Heterostructure titanium-based composite material with nano reinforced phase and preparation method of heterostructure titanium-based composite material

Abstract

Titanium-based composite powder is used as a raw material, the titanium-based composite powder takes titanium or a titanium alloy as a titanium matrix and takes TiBw or TiC as a reinforcing phase, and the mass ratio of the TiBw or TiC reinforcing phase in the titanium-based composite powder is 1 wt.%-5 wt.%; tiBw or TiC reinforcement bodies in the formed heterostructure titanium-based composite material are distributed in titanium-based composite powder in a net-shaped structure along a Ti matrix grain boundary, a reinforcement phase in the composite material has a nanoscale, and matrix grains have an obvious coarse and fine grain heterostructure. The invention further discloses a preparation method of the material, according to the preparation method, different grain sizes are caused by different cooling speeds of powder with different grain sizes, a low-temperature and high-pressure spark plasma sintering process is combined, the material is prepared under the conditions that grains and a reinforced phase do not grow up at a low temperature and are densified at a high pressure, the preparation process is simple, and the cost is low. The preparation method is also suitable for preparation of other alloys.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of metal-based composite materials, and in particular relates to a heterogeneous structure titanium-based composite material with a nano-reinforced phase, and also relates to a preparation method of the composite material. Background Art

[0002] Titanium and titanium alloys are widely used in aerospace, automotive, biomedical and other fields due to their low density, high specific strength and excellent corrosion resistance. However, with the development of my country's aerospace technology, the service requirements for titanium and titanium alloys under extreme environmental conditions are increasing, and their shortcomings such as low high-temperature strength and poor wear resistance have seriously limited their wide application. By adding ceramic reinforcement phases to titanium and titanium alloys to prepare titanium-based composites, it is possible to inherit the excellent properties of the titanium matrix while having the characteristics of high strength and high modulus of the ceramic reinforcement phase. Therefore, titanium-based composites usually exhibit high specific strength, high specific modulus, excellent high temperature resistance and wear resistance, and are considered to be the most promising type of material to further improve the performance of titanium and titanium alloys and broaden their application fields.

[0003] Common reinforcements in titanium-based composites include TiB, SiC, TiC, TiB2 and B4C. According to the reinforcement phase morphology, they can be divided into continuous (fiber) reinforced titanium-based composites and discontinuous (short fibers, particles or whiskers, etc.) reinforced titanium-based composites. Among them, discontinuous reinforced titanium-based composites have attracted widespread attention due to their simple preparation process, low production cost, easy processing and isotropy. Among the many discontinuous reinforcement phases, titanium boride whiskers (TiBw) have a high elastic modulus (about 450-550GPa), good interface bonding with the matrix, and a thermal expansion coefficient similar to that of titanium (TiB: 7.2×10 -6 K -1 , Ti: 8.2×10 -6 K -1 ) and other characteristics, and is considered to be one of the most ideal reinforcement phases for titanium and titanium alloys. At present, the main preparation methods for discontinuously reinforced titanium-based composites are melt casting, powder metallurgy, additive manufacturing, mechanical alloying and self-propagating high-temperature synthesis. Among them, powder metallurgy is currently one of the most common methods for preparing discontinuously reinforced titanium-based composites. However, the higher sintering temperature of the powder metallurgy method causes serious coarsening of the size of TiBw, resulting in TiBw easily becoming a crack source under external loads, causing the improvement of the strength of titanium-based composites to always be at the expense of plasticity, thus showing a serious problem of strength-toughness inversion.

[0004] The introduction of heterogeneous structure metal materials provides a new idea for solving the serious problem of strength and toughness inversion of titanium-based composite materials. The existing technology mainly constructs a certain proportion of coarse grains and fine grains / ultrafine grains in the metal matrix to form a heterogeneous structure. At present, the construction of heterogeneous structure titanium-based composite materials is mostly carried out in the following three ways: large plastic deformation combined with annealing recrystallization; sintering densification of powders of different particle sizes assembled above the phase transition temperature; regulating the spatial distribution of the reinforcing phase. Although the above methods can all construct ideal heterogeneous structures in titanium-based composite materials, in order to achieve the densification of titanium-based composite materials, the above processes are all sintered at a temperature far higher than the titanium phase transition point (900℃~1300℃), resulting in the serious coarsening of the size of the reinforcing phase in the prepared composite material, which is distributed in the micron scale, reducing the strengthening effect of the reinforcing phase, and the grains are easy to grow at high temperatures. Therefore, the design and preparation of a heterogeneous structure titanium-based composite material containing nano-sized TiBw in this application is crucial to maximize its strengthening and toughening effect. Summary of the invention

