CN115821093A - Preparation method of multilayer nano-particle reinforced high-strength and high-toughness titanium-based composite material - Google Patents

Abstract

The invention discloses a preparation method of a multilayer nanoparticle reinforced high-toughness titanium-based composite material, which optimizes the organization of a powder metallurgy titanium-based composite material by pre-implanting a superfine net structure nano reinforcement body in powder and prepares the high-toughness nanoparticle reinforced titanium-based composite material, and relates to the field of metal-based composite materials. The method comprises the following steps: (1) Screening titanium-based composite material powder embedded with a superfine net structure; (2) low-temperature pre-pressing and sintering; (3) high-temperature densification sintering; and (4) aging treatment tissue regulation. Finally, the high-toughness titanium-based composite material with uniform and fine microstructure and multi-level distribution of nano reinforcers in crystal boundary/crystal interior is obtained. The method eliminates coarse widmannstatten structures, synchronously refines matrix grains and the sizes of the reinforcements, realizes the fine regulation and control of the sizes and the distribution of the reinforcements, is beneficial to the near-net forming of high-toughness titanium-based composite materials and components thereof, and has important application value in the field of important equipment such as aerospace and the like.

Description

Preparation method of high-strength and tough titanium-based composite material reinforced by multi-layer nanoparticles

technical field

The invention relates to the field of metal-based composite materials, in particular to a method for preparing a multi-layered nanoparticle-reinforced high-strength and tough titanium-based composite material, which is a method for strengthening and toughening a multi-layered nano-particle-reinforced titanium-based composite material.

Background technique

Titanium matrix composites have low density, high specific strength, good corrosion resistance, anti-oxidation and other excellent properties and have gradually become one of the most potential candidate structural materials in high-tech fields such as automobiles and aerospace. By introducing high-strength and high-modulus ceramic particles such as TiB, TiC, Re ₂ O ₃ into the titanium alloy matrix and optimizing their size and distribution, the modulus, wear resistance and high temperature oxidation resistance of titanium matrix composites can be significantly improved. It is currently one of the effective ways to improve the comprehensive mechanical properties and service temperature of titanium matrix composites.

Powder metallurgy is a net-shaping method for preparing titanium-based composites. Compared with other liquid-phase reaction-based preparation technologies for titanium-based composites, this method has stronger controllability and designability. The design of the powder spreading process realizes the control of the size and distribution of the reinforcement, constructs "core-shell structure", "layered structure", "network structure", etc., and fully exerts the synergistic strengthening and toughening effect of the reinforcement and the configuration. It can greatly improve the comprehensive performance of composite materials, and has been widely used in aerospace, industry, medical and other fields.

The powder pretreatment methods used at home and abroad mainly include ball milling, electrostatic adsorption, fluidized bed vapor deposition, etc. That is to use physical methods or chemical methods to embed or adsorb reinforcement reagents on the surface of titanium alloys, and then induce in-situ reactions on the surface of titanium alloy particles during high-temperature sintering, thereby generating various reinforcements at the particle boundaries. However, when the reinforcement is introduced, in order to ensure the full progress of the in-situ reaction and realize the densification of the material, it is often necessary to sinter above the β-transition point of the material. The increase of sintering temperature will inevitably promote the growth of matrix grains, thereby forming a Widmanstatten structure containing coarse original β grains, and reducing the mechanical properties of the material. In order to further improve the performance of composite materials, it is often necessary to add secondary thermal processing methods such as forging and rolling after sintering, which greatly prolongs the material preparation process and increases production costs. Therefore, how to use a simple and effective method to suppress the growth of matrix grains at high temperature, realize the regulation of matrix structure and reinforcement size distribution, and improve the comprehensive mechanical properties of sintered materials has become one of the key directions of researchers. one.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a high-strength and tough titanium-based composite material reinforced by multi-layered nanoparticles to solve the problems in the prior art. The method controls the initial size of the reinforcement and the network structure by screening titanium-based composite material powders with different particle sizes and ultra-fine network structure, and improves the stability of the nano-reinforcement during the low-temperature pre-pressing sintering process. Subsequently, the sintered material is densified into a block in the β-phase region, and the matrix structure type and the size and distribution of the reinforcement are regulated through process optimization. Finally, the distribution of alloy precipitates is controlled by furnace aging treatment, and a high-strength and tough titanium-based composite material with uniform and fine structure and multi-level distribution of nano-reinforcements in grain boundaries/intragrains is obtained; this method solves the problem of titanium The problem of coarse alloy structure avoids the formation of coarse Widmanstatten structure, refines the size of matrix grains and reinforcements, and realizes the precise regulation of the size distribution of reinforcements, thereby greatly improving the strength and toughness of sintered titanium matrix composites. The method and technology are helpful to guide the direct preparation of high-strength and tough titanium-based composite materials and their components by powder metallurgy, and have important application value in major equipment fields such as aerospace.

