CN116815078A - A high-entropy alloy reinforced metal matrix composite material and its preparation method - Google Patents

Abstract

The invention discloses a high-entropy alloy reinforced metal matrix composite material and a preparation method thereof, which can be used to solve the problem of increasing the tensile strength of the composite material without significantly reducing the elongation of the aluminum matrix composite material. The technical solution of the present invention includes placing the HEA/Al sheet composite material in the mold of a high-pressure torsion (HPT) equipment; by adjusting the number of torsion turns, the HEA/Al composite material generates different strains and obtains a more uniform distribution of the reinforcement phase. , composite materials with good tensile strength. The crystal grains of the present invention can be refined to the nanometer level, while improving the fracture mode of the composite material when it is stretched, and effectively improving the mechanical properties of the composite material. After high-pressure torsion, the hardness value of the composite material does not change significantly. However, as the hardness increases, the hardness error value gradually decreases, which indirectly indicates that the distribution of the reinforcement phase becomes more uniform and the composite material has uniform properties everywhere. .

Description

A high-entropy alloy reinforced metal matrix composite material and its preparation method

Technical field

The invention relates to the technical field of metal/metal composite material preparation, and in particular to a high-entropy alloy reinforced metal matrix composite material and a preparation method thereof.

Background technique

With the rapid development of many industries such as aerospace, rail transportation, and defense industry in recent years, the environmental adaptability of materials has become more and more complex, and the requirements for material performance have become higher and higher. Single materials such as metals and ceramics can no longer meet the growing demand for materials in key industries. The development and application of new materials is the general trend. The emergence of composite materials provides huge development space for materials. Among them, metal matrix composite materials are widely used in various aspects due to their comprehensive mechanical properties such as high shear strength, high toughness and good fatigue resistance.

Current metal matrix composite materials are classified according to the type of metal matrix and can be divided into ferrous metal matrix composite materials (steel, iron, etc.) and non-ferrous metal matrix composite materials (aluminum, magnesium, titanium, etc.). Among them, aluminum and aluminum-based composite materials have the characteristics of light weight, low density, easy to form, etc., and have huge application prospects in many industries. The current main reinforcements include continuous fiber reinforcement, discontinuous reinforcement, lamellar phase reinforcement and autogenous phase reinforcement. Discontinuous reinforcement can be divided into particle reinforcement, fiber reinforcement and whisker reinforcement. The particle reinforcement has high specific strength and hardness, and excellent wear resistance, making this reinforced phase composite material widely used in structural parts and functional lightweight materials. Common particle reinforcements for aluminum-based composites include ceramic particles, metallic glasses, metals, quasicrystal particles, and high-entropy alloy (HEA) particles that have appeared in recent years. Due to its unique organizational structure and good comprehensive properties, the high-entropy alloy particles are widely used in metal matrix composite materials to form a good interface layer to strengthen the bonding ability between the reinforcement and the matrix; on the other hand, through their own The excellent mechanical properties improve the overall performance of composite materials.

At this stage, most of the preparation processes for high-entropy alloy particle-reinforced aluminum matrix composites in relevant literature are sintering first, and then further improving the properties of the composite materials through processes such as heat treatment, hot rolling, and hot extrusion. However, the deformation caused by these subsequent processes The amount is too small to achieve the purpose of refining grains and increasing dislocation density. Therefore, it is necessary to explore how to further improve the microstructure of composite materials to achieve the purpose of improving the mechanical properties of composite materials.

Contents of the invention

The purpose of the present invention is to provide a high-entropy alloy-reinforced aluminum-based composite material with a high degree of grain refinement and good tensile mechanical properties; another purpose of the present invention is to provide a preparation method for a high-entropy alloy-reinforced aluminum-based composite material. method.

