MAGNETIC-PROPERTIES AND STRUCTURE OF HYDROGENATED ND-FE ALLOYS

The magnetic properties and structure of as-cast hypo- and hypereutect ic Fe-Nd alloys processed in hydrogen have been investigated. When pro cessed for a short time, both Fe17Nd2 phase and metastable Al phase ab sorb hydrogen with an increase of their Curie temperatures. Long-term hydrogenation at 600-degrees-C results in a decomposition of all the h ydrides except NdH2-epsilon, which as well as alpha-Fe is stable under these conditions. It has been shown that an fcc. phase encountered in as-cast hypereutectic Fe-Nd alloys is a neodymium-based hydride whose lattice parameter is changed in a complicated manner when the alloy i s heat treated. Multistage decomposition of A1 phase in the hydrogenat ed Fe14Nd86 alloy leads finally to the formation of very fine and appa rently nonequiaxed precipitates of alpha-Fe in the NdH2-epsilon matrix resulting in a coercivity of 0.4 kOe.