The purpose of the present invention can be achieved through the following schemes:

The invention provides a method for preparing a multi-layered nanoparticle-reinforced high-strength and tough titanium-based composite material. The preparation method includes the following steps:

A. Screen titanium-based composite powders with embedded ultra-fine network structures of different particle sizes;

B. Heat the screened titanium-based composite material powder to 20-200°C below the β phase transition temperature (T _β ) of the material, and perform pre-compression sintering;

C. Raise the furnace temperature to 20-300°C above Tβ for densification and sintering;

D. After sintering, cool to the aging temperature set by the material, and perform aging treatment to obtain a high-strength and tough titanium-based composite material in which the nano-reinforcement body presents grain boundary/intra-grain multi-level distribution in the matrix.

Preferably, the titanium-based composite material powder embedded with an ultra-fine network structure described in step A includes a titanium base and a reinforcement, and the reinforcement is distributed in an ultra-fine network structure in the titanium base; the matrix includes pure titanium and Titanium alloy, reinforcements include one or more of TiB, TiC, La ₂ O ₃ , Ti ₅ Si ₃ , (Ti, Zr) _x Si ₃ (x=5~6) reinforcements, preferably TiB and other reinforcements combination of bodies. The preparation technology of the powder is patent CN110340371A, which describes the preparation method of the powder in detail.

Preferably, the particle size range of the titanium-based composite material powder in step A is one of 15-53 μm, 53-100 μm, 100-150 μm, and 150-225 μm. The volume fraction of reinforcements in the powder is 1-5%, and the reinforcements are all in nanometer size (diameter or width < 100nm), and are distributed in an ultrafine network structure. The size of the internal network structure of powders with different particle sizes is different. Generally, the size of the network structure will decrease with the increase of the volume fraction of the reinforcement and the decrease of the particle size of the powder. The size of the network structure will be significantly reduced. The size is between 2 and 10 μm, corresponding to the higher aspect ratio and degree of dispersion of the reinforcement in the sintered material.

Preferably, the method of pre-press sintering in step B includes one of hot press sintering (HP), hot isostatic pressing sintering (HIP) and spark plasma sintering (SPS). The pre-pressing sintering temperature range is: 20-200°C below the β phase transition temperature (T _β ), the pre-pressing temperature does not exceed 900°C, the pressure range is: 50-300MPa, the heating rate is: 10°C-200°C/min, and the heat preservation The time is: 5-60 minutes.

Preferably, the sintering temperature range of the densification sintering in step C is: 20-300°C above the β phase transition temperature (T _β ), the pressure range is 50-300MPa, and the heating rate is 10-200°C/min, The holding time is: 5~240min. The sintering methods include: hot press sintering (HP), hot isostatic pressing sintering (HIP) and spark plasma sintering (SPS). Generally, the lower the sintering temperature, the faster the heating rate, and the shorter the holding time, the smaller the grain size of the matrix and the size of the reinforcement in the material, and the higher the strength of the material. However, if the sintering temperature is too low, the density of the material will be poor, and there will be defects such as obvious holes in the material.

Preferably, the aging treatment method in step D is furnace cooling to the aging temperature; the aging temperature is between 400-800° C., and the aging time is 0.5-8 hours. Aging temperature is controlled according to different materials

Preferably, the high-strength and tough titanium-based composite material described in step D has a uniform and fine equiaxed or near-lamellar structure, the reinforcement is nanoscale, and the matrix is distributed in grain boundaries/intra-grain layers. Moreover, the mechanical properties of the titanium-based composite material are excellent, and its strong plasticity is equivalent to that of similar titanium-based composite material forgings. At the same time, the size and distribution of grains and reinforcements can be regulated by sintering temperature, holding time, and powder particle size. Under different processes, the equiaxed structure ranges from 5 to 20 μm, and the reinforcement scale ranges from 100 nm to 2 μm.

