CN111745162A - Shape memory alloy reinforced magnesium matrix composite material with three-dimensional interpenetrating network structure and preparation method thereof - Google Patents

Abstract

The invention relates to a magnesium-based composite material having a three-dimensional interpenetrating network structure and reinforced by a 3D-printed shape memory alloy reinforcement skeleton and a preparation method thereof. The composite material is composed of a shape memory alloy reinforcement with a volume fraction of 10% to 80% and a magnesium or magnesium alloy matrix, and has a three-dimensional interpenetrating network structure. The reinforcement and the matrix have independent topological structures and are interspersed in three-dimensional space. Complementary binding. The preparation method of the composite material is as follows: using 3D printing technology to prepare a shape memory alloy reinforced body skeleton with a network topology, infiltrating the skeleton with molten magnesium or magnesium alloy melt under vacuum or protective atmosphere, and obtaining a composite after solidification and cooling Material. The composite material of the invention has high strength, high plasticity, strong controllability of structure and mechanical properties, and has a certain shape memory effect, that is, the room temperature deformation can be partially or completely recovered above the martensitic transformation temperature, which serves as a novel structural function. Integrated materials have considerable application prospects.

Description

Shape memory alloy reinforced magnesium matrix composites with three-dimensional interpenetrating network structure and its preparation method

technical field

The invention relates to the field of metal matrix composite materials, in particular to a magnesium matrix composite material having a three-dimensional interpenetrating network structure and reinforced by a 3D-printed shape memory alloy reinforcement skeleton and a preparation method thereof.

Background technique

Under the premise of ensuring safe service, realizing the lightweight of structural materials can effectively reduce the weight of structural parts, which is conducive to saving energy and reducing environmental pollution, so it has important scientific significance and practical value. For example, in the field of transportation, the lightweight design of automobiles can improve fuel efficiency, reduce fuel consumption and exhaust emissions, so it has become one of the main trends in today's automobile development. The realization of lightweight structural materials mainly depends on the improvement of mechanical properties such as specific strength and specific stiffness. Magnesium and magnesium alloys show outstanding specific strength and specific stiffness due to their low density (the density of pure magnesium is 1.74g/cm ³ ), and have good functional properties such as damping and shock absorption, thermal conductivity and electromagnetic shielding. Therefore, It is widely used in transportation, biomedical, electronic products and many other fields.

However, compared with steel, titanium alloy, aluminum alloy and other metal structural materials, the absolute strength and stiffness of magnesium and magnesium alloys are still low, and the wear resistance and heat resistance are poor, while showing lower high temperature strength and High temperature creep resistance, which largely limits its application as a lightweight structural material. One of the effective ways to solve the above problems is to prepare magnesium matrix composites by introducing reinforcing phase into magnesium or magnesium alloy matrix. The commonly used composite method is to introduce randomly and uniformly distributed reinforcing phase particles or fibers into the magnesium or magnesium alloy matrix. However, it is difficult to precisely design and control the structure of traditional magnesium matrix composites, so the mechanical properties of the material cannot be effectively controlled, and the combination of the enhanced phase and the matrix is only achieved through the phase interface, which is prone to stress concentration and cracking at the phase interface. question. In addition, the current magnesium and magnesium alloy composites cannot restore their original shape after plastic deformation, and the damage caused by the deformation is difficult to repair automatically, which leads to an irreversible decline in material properties.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure and a preparation method thereof. The shape memory alloy skeleton with a network topology is used to strengthen magnesium and magnesium alloys, and the 3D printing technology is used to realize the The precise design and control of the reinforcement structure in the magnesium matrix composite material can significantly improve the strength, stiffness and wear resistance of magnesium and magnesium alloys without significantly increasing the material density, and endow the material with a certain shape memory function, The plastic deformation at room temperature can be automatically recovered when heated to above the martensitic transformation temperature of the shape memory alloy.

