Method for preparing titanium-based composite material by using Al4C3 as carbon source

Abstract

The invention provides a method for preparing a titanium-based composite material with Al4C3 as a carbon source, and relates to the technical field of titanium-based composite material preparation.According to the method, a high-energy ball milling technology is adopted for conducting nanoscale refining pretreatment on Al4C3 powder, and in the powder mixing process, the sintering process and the subsequent heat treatment or thermal deformation process, through strict control over the temperature, time and deformation parameters, the titanium-based composite material with the Al4C3 as the carbon source is obtained. The generation speed of TiC is effectively reduced, and intragranular diffusion and precipitation of TiC are promoted, so that a large number of intragranular and nano TiC particles are formed. Compared with a traditional method for preparing the TiC / Ti composite material through carbon sources such as carbon black, the method has the advantages that the uniformity and the refining degree of TiC particles are remarkably improved, the tensile strength and the plasticity of the composite material are greatly improved, and the composite material has more excellent mechanical properties. The technology provides a brand new thought for preparing the high-performance titanium-based composite material, and is particularly suitable for aerospace, automobiles, medical treatment and other fields with strict requirements for high strength, high wear resistance and high-temperature stability of materials.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of titanium matrix composites, and particularly to a method for preparing titanium matrix composites using Al 4 C 3 as a carbon source. Background Art

[0002] Titanium and titanium alloys have been widely used in key fields such as aerospace, automotive, medical, and chemical engineering due to their excellent properties, such as light weight, high strength, good corrosion resistance, excellent high-temperature performance, and biocompatibility. Especially in the aerospace field, titanium alloys are used in engines, fuselages, and other structural components to meet the stringent requirements for high strength and temperature resistance under extreme working conditions. However, despite many advantages of titanium alloys, their performance in some applications still cannot fully meet the requirements, especially in terms of strength and wear resistance. In the application of high-performance structural materials, traditional titanium alloys are often restricted by insufficient strength and limited high-temperature performance.

[0003] To address these problems, titanium matrix composites (TMCs) have gradually become an ideal solution. Compared with traditional titanium alloys, titanium matrix composites have significant advantages in strengthening material strength, hardness, wear resistance, and high-temperature stability. In particular, TiC particles as reinforcement phases, due to their excellent strength, hardness, thermal stability, and good chemical compatibility, have become commonly used reinforcement particles in titanium matrix composites. The thermal expansion coefficients of TiC particles and the titanium matrix match well, which can effectively improve the mechanical properties of the titanium matrix. Therefore, TiC-reinforced titanium matrix composites have shown great application potential in aerospace, automotive, and other fields requiring high strength and wear resistance.

[0004] However, in the actual preparation process of titanium matrix composites, there is a significant challenge, namely the distribution problem of TiC particles. Although TiC particles can improve the performance of titanium matrix composites, in the traditional powder metallurgy method, TiC particles often aggregate at the grain boundaries of the powder. This non-uniform particle distribution leads to limitations in the performance of the composite material. Especially in the solid-state sintering process, due to the poor diffusivity of TiC particles, they can only precipitate at the grain boundaries of titanium powder, resulting in non-uniform particle distribution, which in turn affects the overall mechanical properties of the composite material. This non-uniform distribution causes local stress concentration during the loading process of the composite material, thereby reducing the overall mechanical properties of the material, especially under high-temperature and complex loading conditions. Therefore, how to effectively control the uniform distribution of TiC particles in the titanium matrix has become the key to improving the performance of titanium matrix composites.

[0005] To solve this problem, the use of different carbon sources as TiC precursors has become a research hotspot in recent years. Traditionally, many studies have used carbon black or other carbon sources as TiC precursors. However, these methods still have certain limitations in achieving uniform distribution of TiC particles. Especially during solid-state sintering, TiC particles often remain confined to grain boundaries and it is difficult to achieve uniform distribution. Summary of the Invention

[0006] In view of the problems mentioned in the above background art, the present invention proposes a method for preparing a titanium matrix composite using Al 4 C 3 as a carbon source. By using Al 4 C 3 as a TiC precursor, during solid-state sintering, the release of carbon atoms promotes the diffusion of carbon in the titanium matrix, enabling TiC particles to precipitate uniformly inside titanium powder or inside grains. Combining subsequent heat treatment or hot deformation processes, the uniformly distributed TiC can more effectively provide more recrystallization nucleation sites or pin grain boundaries, further bringing more excellent recrystallization and grain refinement effects to the material.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a titanium matrix composite using Al 4 C 3 as a carbon source, comprising the following steps: Step 1: Mix titanium metal matrix powder and Al 4 C 3 powder by ball milling to uniformly mix the powders and obtain composite powder; Step 2: Perform powder metallurgy sintering on the composite powder obtained in Step 1, and take out the bulk sample after sintering; Step 3: Perform heat treatment processing or hot deformation on the bulk sample obtained in Step 2 to obtain a titanium matrix composite.