Preferably, the high-strength and toughness titanium-based composite material can also be post-processed using conventional thermal processing techniques (such as forging, extrusion, rolling, etc.).

In summary, compared with the prior art, the present invention has the following beneficial effects:

(1) The present invention can obtain ultra-fine network structures of different sizes by screening titanium-based composite material powders of different particle sizes, and obtain network structures of different sizes by screening the particle sizes of the powders to achieve ultra-fine control. The purpose of the size of the mesh structure. First of all, the network structure in the powder breaks through the limitation that the traditional powder mixing process can only introduce reinforcements at the powder particle boundaries. The distribution uniformity of the reinforcement; secondly, the size of the network structure and the reinforcement increases with the increase of the particle size of the powder, and the size of the reinforcement and the size of the network structure can be directly controlled by powder screening.

(2) During the sintering process, since the powder has been pre-implanted with ultra-fine mesh reinforcements, the reinforcements only undergo thermal diffusion and growth at high temperatures, and are introduced by in-situ reaction after mixing with traditional mechanical powders. There is an essential difference in the method of reinforcement, which avoids the problem of uneven distribution of reinforcement and easy introduction of impurities after mechanical powder mixing.

(3) The thermal stability of the nano-reinforcement is poor. For the nano-reinforcement in the powder, the thermal stability temperature is controlled below 900°C. The stability of the nano-reinforcement can be promoted by pre-pressing and sintering, and the high temperature can be reduced. Coarsening of the reinforcement during sintering.

(4) The present invention is mainly applicable to the sintering process with a temperature above Tβ. Only when the sintering temperature is higher than the β phase transition point of the material can the prefabricated ultra-fine network structure in the powder exert an obvious effect of tissue regulation, ensuring that the obtained While the material has high density, the crystal grains are significantly refined, and the formation of coarse Widmanstatten structure is suppressed. At the same time, through the optimization of the sintering process, the distribution form of the reinforcements in the matrix structure can be precisely regulated, so that the nano-reinforcements are distributed in grain boundaries/intragranular layers in the matrix.

(5) The sintered nanoparticle-reinforced titanium-based composite material prepared by the powder metallurgy method of the present invention has excellent mechanical properties, and its strong plasticity can be composited with similar wrought titanium-based composite materials without secondary thermal deformation processing The material is equivalent;

(6) The present invention is applicable to various types of unit-reinforced titanium-based composite materials containing TiB, and titanium-based composite materials containing TiB reinforcement mixed with other reinforcements, such as TiB+TiC, TiB+Ti ₅ Si ₃ , TiB+ La ₂ O ₃ and other hybrid enhancement series such as TiB+Re _x O _y and TiB+TiC+Re _x O _y ;

(7) The present invention is suitable for pure titanium or titanium alloy substrates, including Ti-6Al-4V and IMI834, etc., and has a wide range of applications;

(8) The present invention is applicable to hot pressing sintering, hot isostatic pressing sintering, plasma discharge sintering and other preparation process systems that realize powder molding under high temperature and high pressure;

(9) The ultra-fine network structure prefabricated in the powder of the present invention can effectively hinder the grain growth during sintering, has a remarkable effect of fine crystallization, and eliminates the problem of coarse material structure caused by excessive sintering temperature. The microstructure of titanium-based composites prepared by powder modification shows a uniform and fine equiaxed or near-lamellar structure, and the reinforcement is nanoscale, and it is distributed in grain boundaries/intragranular layers in the matrix. It can give full play to the synergistic strengthening effect of the reinforcing body. Compared with alloys and other composite materials prepared under the same process, the structure has been significantly optimized. The prepared composite material has no anisotropy, uniform structure and excellent mechanical properties.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Figure 1 is a cross-sectional structure diagram of 1.2vol.%TiB+La ₂ O ₃ /IMI834 heat-resistant titanium-based composite powder prepared by gas atomization method in Example 1; where a is the surface morphology of the powder, and b is the cross-section of the powder organizational characteristics;