The specific technical solutions of the present invention are as follows:

A method for preparing high-entropy alloy reinforced metal matrix composite materials, including the following steps:

(1) The high-entropy alloy reinforced metal matrix composite material that has been mixed and sintered in sequence is moved to a high-pressure torsion equipment after wire cutting;

(2) The loading pressure causes the high-entropy alloy reinforced metal matrix composite to move linearly along the central axis;

(3) Make the lower die of the high-pressure torsion equipment rotate around the central axis, and adjust the number of rotations of the lower die so that the high-entropy alloy reinforced metal matrix composite material undergoes shear deformation with the rotation of the grinding tool.

Preferably, the high-entropy alloy reinforced metal matrix composite material includes 85-95 vol.% metal matrix and 5-15 vol.% high-entropy alloy reinforcement phase.

Preferably, the metal base is aluminum or aluminum alloy.

Preferably, the high-entropy alloy reinforcement phase includes at least five metallic elements or non-metallic elements or a combination of both.

Preferably, the proportions of each element in the high-entropy alloy reinforcement phase are equal.

Preferably, the high-entropy alloy reinforcement phase is selected from MnCoCrFeNi and AlCoCrFeNi.

Preferably, in step (1), the sintering process is: discharge plasma sintering under high vacuum, and the sintering temperature is 550-590°C.

Preferably, in step (3), the number of rotations of the lower mold is 1 to 5 turns.

The invention also provides high-entropy alloy reinforced metal matrix composite materials prepared by the preparation method.

Compared with the prior art, the beneficial effects of the present invention are:

1) The present invention can greatly reduce the grain size of the composite material through high-pressure torsion, which can reach the nanometer level to achieve the effect of strengthening the mechanical properties; it can further optimize the distribution of the reinforcing phase in the composite material and squeeze more into the middle of adjacent HEA. The Al matrix optimizes the bonding between HEA particles and Al matrix; it can improve the fracture position when the composite material breaks, thereby improving the fracture strength of the composite material;

(2) The aluminum-based composite material prepared by the present invention has a small density (3.103g/cm ³ ), which can make the structural parts lighter, and there is basically no difference in hardness value everywhere; compared with the composite material obtained only by sintering material, the tensile strength of the composite material is improved after high-pressure torsion. It achieves the effect of reducing weight and saving resources while improving performance.

Description of the drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description serve to explain the principles of the invention, in which:

Figure 1 is a physical diagram of the HEA/Al composite material prepared in Example 1;

Figure 2 is a graph showing the change in hardness of the HEA/Al composite material prepared in Example 1 under different numbers of twisting turns;

Figure 3 is a graph showing the tensile curve changes of the HEA/Al composite material prepared in Example 1 under different numbers of twisting turns;

Figure 4 is a tensile fracture diagram of the HEA/Al composite material obtained in Example 1. Figure 4(a~c) is an enlarged view of the tensile fracture morphology of the composite material before high-pressure torsion; Figure 4(d~f) ) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 1T;

Figure 4(g~i) shows the enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure twisting turns is 2T; Figure 4(j~l) shows the tensile fracture morphology of the composite material when the number of high-pressure twisting turns is 3T. Enlarge the images in sequence;

Figure 5 is the XRD of the HEA/Al composite material obtained in Example 1. The grain size of the Al matrix in the composite material is calculated by Scherrer's formula.

Figure 6 is a graph showing changes in hardness of the HEA/Al composite material prepared in Example 2 under different numbers of twisting turns;

Figure 7 is a graph showing the tensile curve changes of the HEA/Al composite material prepared in Example 2 under different numbers of twisting turns;

Figure 8 is a tensile fracture diagram of the HEA/Al composite material obtained in Example 2. Figure 8(a~b) is an enlarged view of the tensile fracture morphology of the composite material before high-pressure torsion; Figure 8(c~d) ) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 1T;

Figure 8(e~f) shows the enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure twisting turns is 3T; Figure 8(g~h) shows the tensile fracture morphology of the composite material when the number of high-pressure twisting turns is 5T. Enlarge the images in sequence;