In order to achieve the above object, the present invention adopts the following technical solutions:

A shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure, the composite material is composed of a shape memory alloy reinforcement and a magnesium or magnesium alloy matrix, and the content of the shape memory alloy reinforcement is 10% by volume. %～80%, the rest is magnesium or magnesium alloy matrix, the shape memory alloy is one of titanium-nickel alloy, titanium-copper alloy, titanium-nickel-copper alloy, copper-aluminum-nickel alloy, copper-zinc alloy, and does not mix with molten magnesium. Or magnesium alloy reacts; the composite material has a three-dimensional interpenetrating network structure, which is manifested in that the reinforcement and the matrix have independent topological structures and are interspersed and complementary in three-dimensional space.

The compressive strength of the composite material is 250-800 MPa, the compressive strain is greater than 10%, and the density is in the range of 2.2-4.2 g/cm ³ .

The composite material has a certain shape memory effect, that is, after the composite material undergoes plastic deformation at room temperature, its deformation can be automatically recovered when heated to above the martensitic transformation temperature of the shape memory alloy. When it exceeds 20%, the proportion of the response variable to the total response variable is greater than 1%.

The preparation method of the shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure comprises the following steps:

1) Design a shape memory alloy reinforced body skeleton with a network topology, establish a three-dimensional model of the skeleton, import the model into a metal 3D printer formed by laser selective melting technology, and prepare the shape memory alloy powder through 3D printing. Structural shape memory alloy reinforcement skeleton;

2) Put the shape memory alloy reinforcement skeleton printed in step 1) into a crucible together with magnesium or magnesium alloy, place the crucible in a smelting equipment, and heat the magnesium or magnesium alloy under vacuum or a protective atmosphere to melt and infiltrate the shape memory In the alloy reinforcement framework;

3) Stop heating, and after the magnesium or magnesium alloy is solidified and cooled, the crucible is taken out from the smelting equipment to obtain a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure.

In step 1), the particle size of the shape memory alloy powder is 1-200 μm, the shape memory alloy reinforcement skeleton has a three-dimensional network topology, the porosity of the skeleton is 20%-90%, and the average pore diameter is 0.01-3mm , the diameter of the connecting rib is 0.005 to 2.5 mm.

In step 2), the crucible is a kind of graphite crucible, magnesia crucible, corundum crucible, 45 steel crucible, nickel crucible, and the protective atmosphere is a kind of argon, nitrogen, helium, heating The temperature exceeds the melting point of magnesium or magnesium alloy, which is 650 ℃ ~ 1000 ℃, and the holding time is 1 ~ 100min; metal melt infiltration of shape memory alloy skeleton adopts pressureless infiltration or vacuum infiltration, if vacuum infiltration is used, the vacuum degree is -0.005～-0.5MPa.

The design idea of the present invention is:

1) The melting point of the shape memory alloy is much higher than that of magnesium or magnesium alloy, and it does not react with molten magnesium or magnesium alloy, so the composite material can be prepared by the method of infiltrating the shape memory alloy skeleton with magnesium or magnesium alloy melt, and the obtained The metallurgical bond between the reinforcement and the matrix in the composite material is high, and the interface strength is high, so it shows the ideal strengthening and stiffening effect;

2) The martensitic transformation temperature of the shape memory alloy matches the creep temperature of magnesium or magnesium alloy, which can give the material a certain shape memory function. After the material undergoes plastic deformation at room temperature, when heated to the martensitic temperature of the shape memory alloy Above the bulk transformation temperature, the shape memory effect of the reinforced body skeleton can drive the magnesium or magnesium alloy matrix to creep, so that the overall deformation of the material can be automatically recovered;

3) The composite material has a three-dimensional interpenetrating network structure, which enables the reinforcement and the matrix to not only rely on the interface to connect, but also form a whole through the interpenetrating mechanical interlocking, which is beneficial to reduce the stress concentration at the interface and strengthen the two-phase The coordination between stress conduction and deformation;

4) 3D printing technology can realize the rapid prototyping of shape memory alloy reinforced skeleton, and can accurately design and control the three-dimensional network topology of the skeleton, so as to realize the effective control of the structure and mechanical properties of composite materials.

