A method for preparing beryllium aluminum alloy composite materials

Abstract

This invention discloses a method for preparing beryllium-aluminum alloy composite materials, belonging to the field of alloy composite material technology. The method includes: uniformly mixing beryllium powder with an average particle size of less than 18 μm and aluminum powder with an average particle size of less than 48 μm at a mass percentage of 56-66% and 34-44%, respectively, and then loading the mixture into a mold; placing the mold containing the mixed powder into a sintering furnace and performing vacuum pressure-activated sintering to obtain a beryllium-aluminum sintered ingot; and subsequently performing peeling and mechanical processing on the beryllium-aluminum sintered ingot. This invention's method can suppress the growth of beryllium-aluminum alloy particles, resulting in fine and uniform grains, high interfacial bonding strength, good product performance, uniform heating, rapid heating rate, low sintering temperature, short sintering time, and high production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of alloy composite material technology, and particularly relates to a method for preparing beryllium aluminum alloy composite material. Background Technology

[0002] Beryllium-aluminum alloys combine the advantages of both beryllium and aluminum, integrating the rigidity of beryllium with the toughness of aluminum. They are lightweight, have high specific strength and stiffness, good thermal stability, high toughness, high modulus, and corrosion resistance, making them an important new structural material. Beryllium-aluminum alloys also possess excellent thermal and optical properties, leading to their widespread application in aerospace electronic equipment and high-mode-frequency devices. Furthermore, beryllium-aluminum alloys are highly competitive and widely used in civilian sectors such as computer manufacturing, the automotive industry, and the manufacturing of high-precision, high-speed welding machines.

[0003] Common methods for preparing beryllium aluminum alloys include investment casting and hot isostatic pressing (HIP). Investment casting produces alloys with relatively poor properties. Due to the inherent material properties and process limitations, castings inevitably contain shrinkage cavities, porosity, and other casting defects, affecting product performance. Hot isostatic pressing (HIP) has a long process flow, low production efficiency, and requires a long high-temperature sintering time for the powder, resulting in coarse grains. Furthermore, the powder surface is prone to oxygen absorption, leading to numerous intergranular impurities and the formation of impurity phases at grain boundaries. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing beryllium aluminum alloy composite materials. This method can suppress the growth of beryllium aluminum alloy particles, resulting in fine and uniform grains, high interfacial bonding strength, good performance, uniform heating, fast heating rate, low sintering temperature, short sintering time, and high production efficiency.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing a beryllium-aluminum alloy composite material, the method comprising the following steps:

[0007] A method for preparing a beryllium-aluminum alloy composite material, the method comprising the following steps:

[0008] Step S1: Mix beryllium powder with an average particle size of less than 18 μm and aluminum powder with an average particle size of less than 48 μm at a mass percentage of 56-66% and 34-44% respectively, and then put the mixture into a mold.

[0009] Step S2: After placing the mold containing the mixed powder into the sintering furnace, vacuum pressure boosting activation sintering is performed to obtain beryllium aluminum sintered ingots;

[0010] The vacuum boost activation sintering process is as follows: at 6.0*10 -2 ~7.0*10 -2Under a vacuum of Pa, a heating pressure of 1.2 to 4.4 MPa is applied, and a pulsed current of mixed AC and DC is applied. The temperature is raised to 520 to 580°C at a heating rate of 58 to 92°C / min. Then, the temperature is maintained at a sintering pressure of 22 to 28 MPa for 4 to 9 minutes. The temperature is then cooled to 80 to 120°C in the furnace before being removed from the furnace.

[0011] Step S3: The beryllium aluminum sintered ingot is peeled and mechanically shaped in sequence.

[0012] Furthermore, in step S1, the mass percentages of beryllium powder and aluminum powder are 58-62% and 38-42%, respectively.

[0013] Furthermore, in step S1, the average particle size of the beryllium powder is 7–16 μm, and the average particle size of the aluminum powder is 20–44 μm.

