GB625364A - Improvements relating to light metal bodies and methods of manufacturing the same - Google Patents

Abstract

625,364. Powder metallurgy. SOC. ANON. POUR L'INDUSTRIE DE L'ALUMINIUM. July 15, 1947, Nos. 18835 and 18836. Convention dates, July 17, 1946, and May 8, 1947. [Classes 83 (ii) and 83 (iv)] Making rods; working at specified temperatures.-Aluminium or aluminium alloy bodies of high tensile strength and Brinell hardness are made by compressing and sintering or by hot working metal powder of such fineness that at least 50 per cent of the particles have at least one dimension smaller than two microns. In one modification the powder is compacted at a pressure of two metric tons per square cm. and sintered at a temperature exceeding 400‹ C. and preferably between 550‹-and 600‹ C. A billet so produced may be extruded into rod at temperatures of from 200-630‹ C. The powder may be pressed dry but is preferably mixed into a paste with water. An increase in the oxygen content of the powder is said to increase the hardness of the article so that articles having parts of different degrees of hardness may be produced by using powders with different oxide contents. Alternatively the oxide content of the surface could be increased by subsequent treatment. If further oxidation is not required, the pressing and sintering may be carried out in an atmosphere of hydrogen or nitrogen. In a modification, the three steps of compacting, sintering and subsequent working are replaced by a single operation in which the powder is hot-pressed to the required final form in a die or is extruded at 500‹ C. It is stated that an aluminium or aluminium alloy body produced by the above method retains its comparatively high tensile strength and hardness under continued high temperatures.