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 remanence and coercivity for Nd–Fe–B/Nb magnets prepared by sintering of mixed Nd–Fe–B and Nb powders is reported and its mechanism is investigated. The appropriate addition of Nb powder may suppress the appearance of Nd-rich phases at Nd 2Fe 14B grain boundaries and the excess Nd-rich composition may become available to form more of the Nd 2Fe 14B phase, which is responsible for the enhancement of the remanence. The reversal of hard Nd 2Fe 14B grains was suppressed by a decreasing amount of α-Fe, by better decoupling between the magnetic grains due to formation of the Nb-rich phase or by pinning of domains at the Nb-rich phase.