[0014] Furthermore, in step S1, the mixing time is 12 to 14 hours.

[0015] Furthermore, in step S2, the process of applying a mixed AC and DC pulse current is as follows: under a pulse current of 254 to 394 A, discharge for 30 to 50 ms at intervals of 0.6 to 1.4 s until continuous discharge for 27 to 32 s.

[0016] Furthermore, in step S2, the pulse current comprises 16-24% AC current and 76-84% DC current.

[0017] Furthermore, in step S2, the pulse current is 310–340 A;

[0018] The heating rate is 68–84 °C / min.

[0019] Furthermore, in step S2, the heating pressure is 2.6–3.3 MPa; the heating rate is 73–79 °C / min.

[0020] Furthermore, in step S2, the sintering furnace includes an electric spark sintering furnace and a plasma sintering furnace.

[0021] In summary, the beneficial technical effects of the technical solution of the present invention are as follows:

[0022] This invention employs a hybrid AC and DC pulsed current application method and a boost-type activation sintering process to prepare beryllium aluminum alloys. Due to the effective activation effect of pulsed plasma, the self-heating effect between particles and surface activation are effectively utilized, achieving low-temperature and rapid sintering, inhibiting grain growth, achieving rapid densification, significantly shortening sintering time, and saving energy. The hybrid AC and DC pulsed current application utilizes the localized high temperature generated by the discharge shock wave from the pulsed discharge, causing localized melting of the surface, shedding of surface materials, and removal of impurities and adsorbed gases from the powder particle surface. This allows the adsorbed gases on the beryllium powder surface to dissipate, purifying and activating the powder surface, reducing the diffusion free energy of metal atoms, and improving interfacial bonding strength. This invention features uniform heating, rapid temperature rise, low sintering temperature, short sintering time, and high production efficiency. It inhibits the growth of beryllium aluminum alloy composite particles, resulting in fine and uniform grains, high interfacial bonding strength, and excellent performance of the beryllium aluminum alloy composite material. This invention can complete one batch of experiments in an average of 5-10 hours, while conventional hot isostatic pressing requires more than 120 hours. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This embodiment provides a method for preparing a beryllium-aluminum alloy composite material, which includes the following steps:

[0025] Step S1: Mix beryllium powder with an average particle size of less than 18 μm and aluminum powder with an average particle size of less than 48 μm at a mass percentage of 56-66% and 34-44% respectively, and then load the mixture into a mold.

[0026] In this embodiment, the preferred mass percentages of beryllium powder and aluminum powder are 58-62% and 38-42%, respectively. The beryllium-aluminum alloy with these compositions exhibits the low density and high modulus characteristics of beryllium, while also possessing the machinability of aluminum, thus achieving optimal overall performance. The average particle sizes of the beryllium powder and aluminum powder are 7-16 μm and 20-44 μm, respectively, preferably 11-14 μm and 30-40 μm. The mixing time is 12-14 hours.

[0027] Step S2: After placing the mold containing the mixed powder into the sintering furnace, vacuum pressure boosting activation sintering is performed to obtain beryllium aluminum sintered ingots.

[0028] This embodiment utilizes the pulsed discharge of effective pulsed plasma in vacuum boost activation sintering to generate localized high temperatures, causing localized surface melting and shedding of surface materials. This removes impurities and adsorbed gases from the powder particle surface, shortening sintering time and saving energy. It effectively utilizes the spontaneous heating effect and surface activation effect between particles to achieve low-temperature, rapid sintering and inhibit grain growth. The vacuum boost activation sintering process in this embodiment is as follows:

[0029] In 6.0*10 -2 ~7.0*10 -2 Under a vacuum of Pa, a heating pressure of 1.2–4.4 MPa (preferably 2.6–3.3 MPa) is applied, along with a pulsed current of mixed AC and DC current. The temperature is raised to 520–580°C at a heating rate of 58–92°C / min (preferably 68–84°C / min, more preferably 73–79°C / min). The temperature is then maintained at a sintering pressure of 22–28 MPa for 4–9 min, and finally cooled in the furnace to 80–120°C before being removed from the furnace.

