the HIP composite material. Step 5: Forging and Heat Treatment The hot isostatically pressed composite material obtained in step four is forged and heat-treated. The forging temperature is 950–980℃, the deformation is 40%–60%, and the deformation speed is 8–12 mm / s. The heat treatment temperature is 400–700℃, and the heat treatment time is 30–90 min. Air cooling is used to obtain the forged and heat-treated composite material. Step 6: Surface shot peening The forged and heat-treated composite material obtained in step 5 was subjected to surface mechanical grinding, followed by surface shot peening. The shot peening material was S230 steel shot with an average diameter of 0.6 mm, the air pressure was 0.2–0.5 MPa, the shot peening flow rate was 1.0–1.5 kg / min, the shot peening intensity measured using an N-type Alman test piece was 0.2–0.6 mm, the shot peening time was 20–30 min, the incident angle was 45°–90°, and the shot peening coverage was 100%, thus obtaining the surface shot-peened composite material.

3. The preparation method according to claim 2, characterized in that, In the third step, the volume fraction of high-purity nitrogen is 15%–25%, the gas flow rate is 3–5 L / min, the laser power is 700–900 W, the scanning speed is 600–700 mm / min, the powder feeding speed is 10–12 g / min, the melt width is 4–6 mm, the overlap rate is 50%–60%, and the single-pass layer height is 0.5–0.7 mm.

4. The preparation method according to claim 2, characterized in that, In the fourth step, the treatment pressure is 90-120 MPa, the treatment temperature is 1450-1650℃, and the treatment time is 50-70 min.

5. The preparation method according to claim 2, characterized in that, In the fifth step, the forging temperature is 960-970℃, the deformation amount is 50%-60%, and the deformation speed is 9-11 mm / s; the heat treatment temperature is 500-650℃, and the heat treatment time is 40-80 min.

6. The preparation method according to claim 2, characterized in that, In the sixth step, the air pressure is 0.3-0.4 MPa, the shot peening flow rate is 1.2-1.4 kg / min, the shot peening intensity measured using an N-type Almen test piece is 0.3-0.5 mm, the shot peening time is 22-27 min, and the incident angle is 60°-90°.

7. The application of the high-strength, wear-resistant, and oxidation-resistant titanium-based composite material as described in claim 1 in the fields of aviation, aerospace, shipbuilding, and weaponry.

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