Effect of two-step annealing on magnetic properties of Pr-Fe-B base hot-rolled magnet

Abstract

Magnetic properties of a Pr-Fe-B base magnet produced by the hot-rolling method are improved remarkably by a characteristic two-step annealing. The relationship between magnetic properties and microstructure in the two-step annealing is investigated for a Pr/sub 15/Fe/sub 78.0/B/sub 5.5/Cu/sub 1.5/ (at.%) hot rolled magnet, and the effect of Ga replacement for Cu is investigated for Pr/sub 15/Fe/sub 79.0/B/sub 5.5/Ga/sub 0.5/ (at.%). The effect of the two-step annealing is attributed to recovery of disordered microstructure by first step annealing and development of network structure of Pr-rich phase by second-step annealing. The Ga replacement for Cu enhances the improvement of magnetic properties through formation of a more desirable microstructure by the two-step annealing. >