Permanent magnetic properties of Nd–Fe–B melt‐spun ribbons with Y substitution

Abstract

Abstract Phase constituents, microstructures and magnetic properties of melt‐spun Nd 12− x Y x Fe 81 B 6 Nb ribbons were investigated systematically. The influence of Y substitution for Nd on the phase stability, grain size and magnetic exchange coupling was analyzed. It is found that all the ribbons crystallize in the tetragonal 2:14:1 structure, i.e., with single hard magnetic phase at the roll speed of 25 m·s −1 . With the increase in Y doping, Curie temperature ( T C ) increases, while the coercivity decreases monoclinically. However, remanence magnetization ( B r ) and maximum energy product (( BH ) max ) fluctuate and the maximum value is obtained at certain amount of Y. The optimum magnetic properties of intrinsic coercivity of intrinsic coercivity ( H cj ) = 908.2 kA·m −1 and ( BH ) max = 118.52 kJ·m −3 are achieved when x = 1.0. It can be attributed to the strengthened exchange coupling between the neighboring nanograins in Nd–Y–Fe–B melt‐spun powder based on the Henkel curves. Furthermore, Y substitution also significantly improves the temperature stability of magnetic performance. The coercivity temperature coefficient of β = − 0.157%·°C −1 and remanence temperature coefficient of α = − 0.32%·°C −1 are gained, which are greatly reduced compared with those of the undoped Nd–Fe–B compounds.