Figure 9 is a graph showing changes in hardness of the HEA/Al composite material prepared in Example 3 under different numbers of twisting turns;

Figure 10 is a graph showing the tensile curve changes of the HEA/Al composite material prepared in Example 3 under different numbers of twisting turns;

Figure 11 is a tensile fracture diagram of the HEA/Al composite material obtained in Example 3. Figure 11(a~b) is an enlarged view of the tensile fracture morphology of the composite material before high-pressure torsion; Figure 11(c~d) ) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 1T; Figure 11(e~f) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 3T; Figure 11 (g~h) are enlarged views of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 5T;

Figure 12 is a graph showing changes in hardness of the HEA/Al composite material prepared in Example 4 under different numbers of twisting turns;

Figure 13 is a graph showing the tensile curve changes of the HEA/Al composite material prepared in Example 4 under different numbers of twisting turns;

Figure 14 is a tensile fracture diagram of the HEA/Al composite material obtained in Example 4. Figure 14(a~b) is an enlarged view of the tensile fracture morphology of the composite material before high-pressure torsion; Figure 14(c~d) ) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 1T; Figure 14(e~f) is an enlarged view of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 3T; Figure 14 (g~h) are sequentially enlarged views of the tensile fracture morphology of the composite material when the number of high-pressure torsion turns is 5T.

Detailed ways

The following disclosure provides many different embodiments or examples of various structures for implementing the invention. In order to simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numbers and/or reference letters in different examples, such repetition being for purposes of simplicity and clarity and does not itself indicate a relationship between the various embodiments and/or arrangements discussed.

Example 1:

A high-entropy alloy reinforced metal matrix composite material (HEA/Al composite material). In terms of volume percentage, the HEA/Al composite material is composed of: high-entropy alloy reinforced phase HEA (AlCoCrFeNi): 10 vol.%, and the metal matrix is Al: 90 %, the atomic proportions of each element in HEA are equal.

The preparation methods of HEA/Al composite materials include:

(1) Cut the HEA/Al composite material prepared by discharge plasma sintering (sintering temperature is 550~590°C, ensuring a density of more than 99%) into sheets with a diameter of 10mm and a thickness of 1.3mm, and then cut the sheets The composite material is placed in a mold with a high-pressure torsion cavity that matches its size;

(2) Press the above-mentioned circular upper mold into the cavity, and use a loading device to load the HEA/Al composite material with a pressure of 6GPa to make it move linearly along the central axis;

(3) Rotate the lower mold 1 to 3 times, causing the lower mold to rotate around the central axis, thereby causing shear deformation of the aluminum sheet.

The aluminum matrix grain size of the HEA/Al composite material produced by the above method has reached the nanometer level; the yield strength (Figure 3) of the composite material obtained through different twisting turns (0T, 1T, 2T, 3T) is 219MPa. , 231MPa, 301MPa, 315MPa; the average hardness value remains basically unchanged, and the hardness error value gradually decreases (Figure 2).

It can be found from the fracture scanning results in Figure 4 that as the number of high-pressure torsion turns increases, the fracture position of the composite material gradually changes from the shedding of HEA particles to the fracture of HEA and the transition layer; it can be found from the changes in the hardness error value in Figure 2 As the number of high-pressure torsion turns increases, the hardness error value gradually decreases, which indirectly indicates that the distribution of the reinforcement phase gradually becomes uniform.

Example 2:

A high-entropy alloy reinforced metal matrix composite material (HEA/Al composite material). In terms of volume percentage, the HEA/Al composite material is composed of: high-entropy alloy reinforced phase HEA (AlCoCrFeNi): 5 vol.%, and the metal matrix is Al: 95 %, the atomic proportions of each element in HEA are equal.

