Preparation of rare earth-cobalt magnet alloy by reduction-diffusion process

Abstract

Preparation of rare earth-cobalt alloys by reduction-diffusion (R-D) process is described. The process essentially involves mixing of the rare earth oxide and cobalt/cobalt oxide powders in proper proportion and high temperature reduction of the charge in hydrogen atmosphere, followed by aqueous leaching of the reduced mass to yield the alloy powder. Comparison is made of the magnetic properties of the R-D powder with those of the powder prepared by the direct melting (DM) route and it is observed from the reported values for SmCo₅ that the energy product of the R-D powder (∼ 22 MGOe) is only marginally lower than that of the Directly Melted alloy (∼ 25 MGOe). The paper also includes the results of studies carried out at the Bhabha Atomic Research Centre on the preparation of misch metal-cobalt alloy by the R-D process.