Investigation of simultaneous enhancement of remanence and coercivity in Nd-Fe-B/Nb mixed-powder sintered magnets

In the present work, the phenomenon of simultaneous enhancement of remanenc e and coercivity for Nd-Fe-B/Nb magnets prepared by sintering of mixed Nd-F e-B and Nb powders is reported and its mechanism is investigated. The appro priate addition of Nb powder may suppress the appearance of Nd-rich phases at Nd2Fe14B grain boundaries and the excess Nd-rich composition may become available to form more of the Nd2Fe14B phase, which is responsible for the enhancement of the remanence. The reversal of hard Nd2Fe14B grains was supp ressed by a decreasing amount of alpha-Fe, by better decoupling between the magnetic grains due to formation of the Nb-rich phase or by pinning of dom ains at the Nb-rich phase. (C) 1999 Elsevier Science S.A. All rights reserv ed.