Microstructural and magnetic studies on P/M processed (Nd14.9Dy1.9)(Fe65.0Co8.0Cu1.0Ga1.0Nb0.7) B-7.5 alloy

Sintered samples of (Nd-14.9 Dy-1.9) (Fe-65 Co-8 Cu-1.0 Ga-1.0 Nb-0.7)B-7.5 were prepared and subjected to stepwise annealing in the temperature range 875 K-675 K. The XRD and metallographic (optical and electron microscopy) studies reveal a multi-phase microstructure with each phase showing differe nt solubility of the alloying additions. This alloy has T-C of 705 K with a n intrinsic coercivity of 1000 kA/m and energy product of similar to 250 kJ /m(3) at RT. Solubility of Co into the matrix phase and that of Ga and Cu i nto the Nd-rich grain boundary phase are considered to be the main contribu ting factors for the significant enhancement in T-C and H-ci respectively o f the multi-component alloy when compared to those of ternary NdFeB, wherei n H-ci = 720 kA/m and T-C = 585 K. (C) 2001 Kluwer Academic Publishers.