[0030] In this embodiment, the process of applying a mixed AC and DC pulse current is as follows: under a pulse current of 254 to 394 A (preferably 310 to 340 A), discharge for 30 to 50 ms at intervals of 0.6 to 1.4 s until continuous discharge for 27 to 32 s.

[0031] In this embodiment, the pulsed current comprises 16-24% alternating current and 76-84% direct current. This embodiment uses a mixture of alternating and direct current to apply the pulsed current, utilizing the discharge shock wave generated by the pulsed discharge to purify and activate the surface of beryllium powder adsorbed with gas, thereby reducing the diffusion free energy of metal atoms and improving the interfacial bonding strength.

[0032] The sintering furnace in this embodiment can be an electric spark sintering furnace or a plasma sintering furnace.

[0033] The preferred temperature for exiting the furnace in this embodiment is 90–100°C.

[0034] Step S3: The beryllium aluminum sintered ingot is peeled and mechanically shaped in sequence.

[0035] Example 1:

[0036] 1. Mix beryllium powder with an average particle size of 11 μm and aluminum powder with an average particle size of 30 μm at a mass percentage of 62% and 38% respectively, and then fill the mixture into a mold after 13 hours.

[0037] 2. After placing the mold containing the mixed powder into the electric spark sintering furnace, a vacuum of 6.3 x 10⁻⁶ is drawn. -2After Pa, a heating pressure of 2.6 MPa is applied, and a pulse current of 310 A, which is a mixture of 20% AC current and 80% DC current, is applied in a manner that discharges for 40 ms at 1 s intervals until the discharge continues for 30 s. The heating rate is controlled at 73 °C / min. After heating to 560 °C, the pressure is increased to 26 MPa and held for 7 min. After cooling to 100 °C in the furnace, the furnace is removed from the furnace.

[0038] 3. After removing the skin from the beryllium aluminum sintered ingot, polish the surface as required.

[0039] The average grain size of the beryllium aluminum alloy composite material in this embodiment is 4.5 μm, and the production efficiency is 5 hours / furnace.

[0040] Example 2:

[0041] 1. Mix beryllium powder with an average particle size of 14μm and aluminum powder with an average particle size of 40μm at a mass percentage of 58% and 42% respectively, and mix them evenly for 13 hours before loading them into a mold.

[0042] 2. After placing the mold containing the mixed powder into the plasma sintering furnace, evacuate to a vacuum level of 6.0 x 10⁻⁶. -2 After Pa, a heating pressure of 3.3 MPa is applied, and a pulse current of 340 A, which is a mixture of 22% AC current and 78% DC current, is applied at intervals of 1.2 s and 35 ms, until the discharge continues for 28 s. The heating rate is controlled at 84 °C / min. After heating to 560 °C, the pressure is increased to 24 MPa and held for 5 min. After cooling to 90 °C in the furnace, the furnace is removed.

[0043] 3. After removing the skin from the beryllium aluminum sintered ingot, polish the surface as required.

[0044] The average grain size of the beryllium aluminum alloy composite material in this embodiment is 6.5 μm, and the production efficiency is 6 hours / furnace.

[0045] Example 3:

[0046] 1. Mix beryllium powder with an average particle size of 7μm and aluminum powder with an average particle size of 20μm at a mass percentage of 56% and 44% respectively, and then fill the mixture into a mold after 12 hours.

