A high-thermal-conductivity high-elastic-modulus beryllium-aluminum alloy and a method for preparing the same

Abstract

The application provides a high-thermal-conductivity and high-elastic-modulus beryllium-aluminum alloy and a preparation method thereof, and belongs to the technical field of alloy manufacturing. The preparation method comprises the following steps: S1, beryllium powder, aluminum powder and graphene derivatives are loaded into a three-dimensional mixer for intermittent mixing to obtain mixed powder; S3, the beryllium-aluminum alloy blank is placed into a vacuum furnace for high-temperature vacuum primary degassing treatment; S4, after the high-temperature vacuum primary degassing treatment, the beryllium-aluminum alloy blank is shaped and then placed into a steel ladle for secondary degassing and vacuum welding sealing; and S5, after the vacuum welding sealing, the beryllium-aluminum alloy blank is placed into a hot isostatic pressing device for hot isostatic pressing treatment, and then the ladle is removed by using nitric acid to obtain the beryllium-aluminum alloy. The beryllium-aluminum alloy has low alloy density, good mechanical properties, high elastic modulus and high thermal conductivity.

Description

Technical Field

[0001] This invention belongs to the field of alloy manufacturing technology, and in particular relates to a beryllium aluminum alloy with high thermal conductivity and high elastic modulus and its preparation method. 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 possess characteristics such as light weight, high specific strength, high specific stiffness, good thermal stability, high toughness, high modulus, and corrosion resistance, making them an important new structural material. Beryllium-aluminum alloys also exhibit excellent thermal conductivity and elastic modulus, and have already replaced aluminum and titanium alloys as a crucial structural material in the aerospace industry. With the development of the aerospace industry, there is a growing demand for materials with high thermal conductivity and high modulus. Therefore, this patent proposes a high thermal conductivity, high modulus beryllium-aluminum alloy material and its preparation method.

[0003] Existing beryllium-aluminum alloys are prepared by directly mixing beryllium powder and aluminum powder and then isostatically pressing them. However, these alloys have low tensile strength, low thermal conductivity, and low modulus of elasticity, failing to meet future customer requirements. To improve alloy performance, elements such as silver, cobalt, germanium, and nickel are typically added. However, this increases the alloy density and decreases the modulus of elasticity and thermal conductivity, making it impossible to simultaneously meet application requirements. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for preparing a beryllium aluminum alloy with high thermal conductivity and high elastic modulus. The beryllium aluminum alloy prepared by this method has low alloy density, high elastic modulus, and high thermal conductivity.

[0005] The second objective of this invention is to provide a beryllium aluminum alloy with high thermal conductivity and high elastic modulus.

[0006] To achieve one of the above objectives, the present invention employs the following technical solution:

[0007] A method for preparing a beryllium aluminum alloy with high thermal conductivity and high elastic modulus, the method comprising the following steps:

[0008] Step S1: Beryllium powder, aluminum powder and graphene derivatives are loaded into a three-dimensional mixer and intermittently mixed to obtain a mixed powder;

[0009] The beryllium powder, aluminum powder, and graphene derivatives comprise 60–64%, 30–35%, and 1–5% by mass, respectively.

[0010] Step S2: After loading the mixed powder into a rubber sleeve through a vibrating platform and tightening the loading port, cold isostatic pressing is performed to obtain beryllium aluminum alloy powder blank.

[0011] The cold isostatic pressing pressure is ≥200MPa, and the time is ≥5 minutes;

[0012] Step S3: Place the beryllium aluminum alloy blank into a vacuum furnace for high-temperature vacuum degassing treatment.

[0013] The high-temperature vacuum primary degassing process is as follows: [The process involves a temperature range of] less than 1.67 x 10⁻⁶. -2 Under a vacuum of Pa, the temperature is slowly increased to 250-300℃ and held for 1.5-2.5 hours. Then the temperature is increased to 400-500℃ and held for 2.5-3.5 hours. After degassing, the product is removed from the furnace.

[0014] Step S4: After the beryllium aluminum alloy blank has undergone high temperature vacuum degassing treatment once, it is shaped and placed into a steel sleeve for secondary degassing and vacuum welding.

[0015] The secondary degassing process is as follows: [The process involves a temperature range of] less than 1.67 x 10⁻⁶. -2 Under a vacuum of Pa, the temperature is slowly increased to 500-550℃ and degassed for 1-2 hours.

[0016] Step S5: Place the vacuum-sealed beryllium aluminum alloy billet into a hot isostatic pressing (HIP) apparatus for HIP treatment, and then remove the cladding with nitric acid to obtain the beryllium aluminum alloy.

