A nano, micro-nano multi-layer metal composite forming method

Abstract

The application is a nano-micro-nano multilayer metal composite forming method, which aims at the poor room temperature forming performance of the existing TiAlMg alloy material, the difficulty in processing and manufacturing of complex structure parts, and the difficulty in practicability, and proposes a new preparation method of nano-micro-nano multilayer components. In the preparation process, the thermal explosion reaction and the hydrogenation-dehydrogenation reaction are used to realize the metallurgical bonding of Ti, Al and Mg three elements and the multilayer configuration. The multilayer configuration material has better thermal conductivity with the assistance of titanium and aluminum. The heat dissipation fin prepared by using the material has much higher efficiency than the existing magnesium alloy material, which greatly expands the use field of the material.

Description

TECHNICAL FIELD

[0001] The application is a nano, micro-nano multilayer metal composite forming method, belonging to the technical field of heat dissipation component processing and manufacturing. BACKGROUND

[0002] In the development and research of intermetallic compounds, TixAlyMgz alloy with excellent high-temperature specific performance has attracted much attention. In the field of structural materials, it has gradually become a research hotspot. Its high high-temperature specific strength and creep resistance, low density and thermal expansion coefficient, and good plasticity and toughness also make it an ideal material in the aerospace industry, and it has very good application prospects.

[0003] At present, most researches tend to study the influence of the phase combination mode among Ti, Al and Mg on the microstructure and performance. The three elements of Ti, Al and Mg are metallurgically combined by casting, and there are few studies on the configuration mode of the microstructure. This is mainly due to the poor formability of TixAlyMgz alloy material, which belongs to a difficult-to-deform alloy. It is difficult to process and manufacture complex structural parts, which affects its practicality. SUMMARY

[0004] The application is designed to solve the above-mentioned problems in the prior art. The purpose is to use powder metallurgy to prepare a nano, micro-nano multilayer structure Ti-Al-Mg alloy material to realize the processing of complex structural parts and promote the practical application of the material.

[0005] The purpose of the application is achieved by the following technical solutions:

[0006] The steps of the nano, micro-nano multilayer metal composite forming method are as follows:

[0007] Step 1, prepare a powder blank

[0008] A mixture of Ti powder and Al powder is laid on a flat aluminum foil, and then a layer of AZ31 magnesium alloy powder with the same mass as the mixture of Ti powder and Al powder is laid on it. Finally, a layer of Ti powder and Al powder mixture is laid on the AZ31 magnesium alloy powder. The thickness of the above three layers of powder is 5-10 mm. Then the three layers of powder are wrapped with aluminum foil, and the hydraulic press is used to compact at room temperature, the pressure is 100-300 MPa, and the pressure holding time is 0.5-1 h to obtain a powder blank;

[0009] The powder compact is pre-compacted, and the powder particles collide and slightly plastically deform. Since the pre-compaction is performed at room temperature, the powder compact accumulates certain deformation energy, which helps to quickly recover and recrystallize in the subsequent hot deformation process, and to refine the grains;

[0010] Step two, rolling the powder compact

[0011] The compacted powder compact is placed in a rolling mill and rolled. An electric pulse power source is connected to the rolling mill, so that the temperature of the rolling mill can instantaneously reach 1100-1300℃ during rolling. The rolling speed is 5-10 m / s, and the rolling deformation is 30-55%. During the rolling process, the Ti powder and Al powder mixture in the upper and lower layers of the powder compact undergoes thermal explosion reaction, and the AZ31 magnesium alloy powder in the middle layer solidifies, and cracks appear on the upper and lower surfaces of the powder compact.

[0012] During the rolling process of the pre-compacted powder compact, the powder compact itself is not heated, only the rolling mill is rapidly heated by the electric pulse power source. Since the Ti powder and Al powder mixture layer is on the outer surface of the powder compact, and has excellent thermal conductivity, it rapidly undergoes thermal explosion reaction under the influence of the deformation energy accumulated during the rolling deformation and cold compaction, and generates micron-level TixAly. At this time, the densification degree of the Ti powder and Al powder mixture layer reaches 70%-80%.

[0013] The contact part of the Ti powder and Al powder mixture layer and the AZ31 magnesium alloy powder layer undergoes a certain degree of interface reaction due to the influence of rolling deformation and temperature, and generates TixAlyMgz. However, due to the high rolling speed and the protection of the Ti powder and Al powder mixture layer on the outer surface, the AZ31 magnesium alloy powder is not greatly affected by the temperature of the rolling mill. At this time, the densification degree of the AZ31 magnesium alloy powder layer reaches 60%-70%.

[0014] Due to the high rolling speed, cracks appear on the surface of the aluminum foil on the outer surface of the powder compact, which helps hydrogen to enter the AZ31 magnesium alloy powder layer through the cracks and powder void channels during the subsequent hydrogenation process.

