Silicon carbide reinforced beryllium aluminum alloy material and preparation method thereof

Abstract

The invention provides a silicon carbide reinforced beryllium-aluminum alloy material and a preparation method thereof, and belongs to the technical field of alloy material preparation, the preparation method comprises the following steps: loading a beryllium cast ingot and an aluminum block into an alumina crucible, and sequentially carrying out vacuum induction melting, pre-alloying and surface impurity removal; the pre-alloy with surface impurities cut off is loaded into an alumina crucible, vacuumizing is conducted till the pressure is 1 * 10 <-2 > Pa or below, the temperature is increased to 1400-1550 DEG C, silicon carbide particles are added, the alumina crucible is smelted in a tilting mode till the raw materials are completely melted, the raw materials are fully mixed to be uniform, and molten liquid is obtained; and the mold shell is preheated, in the vibration process of the mold shell, molten liquid is cooled and then poured into the preheated mold shell, argon is introduced to the normal pressure, a furnace door is opened, and the mold shell is taken out to be cooled to the room temperature in an air cooling tower. A casting made of the silicon carbide reinforced beryllium aluminum alloy material is good in internal quality, high in tensile strength, high in heat conductivity, good in corrosion resistance, good in heat stability and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy material preparation, and in particular relates to a silicon carbide reinforced beryllium aluminum alloy material and a preparation method thereof. Background Art

[0002] Beryllium aluminum alloy (containing 60-70% beryllium) combines the advantages of beryllium rigidity and aluminum toughness, and has the characteristics of light weight, high specific strength, high specific stiffness, good thermal stability, high toughness, high modulus, corrosion resistance, etc. It is an important new structural material. Beryllium aluminum alloy also has excellent thermal and optical properties, and has been widely used in aerospace electronic equipment and high-wave mode frequency equipment. At the same time, beryllium aluminum alloy has very strong competitiveness in civil fields such as computer manufacturing, automobile industry, and high-precision, high-speed welding machine manufacturing.

[0003] The preparation methods of beryllium aluminum alloy usually include precision casting, powder metallurgy and plastic processing. Since the beryllium phase and aluminum phase in beryllium aluminum alloy are not solid-soluble and the melting points of the two phases are very different, the powder metallurgy method can improve the material properties to a certain extent. Usually, beryllium powder and aluminum powder are directly mixed, isostatically pressed into billets, and then subtractive processing is performed. The finishing cost is high and complex structural parts cannot be produced.

[0004] The precision casting method can produce complex thin-walled castings, and non-critical surfaces do not need to be processed, which can greatly reduce processing costs and improve product production efficiency. Usually, a vacuum medium-frequency induction furnace is used to heat the beryllium ingot and the aluminum ingot to a molten state, and then pour them into the prefabricated mold shell cavity. However, due to the very limited mutual solubility between beryllium and aluminum, beryllium and aluminum exist independently, and aluminum is enriched at the interface of beryllium aluminum alloy, weakening the bonding force of the interface, resulting in poor internal quality, low strength, low thermal conductivity, low chemical corrosion resistance and poor thermal stability of the beryllium aluminum alloy material casting, which limits the application of beryllium aluminum alloy. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for preparing a silicon carbide reinforced beryllium aluminum alloy material. The casting of the silicon carbide reinforced beryllium aluminum alloy material prepared by the method has good internal quality, high tensile strength, high thermal conductivity, good corrosion resistance and good thermal stability (high temperature performance), and low cost.