[0017] The hot isostatic pressing process has a molding pressure >130MPa, a molding temperature of 620-640℃, and a holding time of 1.5-2.5 hours.

[0018] This invention utilizes graphene derivatives (such as graphene, graphene oxide, and graphite nanosheets) to achieve a transition between the beryllium and aluminum phases, thereby improving the bonding between the beryllium and aluminum phases and enhancing the mechanical properties, elastic modulus, and thermal conductivity of beryllium-aluminum alloys. Insufficient graphene content cannot guarantee sufficient interfacial bonding between graphene and beryllium-aluminum. Beryllium-aluminum alloys are widely used in aerospace due to their low density; to ensure both low density and good interfacial bonding, the graphene derivative content is selected between 1% and 5%. This invention employs degassing treatment to prevent surface adsorption of oxygen and water vapor during beryllium powder preparation. By controlling the process conditions of hot isostatic pressing (such as pressure, temperature, and holding time), the densification degree and performance of the material are improved. Excessive temperature can cause chemical changes in beryllium, aluminum, and carbon, affecting material properties; conversely, excessively low temperatures fail to achieve densification and performance improvement.

[0019] Furthermore, prior to step S1, the graphene derivative is dispersed to ensure that the graphene derivative is evenly dispersed and mixed.

[0020] Furthermore, in step S1, the beryllium powder has a purity greater than 99% and a particle size of 4.5–6.5 μm;

[0021] The aluminum powder has a purity greater than 99.9% and a particle size of 10–15 μm;

[0022] The purity of the graphene derivative is greater than 99.9%.

[0023] Furthermore, in step S1, the intermittent mixing process is as follows: the intermittent mixing time is 10 to 15 hours, and after each mixing time is 0.5 to 1.5 hours, the interval between two adjacent mixing times is not less than 1 hour, so as to prevent the graphene from being fully and uniformly mixed and from being oxidized during mixing.

[0024] Furthermore, the intermittent mixing process is as follows: the intermittent mixing time is 12 to 14 hours, each mixing lasts 0.8 to 1.2 hours, and the interval between two adjacent mixing times is 1.5 to 2.5 hours.

[0025] Furthermore, in step S1, the graphene derivative includes one or more of graphene, graphene oxide, and graphite nanosheets.

[0026] Furthermore, in step S2, the pressure of the cold isostatic pressing is 220-240 MPa, and the time is 6-8 minutes.

[0027] Furthermore, in step S5, the molding pressure of the hot isostatic pressing process is 135-140 MPa.

[0028] To achieve the second objective mentioned above, the present invention employs the following technical solution:

[0029] A beryllium aluminum alloy with high thermal conductivity and high elastic modulus is prepared by the preparation method described above.

[0030] Furthermore, the high thermal conductivity and high elastic modulus beryllium aluminum alloy has an elastic modulus greater than 250 GPa and a thermal conductivity greater than 230 W / mk.

[0031] In summary, the technical solution of the present invention has the following beneficial effects:

[0032] The beryllium-aluminum alloy prepared by this invention combines the low density and good dimensional stability of beryllium with the easy processing properties of aluminum. Furthermore, the addition of graphene improves the thermal conductivity and elastic modulus of the beryllium-aluminum alloy. Simultaneously, the addition of graphene derivatives (such as graphene, graphene oxide, and graphite nanosheets) improves the phase interface of the beryllium-aluminum alloy, enhancing the interfacial strength and properties between the beryllium phase, aluminum phase, and graphene, thereby increasing the overall strength of the beryllium-aluminum alloy. The beryllium-aluminum alloy prepared using the method of this invention not only possesses excellent mechanical properties but also exhibits an elastic modulus greater than 250 GPa and a thermal conductivity greater than 230 W / mK, meeting the special material requirements of aerospace applications. Detailed Implementation

[0033] 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.

[0034] Example 1:

[0035] 1. Take beryllium powder with a purity of 99.5% and a particle size of 5μm, aluminum powder with a purity of 99.92% and a particle size of 12μm, and graphene material with a purity of 99.95%, and mix them intermittently in a weight ratio of 61:35:4 for a total of 12 hours. Each mixing session should last 1.2 hours, and the interval between two consecutive mixing sessions should be 1.2 hours.

[0036] 2. Load the mixed powder into a rubber sleeve through a vibrating platform, tighten the sleeve at the filling port, and load it into a cold isostatic press. Hold the pressure at 220MPa for 6 minutes.

[0037] 3. Subsequently, the casing is removed and the billet is placed into a vacuum device for degassing, achieving a vacuum level of 1.67 x 10⁻⁶. -2 After Pa, the temperature was gradually increased to 280℃ and held for 2 hours, then increased to 450℃ and held for 3 hours. The vacuum degree during the degassing process was 6 x 10⁻⁶. -3 After degassing, the food is removed from the oven.

