阅读说明：本技术 一种TiB2颗粒增强镁基复合材料及其制备方法 (TiB2Particle reinforced magnesium-based composite material and preparation method thereof ) 是由 周海萍 卢悦 张弘斌 秦升学 刘杰 张成才 孙帅 于 2021-08-12 设计创作，主要内容包括：本发明公开一种TiB-(2)颗粒增强镁基复合材料的制备方法,包括以下步骤：(1)将镁合金碎屑进行清洗并烘干；(2)按照组分配比将镁合金碎屑与TiB-(2)粉末放入球磨罐中,并加入不锈钢磨球,然后向球磨罐内充入氩气,再将球磨罐放到球磨机上进行球磨,得到纳米晶TiB-(2)颗粒增强AZ31镁合金混合粉末；(3)将步骤(2)得到的镁合金混合粉末转入高强石墨模具中,并将其放入到热压烧结炉中,在真空条件下进行热压烧结,然后随炉冷却至室温,得到镁合金热压坯；(4)将步骤(3)得到的镁合金热压坯进行挤压,得到镁合金挤压棒材。本发明通过高能球磨与热挤压相结合的方法进行制备TiB-(2)颗粒增强镁基复合材料,可提高镁基复合材料的强度及韧性。(The invention discloses a TiB 2 The preparation method of the particle reinforced magnesium-based composite material comprises the following steps: (1) cleaning and drying the magnesium alloy scraps; (2) mixing magnesium alloy scraps and TiB according to the proportion of components 2 Putting the powder into a ball milling tank, adding stainless steel grinding balls, then filling argon into the ball milling tank, putting the ball milling tank on a ball mill for ball milling to obtain nanocrystalline TiB 2 Particle-reinforced AZ31 magnesium alloy mixed powder; (3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite die, putting the high-strength graphite die into a hot-pressing sintering furnace, performing hot-pressing sintering under a vacuum condition, and cooling the high-strength graphite die to room temperature along with the furnace to obtain a magnesium alloy hot-pressed blank; (4) will step withAnd (4) extruding the magnesium alloy hot pressed compact obtained in the step (3) to obtain a magnesium alloy extruded bar. The invention prepares TiB by a method combining high-energy ball milling and hot extrusion 2 The particle reinforced magnesium-based composite material can improve the strength and toughness of the magnesium-based composite material.)

1. TiB₂The preparation method of the particle reinforced magnesium-based composite material is characterized by comprising the following steps:

(1) cleaning and drying the magnesium alloy scraps;

(2) mixing magnesium alloy scraps and TiB according to the proportion of components₂Putting the powder into a ball milling tank, adding stainless steel grinding balls, then filling argon into the ball milling tank, putting the ball milling tank on a ball mill for ball milling to obtain nanocrystalline TiB₂Particle-reinforced AZ31 magnesium alloy mixed powder;

(3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite die, putting the high-strength graphite die into a hot-pressing sintering furnace, performing hot-pressing sintering under a vacuum condition, and cooling the high-strength graphite die to room temperature along with the furnace to obtain a magnesium alloy hot-pressed blank;

(4) and (4) extruding the magnesium alloy hot pressed blank obtained in the step (3) to obtain a magnesium alloy extruded bar.

2. A TiB according to claim 1₂The preparation method of the particle reinforced magnesium-based composite material is characterized in that TiB in the step (2)₂2.5-10% of the mixed powder, and 90-97.5% of the magnesium alloy matrix.

3. A TiB according to claim 1₂The preparation method of the particle reinforced magnesium-based composite material is characterized in that TiB in the step (2)₂The particle size of the powder is 3-10 mu m, and the purity is more than 99.9%.

4. A TiB according to claim 1₂The preparation method of the particle reinforced magnesium-based composite material is characterized in that in the step (2), the rotating speed of a ball mill is 200 r/min-300 r/min, the ball milling time is 110-120 h, the ball-material ratio is 50-80: 1, the argon purity is more than or equal to 99.9%, and the diameter of a milling ball is 5-10 mm.

5. A TiB according to claim 1₂The preparation method of the particle reinforced magnesium-based composite material is characterized in that the vacuum degree in the step (3) is less than or equal to 1 multiplied by 10^-2Pa, the hot-pressing sintering temperature is 300-320 ℃, the pressurizing pressure is 40-50 MPa, and the heat-preserving and pressure-maintaining time is 60-90 min.

