Direct preparation of rare earth-cobalt alloy powders : a perspective

Induction melting and reduction-diffusion are the two processes currently being practised for the commercial production of rare earth-cobalt magnet alloys. The first process involves the melting of the constituents in their elemental form in a medium frequency furnace in argon atmosphere, while the second one developed by R.E. Cech at the General Electric Co., USA, involves the calciothermic reduction of rare earth oxide in presence of cobalt or cobalt oxide. The merits and demerits of these two processes are briefly discussed. (M.G.B.)