Compared with existing materials and technologies, the present invention has the following advantages and beneficial effects:

1) The composite material of the present invention significantly improves the strength, stiffness, wear resistance and high temperature creep resistance of the material without significantly increasing the density of magnesium or magnesium alloy, and has good plastic deformation ability;

2) The preparation method of the composite material of the present invention gives full play to the advantages of the 3D printing technology, and the three-dimensional network topology of the reinforced body skeleton can be precisely designed and controlled in a wide range, so the structure and mechanical properties of the composite material can be effectively controlled. ;

3) The composite material of the present invention has a certain shape memory effect, that is, after the composite material undergoes plastic deformation at room temperature, when it is heated to above the martensitic transformation temperature of the shape memory alloy, its deformation can be automatically recovered. When the variable does not exceed 20%, the proportion of the response variable to the total response variable is greater than 1%.

4) The preparation method of the composite material of the present invention has the advantages of simple process, short period, high efficiency, strong designability and controllability, and is suitable for being extended to other material systems.

Description of drawings

FIG. 1 is a three-dimensional model diagram of a titanium-nickel alloy skeleton with a network topology designed in Example 1. FIG.

FIG. 2 is a physical image (a) and a three-dimensional X-ray structural image (b) of the titanium-nickel alloy skeleton prepared by the 3D printing technology in Example 1.

3 is a physical image (a) and a three-dimensional X-ray structural image (b) of the titanium-nickel alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure prepared in Example 1.

4 is a room temperature compressive stress-strain curve of the titanium-nickel alloy reinforced magnesium-based composite material with a three-dimensional interpenetrating network structure prepared in Example 1 and its comparison with pure magnesium.

FIG. 5 is a three-dimensional model diagram of a titanium-nickel alloy skeleton with a network topology designed in Example 3. FIG.

Detailed ways:

In the specific implementation process, the present invention has a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure and a preparation method thereof as follows:

The composite material is composed of a shape memory alloy reinforcement with a volume fraction of 10% to 80% (preferably 20% to 70%) and a magnesium or magnesium alloy matrix, and has a three-dimensional interpenetrating network structure. Independent topological structures and interspersed complementary combinations in three-dimensional space. The preparation method of the composite material is as follows: using shape memory alloy powder to prepare a shape memory alloy reinforced body skeleton with network topology by 3D printing technology, and infiltrating the skeleton with molten magnesium or magnesium alloy melt under vacuum or protective atmosphere , and the composite material is obtained after solidification and cooling. The particle size of the shape memory alloy powder is 1 to 200 μm (preferably 5 to 70 μm), the porosity of the shape memory alloy reinforcement skeleton is 20% to 90% (preferably 30% to 80%), and the thermal impregnation The temperature exceeds the melting point of magnesium or magnesium alloy, which is 650 ° C ~ 1000 ° C. Metal melt infiltration of shape memory alloy skeleton adopts pressureless infiltration or vacuum infiltration. If vacuum infiltration is used, the vacuum degree is -0.005 ~ -0.5 MPa (preferably -0.005 to -0.1MPa).

The present invention will be further described below in conjunction with specific embodiments, it should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the protection scope of the present invention.

Example 1:

In this example, a titanium-nickel alloy reinforced magnesium-based composite material with a three-dimensional interpenetrating network structure was prepared. The raw materials used include titanium-nickel alloy powder (average particle size is 15 μm, and the atomic ratio of titanium and nickel is 1:1) and metal magnesium. The specific preparation process is as follows:

1) The 3D visualization solid simulation software Autodesk Inventor Professional (AIP2019) is used to design a titanium-nickel alloy reinforced body skeleton with a network topology, and a 3D model of the skeleton is established. As shown in Figure 1, the network topology of the model was established based on the principle of triple periodic minimum surface; the model was imported into the Realizer SLM 100 metal 3D printer formed by laser selective melting technology, and under the protection of argon gas, 3D printing The titanium-nickel alloy powder is prepared into a titanium-nickel alloy reinforced skeleton with a designed structure. Among them, a Yb:YAG (trivalent ytterbium ion-doped yttrium aluminum garnet) laser is selected, with a power of 200W, a laser beam spot diameter of 40 μm, and a powder coating. ^The thickness is 50μm, the laser scanning speed is 200mm/s, the scanning gap is 100μm, and it is cooled naturally under the protection of argon gas. is 70%, the aperture is about 1-2mm, and the diameter of the connecting edge is about 1mm;

2) Put the titanium-nickel alloy reinforcement skeleton printed in step 1) into a high-purity graphite crucible with a diameter of 10 cm (carbon content of graphite > 99.9 wt%), place 25 g of magnesium metal above the skeleton, and place the crucible in a vacuum resistor In the furnace, the temperature was raised from room temperature to 850°C at a rate of 5°C/min in an argon atmosphere, and the temperature was maintained for 5 minutes.

3) Stop heating, cool down to room temperature at a rate of 5°C/min, take out the crucible, and take out the composite material from the crucible to obtain a titanium-nickel alloy reinforced magnesium-based composite material with a three-dimensional interpenetrating network structure. As shown in Figure 3, in the physical picture, the dark part is the titanium-nickel alloy reinforcement, and the light part is the magnesium matrix. In the three-dimensional X-ray structure diagram, the light-colored part is the titanium-nickel alloy reinforcement, and the dark-colored part is the magnesium matrix. The volume fraction of the titanium-nickel alloy reinforcement in the composite material is 30%, and the titanium-nickel alloy reinforcement and the magnesium matrix respectively have independent topological structures and interpenetrate and complement each other in three-dimensional space, showing a three-dimensional interpenetrating network structure.

After testing, the density of the composite material is 3.2 g/cm ³ , the compressive strength is 320 MPa, and the compressive plastic strain exceeds 35%, as shown in FIG. 4 . In addition, the composite material has a shape memory effect. When the compressive strain amount at room temperature is 5%, the composite material is heated to 350 ° C and kept for 5 h, the strain of the composite material can be automatically recovered, and the ratio of the recovery strain amount to the total strain amount is 98.5 %.

Example 2:

In this example, a titanium-nickel alloy reinforced magnesium alloy matrix composite material with a three-dimensional interpenetrating network structure was prepared. The raw materials used include titanium-nickel alloy powder (average particle size is 15 μm, and the atomic ratio of titanium and nickel is 1:1) and AZ91D magnesium alloy. The specific preparation process is as follows:

1) this step is identical to step 1) in Example 1;

2) The difference between this step and step 2) in Example 1 is that the metal used for the infiltration of the nickel-titanium alloy skeleton is AZ91D magnesium alloy, and the infiltration temperature is 860°C;

3) This step is the same as step 3) in Example 1.

After testing, the density of the composite material is 3.4 g/cm ³ , the compressive strength is 400 MPa, and the compressive plastic strain exceeds 30%. In addition, the composite material has a shape memory effect. When the compressive strain at room temperature is 5%, the composite material is heated to 300 ° C and kept for 5 h, the strain of the composite material can be automatically recovered, and the ratio of the recovery strain to the total strain is 96.4 %.

Example 3:

In this example, a titanium-nickel alloy reinforced magnesium-based composite material with a three-dimensional interpenetrating network structure was prepared. The raw materials used include titanium-nickel alloy powder (average particle size is 15 μm, and the atomic ratio of titanium and nickel is 1:1) and metal magnesium. The specific preparation process is as follows:

1) This step is similar to step 1) in Example 1, except that the skeleton structure of the 3D-printed titanium-nickel alloy is different, see Figure 5.

2) this step is the same as step 2) in Example 1;

3) This step is similar to step 3) in Example 1, except that the volume fraction of the titanium-nickel alloy reinforcement in the composite material is 64%.

