Hydrogenation effect on the hysteresis properties of rapidly quenched Nd-Ho-Fe-Co-B alloys

The hydrogenation effect on the hysteresis properties of rapidly quenched (RQ) (Nd0.55Ho0.45)(2.7) (Fe0.8Co0.2)(14)B-1.2 compound obtained by melt-spinning is studied. A comparative study of RQ alloy and its hydride (Nd0.55Ho0.45)(2.7)(Fe0.8Co0.2)(14)B1.2H2.5 has shown that hydrogenation resulted in the increase of magnetization without significant effect on the Curie temperature. In contrast to hydrogen-free alloy having a maximum on the H-c(T) curve, the H-c of the hydrogen-charged compound increased monotonously with decreasing temperature. Among the factors affecting H-c in hydrogenated sample are the increase of the grain size of the crystalline phase and the decrease of both the iron and the rare earth contributions to the magnetocrystalline anisotropy. High-field hysteretic distortions of the magnetization/demagnetization curves of RQ and RQ + hydrogen samples are observed at 4.2 K in fields up to 90 kOe indicating the existence of a magnetic phase with very high local coercivity. (C) 2010 Elsevier B.V. All rights reserved.