Production of Single-Phase Nd_2Fe_14B Alloy Powder by Reduction-Diffusion Process and Application to Production of Nd-Fe-B Sintered Magnets

摘要

The reduction-diffusion process (the R-D process)using Ca as a reducing agent has been practiced in industry in theproduction of the SmCo_5 type, the Nd-Fe-B type and the Tb-Fe-Co type magnetic materials. The advantages of the R-D process arethe generally high yield of rare earth metals and the single-stageconversion of a mixture of oxides and metal powders into aproduct of rare earth alloy powders. On the other hand, one of itsdisadvantages is the slightly high contents of oxygen and calcium.This disadvantage is remarkable in the Nd-Fe-B type. Singe-phaseNd_2Fe_14B alloy powders with low content of O and Ca, isobtained by choosing appropriate raw materials and performing theR-D process in a controlled way. These alloy powders are verysuitable for the production of Nd-Fe-B sintered magnets andexpected higher magnetic properties by adopting advanced magnetproduction method.