Figure 2 is the microstructure and morphology of the 1.2vol.% TiB+La ₂ O ₃ /IMI834 titanium matrix composite prepared in Example 1 (a) and the 2.4vol.%TiB+La ₂ O ₃ prepared in Example 2. IMI834 titanium matrix composite microstructure topography (b);

3 is a schematic diagram of the nano-reinforcement located at the grain boundary/in the sintered 1.2vol.% TiB+La ₂ O ₃ /IMI834 composite material in Example 1;

Fig. 4 is the EBSD structure comparison diagram of the titanium-based composite material (b) obtained in Example 2 and the matrix alloy (a) under the same process;

Fig. 5 shows the tensile properties at room temperature of the nano-TiB+La ₂ O ₃ /IMI834 titanium-based composites prepared in Examples 1 and 2.

Detailed ways

The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. Those of ordinary skill in the art can make several changes and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. The present invention is described in detail below in conjunction with specific embodiment:

A method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, comprising the following steps:

A. Screen titanium-based composite powders with different particle sizes and embedded ultra-fine network structures;

B. Fill the titanium-based composite material powder with different particle sizes after screening into the mold, and heat it in the sintering furnace to 20-200 °C below the β phase transition temperature of the material, and perform pre-pressing sintering;

C. Raise the furnace temperature to 20-300°C above T _β for densification and sintering;

D. After sintering, the furnace is cooled to the aging temperature set by the material for aging treatment. That is, a high-strength and tough titanium-based composite material in which the nano-reinforcement exhibits grain boundary/intra-grain multi-level distribution in the matrix is obtained.

Titanium-based composite powders are prepared by the following methods:

Taking TiB+La ₂ O ₃ /IMI834 composite powder as an example

Step 1. Using intermediate alloys such as sponge titanium, sponge zirconium, aluminum wire, aluminum molybdenum (Al-Mo), titanium tin (Ti-Sn), aluminum niobium (Al-Nb) as alloy raw materials, lanthanum hexaboride (LaB ₆ ) powder is the raw material of the reinforcement, weighed in 2.5kg each, wherein the volume fraction of the reinforcement is controlled to be 1.2vol.% and 2.4vol.%, poured into a mold, and pressed mechanically to form a consumable electrode;

Step 2. Put the electrode into a vacuum consumable electric arc furnace for the first vacuum melting, control the melting current to 1kA, and the vacuum degree to 5×10 ^-3 Pa. Repeat the melting process three times to ensure that the composition of the ingot is uniform. The in situ reaction was carried out completely, and three ingots were obtained;

Step 3, forging and elongating the obtained third ingot at 1100°C to obtain a rough billet bar with an outer diameter of 55mm and a length of 450mm, which is machined into a regular round bar with an outer diameter of 50mm and a length of 500mm;

Step 4: Use electrode induction melting gas atomization powder making equipment, heat the bar electrode to 2000°C with an induction coil, and the melt flows freely downward through the leak hole into the gas atomization furnace, the atomization pressure is 2.5MPa, and the gas used For argon, the alloy melt is broken into fine droplets, and the titanium-based composite material powder is obtained after rapid cooling, which is collected;

Step 5. The obtained titanium-based composite material powder is sieved according to the three particle size distributions of 0-53 μm, 53-150 μm and 150 μm or more, and the powder of 15-53 μm accounts for 32%, and the powder of 53-100 μm accounts for 41%. %, 100-150 μm powder accounted for 22%, and powder above 150 μm accounted for 5%.

Evaluation criteria and methods:

1. Morphology of powder structure--internal TiB, TiC, La ₂ O ₃ and other reinforcements are distributed in a network structure, which realizes the embedding of reinforcements; sintered composite material structure-the material structure is obviously improved after powder modification Refinement, showing a uniform equiaxed structure, while the reinforcement is evenly distributed in the matrix in a micro-nano dual-scale;

The test method is: set 5kV voltage on TASCAN RISE-MAGNA to observe the microstructure.

2. Tensile performance test--tensile strength, elongation;

The test method is as follows: the mechanical performance test is carried out on a Zwick Z100 universal testing machine, the sample is a sheet tensile sample, and the elongation is measured by an extensometer.

