Characterization and microwave absorbing properties of Nd-Fe-Ti intermetallic compounds derived from Nd-Fe-B sintered magnet scraps

Nd-Fe-Ti intermetallic compounds were prepared from rare earth sintered magnet scrap powders (Nd₂Fe₁₄B sludge) and Ti by arc-melting and solidification processes. The resulting alloy ingots were ground into fine powders and some of them were heated at 100°C-250°C for 1-12 h in air. The epoxy resin composites with 83 wt% of these powders showed good microwave absorption properties at gigahertz range, and the maximum absorption peak of -39.4 dB was observed at 12.3 GHz after heating at 250°C for 3 h in air. Compared to Fe-Ti intermetallic compound powders prepared from fresh metals of Fe and Ti, the sludge-derived Nd-Fe-Ti powders showed higher oxidation resistivity due to the preferential oxidation of Nd content.