The preparation methods of HEA/Al composite materials include:

(1) Cut the HEA/Al composite material prepared by spark plasma sintering into sheets with a diameter of 10mm and a thickness of 1.3mm, and then place the sheet composite material in a high-pressure torsion cavity mold that matches its size. ;

(2) Press the above-mentioned circular upper mold into the cavity, and use a loading device to load the HEA/Al composite material with a pressure of 6GPa to make it move linearly along the central axis;

(3) By rotating the lower mold 1 to 5 times, the lower mold is rotated around the central axis, thereby causing shear deformation of the aluminum sheet.

The aluminum matrix grain size of the HEA/Al composite material produced by the above method has reached the nanometer level; the yield strength (Figure 7) of the composite material obtained through different twisting turns (0T, 1T, 3T, 5T) is 160MPa in sequence. , 238MPa, 258MPa, 317MPa; after high-pressure torsion, the hardness error value gradually decreases (Figure 6).

From the fracture scanning results in Figure 8, it can be found that as the number of high-pressure torsion turns increases, the fracture position of the composite material gradually changes from the shedding of HEA particles to the fracture of HEA and the transition layer; it can be found from the changes in the hardness error value in Figure 6 As the number of high-pressure torsion turns increases, the hardness error value gradually decreases, which indirectly indicates that the distribution of the reinforcement phase gradually becomes uniform.

Example 3:

A high-entropy alloy reinforced metal matrix composite material (HEA/Al composite material). In terms of volume percentage, the HEA/Al composite material is composed of: high-entropy alloy reinforced phase HEA (AlCoCrFeNi): 15 vol.%, and the metal matrix is Al: 85 %, the atomic proportions of each element in HEA are equal.

The preparation methods of HEA/Al composite materials include:

(1) Cut the HEA/Al composite material prepared by spark plasma sintering into sheets with a diameter of 10mm and a thickness of 1.3mm, and then place the sheet composite material in a high-pressure torsion cavity mold that matches its size. ;

(2) Press the above-mentioned circular upper mold into the cavity, and use a loading device to load the HEA/Al composite material with a pressure of 6GPa to make it move linearly along the central axis;

(3) By rotating the lower mold 1 to 5 times, the lower mold is rotated around the central axis, thereby causing shear deformation of the aluminum sheet.

The aluminum matrix grain size of the HEA/Al composite material produced by the above method has reached the nanometer level; the yield strength (Figure 10) of the composite material obtained by different twisting turns (0T, 1T, 3T, 5T) is 175MPa. , 193MPa, 209MPa, 236MPa; the hardness error value gradually decreases (Figure 9).

From the fracture scanning results in Figure 11, it can be found that as the number of high-pressure torsion turns increases, the fracture position of the composite material gradually changes from the shedding of HEA particles to the fracture of HEA and the transition layer; it can be found from the changes in the hardness error value in Figure 9 As the number of high-pressure torsion turns increases, the hardness error value gradually decreases, which indirectly indicates that the distribution of the reinforcement phase gradually becomes uniform.

Example 4:

A high-entropy alloy reinforced metal matrix composite material (HEA/Al composite material). In terms of volume percentage, the HEA/Al composite material is composed of: high-entropy alloy reinforced phase HEA (MnCoCrFeNi): 10 vol.%, and the metal matrix is Al: 90 %, the atomic proportions of each element in HEA are equal.

The preparation methods of HEA/Al composite materials include:

(1) Cut the HEA/Al composite material prepared by spark plasma sintering into sheets with a diameter of 10mm and a thickness of 1.3mm, and then place the sheet composite material in a high-pressure torsion cavity mold that matches its size. ;

(2) Press the above-mentioned circular upper mold into the cavity, and use a loading device to load the HEA/Al composite material with a pressure of 6GPa to make it move linearly along the central axis;

(3) Rotate the lower mold 1 to 3 times, causing the lower mold to rotate around the central axis, thereby causing shear deformation of the aluminum sheet.