[0015] Step three, hydrogenation of the powder compact

[0016] The aluminum foil on the surface of the rolled powder compact is removed, and the powder compact is placed in a vacuum environment for heating. The heating temperature is 300-400℃, hydrogen is introduced into the vacuum chamber, and the pressure reaches 0.5-1 atm. The holding and pressure maintaining time is 0.5-2 h, so that hydrogen can penetrate into the AZ31 magnesium alloy through the cracks.

[0017] In the powder blank hydrogenation process, the Ti powder and Al powder mixture layer does not change in phase transition and densification degree because of the low hydrogenation temperature, the powder particles of the AZ31 magnesium alloy powder layer absorb hydrogen, the contact part of the Ti powder and Al powder mixture layer and the AZ31 magnesium alloy powder layer also absorbs hydrogen, and the densification degree of the AZ31 magnesium alloy powder layer does not change either;

[0018] Step four, hot pressing and dehydrogenation of the powder blank

[0019] The hydrogenated powder blank is hot pressed in a vacuum environment, the heating temperature is 300-400 DEG C, and the holding and pressure maintaining time is 0.5-2h, so that the powder blank completes dehydrogenation;

[0020] In the dehydrogenation process, the powder particles of the AZ31 magnesium alloy powder layer and the contact part of the Ti powder and Al powder mixture layer and the AZ31 magnesium alloy powder layer are nanocrystallized, at this time, the structure of the powder blank is micron-micron-nanometer-micron-micron;

[0021] Step five, powder blank stacking

[0022] The hot pressed and dehydrogenated powder blank is equally divided in the length direction and stacked together, and steps three to five are repeated, so that the nanometer, micrometer multi-layer component based on magnesium-aluminum-titanium three metal composite forming is obtained; through one time of stacking, the densification degree of the powder blank reaches 100%, and the powder blank is a nanometer-micron multi-layer structure.

[0023] In the implementation, the purity of the Ti powder, Al powder and AZ31 magnesium alloy powder is 99.99%, and the powder particle size is 300-400 mesh, the Ti powder, Al powder and AZ31 magnesium alloy powder required by the technical measures have the same particle size, and the purpose is that when multiple powder particles contact each other, there are certain size and number of gaps between the powder particles, which facilitates the subsequent hydrogen penetration, thereby promoting the hydrogenation reaction of the AZ31 magnesium alloy powder.

[0024] In the implementation, the thickness of the aluminum foil is less than 1mm.

[0025] In the implementation, the atomic mass ratio of Ti and Al in the mixture of Ti powder and Al powder is 1:1.

[0026] The beneficial effects of the technical scheme of the application are as follows:

[0027] 1. The application is a new method for preparing nano-micro multi-layer components of Ti, Al and Mg, which uses thermal explosion reaction and hydrogenation-dehydrogenation reaction to realize the metallurgical combination of Ti, Al and Mg and multi-layer configuration; the multi-layer configuration material has better thermal conductivity with the help of titanium and aluminum, and the heat dissipation efficiency of the heat dissipation sheet prepared by the material is much higher than that of the existing magnesium alloy material, greatly expanding the application field of the material;

[0028] 2. In order to ensure that the AZ31 magnesium alloy powder is not affected by the thermal explosion reaction temperature, the rolling speed and the rolling roller heating instead of the blank heating are adjusted to avoid the melting of the AZ31 magnesium alloy powder during the rolling process of the powder blank;

[0029] 3. In the application, the hydrogenation-dehydrogenation channel is artificially created by the particle size design of the raw materials combined with the rolling process, and the shape of the formed components is generally plate and wire, and the forming capacity is greatly improved, which provides the possibility for the manufacture of various special-shaped components. DETAILED DESCRIPTION

[0030] The technical scheme of the application will be further described in combination with the embodiments as follows:

[0031] The steps of preparing the nano-micro multi-layer metal composite material by the method of the application are as follows:

[0032] Step one, preparing the powder blank

[0033] A mixture of Ti powder and Al powder is laid on a flat aluminum foil, then a layer of AZ31 magnesium alloy powder with the same mass as the mixture of Ti powder and Al powder is laid on the mixture, and finally a layer of the mixture of Ti powder and Al powder is laid on the AZ31 magnesium alloy powder, the thickness of the three layers of powder is 5-10mm, then the three layers of powder are wrapped with aluminum foil, and the hydraulic machine is used to compact at room temperature, the pressure is 100-300MPa, and the pressure holding time is 0.5-1h to obtain the powder blank; wherein:

[0034] The purity of the Ti powder, Al powder and AZ31 magnesium alloy powder is 99.99%, and the powder particle size is 300-400 mesh;

