Abstract: Superplastically formable aluminum alloys and composite materials are prepared from rapidly solidified, coarse aluminum powder of a precipitation hardenable alloy, processed to have a low oxide and contaminant content. The powder is mixed, together with reinforcement in the case of the composite material, and then consolidated and extruded at a high extrusion ratio to promote microstructural uniformity and to break up the surface oxide present on the particles. The extrusion is then thermomechanically processed to impart a recrystallized fine-grain aluminum microstructure which is suitable for use in superplastic forming. The unreinforced powder alloy exhibits uniform elongations of over 800 percent at a strain rate of 2.times.10.sup.-4 per second, and a composite having 0.10 volume fraction silicon carbide reinforcement exhibits uniform elongations of over 450 percent at the same strain rate.

Abstract: A method is provided to impart a fine grain structure to aluminum alloys which have precipitating constituents. The alloy is overaged to form coarse precipitates, and then plastically deformed at least 40%. Deformation is accomplished at a temperature and at a rate which are sufficient to retain strain energy in the alloy at the end of the deformation step. The alloy is subsequently heated at a rate of at least 0.02.degree. F..multidot.s.sup.-1 to a recrystallization temperature to form a new fine grain structure.

Abstract: A method is provided for imparting a fine grain structure to aluminum alloys which have precipitating constituents. The alloy is first heated to a solid solution temperature to dissolve the precipitating constituents in the alloy. The alloy is then cooled, preferably by water quenching, to below the solution temperature and then overaged to form precipitates by heating it above the precipitation hardening temperature for the alloy but below its solution treating temperature. Strain energy is introduced into the alloy by plastically deforming it in a temperature range of 380.degree. F. to 450.degree. F. to reduce its cross-sectional area a total of 40% minimum, at least 25% of the reduction in area being accomplished in a single continuous deformation operation. The alloy is then subsequently held at a recrystallization temperature so that new grains are nucleated by the overaged precipitates and the development of these grains results in a fine grain structure.