[0008] As a further illustration of the present invention, the Al 4 C 3 powder in Step 1 is prepared by high-energy ball milling method.

[0009] As a further illustration of the present invention, the preparation process of the Al 4 C 3 powder specifically includes: Load milling balls, Al 4 C 3 powder and a process control agent into a ball milling tank in sequence, seal it, and then introduce a protective gas into the ball milling tank; After installing the ball milling jar on the planetary ball mill, ball milling is carried out in a forward and reverse cyclic intermittent manner. After ball milling, the powder is dried, and finally nano-sized Al 4 C 3 powder is reserved for use.

[0010] As a further illustration of the present invention, the parameter settings during ball milling are as follows: the rotational speed is 180 - 230 rpm / min, the ball milling method is to rotate forward for 10 min, stop for 10 min, rotate backward for 10 min, and cycle in turn. The total effective ball milling time is 30 - 60 h. And when the effective ball milling time reaches 2 h, a 1 h stop time is added. The ambient temperature during ball milling is controlled below 20°C.

[0011] As a further illustration of the present invention, the process control agent is analytical pure grade alcohol, and the addition amount of analytical pure grade alcohol is 8 wt.% of the mass of Al 4 C 3 powder. The ball milling jar and the ball milling balls are both made of zirconia; the ball-to-material ratio is set to 10:1; the protective gas is argon.

[0012] As a further illustration of the present invention, in step 1, the ball-to-material ratio is set to 5:1, and the addition amount of Al 4 C 3 powder is 4 wt.% of the titanium metal matrix powder; 1 wt.% of stearic acid is added to the mixed powder composed of the titanium metal matrix powder and Al 4 C 3 powder as the process control agent. The ball milling jar and the ball milling balls are both made of zirconia, and the protective gas is argon.

[0013] As a further illustration of the present invention, in step 1, the parameter settings during ball milling are as follows: the rotational speed is 180 - 230 rpm / min, the ball milling method is to rotate forward for 10 min, stop for 10 min, rotate backward for 10 min, and cycle in turn. The total effective ball milling time is 30 - 60 h. And when the effective ball milling time reaches 2 h, a 1 h stop time is added. The ambient temperature during ball milling is controlled below 20°C.

[0014] As a further illustration of the present invention, in step 2, the temperature and time settings during powder metallurgy sintering are such that Al 4 C 3 completely reacts with the titanium powder to form uniformly distributed TiC.

[0015] As a further illustration of the present invention, in step 3, the heat treatment process adopts one or several of recrystallization heat treatment, solution and aging heat treatment, and stress relief annealing heat treatment.

[0016] As a further illustration of the present invention, in step 3, the hot deformation processing can adopt processing means such as hot extrusion, hot rolling, hot forging, hot drawing, and hot stamping.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: (1) The preparation process of the uniformly distributed TiC-reinforced titanium matrix composite powder provided by the present invention is simple and easy to operate. The obtained reinforcement is uniformly dispersed and has good bonding with the matrix, achieving a more sufficient recrystallization and grain refinement effect. At the same time, there are more intragranular TiC and nano-TiC, showing significant advantages in mechanical properties compared with traditional powder metallurgy TiC / Ti composites.

[0018] (2) The present invention pre-treats Al 4 C 3 by ball milling. Through the protective atmosphere and the addition of process control agents during high-energy ball milling, the nano-scale refinement of the active powder Al 4 C 3 is achieved. Furthermore, it promotes the uniform distribution of Al 4 C 3 on the surface of the matrix powder during the powder mixing stage, and then enables Al 4 C 3 to fully react with the matrix during the sintering stage, increasing the C content of the materials of the present invention.

[0019] (3) The uniformly distributed TiC-reinforced titanium matrix composite prepared by the present invention has significantly excellent strength-ductility matching compared with traditional powder metallurgy TiC / Ti composites. Compared with TiC / Ti composites prepared by the same method, the tensile strength is increased by 42% and the plasticity is increased by 34%. The present invention patent provides a new idea for the design of powder metallurgy TiC / Ti composites and has guiding significance for the preparation of high-performance titanium matrix composites, making titanium matrix composites have good application prospects in the fields of aerospace, weaponry, transportation, etc.

[0020] Other features and advantages of the present technical solution will be described in the subsequent specification. And, partly, they will become obvious from the specification or be understood by implementing the present technical solution. The objectives and other advantages of the present technical solution can be achieved and obtained through the structures specifically pointed out in the written specification and the drawings.

[0021] Next, through the drawings and embodiments, the technical solution of the present technical solution will be further described in detail. Brief Description of the Drawings

[0022] The drawings are used to provide a further understanding of the present technical solution and constitute a part of the specification. They are used together with the embodiments of the present technical solution to explain the present technical solution and do not constitute a limitation to the present technical solution. In the drawings: Figure 1 Schematic flow chart for preparing the TiC / Ti composite material of Embodiment 1 of the present invention.