[0005] The purpose of the present invention is to provide a heterogeneous structure titanium-based composite material with a nano-reinforced phase, which has improved strength while maintaining excellent plasticity and toughness, thereby achieving a good synergistic match between strength and toughness.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned heterogeneous structure titanium-based composite material with a nano-reinforced phase, which solves the problem that the preparation temperature of the existing heterogeneous structure titanium-based composite material is much higher than the titanium phase transition point, resulting in serious coarsening of the reinforcement phase size and grain growth in the prepared composite material, and weakening of the strengthening effect.

[0007] The technical scheme adopted by the present invention is that the heterogeneous structure titanium-based composite material with nano-reinforced phase uses titanium-based composite powder as raw material, the titanium-based composite powder uses titanium or titanium alloy as titanium matrix, TiBw or TiC as reinforcement phase, and the mass ratio of TiBw or TiC reinforcement phase in the titanium-based composite powder is 1wt.%-5wt.%; in the formed heterogeneous structure titanium-based composite material, the TiBw or TiC reinforcement is distributed in the titanium-based composite powder in a network structure along the Ti matrix grain boundary.

[0008] The present invention is also characterized in that:

[0009] The particle size of the titanium-based composite powder is selected to be any one or more combinations of 0 μm-45 μm, 45 μm-75 μm, 75 μm-125 μm, 125 μm-150 μm, and 150 μm-250 μm.

[0010] The titanium-based composite powder is a spherical Ti-TiBw composite powder or a spherical Ti-TiC composite powder.

[0011] The particle size of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 10nm-200nm.

[0012] The second technical solution adopted by the present invention is a method for preparing a heterogeneous structure titanium-based composite material with a nano-reinforced phase, and the specific steps are as follows:

[0013] Step 1, weighing a titanium-based composite powder, wherein the titanium-based composite powder has titanium or a titanium alloy as a titanium matrix and TiBw or TiC as a reinforcement phase, and the mass ratio of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 1wt.%-5wt.%;

[0014] Step 2, putting the weighed titanium-based composite powder into a drum and mixing it with a low-energy ball mill for 3h-6h to obtain a mixed powder;

[0015] Step 3, placing the mixed powder into a vacuum drying oven at a vacuum degree of 0.05MPa-0.08MPa and a temperature of 40°C-60°C and drying for 2h-6h;

[0016] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 10s-30s to obtain a pre-pressed sample;

[0017] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering to obtain a heterogeneous structure titanium-based composite material.

[0018] The present invention is also characterized in that:

[0019] In step 1, the particle size of the titanium-based composite powder is selected to be any one or more combinations of 0 μm-45 μm, 45 μm-75 μm, 75 μm-125 μm, 125 μm-150 μm, and 150 μm-250 μm.

[0020] In step 1, the titanium-based composite powder is a spherical Ti-TiBw composite powder or a spherical Ti-TiC composite powder.

[0021] In step 1, the particle size of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 10nm-200nm.

[0022] The ball milling in step 2 is low-energy ball milling, the ball milling aid is anhydrous ethanol, the ball-to-material ratio is 4-6:1, and the ball milling speed is 200r / min-250r / min.

[0023] The low temperature and high pressure sintering process in step 5 is: heating to 400-800°C at a heating rate of 50°C / min, keeping warm for 5-15 minutes and then cooling with the furnace. The sintering pressure is 100MPa-600MPa.

[0024] The beneficial effects of the present invention are: compared with the prior art, the present invention has the following advantages:

[0025] (1) The size of the reinforcing phase in the heterogeneous structure titanium-based composite material prepared by the present invention is at the nanometer level, which can effectively improve the load transfer effect of the reinforcing phase. At the same time, the material has a coarse-fine grain heterogeneous structure. There is a difference in mechanical properties between the coarse and fine grains during deformation, which will generate back stress and lead to heterogeneous deformation-induced strengthening and hardening to improve the mechanical properties of the material, so that the material has good strength-plasticity synergy;

