GB812848A - Improvements in and relating to high density sintered metal compositions or alloys - Google Patents

Abstract

A high density, high strength, sintered metal composition or alloy is composed of W, Ni, Cu, and Mo, (apart from impurities) has a sintered density at least 93 per cent of a theoretical density of not less than 13.5 gm/ccm., is made by pressing and sintering particles of the constituent metals all of average size from 2 to 8m , and comprises W at least 65 per cent by weight, Ni and Cu in a ratio between 0.5 and 2.5 by weight and in such amounts that their sum is equal to 4 to 25 per cent of the weight of tin alloy, and Mo in amount from 0.1 to 1.5 times the combined weight of Ni and Cu. There may also be present Fe in amount up to 1.5 times the sum of the Ni and Cu, but not exceeding 10 per cent of the alloy. Preferably reducible compounds, particularly the oxides of the metals are used as starting materials and heater to produced prealloyed powder of 2 to 8m which is then compacted and sintered. Thus the oxides in amounts which will lead to the desired composition are mixed thoroughly and reduced by heating in hydrogen or cracked ammonia at 900 DEG to 1100 DEG C., the resulting range of particle size depending upon the time, temperature, and bed thickness. The resulting powder with or without glyptal as binder is compacted at 10-30 tons p.s.i. and the compacts sintered in a reducing atmosphere at between 1350 DEG and 1500 DEG C., and preferably between 1400 DEG and 1440 DEG C., for 4 to 60 minutes.