GB805100A - Improvements relating to sintered metal and articles made therefrom - Google Patents

Abstract

A sintered Al or Al-base alloy made by a powder metallurgy process contains 0.5 to 15 per cent by weight of a Ni-Ti alloy, the latter containing 15 to 65 per cent Ti and 35 to 85 per cent Ni, and is suitable for bearing members, piston rings, gears and the like articles subject to frictional wear. In this modification of the alloys of the parent Specification, there may also be present up to 3.3 per cent C, 10 per cent Si, 5 per cent Cd; whilst Si, Al, Fe, Cr, Mn may occur in the Ni-Ti alloy, and Mg, Cr, Ni, Cu, Pb, Bi, Sn, In, Mn, Fe in the Al-base alloy or powder mixture. The particles may be 200 to 400 mesh; mixed with up to 2.5 per cent Zn stearate and between 0.3 and 4 per cent graphite; briquetted at 60,000 to 100,000 lb. per sq. inch in a suitably contoured die and sintered e.g. at 1150 DEG F. for 30 min. in an atmosphere of 20 per cent CO, 3 per cent H, 77 per cent N, or 1.5 per cent CO, 1.5 per cent H, 97 per cent N, with or without natural gas in a proportion of 1 : 100. The sintered article may be hot forged and/or cold pressed to a final porosity of e.g. 2 to 13 per cent. It may also then be heat treated e.g. at 900-1050 DEG F. for 8-15 hours. followed by a water quench, and if desired also by a precipitation hardening e.g. heating at 370 DEG F. for 8 hours, followed by water cooling. The powder may also be sintered direct on to a preferably electro-plated steel backing, rolled, and re-sintered or annealed.