After testing, the density of the composite material is 4.1 g/cm ³ , the compressive strength is 590 MPa, and the compressive plastic strain exceeds 25%. In addition, the composite material has a shape memory effect. When the compressive strain amount at room temperature is 5%, the composite material is heated to 350 ° C and kept for 5 h, the strain of the composite material can be automatically recovered, and the ratio of the recovery strain amount to the total strain amount is 99.4 %.

The results of the examples show that the composite material of the present invention has excellent properties such as light weight, high strength and high plasticity, as well as a shape memory function, that is, the room temperature deformation can be partially or completely recovered above the martensitic transformation temperature, and its structure and mechanical properties. It can be designed and effectively controlled by 3D printing technology, so it has considerable application prospects as a new structure-function integrated material.

Claims (6)

1. a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure is characterized in that, the composite material is made up of shape memory alloy reinforcement and magnesium or magnesium alloy matrix, and in volume percentage, shape memory The content of alloy reinforcement is 10% to 80%, and the rest is magnesium or magnesium alloy matrix. The shape memory alloy is one of titanium-nickel alloy, titanium-copper alloy, titanium-nickel-copper alloy, copper-aluminum-nickel alloy, and copper-zinc alloy. And it does not react with molten magnesium or magnesium alloy; the composite material has a three-dimensional interpenetrating network structure, which shows that the reinforcement and the matrix have independent topological structures and are interspersed and complementary in three-dimensional space. 2 . The shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure according to claim 1 , wherein the compressive strength of the composite material is 250-800 MPa, the compressive strain is greater than 10%, and the density The range is 2.2 to 4.2 g/cm ³ . 3. The shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure according to claim 1, wherein the composite material has a certain shape memory effect, that is, after the composite material undergoes plastic deformation at room temperature , when the shape memory alloy is heated to above the martensitic transformation temperature, its deformation can automatically recover. When the total room temperature strain does not exceed 20%, the proportion of the recovery strain to the total strain is greater than 1%. 4. The preparation method of the shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure according to one of claims 1 to 3, characterized in that, comprising the following steps: 1) Design a shape memory alloy reinforced body skeleton with a network topology, establish a three-dimensional model of the skeleton, import the model into a metal 3D printer formed by laser selective melting technology, and prepare the shape memory alloy powder through 3D printing. Structural shape memory alloy reinforcement skeleton; 2) Put the shape memory alloy reinforcement skeleton printed in step 1) into a crucible together with magnesium or magnesium alloy, place the crucible in a smelting equipment, and heat the magnesium or magnesium alloy under vacuum or a protective atmosphere to melt and infiltrate the shape memory In the alloy reinforcement framework; 3) Stop heating, and after the magnesium or magnesium alloy is solidified and cooled, the crucible is taken out from the smelting equipment to obtain a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure. 5. The method for preparing a shape memory alloy reinforced magnesium matrix composite material with a three-dimensional interpenetrating network structure according to claim 4, wherein in step 1), the particle size of the shape memory alloy powder is 1 ~200 μm, the shape memory alloy reinforcement skeleton has a three-dimensional network topology, the porosity of the skeleton is 20% to 90%, the average pore diameter is 0.01 to 3 mm, and the diameter of the connecting rib is 0.005 to 2.5 mm. 6. The method for preparing a shape memory alloy reinforced magnesium-based composite material with a three-dimensional interpenetrating network structure according to claim 4, wherein in step 2), the crucible is a graphite crucible, a magnesia crucible, a corundum One of the crucible, 45 steel crucible and nickel crucible, the protective atmosphere is one of argon, nitrogen and helium, and the heating temperature exceeds the melting point of magnesium or magnesium alloy, which is 650℃～1000℃, and the holding time is 650℃～1000℃. 1 ~ 100min; metal melt infiltration of shape memory alloy skeleton adopts pressureless infiltration or vacuum infiltration, if vacuum infiltration is used, the vacuum degree is -0.005 ~ -0.5MPa.

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