Example 1

This embodiment provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, including the following steps:

A. Select the 0.91vol.% TiB+0.29vol.% La ₂ O ₃ reinforced IMI834 composite material powder (1.2vol.% TiB+La ₂ O ₃ /IMI834) prepared by the gas atomization method, through vibrating sieving, screening Produce powder with a particle size of 53-100 μm;

B. Fill the screened titanium-based composite material powders with different particle sizes into a mold, and perform pre-press sintering in a hot-press sintering furnace. The pre-pressing sintering temperature range is: 900°C, the pressure range is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

C. After the pre-pressing sintering is completed, the furnace temperature is raised to 1200°C for densification sintering. The sintering pressure is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

D. After sintering, the furnace is cooled to 700°C for aging treatment, and after holding for 2 hours, the furnace is cooled to room temperature. That is to say, the high-strength and tough titanium-based composite material with a uniform fine structure and nano-reinforcement in the matrix presents grain boundary/intra-grain multi-level distribution.

Figure 1 shows the morphology of the powder structure. It can be seen that the internal TiB and La ₂ O ₃ reinforcements are distributed in a network structure, realizing the embedding of the reinforcements. Figure 2(a) is a schematic diagram of the sintered structure. The coarse original β-crystal and Widmanstatten structure were not observed in the material structure, and the material showed a uniform and fine near-lamellar structure. Figure 3 is a schematic diagram of the morphology and distribution of the 1.2vol.%TiB+La ₂ O ₃ /IMI834 heat-resistant titanium-based composite reinforcement. It can be seen that both TiB and La ₂ O ₃ are kept in nanometer size, and the Multi-level distribution within the boundaries/grains. Figure 5 shows the test results of tensile properties. For 1.2vol.% composite material, its tensile strength reaches 1100MPa, and maintains an elongation of more than 10%. Compared with the matrix alloy prepared under the same process, it does not lose strength. Under the premise, the elongation rate increased by 5 times.

Example 2

This embodiment provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, including the following steps:

A. Select 2.4vol TiB+La ₂ O ₃ /IMI834 prepared by the gas atomization method, and screen the powder with a particle size of 53-100 μm through vibratory screening;

B. Fill the screened titanium-based composite material powders with different particle sizes into a mold, and perform pre-press sintering in a hot-press sintering furnace. The pre-pressing sintering temperature range is: 900°C, the pressure range is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

C. After the pre-pressing sintering is completed, the furnace temperature is raised to 1100°C for densification sintering. The sintering pressure is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

D. After sintering, the furnace is cooled to 700°C for aging treatment, and after holding for 2 hours, the furnace is cooled to room temperature. That is to say, the high-strength and tough titanium-based composite material with a uniform fine structure and nano-reinforcement in the matrix presents grain boundary/intra-grain multi-level distribution.

In the material prepared in this example, the microstructure is similar to that in Example 1, and a network structure is formed in the powder. In addition, it can be seen from the photo of the structure in Figure 2(b) that the volume fraction of the reinforcement increases It promotes the refinement of the matrix, further refines the matrix into fine equiaxed tissues, and achieves the purpose of tissue regulation. Figure 4 is the EBSD structure comparison of the obtained 2.4vol.%TiB+La ₂ O ₃ /IMI834 heat-resistant titanium-based composite material and the IMI834 matrix alloy under the same process. It is found that the ultra-fine network structure in the composite material powder is being refined Grains play a role in regulating the matrix organization. Figure 5 shows the tensile performance test. The 2.4vol.%TiB+La ₂ O ₃ reinforced composite material has a tensile strength above 1181MPa and an elongation higher than 3.5%. Compared with the matrix alloy prepared under the same process, Both strength and plasticity are improved.

Example 3

This embodiment provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, including the following steps:

A. Select 2.5vol.% TiB/IMI834 prepared by gas atomization method, and screen out the powder with a particle size of 15-53 μm through vibratory screening;

B. Fill the titanium-based composite material powder with different particle sizes after screening into the mold, and perform pre-press sintering in a hot-press sintering furnace. The pre-pressing sintering temperature range is: 900°C, the pressure range is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

C. After the pre-pressing sintering is completed, the furnace temperature is raised to 1200°C for densification sintering. The sintering pressure is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

D. After sintering, the furnace is cooled to 700°C for aging treatment, and after holding for 2 hours, the furnace is cooled to room temperature. That is to say, the high-strength and tough titanium-based composite material with a uniform fine structure and nano-reinforcement in the matrix presents grain boundary/intra-grain multi-level distribution.