[0023] Figure 2 XRD phase analysis spectra of the uniformly distributed TiC / Ti composite material prepared in Embodiment 1 of the present invention, the material prepared in Comparative Example 1, and pure titanium.

[0024] Figure 3 SEM images of the uniformly distributed TiC / Ti composite material prepared in Embodiment 1 of the present invention and the material prepared in Comparative Example 1; wherein, (a) and (b) are the materials of Comparative Example 1 in the sintered state and the extruded state respectively, and (c) and (d) are the materials of Embodiment 1 in the sintered state and the extruded state respectively.

[0025] Figure 4 TEM images of the extruded uniformly distributed TiC / Ti composite material prepared in Embodiment 1 of the present invention and the extruded composite material prepared in Comparative Example 1, wherein, (a) is the TEM characterization image of the material of Comparative Example 1, and (b) is the TEM characterization image of the material of Embodiment 1.

[0026] Figure 5 Mechanical property data of the uniformly distributed TiC / Ti composite material prepared in Embodiment 1 of the present invention, the material of Comparative Example 1, and pure titanium.

[0027] Figure 6 SEM characterization image of the microstructure of the sintered material obtained in Comparative Example 2.

[0028] Figure 7 SEM characterization image of the microstructure of the extruded material obtained in Comparative Example 2.

[0029] Figure 8 Room temperature mechanical property curves of the extruded material obtained in Comparative Example 2 and the extruded material obtained in Embodiment 1. Detailed implementation manners

[0030] The following is a description of the preferred embodiments of the present technical solution with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustration and explanation of the present technical solution, and are not used to limit the present technical solution.

[0031] Many studies have used carbon black or other carbon sources as the precursor of TiC. However, these methods still have certain limitations in achieving uniform distribution of TiC particles. Especially during the solid-state sintering process, TiC particles often remain confined at the grain boundaries and it is difficult to achieve uniform distribution. The present invention provides a new solution by using Al 4 C 3 as the precursor of TiC. Compared with traditional carbon sources, Al 4 C3 It can not only effectively improve the diffusivity of carbon, but also promote the uniform diffusion of carbon atoms inside the titanium powder, and then form uniformly distributed TiC particles inside the powder or grains. The present invention effectively overcomes the problem of TiC particle aggregation in the traditional method and ensures the uniform distribution of TiC particles in the titanium matrix. More importantly, using Al 4 C 3 as a precursor can not only improve the distribution of TiC particles, but also promote the refinement of TiC particles, precipitate more nano-TiC particles, and thus further improve the strength and plasticity of the composite material.

[0032] Through the method provided by the present invention, the strength and ductility of the composite material have been significantly improved. Due to the uniform distribution of TiC particles inside the titanium matrix, the material shows a more effective and uniform recrystallization or grain refinement effect during the hot working process, thereby improving the strength and toughness of the material. Compared with the traditional TiC-reinforced composite material, the composite material prepared by the present invention not only exhibits better strength and ductility at room temperature, but also has more excellent mechanical properties in a high-temperature environment. Therefore, the present invention not only solves the problem of uneven distribution of TiC particles, but also significantly improves the mechanical properties of the composite material by controlling the precipitation and distribution of TiC particles, and broadens its application prospects in high-demand structural materials.

[0033] The present invention provides a method for preparing a titanium matrix composite material using Al 4 C 3 as a carbon source, comprising the following steps: Step 1: Mix the titanium metal matrix powder and Al 4 C 3 powder by ball milling to make the powder uniformly mixed and obtain the composite material powder.

[0034] Among them, the metal matrix powder is pure titanium with a low Al element content, an α-titanium alloy or a near-α-titanium alloy powder. The Al 4 C 3 powder is a reinforcing powder.

[0035] Specifically, the Al 4 C 3 powder in Step 1 is prepared by a high-energy ball milling method, which specifically includes the following process: Step 101: Put the ball milling balls, Al 4 C 3 powder and the process control agent into the ball milling tank in sequence, seal it, and then introduce a protective gas into the ball milling tank.

[0036] Specifically, the process control agent is analytical pure grade alcohol, and the addition amount of the analytical pure grade alcohol is Al 4 C3 8 wt.% of the powder mass, Al 4 C 3 The powder selected is 5 μm powder; both the ball milling tank and the ball milling balls are made of zirconia; the ball-to-material ratio is set to 10:1; the protective gas is argon.

[0037] Specifically, to ensure the ball milling efficiency, the volume of the powder and the ball milling balls finally added into the ball milling tank does not exceed 50% of the volume of the ball milling tank. First, add the ball milling balls, and then add the matrix metal powder and the process control agent in sequence. The addition of the process control agent can prevent the powder from caking.

