Structure evolution and changes in magnetic properties of severe plastic deformed Nd(Pr)-Fe-B alloys during annealing

Structural changes and hysteresis properties of Nd(Pr)-Fe-B alloys of vario us compositions were studied after severe torsion straining under high pres sure and following annealing. It was shown that in all the alloys studied, severe plastic deformation leads to formation of ultrafine-grained non-equi librium structure and, at extremely large strains, even to formation of an amorphous structure. Annealing resulted in crystallization of alloys, forma tion of stable magnetic and non-magnetic phases and in marked improvements in hard magnetic properties. Homogenization of alloys is responsible for an increase in coercivity of the deformed samples. (C) 1998 Elsevier Science S.A. All rights reserved.