[0006] A method for preparing a silicon carbide reinforced beryllium aluminum alloy material, the preparation method comprising:

[0007] Step S1, after the beryllium ingot and the aluminum block are loaded into an alumina crucible, vacuum induction melting, pre-alloying and surface impurity removal are sequentially performed;

[0008] Step S2: Place the pre-alloy after the surface impurities are removed into an alumina crucible and evacuate to 1×10 -2Pa, then raise the temperature to 1400-1550°C, add silicon carbide particles, tilt the alumina crucible for smelting, until the raw materials are completely melted and fully mixed to obtain a molten liquid;

[0009] The mass percentages of the beryllium ingot, the aluminum block and the silicon carbide particles are 45% to 80%, 10% to 45% and 1% to 10% respectively;

[0010] Step S3, preheating the mold shell, and during the vibration of the mold shell, cooling the molten liquid to 1280-1330°C and pouring it into the preheated mold shell, then filling it with argon gas to normal pressure, opening the furnace door, taking out the mold shell and cooling it to room temperature in an air cooling tower.

[0011] Furthermore, in step S1, the vacuum degree of the vacuum induction melting is 0.7 to 0.8×10 -2 Pa, temperature is 1440~1460℃, time is 2.5~3h.

[0012] Furthermore, in the step S1, the purity of the beryllium ingot is greater than 98.5wt%;

[0013] The purity of the aluminum block is greater than 99.0 wt %.

[0014] Furthermore, in the step S2, the particle size of the silicon carbide particles is 10 to 100 microns.

[0015] Furthermore, in step S2, the vacuum degree in the alumina crucible after evacuation is 0.7 to 0.8×10 - 2 Pa;

[0016] The tilting angle of the alumina melting crucible is 20-60°.

[0017] Furthermore, in step S2, the time for the raw material to be completely melted is 2.5 to 3 hours.

[0018] Furthermore, in step S3, the temperature of the preheated mold shell is 740-780°C.

[0019] Furthermore, in step S3, the vibration frequency is 10-50 Hz, the amplitude is 5-15 mm, and the vibration time is 1-5 min.

[0020] In order to achieve the second objective above, the present invention adopts the following technical solution:

[0021] A silicon carbide reinforced beryllium aluminum alloy material is prepared by the above-mentioned preparation method.

[0022] Furthermore, the silicon carbide reinforced beryllium aluminum alloy material has a tensile strength of 255 to 290 MPa and a thermal conductivity of 162 to 210 W / m·k.

[0023] In summary, the technical solution of the present invention has the following technical effects:

[0024] The present invention forms obstacles on the dislocation movement path by placing silicon carbide particles in the beryllium aluminum alloy matrix to hinder the dislocation movement, thereby improving the strength and hardness of the beryllium aluminum alloy; the present invention utilizes the good interface bonding between silicon carbide and the beryllium aluminum alloy to avoid the enrichment of aluminum at the interface of the beryllium aluminum alloy, improves the corrosion resistance of the beryllium aluminum alloy, makes the beryllium aluminum alloy more stable in a corrosive environment, improves the thermal stability of the beryllium aluminum alloy, reduces the difference in thermal expansion coefficient, reduces the thermal stress of the beryllium aluminum alloy, and can still maintain good performance in a high temperature environment, that is, improves the high temperature resistance of the beryllium aluminum alloy. The present invention improves the density and surface quality of beryllium aluminum alloy castings through vibration, and at the same time helps to evenly distribute silicon carbide particles, enhances the performance of cast beryllium aluminum alloy, and avoids negative impact on the performance of beryllium aluminum alloy; the casting of the silicon carbide reinforced beryllium aluminum alloy material of the present invention has good internal quality, high tensile strength, high thermal conductivity, good corrosion resistance and thermal stability (high temperature performance), and low cost, and is suitable for the production of complex structural parts, which not only meets the requirements of aviation and aerospace fields for beryllium aluminum alloy, but also meets the requirements of my country's national defense, military industry and other fields for beryllium aluminum alloy. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1:

[0027] (1) Beryllium ingot, aluminum block and silicon carbide particles were weighed according to the mass percentages of 60%, 35% and 5%, wherein the purity of the beryllium ingot was 99.0wt% and the purity of the aluminum block was 99.2wt%.

[0028] (2) After the beryllium ingot and aluminum block were placed in an alumina crucible, -2 Pa, at a temperature of 1450 ° C, after vacuum induction melting for 2.8 h, pre-alloying and surface impurity removal were carried out in sequence.