[0038] Specifically, seal the zirconia ball milling tank that has been filled with Al 4 C 3 powder, process control agent and ball milling balls. Utilize the characteristic that the density of argon is greater than that of air, and discharge the air by filling high-purity argon into the ball milling tank, so as to achieve the purpose of preventing the powder from oxidizing during the ball milling process. It should be noted that the gas flow rate during the argon filling process cannot be too large to prevent the powder from flying out. First, open the outlet valve to ensure the normal gas path, adjust the gas flow rate to 1.0 L / min, and introduce argon at the inlet hole to ensure that the ventilation time is not less than 8 min; when stopping the gas inlet, first close the valve at the inlet, and then close the outlet valve. The relatively low gas flow rate in the above operations is beneficial for the argon protective gas to slowly discharge the air and will not cause the reduction of the powder quality.

[0039] Step 102: After installing the ball milling tank on the planetary ball mill, carry out ball milling in a forward and reverse cyclic intermittent ball milling mode. After the ball milling is completed, dry the powder, and finally obtain nano-sized Al 4 C 3 powder for standby.

[0040] After the inflation is completed, fix the ball milling tank on the planetary ball mill through a fixture. The parameters during ball milling are set as follows: the rotation speed is 180 - 230 rpm / min, the ball milling mode is to rotate forward for 10 min, stop for 10 min, rotate backward for 10 min, and cycle in sequence. To avoid chemical reactions caused by too high temperature in the ball milling tank, on the one hand, when the effective ball milling time reaches 2 h, add another 1 h of stop time to allow the ball milling tank to cool down sufficiently, and on the other hand, control the ambient temperature below 20°C to ensure the consistency of the temperature at the start of each ball milling. The total effective ball milling time is 30 - 60 h. When the size of Al4C3 drops to the nano level, the powder can be taken out. When taking out the powder, it is necessary to ensure that the ball milling tank cools down to room temperature, and the entire powder taking process is carried out in a glove box under an argon atmosphere. After the powder is stable, place it in a vacuum drying oven to dry (>85˚C) to remove the alcohol residue in the fine powder and prevent unnecessary O elements from entering the material in the subsequent process.

[0041] Al4 C 3 The mass fraction of C is 25%, so a large amount of Al is required in the preparation of TiC / Ti with a high C content. 4 C 3 Powder. Under such conditions, small-sized powder is beneficial to the 4 C 3 uniform distribution of the Al 4 C 3 powder on the surface of the matrix powder without agglomeration, which is further beneficial to the 4 C 3 complete reaction of Al 4 C 3 powder during the sintering stage. Al

[0042] In step 1, the ball milling and mixing operation is also carried out using a planetary ball mill. The ball-to-powder ratio is set to 5:1, and the addition amount of the Al 4 C 3 powder is 4 wt.% of the titanium metal matrix powder; 1 wt.% of stearic acid is added to the mixed powder composed of the titanium metal matrix powder and the Al 4 C 3 powder as a process control agent to prevent powder caking during ball milling. The ball milling tank and the ball milling balls are both made of zirconia, and the protective gas is argon.

[0043] In step 1, the parameter settings during ball milling are as follows: the rotation speed is 180 - 230 rpm / min, the ball milling method is to rotate forward for 10 min, stop for 10 min, and rotate backward for 10 min, and this cycle is carried out in turn. The total effective ball milling time is 30 - 60 h, and when the effective ball milling time reaches 2 h, a 1 h stop time is added. The environmental temperature during ball milling is controlled below 20°C. Specifically, the argon condition and the ball milling parameter settings in step 1 are the same as those in the high-energy ball milling process of the Al 4 C 3 powder, except that the total ball milling duration is changed to 4 - 8 h to make the powder evenly mixed.

[0044] Step 2: Perform powder metallurgy sintering on the composite powder obtained in step 1, and take out the bulk sample after sintering.

[0045] When performing powder metallurgy sintering on the prepared composite powder, methods such as plasma sintering, hot press sintering, and hot isostatic pressing can be selected for forming. The sintering temperature and time are controlled according to the material system to make the Al 4 C 3Fully react with titanium powder to form uniformly distributed TiC. At the same time, since process control agents are added during both ball milling before and after heat treatment in the powder preparation process, in order to avoid the added process control agents from increasing the oxygen content of the material, a specific temperature is designed during sintering to remove the process control agents, and then it enters the final target temperature and is held under pressure for a certain time. After sintering, the bulk sample is taken out.

[0046] Variable-temperature sintering can also be carried out on the material: sinter at a temperature below the phase transition point to achieve the complete reaction of Al 4 C 3 and the complete dissolution of a large amount of TiC; then quickly raise the temperature above the phase transition point for short-time sintering to promote the rapid precipitation of the dissolved C in the form of TiC, realizing the uniform distribution of TiC. The selection of specific temperature and time parameters needs to meet the above requirements.

[0047] Step 3: Perform heat treatment processing or hot deformation on the bulk sample obtained in Step 2 to obtain a titanium matrix composite material.