6. A TiB according to claim 1₂The preparation method of the particle reinforced magnesium-based composite material is characterized in that in the step (4), the temperature of the magnesium alloy hot pressed blank is 350-370 ℃, the temperature of a die is 350-370 ℃, the extrusion ratio is 12-15, and the extrusion speed is 1.5-2.5 mm/min.

7. TiB according to any one of claims 1 to 6₂The magnesium-based composite material prepared by the preparation method of the particle reinforced magnesium-based composite material is characterized in that the room-temperature tensile strength of the extruded magnesium-based composite material is 290-320 MPa, the yield strength is 200-240 MPa, and the fracture elongation is 13.7-15.5%.

Technical Field

The invention relates to the technical field of magnesium-based composite materials, in particular to TiB₂A particle reinforced magnesium-based composite material and a preparation method thereof.

Background

The magnesium alloy is the lightest metal structure material in the prior art, has a series of outstanding advantages of high specific strength, large specific rigidity, good electromagnetic shielding performance, good damping performance, easy recycling and the like, and plays an extremely important role in the industrial fields of aerospace, automobiles, electronics, communication and the like. In addition, the magnesium alloy also has the property of recycling, belongs to environment-friendly materials, and is more known as green engineering materials in the 21 st century.

However, most magnesium alloys have low absolute strength and poor heat resistance, which greatly limits the wide use of structural materials for magnesium alloys. Ceramics of high hardness, e.g. SiC, TiC, Al₂O₃And TiB₂The particles are added into the magnesium alloy to obtain the particle reinforced magnesium-based composite material, so that the mechanical property of the alloy can be effectively improved, and the application range of the magnesium alloy is further expanded. At present, the preparation method of the particle reinforced magnesium-based composite material mainly focuses on a stirring fusion casting method. The method is that the particle reinforcement is directly added into a magnesium alloy melt, the magnesium alloy melt is dispersed and distributed in a matrix by adopting a mechanical stirring or electromagnetic stirring method, and then the magnesium alloy melt is cast into an ingot to obtain the particle reinforced magnesium-based composite material. For example: TiB is prepared by adopting the electromagnetic stirring method of the king tiger₂Particle-reinforced AZ31 magnesium-based composite material (king tiger, preparation and tissue performance research of magnesium-based composite material in outfield, university of continental regulations, 2013); the nano SiC particle reinforced AZ91D magnesium-based composite material is prepared by adopting a mechanical stirring high-energy ultrasonic compounding method (nano SiCStrengthening mechanism research of particle reinforced AZ91D magnesium-based composite material, university of qinghua, 2012). However, the particle reinforced magnesium-based composite material prepared by the method has more casting pores and uneven particle distribution. Powder metallurgy is another method for preparing particle-reinforced magnesium-based composite materials, which is to mix a reinforcement with magnesium alloy powder having a fine size in a ball mill, followed by sintering to obtain the particle-reinforced magnesium-based composite material. For example: aydin et al prepared TiB by powder metallurgy₂Mg-based composite material (Fatih Ayd)₁n,Yavuz Sun.Investigation of wear behaviour and microstructure of hot-pressed TiB₂ particulate-reinforced magnesium matrix composites[J]Canadian Metallurgical quartrly 2018,57(3): 1-15). The method can realize the uniform distribution of the reinforcement in the matrix through powder mixing, but the method has higher requirements on process equipment, is easy to generate powder combustion and explosion accidents, and is not suitable for large-scale production.

Therefore, it is necessary to develop a method for preparing a particle-reinforced high-performance magnesium alloy, which is efficient, low-cost, simple in process and suitable for mass production.

Disclosure of Invention

The invention aims to provide a TiB₂The particle reinforced magnesium-based composite material and the preparation method thereof are prepared by a method of combining high-energy ball milling and hot extrusion so as to improve the tensile strength and the yield strength of the magnesium-based composite material.

The invention specifically adopts the following technical scheme:

TiB₂The preparation method of the particle reinforced magnesium-based composite material comprises the following steps:

(1) cleaning and drying the magnesium alloy scraps;

(2) mixing magnesium alloy scraps and TiB according to the proportion of components₂Putting the powder into a ball milling tank, adding stainless steel grinding balls, then filling argon into the ball milling tank, putting the ball milling tank on a ball mill for ball milling to obtain nanocrystalline TiB₂Particle-reinforced AZ31 magnesium alloy mixed powder;

(3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite die, putting the high-strength graphite die into a hot-pressing sintering furnace, performing hot-pressing sintering under a vacuum condition, and cooling the high-strength graphite die to room temperature along with the furnace to obtain a magnesium alloy hot-pressed blank;

(4) and (4) extruding the magnesium alloy hot pressed blank obtained in the step (3) to obtain a magnesium alloy extruded bar.