[0029] (3) The pre-alloy after the surface impurities are removed is placed in the alumina crucible melted in the vacuum induction melting furnace equipment, and the vacuum system is turned on until the vacuum degree reaches 0.7×10 -2 Pa, turn on the medium-frequency induction heating device for the melting crucible in the melting system, slowly adjust the power of the device to raise the melting temperature of the crucible to 1480°C, add silicon carbide with a particle size of 19 microns, and slowly rotate the melting crucible at an amplitude of 40° until the raw materials are completely melted and fully mixed for 2.8 hours to obtain a molten liquid, and then close the furnace door.

[0030] (4) Turn on the mold preheating power supply in the smelting crucible in the smelting system, preheat the mold to 760°C, and during the vibration of the mold, cool the molten liquid to 1300°C and pour it into the preheated mold. After all the molten liquid is poured, turn off the vibration source, fill with argon to normal pressure, open the furnace door, take out the mold and cool it to room temperature in an air cooling tower.

[0031] Among them, the frequency of the mold shell vibration is 30HZ, the amplitude is 9 mm, and the vibration time is 3min.

[0032] The casting of the silicon carbide reinforced beryllium aluminum alloy material of this embodiment has a dense internal structure, a fine and uniform structure, and a tensile strength of 290 MPa and a thermal conductivity of 210 W / m·k.

[0033] Embodiment 2:

[0034] (1) Beryllium ingot, aluminum block and silicon carbide particles were weighed at 45%, 45% and 10% by weight, wherein the purity of the beryllium ingot was 99.2wt% and the purity of the aluminum block was 99.1wt%.

[0035] (2) After the beryllium ingot and aluminum block were placed in an alumina crucible, -2 Pa, at a temperature of 1440 ° C, after vacuum induction melting for 2.5 h, pre-alloying and surface impurity removal were carried out in sequence.

[0036] (3) The pre-alloy after the surface impurities are removed is placed in the alumina crucible melted in the vacuum induction melting furnace equipment, and the vacuum system is turned on until the vacuum degree reaches 0.8×10 -2 Pa, turn on the medium-frequency induction heating device for the melting crucible in the melting system, slowly adjust the power of the device to raise the melting temperature of the crucible to 1400°C, add silicon carbide with a particle size of 10 μm, and slowly rotate the melting crucible at an amplitude of 20° until the raw materials are completely melted and fully mixed for 2.5 hours to obtain a molten liquid, and then close the furnace door.

[0037] (4) Turn on the mold preheating power supply in the smelting crucible in the smelting system, preheat the mold to 740°C, and during the vibration of the mold, cool the molten liquid to 1280°C and pour it into the preheated mold. After all the molten liquid is poured, turn off the vibration source, fill with argon to normal pressure, open the furnace door, take out the mold and cool it to room temperature in an air cooling tower.

[0038] Among them, the frequency of the mold shell vibration is 10HZ, the amplitude is 5mm, and the vibration time is 1min.

[0039] The casting of the silicon carbide reinforced beryllium aluminum alloy material of this embodiment has a dense internal structure, a fine and uniform structure, and a tensile strength of 255 MPa and a thermal conductivity of 162 W / m·k.

[0040] Embodiment 3:

[0041] (1) Beryllium ingot, aluminum block and silicon carbide particles were weighed according to the mass percentages of 80%, 10% and 10%, wherein the purity of the beryllium ingot was 99.3wt% and the purity of the aluminum block was 99.5wt%.

[0042] (2) After the beryllium ingot and aluminum block were placed in an alumina crucible, -2 Pa, at a temperature of 1440 ° C, vacuum induction melting was carried out for 3 h, followed by pre-alloying and surface impurity removal.