[0048] The sintered samples above can be subjected to a variety of different heat treatment processes or hot deformations to further optimize the material properties.

[0049] If heat treatment is selected, the material needs to be carried out in a vacuum or protective atmosphere, and sponge titanium is placed near the sample to prevent the sample from absorbing oxygen. The material can be designed with a variety of different types of heat treatment to optimize the performance. Different heat treatment strategies correspond to different heat treatment conditions, including but not limited to: Recrystallization heat treatment: The recrystallization temperature needs to be slightly higher than the recrystallization temperature of the Ti matrix material, and should not be too high to cause significant coarsening of TiC; the heat treatment time should not be too long to cause significant coarsening of TiC; the cooling can be carried out by furnace cooling, air cooling, water cooling or oil cooling, etc. The specific parameter selection needs to meet the complete recrystallization of the material and keep the size of TiC from coarsening significantly.

[0050] Solution and aging heat treatment: The solution temperature should be lower than the phase transition temperature of titanium. The specific parameter selection of the solution temperature and time should meet the maximum dissolution of TiC and the saturation of the overall solution C in the material. After solution, the material is water-cooled or oil-cooled to room temperature. The solution-treated material is subjected to aging heat treatment. The aging temperature should be higher than the phase transition temperature, and the material should not be heated with the furnace. The aging time should not be too long, just a few minutes, to promote the rapid precipitation of the dissolved C without obvious growth, realizing the uniform and dispersed precipitation and distribution of TiC. After aging, the material needs to be water-cooled or oil-cooled to room temperature. The selection of specific temperature, time and other parameters needs to meet the above requirements.

[0051] Stress-relieving annealing heat treatment: If the sintering process of the material introduces high internal stress, annealing of the material is required to optimize the microstructure and properties of the material. The selection of annealing temperature and time has a large degree of freedom. Heat treatment can be carried out for a long time at a lower temperature (such as 500˚C), or for a short time at a higher temperature (such as 850˚C). The growth of TiC and abnormal coarsening of grains should be avoided under high-temperature conditions. After annealing, the material can be cooled to room temperature by furnace cooling, air cooling, water cooling or oil cooling. The specific heat treatment parameters should meet the requirements that sufficient recovery occurs in the material, the grains do not coarsen significantly, and the plasticity of the material is significantly improved.

[0052] If hot deformation is selected, the material needs to be protected by a jacket or glass glue to prevent significant oxygen absorption during the hot deformation process. The designed material can be subjected to various types of heat treatment to optimize its properties, including but not limited to: Hot extrusion: For hot extrusion, it is recommended to coat the material with glass glue to achieve the purpose of heat preservation and anti-oxidation. The heat preservation temperature for hot extrusion should be lower than the phase transformation temperature of the material. The selection of the corresponding extrusion ratio and extrusion speed aims to ensure sufficient recrystallization of the material. After hot extrusion, the material can be air-cooled to room temperature.

[0053] Hot rolling, hot forging: Since hot working methods such as hot rolling and hot forging involve multiple deformations, methods such as jacket treatment are used to process the material. The heat preservation temperature should be lower than the phase transformation temperature of the material. The selection of the corresponding deformation amount and number of deformations aims to ensure compositional recrystallization of the material. After hot deformation, the material can be air-cooled to room temperature.

[0054] The composite material finally prepared by the above preparation method is a TiC / Ti composite material with uniformly distributed TiC, and the reinforcing phase used is 4 wt.% Al 4 C 3 , and the corresponding content of C is 1 wt.%. TiC in the material is successfully precipitated inside the Ti powder, uniformly distributed in the matrix, and a large number of nano-TiC are generated. During the sintering, heat treatment or hot deformation stage, the parameters such as temperature, time and deformation amount are controlled to avoid significant coarsening of TiC.

[0055] The preparation method provided by the present invention promotes the precipitation of nano-TiC particles, and further improves the strength and plasticity of the composite material through the Orowan strengthening mechanism. By this method, the TiC particles in the composite material are not only more uniformly distributed, but also have smaller sizes. This refinement effect enhances the strength and plasticity of the composite material. The uniformly distributed TiC particles, grain refinement and precipitation of nano-TiC particles have significantly improved the strength and ductility of the material at room temperature, laying a foundation for the preparation of high-performance TiC / Ti composite materials.

[0056] The titanium-based composite material of the present invention has broad application prospects and is particularly suitable for fields such as aerospace, automotive, medical, and other fields that require high strength, high wear resistance, and high temperature stability, providing a material selection with more excellent performance. Through the method of the present invention, the comprehensive performance of the titanium-based composite material can be effectively improved to meet the requirements of high-performance structural materials.

[0057] The present invention will be further described below in conjunction with specific embodiments: In the following embodiments, the uniformly distributed TiC / Ti composite material is taken as an example for illustration.

