Microstructural and magnetic studies on P/M processed (Nd14.9Dy1.9)(Fe65.0Co8.0Cu1.0Ga1.0Nb0.7) B7.5 alloy

Sintered samples of (Nd14.9 Dy1.9) (Fe65 Co8 Cu1.0 Ga1.0 Nb0.7)B7.5 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 different solubility of the alloying additions. This alloy has TC of 705 K with an intrinsic coercivity of 1000 kA/m and energy product of ∼250 kJ/m3 at RT. Solubility of Co into the matrix phase and that of Ga and Cu into the Nd-rich grain boundary phase are considered to be the main contributing factors for the significant enhancement in TC and Hci respectively of the multi-component alloy when compared to those of ternary NdFeB, wherein Hci = 720 kA/m and TC = 585 K.