Aluminum-Tungsten Composite Super Synthesis Process

Tungsten has the characteristics of high temperature resistance, high strength, high hardness and low thermal expansion coefficient. It is an irreplaceable key material in many fields, especially in the field of national defense, military industry and aerospace. However, its high density (too heavy) limits its application, so it is necessary to develop new lightweight materials with better comprehensive properties than tungsten.

Aluminum is the most abundant metal element in the earth's crust. It has good ductility and oxidation resistance, and its density is small (relatively light), which makes it widely used in the field of aerospace and aviation. Some studies have shown that adding tungsten powder as reinforcement in aluminium alloy can obtain a special light alloy material with high hardness, high thermal stability, high wear resistance, high elastic modulus and low density.

However, due to the large density difference between aluminium and tungsten, it is difficult to obtain uniform composition of aluminium-tungsten composites by conventional alloy casting method. For this reason, some scholars have designed a new synthetic scheme to obtain Al-W composites with uniform composition. The technological process is as follows:

(1)Ingredients: according to the composition of Zn: 12%, Mg: 3%, Cu: 1.5%, Mn: 0.1%, Cr: 0.2%, Zr: 0.2%, Ti: 0.1%, W: 5%, Al: 77.9%;

(2)Melting: pure Zn, pure Mg, Al-Cu master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Zr master alloy, Al-Ti master alloy and pure Al are heated in the smelting furnace, and superheated to 780 ℃. Aluminum alloy melt is refined and slag is scraped with hexachloroethane.

(3)Adding W powder: After refining and scraping the slag, the temperature of the molten aluminum alloy is reduced to 20-30 degrees below the liquidus temperature, that is 620 degrees Celsius. Then the semi-solid aluminum alloy liquid is stirred with a stirring head, and tungsten powder is added. The stirring time is 10 minutes, and the rotating speed of the stirring head is 310-350 rpm.

(4) After adding tungsten powder, remove the stirring head, and then stand. At the same time, the temperature of semi-solid aluminium alloy liquid is raised to 750 ℃ so that it can be reconstituted into aluminium alloy melt. After stirring again for 5 minutes, it is poured immediately to prepare aluminium-tungsten composite ingot with uniform composition.

By adding tungsten powder in semi-solid state of aluminium alloy liquid and stirring at the same time, the problem of large proportion of tungsten powder and easy precipitation can be overcome, which is conducive to the preparation of aluminium-tungsten composites with uniform composition. Moreover, the process is simple and the production cost is low. It can be used in the manufacture of products with complex structure and various sizes.

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