[0058] The following are the raw materials, planetary ball milling, plasma sintering, hot extrusion, and performance testing equipment used in the embodiments: The German Pulverisette 5 type planetary ball mill is used for the powder pretreatment and powder mixing of Al 4 C 3 powder; The Shanghai Chenhua SPS-20T-10-III plasma sintering equipment is used to prepare the SPS state composite material block; The Ningbo Pawell vertical hot extrusion equipment YP61-315 is used for the hot extrusion process of the sintered specimen; The German ZEISS Sigma 300 is used for the powder morphology and its internal morphology characterization; The American FEI Talos F200X high-resolution transmission equipment is used for the powder and block TEM analysis and characterization; The D8 Discover X-ray diffractometer is used for the XRD characterization and analysis of the powder; The American INSTRON 3382 electronic universal testing machine is used for the tensile property testing of the extruded composite material; The powder uses 45 μm spherical pure Ti powder and 5 μm Al 4 C 3 powder prepared by Shanghai Buwei Company. The carbon black powder is 100 nm carbon black produced by Ningbo Jinlei Nano Materials Technology Co., Ltd., and the stearic acid is produced by Macklin Company with the chemical formula C 18 H 36 O 2 .

[0059] In the following embodiments, the high-energy ball milling method is used. Through the ball milling process, the Al 4 C 3 powder is first refined to the nanoscale, and the Al 4 C 3After that, ball milling is carried out again to obtain a uniformly mixed powder. Subsequently, the powder is sintered, and finally the bulk is further densified by hot extrusion to finally obtain a dense composite material rod without obvious defects.

[0060] Example 1 In this example, the preparation method of the uniformly distributed TiC / Ti composite material includes high-energy ball milling to reduce the size of Al 4 C 3 , and then uniformly mixing it with the titanium matrix powder. Subsequently, the mixed powder is sintered and extruded to form a process, and finally a composite material bulk is obtained.

[0061] The specific preparation method of the above-mentioned uniformly distributed TiC / Ti composite material includes the following steps: Step 1, pretreatment of Al 4 C 3 powder: A total of 120 grams of 5 μm Al 4 C 3 powder and 9.6 g of absolute ethanol are loaded into the ball milling tank. The ball milling balls are zirconia balls with a diameter of 10 mm, and the ball-to-powder ratio is 10:1.

[0062] During the above preparation process, the materials loaded into the tank are in the order of first adding the ball milling balls, and then adding Al 4 C 3 powder and absolute ethanol, and evenly stirring with a medicine spoon to make the initial Al 4 C 3 powder and absolute ethanol premixed evenly, and then seal the ball milling tank.

[0063] Open the outlet valve to ensure the normal gas path, adjust the gas flow rate to 1.0 L / min, and introduce argon gas into the air inlet hole of the ball milling tank to ensure that the ventilation time is not less than 8 minutes; when stopping the intake, first close the valve at the intake port, and then close the outlet valve. The relatively low gas flow rate in the above operation is beneficial for the argon protective gas to slowly discharge the air and will not cause a reduction in the powder quality.

[0064] After the inflation is completed, fix the ball milling tank on the planetary ball mill with a clamp. Set the ball milling parameters as the rotation speed of 180 - 230 rpm / min, the ball milling mode is forward rotation for 10 minutes, stop for 10 minutes, reverse rotation for 10 minutes, and cycle in turn. To avoid chemical reactions caused by too high temperature in the ball milling tank, on the one hand, when the effective ball milling time reaches 2 hours, add another 1 hour of stop time to fully cool the ball milling tank, and on the other hand, control the ambient temperature below 20°C to ensure the consistency of the temperature at each ball milling start. The effective ball milling time is 40 hours, until Al 4 C 3The average size decreased to 70 nm. The powder was taken out in a glove box and placed in a vacuum drying oven for drying at 85˚C for 10 h.

[0065] Step 2, Process and parameter design of powder mixing and ball milling: The same ball milling equipment as in Step 101 was used, and the ball-to-material ratio was changed to 5:1. 117.6 g of titanium metal matrix powder and 2.4 g of Al 4 C 3 powders were placed in the ball milling tank according to the designed ratio. Additionally, 1.2 g of stearic acid was added to prevent powder agglomeration during ball milling. Ball milling was carried out for 4 h under the same argon and rotation speed conditions as in Step 1 to uniformly mix the powders.

[0066] Step 3, Discharge plasma sintering process of the mixed powder: The composite powder obtained after ball milling was respectively loaded into graphite molds with a diameter of 30, pre-pressed with a pressure of 0.5 T, and the pressure holding time was not less than 10 min. Subsequently, the molds were loaded into the furnace of the plasma sintering equipment for sintering. The sintering temperature was 950˚C, the pressure was 30 MPa, the vacuum degree was 1.5×10 -1 Pa, and the heat preservation time was 30 min to densify the samples. K-type thermocouple contact temperature measurement was used to ensure the accuracy of the temperature.