[0026] (2) The method for preparing a heterogeneous structure titanium-based composite material of the present invention utilizes the characteristic that different cooling rates of powders with different particle sizes cause different grain sizes during the preparation process, and combines the low-temperature and high-pressure sintering process to solve the problem of coarsening or agglomeration of the reinforcing phase, retain the nano-reinforcement phase in the composite powder, avoid grain growth, and make the grains not grow at low temperatures, but densify under high pressure, thereby realizing the preparation of a heterogeneous structure titanium-based composite material. Compared with other processes for preparing multi-modal grain distribution structures, the reinforcing phase in the composite material prepared by this process is nanoscale and has the advantage of simple process. The heterogeneous structure prepared by this process is not only suitable for titanium-based composite materials, but can also be used for the preparation of coarse and fine grain heterogeneous structures in titanium alloy matrices. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a surface morphology diagram of the raw material used in preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase in the present invention;

[0028] Figure 2 This is a metallographic micrograph of a uniform structure titanium-based composite material prepared by high temperature and low pressure in comparative example 1 of the heterogeneous structure titanium-based composite material with a nano-reinforced phase of the present invention;

[0029] Figure 3 This is a scanned photo of a uniform structure titanium-based composite material prepared by high temperature and low pressure in comparative example 1 of the heterogeneous structure titanium-based composite material with a nano-reinforced phase of the present invention;

[0030] Figure 4 This is a scanned photo of a pure titanium material prepared by low temperature and high pressure in comparative example 2 of the heterogeneous structure titanium-based composite material with a nano-reinforced phase of the present invention;

[0031] Figure 5 This is a metallographic micrograph of the titanium-based composite material prepared in Example 1 of the heterogeneous structure titanium-based composite material with nano-reinforced phase of the present invention;

[0032] Figure 6 is a scanned photo of the titanium-based composite material prepared in Example 1 of the heterogeneous structure titanium-based composite material with nano-reinforced phase of the present invention;

[0033] Figure 7This is a high-magnification scanning photograph of the titanium-based composite material prepared in Example 1 of the heterogeneous structure titanium-based composite material with nano-reinforced phase of the present invention;

[0034] Figure 8 is a scanned photo of the titanium-based composite material prepared in Example 2 of the heterogeneous structure titanium-based composite material with nano-reinforced phase of the present invention;

[0035] Fig. 9 These are stress-strain curves of the heterogeneous structure titanium-based composite material with nano-reinforced phase prepared in Example 1 and Example 6 of the present invention and the titanium-based composite material prepared by high temperature and low pressure sintering in Comparative Example 1. DETAILED DESCRIPTION

[0036] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] The heterogeneous structure titanium-based composite material with nano-reinforced phase of the present invention uses titanium-based composite powder as raw material, titanium-based composite powder uses titanium or titanium alloy as titanium matrix, TiBw or TiC as reinforcing phase, and the mass ratio of TiBw or TiC as reinforcing phase in the titanium-based composite powder is 1wt.%-5wt.%; the TiBw or TiC reinforcement in the formed heterogeneous structure titanium-based composite material is distributed in the interior of the titanium-based composite powder in a network structure along the grain boundary of the Ti matrix. The particle size of the titanium-based composite powder is selected as any one of 0μm-45μm, 45μm-75μm, 75μm-125μm, 125μm-150μm, 150μm-250μm or a combination of multiple ones. The titanium-based composite powder is spherical Ti-TiBw composite powder or spherical Ti-TiC composite powder. The particle size of the TiBw or TiC reinforcing phase in the titanium-based composite powder is 10nm-200nm.

[0038] Titanium-based composite powders with different particle sizes have different cooling rates. The smaller the powder particle size, the faster the cooling rate, the finer the grains inside the powder, and the heterogeneous structure titanium-based composite material has obvious coarse and fine crystal distribution. Therefore, titanium-based composite powders with different particle sizes are selected as raw materials in this application, and the final prepared heterogeneous structure titanium-based composite material TiBw or TiC reinforcement is distributed in the titanium-based composite powder in a network structure along the Ti matrix grain boundary. The reinforcement phase TiBw or TiC is nanoscale and has a good load transfer effect.

[0039] The raw material titanium-based composite powder used in this application is Ti-TiBw composite powder or Ti-TiC composite powder prepared using the patented technology of this research group (application number: CN201910528485.4, publication number: CN110218907B). The prepared Ti-TiBw composite powder and Ti-TiC composite powder both have good sphericity and smooth surface. The nano-reinforced phase (TiBw or TiC, the diameter of the reinforcement phase is 10nm-200nm) is distributed in a network inside the powder particles. The prepared titanium-based composite material has obvious coarse and fine grain heterogeneity and retains the nano-scale reinforcement phase inside the composite material. The specific structure of the Ti-TiBw composite powder is as follows: Figure 1 as shown in .