The aluminum matrix grain size of the HEA/Al composite material produced by the above method has reached the nanometer level; the yield strength (Figure 13) of the composite material obtained by different twisting turns (0T, 1T, 3T, 5T) is 170MPa in sequence. , 309MPa, 339MPa, 350MPa; the hardness error value gradually decreases (Figure 12).

From the fracture scanning results in Figure 14, it can be found that as the number of high-pressure torsion turns increases, the fracture position of the composite material gradually changes from the shedding of HEA particles to the fracture of HEA and the transition layer; it can be found from the changes in the hardness error value in Figure 12 As the number of high-pressure torsion turns increases, the hardness error value gradually decreases, which indirectly indicates that the distribution of the reinforcement phase gradually becomes uniform.

The high-entropy alloy reinforcement phase in the present invention includes at least five metal elements or five non-metal elements or five metal/non-metal element combinations, and the elements include but are not limited to the types described in the embodiments.

During the high-pressure torsion process, on the one hand, the internal structure of the sample is changed through hydrostatic pressure, torsional pressure and friction, and submicron or even nanometer-level bulk materials are generated inside the material; on the other hand, the combination of various phases in the composite material is strengthened ability to comprehensively improve the performance of composite materials. The results of this study show that after the composite material undergoes severe plastic deformation under high pressure, the fracture location changes greatly, thereby greatly improving the tensile strength of the composite material and providing a more effective way to improve the mechanical properties of the composite material. Methods.

Table 1 Diffraction angle, corresponding FWHM and calculated grain size of aluminum matrix composites after high-pressure torsion

Other embodiments of the invention will be readily apparent to those skilled in the art from consideration of the specification and practice of the invention herein. The present invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common common sense or customary technical means in the technical field of the invention. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It is to be understood that the present invention is not limited to the precise construction described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims (9)

1. A method for preparing high-entropy alloy-reinforced metal matrix composite materials, which is characterized by comprising the following steps: (1) The high-entropy alloy reinforced metal matrix composite material that has been mixed and sintered in sequence is moved to a high-pressure torsion equipment after wire cutting; (2) The loading pressure causes the high-entropy alloy reinforced metal matrix composite material to move linearly along the central axis; (3) Make the lower die of the high-pressure torsion equipment rotate around the central axis, and adjust the number of rotations of the lower die so that the high-entropy alloy reinforced metal matrix composite material undergoes shear deformation with the rotation of the grinding tool. 2. The preparation method of a high-entropy alloy-reinforced metal matrix composite material according to claim 1, characterized in that the high-entropy alloy-reinforced metal matrix composite material includes 85 to 95 vol.% metal matrix, 5 to 15 vol. % high entropy alloy reinforcement phase. 3. A method for preparing high-entropy alloy-reinforced metal matrix composite materials according to claim 2, characterized in that the metal matrix is aluminum or aluminum alloy. 4. A method for preparing high-entropy alloy reinforced metal matrix composite materials according to claim 2, characterized in that the high-entropy alloy reinforced phase includes at least five metallic elements or non-metallic elements or a combination of both. 5. A method for preparing a high-entropy alloy reinforced metal matrix composite material according to claim 4, characterized in that the proportions of each element in the high-entropy alloy reinforced phase are equal. 6. A method for preparing a high-entropy alloy reinforced metal matrix composite material according to claim 5, characterized in that the high-entropy alloy reinforcing phase is selected from any one of MnCoCrFeNi and AlCoCrFeNi. 7. A method for preparing high-entropy alloy-reinforced metal matrix composite materials according to claim 1, characterized in that, in step (1), the sintering process is: discharge plasma sintering is performed under high vacuum, so The sintering temperature is 550~590℃. 8. A method for preparing high-entropy alloy reinforced metal matrix composite materials according to claim 1, characterized in that in step (3), the number of rotations of the lower mold is 1 to 5. 9. The high-entropy alloy reinforced metal matrix composite material prepared by the preparation method according to any one of claims 1 to 8.