GB659998A - Improvements in or relating to the production of sintered metal products for anisotropic permanent magnets - Google Patents

Abstract

Sintered metal products for anisotropic permanent magnets containing iron, nickel, aluminium at least 14 per cent cobalt and, optionally, other elements up to 10 per cent in total, are made by sintering a pressed body of the powdered material in a non-oxidizing atmosphere whilst protected from direct access of the atmosphere by a porous mass containing a powdered or granulated alloy of titanium and/or other element or elements having a high affinity for carbon and nitrogen and aluminium and/or other metal or metals readily oxidizible at high temperature. The protective alloy may be mixed with an inert refractory material such as alumina and a porous mass of refractory material may be interposed between the protective alloy and the pressed body. The pressed body may be completely surrounded by the refractory mass and protective mass, the whole being contained in a boat or other container which is introduced into the sintering furnace. The material to be sintered may have the composition Co 14-30 per cent, Ni 7-30 per cent, Al 5-11 per cent, Cu 0-10 per cent, Ti 0-5 per cent, Si 0-5 per cent, Zr 0-5 per cent and the rest Fe, the sum of the contents of Cu, Ti, Si and Zr not exceeding 10 per cent. Specifications 522,731, 577,135 and 583,411 are referred to.