[0040] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase in the present application comprises the following specific steps:

[0041] Step 1, weighing a titanium-based composite powder, wherein the titanium-based composite powder has titanium or a titanium alloy as a titanium matrix and TiBw or TiC as a reinforcement phase, and the mass ratio of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 1wt.%-5wt.%;

[0042] The particle size of the titanium-based composite powder is selected from any one or more combinations of 0 μm-45 μm, 45 μm-75 μm, 75 μm-125 μm, 125 μm-150 μm, and 150 μm-250 μm; the titanium-based composite powder is a spherical Ti-TiBw composite powder or a spherical Ti-TiC composite powder; the particle size of the TiBw or TiC reinforcement phase is 10 nm-200 nm;

[0043] Step 2, putting the titanium-based composite powder into a drum and mixing it with a low-energy ball mill for 3h-6h to obtain a mixed powder;

[0044] Among them, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 4-6:1, and the ball milling speed is 200r / min-250r / min;

[0045] Step 3, placing the mixed powder into a vacuum drying oven at a vacuum degree of 0.05MPa-0.08MPa and a temperature of 40°C-60°C and drying for 2h-6h;

[0046] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 10s-30s to obtain a pre-pressed sample;

[0047] Step 5: Place the pre-pressed sample in a plasma activated sintering machine and perform low-temperature high-pressure sintering at a temperature of 400°C-800°C and a pressure of 100MPa-600MPa. After keeping the temperature for 5min-15min, cool it with the furnace to obtain a heterogeneous structure titanium-based composite material. The heating rate during the low-temperature high-pressure sintering process is 50°C / min.

[0048] The present application selects sintering below the phase transition point of titanium, and the sintering temperature is 400℃-800℃ to avoid the coarsening of the nano-reinforced phase and prevent the growth of grains. The heating rate is 50℃ / min, the holding time is 5min-15min, the sintering pressure is 100MPa-600MPa, and the high pressure conditions ensure the densification of the material.

[0049] The heterogeneous structure titanium-based composite material with a nano-reinforced phase and the preparation method thereof of the present application will be described in detail below in combination with examples and experimental data.

[0050] Comparative Example 1:

[0051] As Comparative Example 1 of the present invention, a titanium alloy-based composite material with uniform distribution of TiBw is prepared by spark plasma sintering at high temperature and low pressure, which is specifically implemented according to the following steps:

[0052] Step 1, weighing 20g of spherical Ti-TiBw composite powder with a particle size of 45μm-75μm, the mass ratio of TiBw reinforcement in the Ti-TiBw composite powder is 3wt.%;

[0053] Step 2: Place the mixed powder in a vacuum drying oven at 60°C and dry for 6 hours at a vacuum degree of 0.08 MPa;

[0054] Step 3, pour the dried composite powder into a graphite mold padded with graphite paper, and use a hydraulic press to pre-press for 30 seconds to obtain a pre-pressed sample;

[0055] Step 4: Place the pre-pressed sample in a plasma activated sintering machine for sintering. The sintering process is: heating to 1300°C at a heating rate of 50°C / min, keeping warm for 30 minutes and then cooling with the furnace. The sintering pressure is 30MPa, and finally a titanium-based composite material with uniformly distributed reinforcement phase TiBw is obtained.

[0056] like Figure 2 and Figure 3 As shown, Figure 2 is a microstructure diagram of a titanium-based composite material with uniformly distributed reinforcement phase TiBw prepared in the comparative example, Figure 3 This is a scanned photo. It can be clearly seen from the picture that the material structure has been homogenized under high temperature conditions, and there is no obvious coarse and fine grain isomerism. At the same time, TiBw is obviously coarsened under high temperature conditions.

[0057] Comparative Example 2:

[0058] As comparative example 2 of the present invention, a pure titanium sample was prepared by spark plasma sintering at high pressure and low temperature, and the process was specifically carried out in the following steps:

[0059] Step 1, weigh 20 g of spherical pure Ti powder with a particle size of 45 μm-75 μm;

[0060] Step 2: Place the pure Ti powder in a vacuum drying oven and dry for 2 h at a vacuum degree of 0.08 MPa;

[0061] Step 3, pour the composite powder dried in step 2 into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 30 seconds to obtain a pre-pressed sample;

[0062] Step 4: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heat up to 700°C at a rate of 50°C / min, keep warm for 5 minutes, and then cool with the furnace. The sintering pressure is 200MPa, and finally a pure titanium sample prepared at low temperature and high pressure is obtained.