[0047] 2. After placing the mold containing the mixed powder into the electric spark sintering furnace, evacuate to 7.0 x 10⁻⁶. -2 After Pa, a heating pressure of 1.2 MPa is applied, and a pulse current of 254 A, which is a mixture of 16% AC current and 84% DC current, is applied in a manner that discharges for 30 ms at 0.6 s intervals until a continuous discharge of 27 s. The heating rate is controlled at 58 °C / min. After heating to 520 °C, the pressure is increased to 22 MPa and held for 4 min. After cooling to 80 °C in the furnace, the furnace is removed from the furnace.

[0048] 3. After removing the skin from the beryllium aluminum sintered ingot, polish the surface as required.

[0049] The average grain size of the beryllium aluminum alloy composite material in this embodiment is 4.1 μm, and the production efficiency is 5 hours / furnace.

[0050] Example 4:

[0051] 1. Mix beryllium powder with an average particle size of 16μm and aluminum powder with an average particle size of 44μm at a mass percentage of 66% and 34% respectively, and then fill the mixture into a mold after 14 hours.

[0052] 2. After placing the mold containing the mixed powder into the plasma sintering furnace, a vacuum of 6.8 x 10⁻⁶ is drawn. -2 After Pa, a heating pressure of 4.4 MPa is applied, and a pulse current of 394 A, which is a mixture of 24% AC current and 76% DC current, is applied in a manner that discharges for 50 ms at 1.4 s intervals until a continuous discharge of 32 s is achieved. The heating rate is controlled at 92 °C / min. After heating to 580 °C, the pressure is increased to 28 MPa and held for 9 min. The furnace is then cooled to 120 °C before being removed from the furnace.

[0053] 3. After removing the skin from the beryllium aluminum sintered ingot, polish the surface as required.

[0054] The average grain size of the beryllium aluminum alloy composite material in this embodiment is 5.6 μm, and the production efficiency is 5 hours / furnace.

[0055] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for preparing a beryllium-aluminum alloy composite material, characterized in that, The preparation method includes the following steps: Step S1: Mix beryllium powder with an average particle size of less than 18 μm and aluminum powder with an average particle size of less than 48 μm at a mass percentage of 56-66% and 34-44% respectively, and then load the mixture into a mold. Step S2: After placing the mold containing the mixed powder into the sintering furnace, vacuum pressure boosting activation sintering is performed to obtain beryllium aluminum sintered ingots; The vacuum boost activation sintering process is as follows: at 6.0 10 -2 ~7.0 10 -2 Under a vacuum of Pa, a heating pressure of 1.2~4.4MPa is applied, and a pulsed current of mixed AC and DC is applied. The temperature is raised to 520~580℃ at a heating rate of 58~92℃ / min. Then, the temperature is maintained at a sintering pressure of 22~28MPa for 4~9min. After cooling in the furnace to 80~120℃, the furnace is removed from the furnace. In step S2, the process of applying a mixed AC and DC pulse current is as follows: under a pulse current of 254~394A, discharge for 30~50ms at intervals of 0.6~1.4s until continuous discharge for 27~32s. Step S3: The beryllium aluminum sintered ingot is peeled and mechanically shaped in sequence.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass percentages of beryllium powder and aluminum powder are 58-62% and 38-42%, respectively.

3. The preparation method according to claim 2, characterized in that, In step S1, the average particle size of the beryllium powder is 7~16μm, and the average particle size of the aluminum powder is 20~44μm.

4. The preparation method according to claim 3, characterized in that, In step S1, the mixing time is 12 to 14 hours.

5. The preparation method according to claim 4, characterized in that, In step S2, the pulse current comprises 16-24% AC current and 76-84% DC current.

6. The preparation method according to claim 5, characterized in that, In step S2, the pulse current is 310~340A; The heating rate is 68~84℃ / min.

7. The preparation method according to claim 6, characterized in that, In step S2, the heating pressure is 2.6~3.3MPa; the heating rate is 73~79℃ / min.

8. The preparation method according to any one of claims 1 to 3, characterized in that, In step S2, the sintering furnace includes an electric spark sintering furnace and a plasma sintering furnace.

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