The effects of the alpha -Fe precipitation on the coercive force of the rapidly quenched Pr-Fe-B-Zr alloys

It has been found that the magnetic properties of the optimally heat-treated overquenched ribbons are inferior to those of the ribbons optimally quenched directly from the molten alloy. An attempt is made to elucidate the difference in coercive force between the two states. X-ray diffraction and thermomagnetic analysis confirm that the alpha -Fe phase is precipitated during the underquenching and the annealing after overquenching. This indicates that the degradation of coercive force of the annealed overquenched ribbons originates from the alpha -Fe precipitates. The existence of alpha -Fe is less detrimental to the coercive force than expected, suggesting that the grain boundary suppresses the propagation of domain walls.< >