CRYSTALLOGRAPHIC AND MAGNETIC ALIGNMENT IN HOT-ROLLED PR20FE74B4CU2 ALLOYS

Ingot material with the composition Pr20Fe74B4Cu2, in the form of a ci rcular cross section billet, was hot-rolled at temperatures 800-1000 d egrees C using a strain rate of approximately 3 s(-1). The magnetic me asurements revealed that the crystallographic alignment, and as a cons equence the remanence J(r) increased significantly in a direction perp endicular to that of the rolling direction, with values of J(r) up to 1000 mT, despite the use of high strain rate processing. The anisotrop y is considered to develop through a contribution of grain boundary li quid phase diffusion and rotation of the initial plate-shaped primary crystals. It is possible that this induced alignment was more pronounc ed at high temperatures as a result, it is proposed, of a higher diffu sion rate in the liquid grain boundary phase. In contrast, the coerciv ity was found to decrease at higher rolling temperatures as a result o f the coarsening of the microstructure.