Further, TiB in the step (2)₂2.5-10% of the mixed powder, and 90-97.5% of the magnesium alloy matrix.

Further, TiB in the step (2)₂The particle size of the powder is 3-10 mu m, and the purity is more than 99.9%.

Further, in the step (2), the rotating speed of the ball mill is 200 r/min-300 r/min, the ball milling time is 110-120 h, the ball-material ratio is 60:1, and the argon purity is more than or equal to 99.9%.

Further, the vacuum degree in the step (3) is less than or equal to 1 multiplied by 10^-2Pa, the hot-pressing sintering temperature is 300-320 ℃, the pressurizing pressure is 40-50 MPa, and the heat-preserving and pressure-maintaining time is 60-90 min.

Further, in the step (4), the temperature of the magnesium alloy hot pressed blank is 350-370 ℃, the temperature of the die is 350-370 ℃, the extrusion ratio is 12-15, and the extrusion speed is 1.5-2.5 mm/min.

By a TiB₂The magnesium-based composite material prepared by the preparation method of the particle reinforced magnesium-based composite material has the room-temperature tensile strength of 290-320 MPa, the yield strength of 200-240 MPa and the fracture elongation of 13.7-15.5%.

In the technical scheme, the magnesium-based composite material is prepared by adopting a method combining high-energy ball milling and powder metallurgy, wherein the high-energy ball milling can cause severe plastic deformation of powder to generate a dense dislocation network to refine magnesium grains to a nanometer size, and TiB can be realized₂The particles are uniformly distributed in the magnesium matrix, thereby effectively avoiding the occurrence of agglomeration phenomenon and fully playing the reinforcing effect; the powder metallurgy process is energy-saving, material-saving, near-net-shape, and the obtained product has excellent performance and high precision, and is suitable for large-scale production.

The strengthening mechanism of the magnesium-based composite material provided by the invention is mainly dispersion strengthMelting, by high energy ball milling, TiB₂The particles are uniformly distributed in the magnesium matrix structure, so that the dislocation migration is blocked, and the strength and the plasticity of the magnesium matrix structure are enhanced.

The invention has the following beneficial effects:

(1) the magnesium-based composite material provided by the invention has fine magnesium crystal grains in a matrix and uniformly distributed TiB₂The yield strength, tensile strength and plasticity of the particles are obviously enhanced;

(2) compared with the prior art for preparing the magnesium-based composite material by the powder metallurgy method, the method adopts magnesium or magnesium alloy scraps as raw materials, the scraps can be from scraps produced in the processing of industrial magnesium alloy, the recycling and reutilization of the magnesium alloy can be realized, and the TiB₂The method has the advantages of simple process, low cost and suitability for large-scale production.

Drawings

FIG. 1 is a graph showing room temperature elongation curves of examples 1 to 3 of the present invention and comparative example 1;

FIG. 2 shows AZ31/TiB after ball milling in step (2) of example 2₂SEM detection images of the magnesium alloy composite powder;

FIG. 3 shows AZ31/TiB after ball milling in step (2) of example 2₂Carrying out an X-ray diffraction pattern on the magnesium alloy composite powder;

FIG. 4 shows AZ31/TiB obtained after hot extrusion in step (4) of example 2₂Microstructure diagram of the magnesium alloy extrusion bar;

FIG. 5 shows AZ31/TiB obtained after hot extrusion in step (4) of example 3₂Microstructure diagram of the magnesium alloy extrusion bar;

FIG. 6 shows AZ31/TiB obtained in step (4) of example 2₂And macroscopically observing the entering and exiting of the magnesium alloy extrusion bar.

Detailed Description

The invention provides a TiB₂In order to make the advantages and technical solutions of the present invention clearer and clearer, the present invention will be described in detail below with reference to specific embodiments and drawings.

