The effects of long term annealing at 1000°C for 24 h on the microstructure and magnetic properties of Pr–Fe–B/Nd–Fe–B magnets based on Nd16Fe76B8 and Pr16Fe76B8

Magnets produced via a hydrogen decrepitation/roller-milling route have been subjected to a post sintering heat treatment of 1000°C for 24 h. Alloys of nominal composition Pr16Fe76B8 and Nd16Fe76B8 have been studied in terms of both microstructure and magnetic properties to determine the influence of this 24-h annealing treatment. The effect of annealing the Pr16Fe76B8 magnets at 1000°C for up to 24 h resulted in a general increase in the overall magnetic properties, especially in the intrinsic coercivity. In contrast to these observations, the same heat treatment was found to be detrimental to all the magnetic properties of the Nd16Fe76B8 magnets.