[0035] The thickness of the aluminum foil is less than 1mm;

[0036] In the mixture of Ti powder and Al powder, the atomic mass ratio of Ti to Al is 1:1;

[0037] Step two, powder blank rolling

[0038] The compacted powder blank is put into a rolling mill, and a power supply is connected to the rollers to make the temperature of the rollers reach 1100-1300℃ instantaneously during rolling, the rolling speed is 5-10m / s, and the rolling deformation is 30-55%. During the rolling, the mixture of Ti powder and Al powder in the upper and lower layers of the powder blank reacts, the AZ31 magnesium alloy powder in the middle layer solidifies, and cracks appear on the upper and lower surfaces of the powder blank;

[0039] Step three, hydrogenation of the powder blank

[0040] The aluminum foil on the surface of the rolled powder blank is removed, and the powder blank is heated in a vacuum environment. The heating temperature is 300-400℃, hydrogen is introduced into the vacuum chamber to make the pressure reach 0.5-1atm, and the holding and pressure maintaining time is 0.5-2h. Hydrogen is allowed to penetrate into the AZ31 magnesium alloy through the cracks.

[0041] Step four, hot pressing and dehydrogenation of the powder blank

[0042] The hydrogenated powder blank is hot pressed in a vacuum environment. The heating temperature is 300-400℃, and the holding and pressure maintaining time is 0.5-2h to complete the dehydrogenation of the powder blank.

[0043] Step five, stacking and rolling of the powder blank

[0044] The dehydrogenated powder blank is equally divided in the length direction and stacked together. Steps three to five are repeated to obtain a nano, micro-nano multilayer component based on magnesium-aluminum-titanium three-metal composite forming.

Claims

1. A method for nano, micro-nano multilayer metal composite forming, characterized in that: The steps of the forming method are as follows: Step one, preparation of the powder blank A mixture of Ti powder and Al powder is laid on a flat aluminum foil, and then a layer of AZ31 magnesium alloy powder with the same mass as the mixture of Ti powder and Al powder is laid on the mixture, and finally, a layer of the mixture of Ti powder and Al powder is laid on the AZ31 magnesium alloy powder, the thickness of the three layers of powder is 5-10 mm, then the three layers of powder are wrapped with aluminum foil, and the powder blank is obtained by compaction using a hydraulic press at room temperature, the pressure is 100-300 MPa, and the pressure holding time is 0.5-1 h; Step two, rolling of the powder blank The compacted powder blank is placed in a rolling mill, and the temperature of the roller can instantaneously reach 1100-1300 ℃ during rolling by connecting the roller to an electric pulse power source, the rolling speed is 5-10 m / s, and the rolling deformation is 30-55%; during the rolling process, the mixture of Ti powder and Al powder in the upper and lower layers of the powder blank undergoes thermal explosion reaction, and the AZ31 magnesium alloy powder in the middle layer solidifies, and cracks appear on the upper and lower surfaces of the powder blank; Step three, hydrogenation of the powder blank The aluminum foil on the surface of the rolled powder blank is removed, and the powder blank is placed in a vacuum environment for heating, the heating temperature is 300-400 ℃, hydrogen gas is introduced into the vacuum chamber to a pressure of 0.5-1 atm, and the hydrogenation is carried out by allowing the hydrogen gas to penetrate into the AZ31 magnesium alloy through the cracks; Step four, hot pressing and dehydrogenation of the powder blank The hydrogenated powder blank is hot pressed in a vacuum environment, the heating temperature is 300-400 ℃, and the holding and pressure holding time is 0.5-2 h, so that the powder blank completes dehydrogenation; Step five, stacking and rolling of the powder blank The powder blank after hot pressing and dehydrogenation is equally divided in the length direction and stacked together, and steps three to five are repeated to obtain a nano, micro-nano multilayer component based on magnesium-aluminum-titanium composite forming.

2. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: The purity of the Ti powder, Al powder and AZ31 magnesium alloy powder is 99.99%, and the powder particle size is 300-400 mesh.

3. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: The thickness of the aluminum foil is less than 1 mm.

4. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: In the mixture of Ti powder and Al powder, the atomic mass ratio of Ti to Al is 1:

1.

5. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: In step two, the densification degree of the Ti powder and Al powder mixture layer reaches 70%-80%, and the densification degree of the AZ31 magnesium alloy powder layer reaches 60%-70%.

6. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: In step three, the densification degree of the powder blank does not change.

7. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: In step four, the structure of the powder blank after completing dehydrogenation is micron-micro-nano-micro-nano-micron.

8. The nanometer, micro-nanometer multilayer metal composite forming method according to claim 1, characterized in that: In step five, the densification degree of the powder blank after one stacking and rolling reaches 100%.