We have investigated the effects of Hf, Ti and Ta addition on crystallization behavior, microstructure and magnetic properties of melt-spun Fe 90Nd 5B 3.5M 1.5 (M Hf, Ti and Ta) alloy ribbons. Optimization of processing conditions lead to the development of nano-composite magnets, made from high B s soft magnetic bcc α-Fe (grain size ∼20 nm) and tetragonal Nd 2Fe 14B (grain size ∼18 nm) hard magnetic phases. Hf is most effective in restraining the growth of α-Fe and Nd 2Fe 14B phases during annealing. The Fe 90Nd 5B 3.5Hf 1.5 ribbon annealed at 1003 K for 600 s exhibits very high maximum energy product (BH) max ∼127 kJ/m 3 and reduced remanence ∼1.34 T. Strong exchange coupling among the nano-sized soft and hard magnetic phases is shown to be responsible for the excellent magnetic properties. Among low Nd-containing NdFeB nano-composite magnets, the present alloy seems to have highest (BH) max.
ASJC Scopus subject areas
- Physics and Astronomy(all)