[0063] like Figure 4 As shown, Figure 4 This is a scanning photo of the pure titanium sample prepared by spark plasma sintering under low temperature and high pressure conditions in the comparative example. It can be seen from the figure that the sample grains have grown and are uniform equiaxed crystals with basically consistent grain sizes. There is no coarse and fine grain isomerism in the pure titanium sample under low temperature and high pressure conditions.

[0064] Embodiment 1:

[0065] In this embodiment, titanium-based composite powder with a particle size of 45μm-75μm is used as raw material. The titanium-based composite powder uses titanium alloy as the titanium matrix and TiBw as the reinforcement phase. The mass ratio of the TiBw reinforcement phase in the titanium-based composite powder is 3wt.%; in the formed heterogeneous structure titanium-based composite material, the TiBw reinforcement is distributed in the interior of the titanium-based composite powder in a network structure along the Ti matrix grain boundary.

[0066] The preparation method is as follows:

[0067] Step 1, weighing 20g of spherical Ti-TiBw composite powder with a particle size of 45-75μm, the mass ratio of the reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%;

[0068] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 3 hours, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 4:1, and the ball milling speed is 200 r / min to obtain a mixed powder;

[0069] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.08 MPa and a temperature of 40°C and drying for 2 h;

[0070] Step 4: Pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and pre-press for 30 seconds using a hydraulic press to obtain a pre-pressed sample;

[0071] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 700°C at a heating rate of 50°C / min, keeping warm for 5 minutes, and then cooling with the furnace. The sintering pressure is 200 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0072] like Figure 5 , Figure 6 , Figure 7 As shown, Figure 5 is a metallographic micrograph of the heterogeneous structure titanium-based composite material prepared in Example 1, Figure 6 and Figure 7 This is a scanned photo of the heterogeneous structure titanium-based composite material prepared in Example 1. It can be clearly seen from the figure that the different powder particle sizes lead to significant differences in grain size, and no coarsened TiBw is found, which shows that the present invention not only inhibits the growth of grains but also inhibits the coarsening of the reinforcement phase.

[0073] Figure 7 This is a high-magnification scanning photograph of the heterogeneous structure titanium-based composite material prepared in this embodiment. It can be clearly seen from the figure that the diameter size of TiBw is nanometer level (30-90nm).

[0074] Embodiment 2:

[0075] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0076] Step 1, weighing 20g of spherical Ti-TiBw composite powder with a particle size of 45μm-75μm, the mass ratio of the reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%;

[0077] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 6 hours, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 250 r / min to obtain a mixed powder;

[0078] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.06 MPa and a temperature of 60°C and drying for 4 hours;

[0079] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0080] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 600°C at a heating rate of 50°C / min, keeping warm for 10 minutes, and then cooling with the furnace. The sintering pressure is 400MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0081] Figure 8 This is a scanning micrograph of the heterogeneous structure titanium-based composite material prepared in Example 2. The material maintains a coarse and fine grain heterogeneous structure inside, and the high pressure condition of 400 MPa ensures that the material is densified when sintered at 600°C.

[0082] Embodiment 3:

[0083] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0084] Step 1, weighing 20g of spherical Ti-TiBw composite powder with a particle size of 150μm-250μm, the mass ratio of the reinforcement TiBw in the Ti-TiBw composite powder is 1wt.%;

[0085] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 4 hours, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 6:1, and the ball milling speed is 220 r / min to obtain a mixed powder;

[0086] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.05 MPa and a temperature of 50°C and drying for 6 hours;

[0087] Step 3, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 10 seconds to obtain a pre-pressed sample;

[0088] Step 4: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 800°C at a heating rate of 50°C / min, keeping warm for 15 minutes, and then cooling with the furnace. The sintering pressure is 300 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0089] Embodiment 4:

[0090] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0091] Step 1, weighing 20g of spherical Ti-TiBw composite powder with a particle size of 75μm-125μm, the mass ratio of the reinforcement TiBw in the Ti-TiBw composite powder is 5wt.%;

[0092] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 5 hours, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 4:1, and the ball milling speed is 200 r / min to obtain a mixed powder;

