| 摘要 |
1,192,030. Aluminium alloys. T.I. (GROUP SERVICES) Ltd. Dec. 30, 1968 [Dec. 30, 1967], No. 59285/67. Heading C7A. An Al alloy consisting of note more than 30% by weight Fe, the balance being Al and any impurities, has a structure obtained by cooling the liquidus at at least 10<SP>5</SP> degrees C. per second and a hardness four times that of a structure produced by chill casting the same alloy. The high rate of cooling may be achieved by (a) projecting at high velocity small quantities of molten alloy obliquely against a cold surface of good thermal conductivity, (b) dropping molten alloy into a spinning crucible from which it is flung on to a surrounding cooled cylindrical copper wall, (c) spraying on to a cooled and rotating wheel or drum or travelling belt, (d) dropping the alloy between two converging flat metal plates of high thermal conductivity, and (e) locally melting, e.g. by laser beam or capacitance discharge from a pointed electrode, a small region in the surface of a body of the alloy, and then removing the heat input to allow rapid cooling of the molten pool by conduction into the remainder of the body. A hard skin on one or both faces of sheet or strip alloy may be formed by flash-melting the surface and then rapidly cooling into the remainder of the sheet or strip. |