In the material prepared in this example, the microstructure morphology is similar to that of Example 2, a network structure is formed in the powder, and the sintered titanium alloy presents a uniform and fine equiaxed structure.

Example 4

This embodiment provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, including the following steps:

A. Select the 4vol.%TiB+1vol.%TiC reinforced TC4 composite material powder prepared by the gas atomization method, and screen the powder with a particle size of 53-100 μm through vibratory screening;

B. Fill the screened titanium-based composite material powders with different particle sizes into a mold, and perform pre-press sintering in a hot-press sintering furnace. The pre-pressing sintering temperature range is: 800°C, the pressure range is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

C. After the pre-pressing sintering is completed, the furnace temperature is raised to 1200°C for densification sintering. The sintering pressure is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

D. After sintering, the furnace is cooled to 600°C for aging treatment, and after 2 hours of heat preservation, the furnace is cooled to room temperature. That is to say, the high-strength and tough titanium-based composite material with a uniform and fine structure and two kinds of nano-reinforcements of TiB and TiC presenting multi-level distribution in the grain boundary/intra-grain in the matrix is obtained.

In the material prepared in this example, the microstructure of the matrix is the same as that in Example 2, which is a fine equiaxed structure. However, with the addition of TiC, the sintered microstructure is further refined, and the TiB and TiC nano-reinforcements present multi-level distribution at the grain boundary/intra-grain.

Example 5

This embodiment provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials, including the following steps:

A. Select the 2.5vol.% TiB+2.5vol.% TiC reinforced TC4 composite material powder prepared by the gas atomization method, and screen out the powder with a particle size of 15-53 μm through vibratory screening;

B. Fill the screened titanium-based composite material powders with different particle sizes into a mold, and perform pre-press sintering in a hot-press sintering furnace. The pre-pressing sintering temperature range is: 800°C, the pressure range is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

C. After the pre-pressing sintering is completed, the furnace temperature is raised to 1200°C for densification sintering. The sintering pressure is: 50MPa, the heating rate is: 10°C/min, the holding time is: 60min, and the vacuum degree is greater than 5×10 ^-2 Pa.

D. After sintering, the furnace is cooled to 600°C for aging treatment, and after 2 hours of heat preservation, the furnace is cooled to room temperature. That is to say, the high-strength and tough titanium-based composite material with a uniform and fine structure and two kinds of nano-reinforcements of TiB and TiC presenting multi-level distribution in the grain boundary/intra-grain in the matrix is obtained.

In the material prepared in this example, the microstructure of the sintered material is similar to Example 2, which proves that the method can be applied to different titanium alloy systems, and can be applied to composite materials with high volume fraction.

Comparative example 1

This comparative example provides a multi-layered nanoparticle-reinforced titanium-based composite material strengthening and toughening method, the steps of which are basically the same as in Example 1, the only difference is that no pre-compression sintering is carried out, and the densification is carried out at 1100-1200 °C Sintering, sintering pressure: 50MPa, heating rate: 10°C/min, holding time: 120min, vacuum degree greater than 5×10 ^-2 Pa.

Compared with the two-step sintering process, although the one-step sintering process obtains a densified bulk material, due to the poor thermal stability of the nano-reinforcement at high temperature, the size of the material reinforcement without low-temperature stabilization treatment is obviously coarsened, and most Growth into micron-sized reinforcements leads to a decrease in material strength and plasticity at the same time. Compared with two-step sintering, the strength of the material sintered by one-step densification is reduced by 30-50 MPa, and the elongation is reduced by 1-3%.

Comparative example 2

This comparative example provides a multi-layered nanoparticle-reinforced titanium-based composite material strengthening and toughening method, the steps of which are basically the same as in Example 1, the only difference is that in step A, conventional equivalents of TiB ₂ and La ₂ O are used _3. The reinforcement reactant is mixed with the spherical titanium alloy powder, and in step C, a high-temperature in-situ reaction is used to obtain a titanium-based composite material.