[0067] Step 4, Hot extrusion process: The sintered block was preheated to 120˚C and coated with glass glue. After the glass glue dried, the material was placed in a box furnace and held at 950˚C for 30 min, and then put into an extrusion equipment preheated to 370˚C. The extrusion ratio was 17:1, and the extrusion speed was 4 mm / s. Finally, a composite extrusion rod with a diameter of 7 mm and a smooth surface without cracks was obtained.

[0068] To highlight the material property advantages of this design scheme, the following control groups were used for illustration: Comparative Example 1 A preparation method of a non-uniformly distributed traditional powder metallurgy TiC / Ti composite material, including the following steps: Step 1: 100 nm carbon black was directly ball milled and mixed with titanium matrix powder. The specific ball milling process was the same as that in Step 2 of Example 1, except that the metal matrix powder was 119.4 g, the 100 nm carbon black powder was 0.6 g, and the stearic acid was 1.2 g.

[0069] Step 2: The mixed powder obtained in Step 1 was subjected to discharge plasma sintering, and the specific sintering parameter settings were the same as those in Step 3 of Example 1.

[0070] Step 3: The sintered block samples obtained in Step 2 are subjected to hot extrusion treatment, and the specific hot extrusion parameter settings are the same as those in Step 4 of Example 1.

[0071] For the TiC / Ti composite block prepared in Comparative Example 1, the average yield strength is 464 MPa, the average tensile strength is 634 MPa, and the average elongation at break is 16.5%. For the uniformly distributed TiC / Ti composite block prepared in Example 1, the average yield strength is 721 MPa, the average tensile strength is 901 MPa, and the average elongation at break is 22.1%. It can be seen that after the TiC is regulated to be uniformly distributed by Al 4 C 3 its strength and plasticity have significant advantages compared with the traditional powder metallurgy TiC / Ti composite with non-uniform TiC distribution.

[0072] Comparative Example 2 A method for preparing a TiC / Ti composite using elemental powder as a precursor is provided. The difference between the method provided in this comparative example and Comparative Example 1 is only that 1.8 g of pure Al powder is added to the material in Step 1 of Comparative Example 1 based on 0.6 g of carbon black, and the metal matrix powder is changed to 117.6 g.

[0073] The following test and analysis are carried out on the TiC / Ti composites prepared in the examples and comparative examples of the present invention: (1)XRD phase characterization of sintered materials Figure 2 It is the XRD characterization pattern of the materials after sintering of Example 1, Comparative Example 1 (the control group in the figure), and pure titanium. The calibration results show that TiC is generated in both the materials of Example 1 and Comparative Example 1 after sintering, and there are no other impurity phase peaks, indicating that the Al element in Al 4 C 3 does not generate Ti-Al intermetallic compound strengthening phases in the material.

[0074] (2)TiC distribution characterization of sintered and extruded states Figure 3 It is the SEM characterization diagram of the materials of Example 1 and Comparative Example 1 in sintered and extruded states. Among them, (a) and (b) are the materials of Comparative Example 1 in sintered and extruded states respectively, and (c) and (d) are the materials of Example 1 in sintered and extruded states respectively. In the materials of Comparative Example 1 in both states, TiC shows obvious non-uniform distribution, and TiC is only distributed at grain boundaries. While in the materials of Example 1, TiC is evenly distributed as a whole, and more intragranular TiC is generated. At the same time, it can be observed that the matrix grain size of the materials in Example 1 is significantly smaller than that of the control group materials in the same state. It is confirmed that uniformly distributed TiC can provide a more significant grain refinement effect and more sufficient recrystallization.

[0075] Figure 6 SEM characterization diagram of the microstructure of the material of Comparative Example 2 in the sintered state. After using elemental powders of Al and C in equal proportions, in-situ TiC is still distributed at the boundaries of primary powders, forming a non-uniform distribution, which is consistent with the distribution of TiC in conventional TiC / Ti composites. Moreover, a large amount of aluminum powder only partially dissolves, and a large amount of aluminum powder still remains in the material.

[0076] Figure 4 TEM characterization diagram of the materials of Comparative Example 1 and Example 1 in the extruded state. Among them, (a) is the TEM characterization diagram of the material of Comparative Example 1, and (b) is the TEM characterization diagram of the material of Example 1. It can be observed from the figure that only micron-sized TiC exists in the material of Comparative Example 1, while in addition to micron-sized TiC, a large amount of nano-TiC also exists in the material of Example 1. These nano-TiC are uniformly dispersed in the matrix material. These nano-TiC can significantly improve the strength and plasticity of the material through the Orowan mechanism.

[0077] Figure 7 SEM characterization diagram of the microstructure of the material of Comparative Example 2 in the extruded state. After extrusion, the uniformity of TiC is improved, but it still shows a non-uniform distribution, with a large number of TiC enrichment areas and depletion areas. In addition, the unmolten aluminum powder is still retained, and due to the large difference in deformation ability between aluminum and titanium, cracks are generated in the material after extrusion, further affecting the mechanical properties of the material.

