Reduction-Diffusion Preparation of Nd_(15)Fe_(77)B_8, NdFe_(11)Ti, NdFe_(10.5)Mo_(1.5) and NdFe_(10.75)Mo_(1.25) Alloys for Magnets

摘要

The calciothermic reduction-diffusion (CRD) process is a alternative preparation route for Nd_(15)Fe_(77)B_8, NdFe_(11)Ti, NdFe_(10.5)Mo_(1.5) and NdFe_(10.5)Mo_(1.25) alloys, which eliminates the need for long homogenizing heat treatment; in addition, the resulting alloy is already in powder form. We have examined the effect of various processing variables in the preparation of mother alloys. Compacts made of NdCl_3, Fe, Ti, Mo and Fe-B powders and Ca granules were heated under argon for different times and temperatures. The alloys as-prepared contained mostly the hard magnetic phase. The NdFe_(11)Ti, NdFe_(10.75)Mo_(1.25) and NdFe_(10.5)Mo_(1.5) alloys have been successfully nitrogenated by heating a mixture of powdered alloys with sodium azide (NaN_3) at temperatures between 330 and 450 °C.