Effect of Nb substitution on the temperature characteristics and microstructures of rapid-quenched NdFeB alloy

Effect of Nb substitution on the magnetic properties, temperature characteristics and microstructure of rapid-quenched Nd11Dy0.5Fe82.4−nNbnB6.1 (n = 0, 0.5, 1, 1.5, 2) permanent magnets has been investigated. It is found that Hcj increases with increasing Nb content and the irreversible flux loss decreases with that. Nb substitution makes grains smaller and leads to the homogenization and regularization of grains. Also Nb substitution can enhance exchange coupling pining field and reduce inner dispersal magnetic field. As a result, the irreversible flux loss decreases notably and the magnets can be used at higher temperature. The maximum operating temperature of Nd11Dy0.5Fe81.4Nb1B6.1 alloy is higher than 150 °C.