[0078] (3) Room temperature mechanical property test The room temperature mechanical properties of the material of Example 1, Comparative Example 1 and pure titanium material were tested, and the engineering stress-strain results are as Figure 5 shown. It can be seen that after the process designed by the present invention, both the strength and plasticity of the material are significantly improved compared with the traditional non-uniform TiC / Ti composite material (Comparative Example 1), which proves that the distribution regulation of TiC in the powder metallurgy TiC / Ti composite material of the present invention has an excellent effect on improving performance. The uniformly distributed TiC and nano-TiC obtained by the present invention provide a new idea for the design of powder metallurgy TiC / Ti composite materials, and it is expected to obtain nano-reinforced metal matrix composite materials with excellent comprehensive mechanical properties, meeting the applications of composite materials in important national fields such as aerospace and weaponry.

[0079] Figure 8The room-temperature mechanical property curves of the extruded material of Comparative Example 2 and the extruded material of Example 1 are shown in the figure. It can be seen from the figure that the TiC / Ti of the present application shows significant advantages in room-temperature mechanical properties, proving that even if the precursors are replaced with equal amounts of Al and C elemental powders, the same performance optimization effect of the present invention cannot be achieved. Elemental powders cannot achieve the regulation of the size and distribution of TiC and cannot significantly improve the material properties. Therefore, the invention has uniqueness in tissue and property regulation and cannot be simply replaced by elemental powders with the same ratio.

[0080] Obviously, those skilled in the art can make various changes and modifications to the technical solution without departing from the spirit and scope of the technical solution. Thus, if these modifications and variations of the technical solution fall within the scope of the claims of the technical solution and its equivalent technologies, the technical solution is also intended to include these modifications and variations.

Claims

1. A method for preparing a titanium-based composite material using Al4C3 as a carbon source, characterized in that: The steps include: Step 1: Mix titanium metal matrix powder and Al4C3 powder by ball milling to make the powders evenly mixed to obtain composite material powder; Step 2: performing powder metallurgy sintering on the composite material powder obtained in step 1, and taking out a block sample after sintering; Step 3: The block sample obtained in step 2 is subjected to heat treatment or thermal deformation to obtain a titanium-based composite material.

2. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 1, characterized in that: The Al4C3 powder in step 1 is prepared by high-energy ball milling.

3. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 2, characterized in that: The preparation process of Al4C3 powder in step 1 specifically includes: The ball milling balls, Al4C3 powder and process control agent are sequentially loaded into the ball milling jar and sealed, and then protective gas is introduced into the ball milling jar; After the ball mill is installed on the planetary ball mill, the ball milling is carried out by using a forward and reverse cycle intermittent ball milling method. After the ball milling is completed, the powder is dried to finally obtain nano-sized Al4C3 powder for use.

4. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 3, characterized in that: The parameters for ball milling were set as follows: rotation speed 180-230 rpm / min, the ball milling mode was forward rotation for 10 min, stop for 10 min, reverse rotation for 10 min, and so on, the total effective ball milling time was 30-60 h, and when the effective ball milling time reached 2 h, a stop time of 1 h was added, and the ambient temperature during ball milling was controlled below 20 °C.

5. The method for preparing a titanium-based composite material using Al4C3 as a carbon source as claimed in claim 3, characterized in that: The process control agent is analytical grade alcohol, and the addition amount of analytical grade alcohol is 8 wt.% of the mass of Al4C3 powder. The ball mill and ball mill are made of zirconia; the ball-to-material ratio is set to 10:1; the protective gas is argon.

6. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 1, characterized in that: In step 1, the ball-to-material ratio is set to 5:1, and the addition amount of Al4C3 powder is 4 wt.% of the titanium metal matrix powder; 1 wt.% of stearic acid is added to the mixed powder consisting of titanium metal matrix powder and Al4C3 powder as a process control agent. The ball mill and ball mill are made of zirconia, and the protective gas is argon.

7. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 1, characterized in that: In step 1, the parameters during ball milling are set as follows: rotation speed 180-230 rpm / min, ball milling mode is forward rotation 10 min, stop 10 min, reverse 10 min, and so on, the total effective ball milling time is 30-60 h, and when the effective ball milling time reaches 2 h, a stop time of 1 h is added, and the ambient temperature during ball milling is controlled below 20°C.

8. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 7, characterized in that: The temperature and time settings during powder metallurgy sintering in step 2 need to allow Al4C3 to react completely with titanium powder to generate uniformly distributed TiC.

9. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 1, characterized in that: In step 3, the heat treatment process adopts one or more of recrystallization heat treatment, solution and aging heat treatment and stress relief annealing heat treatment.

10. The method for preparing a titanium-based composite material using Al4C3 as a carbon source according to claim 1, characterized in that: In step 3, the hot deformation processing is one or more of hot extrusion, hot rolling and hot forging.

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