[0093] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.06 MPa and a temperature of 40°C and drying for 4 hours;

[0094] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0095] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 650°C at a heating rate of 50°C / min, keeping warm for 12 minutes, and then cooling with the furnace. The sintering pressure is 300 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0096] Embodiment 5:

[0097] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0098] Step 1, weighing 20g of spherical Ti-TiBw composite powder with particle sizes of 0μm-45μm and 75μm-125μm, the mass ratio of reinforcement TiBw in the Ti-TiBw composite powder is 4wt.%, and the mass ratio of spherical Ti-TiBw composite powders of 0μm-45μm and 75μm-125μm is 1:3;

[0099] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 3 hours, the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 250 r / min to obtain a mixed powder;

[0100] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.06 MPa and a temperature of 60°C and drying for 5 hours;

[0101] Step 4: Pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and pre-press for 30 seconds using a hydraulic press to obtain a pre-pressed sample;

[0102] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 550°C at a heating rate of 50°C / min, keeping warm for 15 minutes, and then cooling with the furnace. The sintering pressure is 250MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0103] Embodiment 6:

[0104] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0105] Step 1, weighing 20g of spherical Ti-TiBw composite powder with particle sizes of 125μm-150μm and 45μm-75μm, the mass ratio of reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%, and the ratio of spherical Ti-TiBw composite powders of 125μm-150μm and 45μm-75μm is 1:4;

[0106] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 5 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 220 r / min;

[0107] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 50°C and drying for 4 hours;

[0108] Step 4, pour the composite powder dried in step 3 into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0109] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 400°C at a heating rate of 50°C / min, keeping warm for 10 minutes and then cooling with the furnace. The sintering pressure is 100 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0110] Embodiment 7:

[0111] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0112] Step 1, weighing 20g of spherical Ti-TiBw composite powder with particle sizes of 0μm-45μm, 125μm-150μm and 45μm-75μm, the mass ratio of reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%, and the ratio of spherical Ti-TiBw composite powder with particle sizes of 0μm-45μm, 125μm-150μm and 45μm-75μm is 1:4:3;

[0113] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 5 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 220 r / min;

[0114] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 60°C and drying for 4 hours;

[0115] Step 4, pour the composite powder dried in step 3 into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0116] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 700°C at a heating rate of 50°C / min, keeping warm for 10 minutes and then cooling with the furnace. The sintering pressure is 200 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0117] Embodiment 8:

[0118] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0119] Step 1, weighing 20g of spherical Ti-TiBw composite powder with particle sizes of 0μm-45μm, 45μm-75μm, 125μm-150μm and 150μm-250μm, the mass ratio of reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%, and the ratio of titanium-based composite powder with particle sizes of 0μm-45μm, 45μm-75μm, 125μm-150μm and 150μm-250μm is 3:1:1:1;

[0120] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 5 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 220 r / min;

[0121] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 50°C and drying for 4 hours;

[0122] Step 4, pour the composite powder dried in step 3 into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0123] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 600°C at a heating rate of 50°C / min, keeping warm for 10 minutes, and then cooling with the furnace. The sintering pressure is 400MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0124] Embodiment 9:

[0125] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0126] Step 1, weighing 20g of spherical Ti-TiBw composite powders with particle sizes of 0μm-45μm, 45μm-75μm, 75μm-125μm, 125μm-150μm and 150μm-250μm, the mass ratio of reinforcement TiBw in the Ti-TiBw composite powder is 3wt.%, and the ratio of spherical Ti-TiBw composite powders with particle sizes of 0μm-45μm, 45μm-75μm, 75μm-125μm, 125μm-150μm and 150μm-250μm is 1:1:1:1:1;

[0127] Step 2, putting the Ti-TiBw composite powder into a drum and mixing it with a low-energy ball mill for 6 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 250 r / min;

[0128] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 60°C and drying for 4 hours;

[0129] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0130] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 800°C at a heating rate of 50°C / min, keeping warm for 10 minutes, and then cooling with the furnace. The sintering pressure is 400 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0131] Embodiment 10:

[0132] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0133] Step 1, weighing 20g of spherical Ti-TiC composite powder with particle sizes of 125μm-150μm and 45μm-75μm, the mass ratio of reinforcement TiC in the Ti-TiC composite powder is 3wt.%, and the ratio of spherical Ti-TiC composite powders of 125μm-150μm and 45μm-75μm is 1:4;