[0038] 4. After shaping the billet, place it into a suitable steel sleeve and evacuate it to a depth of 1.67x10 mm. -2 Pa was heated to 530℃ and degassed for 1.5 hours, after which the suction pipe became stuck.

[0039] 5. The steel ladle containing the billet is then placed in a hot isostatic pressing furnace and treated at 640°C and 135MPa pressure for 2.5 hours. After cooling, it is taken out of the furnace and the ladle is removed by acid washing with nitric acid.

[0040] The beryllium aluminum alloy in this embodiment has an elastic modulus of 280 GPa and a thermal conductivity of 250 W / (mk).

[0041] Example 2:

[0042] 1. Take beryllium powder with a purity of 99.2% and a particle size of 6.5μm, aluminum powder with a purity of 99.95% and a particle size of 15μm, and graphene material with a purity of 99.92%, and mix them intermittently in a weight ratio of 64:35:1 for a total of 15 hours. After each mixing session, the interval between two consecutive mixing sessions is 1.5 hours.

[0043] 2. The mixed powder is loaded into a rubber sleeve through a vibrating platform, the sleeve is tied tightly at the filling port, and then loaded into a cold isostatic press and held at 240MPa for 8 minutes.

[0044] 3. Subsequently, the casing is removed and the billet is placed into a vacuum device for degassing, achieving a vacuum level of 1.67 x 10⁻⁶. -2 After Pa, the temperature was gradually increased to 250℃ and held for 1.5 hours, then increased to 400℃ and held for 2.5 hours. The vacuum degree during degassing was 5.7 x 10⁻⁶. -3 After degassing, the food is removed from the oven.

[0045] 4. After shaping the billet, place it into a suitable steel sleeve and evacuate it to a depth of 1.67x10 mm. -2 The pump tube jammed after being heated to 500°C for 1 hour to remove the gas.

[0046] 5. The steel ladle containing the billet is then placed in a hot isostatic pressing furnace and treated at 630°C and 140MPa pressure for 1.5 hours. After cooling, it is taken out of the furnace and the ladle is removed by acid washing with nitric acid.

[0047] The beryllium aluminum alloy in this embodiment has an elastic modulus of 270.5 GPa and a thermal conductivity of 245 W / (mk).

[0048] Example 3:

[0049] 1. Take beryllium powder with a purity of 99.1% and a particle size of 4.5μm, aluminum powder with a purity of 99.95% and a particle size of 10μm, and graphene oxide material with a purity of 99.95%, and mix them intermittently in a weight ratio of 62:33:5 for a total of 10 hours. After each 0.5-hour mixing, the interval between two adjacent mixing times is 1 hour.

[0050] 2. The mixed powder is loaded into a rubber sleeve through a vibrating platform, the sleeve is tied tightly at the filling port, and then loaded into a cold isostatic press and held under pressure of 200MPa for 5 minutes.

[0051] 3. Subsequently, the casing is removed and the billet is placed into a vacuum device for degassing, achieving a vacuum level of 1.67 x 10⁻⁶. -2 After Pa, the temperature was gradually increased to 300℃ and held for 2.5 hours, then increased to 500℃ and held for 3.5 hours. The vacuum degree during degassing was 4.8 x 10⁻⁶. -3After degassing, the food is removed from the oven.

[0052] 4. After shaping the billet, put it into a suitable steel sleeve, evacuate it to 1.67x10-2 Pa and heat it. After degassing at 550℃ for 1.8 hours, lock the evacuation pipe.

[0053] 5. Subsequently, the steel ladle containing the billet is placed into a hot isostatic pressing furnace and treated at 620℃ and 130MPa pressure for 1 hour. After cooling, it is taken out of the furnace and the ladle is removed by acid washing with nitric acid.

[0054] The beryllium aluminum alloy in this embodiment has an elastic modulus of 289.2 GPa and a thermal conductivity of 261.8 W / (mk).

[0055] Example 4:

[0056] 1. Take beryllium powder with a purity of 99.2% and a particle size of 5.5μm, aluminum powder with a purity of 99.95% and a particle size of 14μm, and graphite nanosheets and graphene oxide materials with a purity of 99.95%, and mix them intermittently in a weight ratio of 65:30:5 for a total of 14 hours. Each mixing session lasts 0.8 hours, and the interval between two adjacent mixing sessions is 2.5 hours. Graphite nanosheets and graphene oxide each account for 50%.

[0057] 2. The mixed powder is loaded into a rubber sleeve through a vibrating platform, the sleeve is tightened at the filling port, and then loaded into a cold isostatic press and held at 240MPa for 7 minutes.