[0043] (3) The pre-alloy after the surface impurities are removed is placed in the alumina crucible melted in the vacuum induction melting furnace equipment, and the vacuum system is turned on until the vacuum degree reaches 0.75×10 -2 Pa, turn on the medium-frequency induction heating device for the melting crucible in the melting system, slowly adjust the power of the device to raise the melting temperature of the crucible to 1550°C, add silicon carbide with a particle size of 100 μm, and slowly rotate the melting crucible at an amplitude of 60° until the raw materials are completely melted and fully mixed for 3 hours to obtain a molten liquid, and then close the furnace door.

[0044] (4) Turn on the mold preheating power supply in the smelting crucible in the smelting system, preheat the mold to 780°C, and during the vibration of the mold, cool the molten liquid to 1330°C and pour it into the preheated mold. After all the molten liquid is poured, turn off the vibration source, fill with argon to normal pressure, open the furnace door, take out the mold and cool it to room temperature in an air cooling tower.

[0045] Among them, the frequency of the mold shell vibration is 50HZ, the amplitude is 15mm, and the vibration time is 5min.

[0046] The casting of the silicon carbide reinforced beryllium aluminum alloy material of this embodiment has a dense internal structure, a fine and uniform structure, and a tensile strength of 270 MPa and a thermal conductivity of 182 W / m·k.

[0047] Please note that the technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above embodiments only express several implementation methods of the present application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all belong to the scope of protection of the present application. Therefore, the scope of protection of the patent in this application shall be based on the attached claims.

Claims

1. A method for preparing a silicon carbide reinforced beryllium aluminum alloy material, characterized in that: The preparation method comprises: Step S1, after the beryllium ingot and the aluminum block are loaded into an alumina crucible, vacuum induction melting, pre-alloying and surface impurity removal are sequentially performed; Step S2: Place the pre-alloy after the surface impurities are removed into an alumina crucible and evacuate to 1×10 -2 Pa, then raise the temperature to 1400-1550°C, add silicon carbide particles, tilt and melt the alumina crucible until the raw materials are completely melted and fully mixed to obtain a molten liquid; The mass percentages of the beryllium ingot, the aluminum block and the silicon carbide particles are 45% to 80%, 10% to 45% and 1% to 10% respectively; Step S3, preheating the mold shell, and during the vibration of the mold shell, cooling the molten liquid to 1280-1330°C and pouring it into the preheated mold shell, then filling it with argon gas to normal pressure, opening the furnace door, taking out the mold shell and cooling it to room temperature in an air cooling tower.

2. The preparation method according to claim 1, characterized in that: In step S1, the vacuum degree of the vacuum induction melting is 0.7-0.8×10 -2 Pa, temperature is 1440~1460℃, time is 2.5~3h.

3. The preparation method according to claim 2, characterized in that: In the step S1, the purity of the beryllium ingot is greater than 98.5wt%; The purity of the aluminum block is greater than 99.0 wt %.

4. The preparation method according to claim 3, characterized in that: In the step S2, the particle size of the silicon carbide particles is 10 to 100 microns.

5. The preparation method according to claim 4, characterized in that: In step S2, the vacuum degree in the alumina crucible after evacuation is 0.7 to 0.8×10 -2 Pa; The tilting angle of the alumina melting crucible is 20-60°.

6. The preparation method according to claim 5, characterized in that: In step S2, the time for the raw material to be completely melted is 2.5 to 3 hours.

7. The preparation method according to claim 6, characterized in that: In step S3, the temperature of the preheated mold shell is 740-780°C.

8. The preparation method according to claim 7, characterized in that: In step S3, the vibration frequency is 10-50 Hz, the amplitude is 5-15 mm, and the vibration time is 1-5 min.

9. A silicon carbide reinforced beryllium aluminum alloy material, characterized in that: The silicon carbide reinforced beryllium aluminum alloy material is prepared by the preparation method described in any one of claims 1 to 8.

10. The silicon carbide reinforced beryllium aluminum alloy material according to claim 9, characterized in that: The silicon carbide reinforced beryllium aluminum alloy material has a tensile strength of 255-290 MPa and a thermal conductivity of 162-210 W / m·k.