Reduction-Diffusion Preparation of Nd{sub}15Fe{sub}77B{sub}8, NdFe{sub}11Ti, NdFe{sub}10.5Mo{sub}1.5 and NdFe{sub}10.75Mo{sub}1.25 Alloys for Magnets

摘要

The calciothermic reduction-diffusion (CRD) process is a alternative preparation route for Nd{sub}15Fe{sub}77B{sub}8, NdFe{sub}11Ti, NdFe{sub}10.5Mo{sub}1.5 and NdFe{sub}10.75Mo{sub}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{sub}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{sub}11Ti, NdFe{sub}10.75Mo{sub}1.25 and NdFe{sub}10.5Mo{sub}1.5 alloys have been successfully nitrogenated by heating a mixture of powdered alloys with sodium azide (NaN{sub}3) at temperatures between 330 and 450°C.