[0134] Step 2, putting the Ti-TiC composite powder into a drum and mixing it with a low-energy ball mill for 5 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 220 r / min;

[0135] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 60°C and drying for 4 hours;

[0136] Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0137] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 700°C at a heating rate of 50°C / min, keeping warm for 10 minutes, and then cooling with the furnace. The sintering pressure is 600MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0138] Embodiment 11:

[0139] The preparation method of the heterogeneous structure titanium-based composite material with nano-reinforced phase comprises the following specific steps:

[0140] Step 1, weighing 20g of spherical Ti-TiC composite powder with particle sizes of 0μm-45μm, 125μm-150μm and 45μm-75μm, the mass ratio of reinforcement TiC in the Ti-TiC composite powder is 3wt.%, and the ratio of spherical Ti-TiC composite powder with particle sizes of 0μm-45μm, 125μm-150μm and 45μm-75μm is 3:1:1;

[0141] Step 2, putting the Ti-TiC composite powder into a drum and mixing it with a low-energy ball mill for 5 hours to obtain a mixed powder, wherein the low-energy ball milling aid is anhydrous ethanol, the ball-to-material ratio is 5:1, and the ball milling speed is 220 r / min;

[0142] Step 3, placing the mixed powder in a vacuum drying oven at a vacuum degree of 0.07 MPa and a temperature of 50°C and drying for 4 hours;

[0143] Step 4, pour the composite powder dried in step 3 into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 25 seconds to obtain a pre-pressed sample;

[0144] Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering. The sintering process is as follows: heating to 700°C at a heating rate of 50°C / min, keeping warm for 10 minutes and then cooling with the furnace. The sintering pressure is 200 MPa, and finally a titanium-based composite material with coarse and fine grain heterogeneity is obtained.

[0145] The microstructure morphology analysis and room temperature mechanical property test of the heterogeneous titanium-based composite material with nano-reinforced phase prepared by the present invention are as follows:

[0146] The density of the composite material prepared by this process can reach more than 98%.

[0147] Figure 2 and Figure 3 It is a uniform structure prepared by high temperature and low pressure in Comparative Example 1, Figure 2 For the microstructure diagram, Figure 3 This is a scanned photo. It can be clearly seen from the picture that the material structure has been homogenized under high temperature conditions, and there is no obvious coarse and fine grain isomerism. At the same time, TiBw is obviously coarsened under high temperature conditions.

[0148] like Figure 4 As shown, Figure 4 This is a scanned photo of the pure titanium sample prepared by spark plasma sintering under low temperature and high pressure conditions in Comparative Example 2. It can be seen from the figure that the sample grains have grown and are uniform equiaxed crystals with basically consistent grain sizes. The pure titanium sample under low temperature and high pressure conditions does not show coarse and fine grain isomerism.

[0149] like Figure 5 , Figure 6 , Figure 7 As shown, Figure 5 is a metallographic micrograph of the heterogeneous structure titanium-based composite material prepared in Example 1, Figure 6 and Figure 7 This is a scanned photo of the heterogeneous structure titanium-based composite material prepared in Example 1. It can be clearly seen from the figure that the different powder particle sizes lead to significant differences in grain size, and no coarsened TiBw is found, which shows that the present invention not only inhibits the growth of grains but also inhibits the coarsening of the reinforcement phase; Figure 7 This is a high-magnification scanning photo of the heterogeneous structure titanium-based composite material prepared in Example 1. It can be clearly seen from the figure that the diameter of TiBw is nanometer-level (30-90nm); Figure 8 This is a scanning micrograph of the heterogeneous structure titanium-based composite material prepared in Example 2. The material maintains a coarse and fine grain heterogeneous structure inside, and the high pressure condition of 400 MPa ensures that the material is densified when sintered at 600°C.

