Effects of reduced hydrogen pressure on magnetic properties of HDDR-treated NdFeGaB alloy powders

The Nd(13)Fe(7)9Ga(1)B(7) alloy powders were treated by the HDDR process under different reduced hydrogen pressures in the range 0.2-0.8 bar, and the effects of the reduced hydrogen pressure on magnetic properties of the HDDR-treated alloy powders were investigated. It was found that the HDDR-treated alloy powders exhibit a considerable anisotropy in addition to an appropriate coercivity. As the reduced hydrogen pressure is lowered, the degree of anisotropy decreases significantly, whereas the intrinsic coercivity increases. The largest anisotropy of up to 1.62 is achieved in the powders HDDR-treated under a reduced hydrogen pressure of 0.8 bar, and the high coercivity of 724 kA m(-1) is attained in the powders HDDR-treated under 0.4 bar. (C) 1998 Elsevier Science S.A.