[0058] 3. Subsequently, the casing is removed and the billet is placed into a vacuum device for degassing, achieving a vacuum level of 1.67 x 10⁻⁶. -2 After Pa, the temperature was gradually increased to 270℃ and held for 2 hours, then increased to 450℃ and held for 3 hours. The vacuum degree during degassing was 4.5 x 10⁻⁶. -3 After degassing, the food is removed from the oven.

[0059] 4. After shaping the billet, place it into a suitable steel sleeve, evacuate to 1.67 x 10⁻² Pa, heat to 520℃ for 1.6 hours to degas, and then lock the evacuation pipe.

[0060] 5. Subsequently, the steel ladle containing the billet is placed into a hot isostatic pressing furnace and treated at 635℃ and 140MPa pressure for 2 hours. After cooling, it is taken out of the furnace and the ladle is removed by nitric acid washing.

[0061] The beryllium aluminum alloy in this embodiment has an elastic modulus of 290.1 ​​GPa and a thermal conductivity of 268.6 W / (mk).

[0062] 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 of producing a high thermal conductivity, high modulus beryllium aluminum alloy, characterized by, The preparation method comprises the following steps: Step S1, loading beryllium powder, aluminum powder and carbon-containing material into a three-dimensional mixer for intermittent mixing to obtain mixed powder; The mass percentage of the beryllium powder, the aluminum powder and the carbon-containing material is 60-64%, 30-35% and 1-5%, respectively; Before the step S1, the carbon-containing material is subjected to dispersion treatment; In the step S1, the carbon-containing material is one of graphene material and graphene oxide material; Alternatively, the carbon-containing material is graphite nanosheet and graphene oxide material; In the step S1, the intermittent mixing process is that the intermittent mixing time is 10-15 hours, and after each mixing for 0.5-1.5 hours, the interval between adjacent two mixing times is not less than 1 hour; Step S2, loading the mixed powder into a rubber jacket through a vibration platform, tightening the charging port and then performing cold isostatic pressing to obtain a beryllium aluminum alloy powder blank; The cold isostatic pressing pressure is greater than or equal to 200 MPa, and the time is greater than or equal to 5 minutes; Step S3, placing the beryllium aluminum alloy powder blank after high-temperature vacuum primary degassing treatment into a vacuum furnace; The high-temperature vacuum primary degassing process is: slowly heating to 250-300℃ under vacuum of less than 1.67x10 -2 Pa, keeping for 1.5-2.5 hours, then heating to 400-500℃, keeping for 2.5-3.5 hours, and discharging after degassing is completed. Step S4, shaping the beryllium aluminum alloy powder blank after high-temperature vacuum primary degassing treatment, loading it into a steel jacket and then performing secondary degassing and vacuum welding sealing; The secondary degassing process is: slowly heating to 500-550℃ under vacuum of less than 1.67x10 -2 Pa, and degassing for 1-2 hours. Step S5, placing the beryllium aluminum alloy powder blank after vacuum welding sealing into a hot isostatic pressing device for hot isostatic pressing treatment, and then removing the jacket with nitric acid to obtain a beryllium aluminum alloy; The hot isostatic pressing forming pressure is greater than 130 MPa, the forming temperature is 620-640°C, and the pressure holding time is 1.5-2.5 hours.

2. The production method according to claim 1, characterized by, In the step S1, the purity of the beryllium powder is greater than 99%, and the particle size is 4.5-6.5 μm; The purity of the aluminum powder is greater than 99.9%, and the particle size is 10-15 μm; The purity of the carbon-containing material is greater than 99.9%.

3. The preparation method according to claim 2, characterized in that, The intermittent mixing process is that the intermittent mixing time is 12-14 hours, and after each mixing for 0.8-1.2 hours, the interval between adjacent two mixing times is 1.5-2.5 hours.

4. The production method according to claim 3, characterized by, In the step S2, the cold isostatic pressing pressure is 220-240 MPa, and the time is 6-8 minutes.

5. The production method according to claim 4, characterized by, In the step S5, the hot isostatic pressing forming pressure is 135-140 MPa.

6. A high thermal conductivity, high modulus beryllium aluminum alloy characterized by, The high-thermal-conductivity and high-elastic-modulus beryllium aluminum alloy is prepared by the preparation method in any one of claims 1-5.

7. The high thermal conductivity, high modulus beryllium aluminum alloy of claim 6, wherein, The elastic modulus of the high-thermal-conductivity and high-elastic-modulus beryllium aluminum alloy is greater than 250 GPa, and the thermal conductivity is greater than 230 W / mk.