[0150] The titanium-based composite material with coarse and fine grain heterogeneity of the present invention has excellent mechanical properties and maintains good plasticity while improving strength. Fig. 9The stress-strain curves of the composite materials obtained in Example 1, Example 7 and Comparative Example 1. By comparing the stress-strain curves of Example 1 and Comparative Example 1, it can be seen that the maximum tensile strength of the titanium-based composite material with coarse and fine grain heterogeneity under the same particle size is 668MPa, and the yield strength is 468MPa; while the maximum tensile strength of the uniformly distributed TiBw reinforced titanium alloy-based composite material prepared at high temperature and low pressure is 485MPa, and the yield strength is 319MPa. Compared with the traditional titanium alloy-based composite material with uniform distribution of TiBw, the titanium-based composite material with coarse and fine grain heterogeneity has a tensile strength increased by 37.7%, and a yield strength increased by 46.7%, while maintaining an elongation of 15.5%, obtaining a titanium alloy-based composite material with good strength and plasticity matching. By mixing powders of different particle sizes and adjusting the material properties, in Example 6, spherical Ti-TiBw composite powders of 125μm-150μm and 45μm-75μm were mixed in a ratio of 1:4 and then sintered, and the maximum tensile strength was increased to 714MPa, which was 47.2% higher than that of the uniform structure, while maintaining 17.2% of the plasticity. This is because the titanium-based composite material with coarse and fine grains prepared at low temperature and high pressure inhibits the growth of grains. At the same time, the coarse and fine grains produce stress gradients during deformation, causing abnormal induced hardening, which hinders the coarsening of the reinforcement phase under low temperature conditions, increases the load transfer strengthening of TiBw, and thus improves the mechanical properties of the material.

Claims

1. Heterogeneous structure titanium matrix composites with nano-reinforced phase, It is characterized in that Titanium-based composite powder is used as raw material, the titanium-based composite powder uses titanium or titanium alloy as titanium matrix, TiBw or TiC as reinforcement phase, and the mass ratio of TiBw or TiC reinforcement phase in the titanium-based composite powder is 1wt.%-5wt.%; in the formed heterogeneous structure titanium-based composite material, TiBw or TiC reinforcement is distributed in the titanium-based composite powder in a network structure along the Ti matrix grain boundary.

2. The heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 1, It is characterized in that The particle size of the titanium-based composite powder is selected to be any one or more combinations of 0 μm-45 μm, 45 μm-75 μm, 75 μm-125 μm, 125 μm-150 μm, and 150 μm-250 μm.

3. The heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 2, It is characterized in that The titanium-based composite powder is a spherical Ti-TiBw composite powder or a spherical Ti-TiC composite powder.

4. The heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 3, It is characterized in that The particle size of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 10nm-200nm.

5. Preparation method of heterogeneous structure titanium-based composite material with nano-reinforced phase, It is characterized in that The specific steps are as follows: Step 1, weighing a titanium-based composite powder, wherein the titanium-based composite powder has titanium or a titanium alloy as a titanium matrix and TiBw or TiC as a reinforcement phase, and the mass ratio of the TiBw or TiC reinforcement phase in the titanium-based composite powder is 1wt.%-5wt.%; Step 2, putting the weighed titanium-based composite powder into a drum and mixing it with a low-energy ball mill for 3h-6h to obtain a mixed powder; Step 3, placing the mixed powder into a vacuum drying oven at a vacuum degree of 0.05MPa-0.08MPa and a temperature of 40°C-60°C and drying for 2h-6h; Step 4, pour the dried mixed powder into a cemented carbide mold padded with graphite paper, and use a hydraulic press to pre-press for 10s-30s to obtain a pre-pressed sample; Step 5: Place the pre-pressed sample into a plasma activated sintering machine for low-temperature and high-pressure sintering to obtain a heterogeneous structure titanium-based composite material.

6. The method for preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 5, It is characterized in that The particle size of the titanium-based composite powder in step 1 is selected to be any one or more combinations of 0 μm-45 μm, 45 μm-75 μm, 75 μm-125 μm, 125 μm-150 μm, and 150 μm-250 μm.

7. The method for preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 5, It is characterized in that The titanium-based composite powder in step 1 is a spherical Ti-TiBw composite powder or a spherical Ti-TiC composite powder.

8. The method for preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 5, It is characterized in that The particle size of the TiBw or TiC reinforcement phase in the titanium-based composite powder in step 1 is 10nm-200nm.

9. The method for preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 5, It is characterized in that The ball milling in step 2 is low-energy ball milling, the ball milling aid is anhydrous ethanol, the ball-to-material ratio is 4-6:1, and the ball milling speed is 200r / min-250r / min.

10. The method for preparing the heterogeneous structure titanium-based composite material with nano-reinforced phase according to claim 5, It is characterized in that The low temperature and high pressure sintering process in step 5 is: heating to 400-800°C at a heating rate of 50°C / min, keeping the temperature for 5-15 minutes and then cooling with the furnace. The sintering pressure is 100-600MPa.

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