This process is similar to the method disclosed in the patent CN101333607, and its essential difference lies in: (1) The titanium-based composite material powder used in this method has realized the homogenization and compounding of the reinforcement before sintering, and does not need to be homogenized or surface-treated by ball milling. The coating process shortens the preparation process and avoids the introduction of impurities; (2) the comparison process needs to use the in-situ reaction between the reactant and the matrix at high temperature to introduce the reinforcement. Generally, the temperature required for sintering and densification is higher, so that the reinforcement The size of the reinforcement is obviously coarsened with the matrix, and the size of the reinforcement is generally >5 μm, and the matrix is a coarse lamellar structure. The material prepared by the present invention has a fine equiaxed structure, and the reinforcements are all nanoscale, and have better room temperature strength. Plasticity; (3) The reactive agent of the reinforcement in the comparative process generally adheres to the surface of the spherical titanium alloy powder, and forms a network structure with a diameter of about 50-150 μm at the particle boundary after sintering, while the material nano-reinforcement obtained in the present invention is at the grain boundary The / grain is distributed in multiple layers, the degree of dispersion is higher, and there are obvious differences in organizational characteristics.

Comparative example 3

This comparative example provides a method for strengthening and toughening multi-layer nanoparticle-reinforced titanium-based composite materials. The steps are basically the same as in Example 1, except that the densification and sintering temperatures in Step C are 950°C and 1000°C respectively. °C, lower than the β phase transition temperature. Although the low sintering temperature can significantly refine the grain size, the density of the material is only 91.6% and 96.3%, which is far lower than the 99.3% of Example 1. There are a large number of micropores in the microstructure of the material, which makes the material exhibit The obvious room temperature brittleness and elongation are 1.1% and 4.3%, respectively, which are far lower than that of Example 1. Therefore, the preferred preparation parameters of the present invention are an important basis for material structure regulation and comprehensive performance improvement.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (10)

1. A preparation method of a multilayer nanoparticle reinforced high-toughness titanium-based composite material is characterized by comprising the following steps:

A. screening titanium-based composite material powder embedded with a superfine mesh structure with different particle sizes;

B. heating the screened titanium-based composite material powder to 20-200 ℃ below the beta phase transition temperature of the material, and performing pre-pressing sintering;

C. raising the furnace temperature to 20-300 ℃ above the beta phase transition temperature for densification sintering;

D. and cooling to the set aging temperature of the material after sintering, and performing aging treatment to obtain the high-toughness titanium-based composite material with the nano reinforcement in which the nano reinforcement is distributed in a crystal boundary/intragranular multilayer manner in the matrix.

2. The method according to claim 1, wherein in step A, the titanium-based composite powder embedded with the ultrafine mesh structure comprises titanium-based materials and reinforcing bodies, and the reinforcing bodies are distributed in the ultrafine mesh structure in the titanium-based materials.

3. The method of claim 2, wherein the matrix comprises pure titanium and titanium alloy, and the reinforcement comprises TiB, tiC, la ₂ O ₃ 、Ti ₅ Si ₃ 、(Ti，Zr) _x Si ₃ One or more of the reinforcement bodies, wherein x is 5-6.

4. The preparation method of claim 2, wherein the volume fraction of the reinforcement in the powder is 1-5%, and the reinforcement is nano-sized, has a diameter or width less than 100nm, and is distributed in a superfine network structure.

5. The preparation method according to claim 1, wherein in the step a, the particle size of the titanium-based composite material powder is in one of the ranges of 15 to 53 μm, 53 to 100 μm, 100 to 150 μm, and 150 to 225 μm.

6. The method of claim 1, wherein the pre-press sintering in step B comprises one of hot press sintering, hot isostatic pressing sintering, and spark plasma sintering.

7. The preparation method according to claim 1, wherein in the step B, the pre-pressing sintering temperature is 20-200 ℃ below the beta phase transition temperature, the pressure is 50-300 MPa, the temperature rising rate is 10-200 ℃/min, and the holding time is 5-60 min.

8. The method according to claim 1, wherein the vacuum sintering in step C comprises: hot pressing sintering, hot isostatic pressing sintering and spark plasma sintering.

9. The preparation method according to claim 1, wherein the sintering temperature of the densification sintering in the step C is 20-300 ℃ above the beta transformation temperature, the pressure is 50-300 MPa, the heating rate is 10-200 ℃/min, and the holding time is 5-240 min.

10. The method according to claim 1, wherein the aging treatment in step D is furnace cooling to an aging temperature; the aging temperature is 400-800 ℃, and the aging time is 0.5-8 h.

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