Example 1

The TiB provided by the embodiment₂The preparation method of the particle reinforced magnesium-based composite material comprises the following steps:

(1) cleaning and drying the magnesium alloy scraps, taking AZ31 magnesium alloy cast rods from the magnesium alloy scraps, and turning the magnesium alloy scraps into scraps;

(2) mixing magnesium alloy scraps and TiB according to the proportion of components₂The powder is put into a ball milling pot, wherein TiB₂The mass ratio of the powder to the mixed powder is 2.5%, and the mass ratio of the powder to the mixed powder is TiB₂The particle size of the powder is 3 microns, the purity is more than or equal to 99.9 percent, stainless steel grinding balls with the diameter of 8mm and the mass ratio of the stainless steel grinding balls to the mixed powder is 60:1 are added, argon is filled into a ball milling tank (the purity of the argon is more than or equal to 99.9 percent), the ball milling tank is put on a planetary ball mill for ball milling, the rotating speed of the ball mill is 300r/min, the ball milling time is 110 hours, and the nanocrystalline TiB is obtained₂Particle-reinforced AZ31 magnesium alloy mixed powder;

(3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite mold, wherein the flexural strength of the graphite mold is more than 60MPa, putting the graphite mold into a hot-pressing sintering furnace, and carrying out hot-pressing sintering under the vacuum condition, wherein the hot-pressing sintering temperature is 300 ℃, and the vacuum degree is less than or equal to 1 x 10^-2Pa, pressurizing at 40MPa, keeping the temperature and the pressure for 60min, and then cooling to room temperature along with the furnace to obtain AZ31/TiB₂Hot pressing magnesium alloy blank;

(4) extruding the magnesium alloy hot-pressed blank obtained in the step (3) at the extrusion temperature of 350 ℃, the die temperature of 350 ℃, the extrusion ratio of 14.7 and the extrusion speed of 2mm/min to obtain densified AZ31/TiB₂The magnesium alloy is extruded into a bar.

AZ31/TiB obtained in example 1₂The magnesium alloy extrusion bar is sampled and is subjected to room temperature mechanical property detection, the tensile strength is 297MPa, the yield strength is 202MPa, and the fracture elongation is 14.9%.

The sampling and sample preparation process comprises the following steps: (1) machining: for AZ31/TiB₂Turning the magnesium alloy extrusion bar to obtain a room-temperature tensile sample; (2) and (3) heat treatment: carrying out heat treatment on the obtained tensile sample at 150 ℃ for 1.5h, then cooling along with a furnace, eliminating the work hardening caused by the turning process, and detecting the accurate mechanical property。

Example 2

The TiB provided by the embodiment₂The preparation method of the particle reinforced magnesium-based composite material comprises the following steps:

(1) cleaning and drying the magnesium alloy scraps, taking AZ31 magnesium alloy cast rods from the magnesium alloy scraps, and turning the magnesium alloy scraps into scraps;

(2) mixing magnesium alloy scraps and TiB according to the proportion of components₂The powder is put into a ball milling pot, wherein TiB₂The powder accounts for 5 percent of the mixed powder by mass, and TiB₂The grain diameter of the powder is 3 mu m, stainless steel grinding balls with the diameter of 8mm and the mass ratio of the stainless steel grinding balls to the mixed powder of 60:1 are added, then argon gas is filled into a ball milling tank (the purity of the argon gas is more than or equal to 99.9 percent), the ball milling tank is put on a planetary ball mill for ball milling, the rotating speed of the ball mill is 300r/min, the ball milling time is 110 hours, and the nanocrystalline TiB is obtained₂Particle-reinforced AZ31 magnesium alloy mixed powder;

(3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite mold, wherein the flexural strength of the graphite mold is more than 60MPa, putting the graphite mold into a hot-pressing sintering furnace, and carrying out hot-pressing sintering under the vacuum condition, wherein the hot-pressing sintering temperature is 300 ℃, and the vacuum degree is less than or equal to 1 x 10^-2Pa, pressurizing at 40MPa, keeping the temperature and the pressure for 60min, and then cooling to room temperature along with the furnace to obtain AZ31/TiB₂Hot pressing magnesium alloy blank;

(4) extruding the magnesium alloy hot-pressed blank obtained in the step (3) at the extrusion temperature of 350 ℃, the die temperature of 350 ℃, the extrusion ratio of 14.7 and the extrusion speed of 2mm/min to obtain densified AZ31/TiB₂The magnesium alloy is extruded into a bar.

For AZ31/TiB obtained in example 2₂The magnesium alloy extruded bar was sampled according to the sampling method of example 1 to perform room temperature mechanical property detection, and the tensile strength was 312MPa, the yield strength was 219MPa, and the elongation at break was 15.5%.

Example 3

The TiB provided by the embodiment₂The preparation method of the particle reinforced magnesium-based composite material comprises the following steps:

(1) cleaning and drying the magnesium alloy scraps, taking AZ31 magnesium alloy cast rods from the magnesium alloy scraps, and turning the magnesium alloy scraps into scraps;

(2) mixing magnesium alloy scraps and TiB according to the proportion of components₂The powder is put into a ball milling pot, wherein TiB₂The powder accounts for 10 percent of the mixed powder by mass, and TiB₂The grain diameter of the powder is 3 mu m, stainless steel grinding balls with the diameter of 8mm and the mass ratio of the stainless steel grinding balls to the mixed powder of 60:1 are added, then argon gas is filled into a ball milling tank (the purity of the argon gas is more than or equal to 99.9 percent), the ball milling tank is put on a planetary ball mill for ball milling, the rotating speed of the ball mill is 300r/min, the ball milling time is 110 hours, and the nanocrystalline TiB is obtained₂Particle-reinforced AZ31 magnesium alloy mixed powder;

(3) transferring the magnesium alloy mixed powder obtained in the step (2) into a high-strength graphite mold, wherein the flexural strength of the graphite mold is more than 60MPa, putting the graphite mold into a hot-pressing sintering furnace, and carrying out hot-pressing sintering under the vacuum condition, wherein the hot-pressing sintering temperature is 300 ℃, and the vacuum degree is less than or equal to 1 x 10^-2Pa, pressurizing at 40MPa, keeping the temperature and the pressure for 60min, and then cooling to room temperature along with the furnace to obtain AZ31/TiB₂Hot pressing magnesium alloy blank;

(4) extruding the magnesium alloy hot-pressed blank obtained in the step (3) at the extrusion temperature of 350 ℃, the die temperature of 350 ℃, the extrusion ratio of 14.7 and the extrusion speed of 2mm/min to obtain densified AZ31/TiB₂The magnesium alloy is extruded into a bar.

AZ31/TiB obtained in example 3₂The magnesium alloy extruded bar was sampled according to the sampling method of example 1 to perform room temperature mechanical property detection, and the magnesium alloy extruded bar had a tensile strength of 320MPa, a yield strength of 240MPa, and a breaking elongation of 13.7%.

Comparative example 1

The initial as-cast AZ31 magnesium alloy was selected as comparative example 1, and the tensile strength was 179MPa, the yield strength was 75MPa, and the elongation at break was 9.6% by mechanical property test.

The room temperature tensile curves of examples 1-3 and comparative example 1 were compared, as shown in FIG. 1, and combined with the mechanical property measurements, followed by TiB₂Increasing the content, increasing the tensile strength and yield strength, and adding TiB₂And then, the tensile strength, yield strength and elongation of the magnesium alloy material are obviously increased, and simultaneously, higher strength and toughness are kept.

To further study TiB₂The influence of the reinforcement on the magnesium alloy material is detected as follows:

to the ball-milled AZ31/TiB of step (2) of example 2₂SEM detection of the magnesium alloy composite powder, as shown in FIG. 2, the white particles in the figure are TiB₂The gray base being a magnesium matrix, TiB₂The particles are uniformly distributed in the magnesium matrix without obvious agglomeration, wherein the TiB₂The average size of the particles is about 400nm, and the submicron level is achieved.

To the ball-milled AZ31/TiB of step (2) of example 2₂The magnesium alloy composite powder is detected by X-ray diffraction, as shown in figure 3, the diffraction peak of XRD test result in the figure, Mg and TiB₂The standard peaks of the standard PDF card correspond to one another, and no second phase structure is generated, which indicates that the composite material has good chemical stability in the ball milling process, and the Mg phase and the TiB phase₂No reaction between the phases produces compounds.

AZ31/TiB obtained after hot extrusion in step (4) of example 2₂Metallographic examination of the magnesium alloy bars was carried out, as shown in FIG. 4, and it can be seen from FIG. 4 that AZ31/TiB prepared in example 2₂The magnesium alloy extrusion bar has fine and uniform grain size, obvious grain boundary and average grain size of 2.01 mu m.

AZ31/TiB obtained after hot extrusion in step (4) of example 3₂The magnesium alloy extruded bar was examined metallographically as shown in FIG. 5, and from FIG. 5, AZ31/TiB prepared in example 3 was seen in comparison with FIG. 4₂The grain size of the magnesium alloy extrusion bar is finer and more uniform, the grain boundary is more obvious, the average grain size reaches 1.67 mu m, and the result shows that TiB₂The increase of the content is beneficial to the refinement of the magnesium alloy matrix grains.

In addition, AZ31/TiB obtained in step (4) of example 2 was also used₂The magnesium alloy extruded bar was observed macroscopically in and out of FIG. 6, and it can be seen from the figure that the magnesium alloy extruded bar showed a high degree of finish without significant macroscopicallyCracks appear, which indicates that the densification process is reasonable.

It should be noted that the parts not described in the present application can be implemented by the prior art.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.