Substitution of Nd in flake by rare earth dopant and its effect on coercivity of hot-pressed Nd-Fe-B magnet doped with RF3

Having been used as an essential part in the traction motor and generator of HEV, EV and wind turbine, the Nd-Fe-B-type magnets are required to have further enhanced coercivity because of its high operating temperature. The need for developing new and cost effective technique for enhancing coercivity has been ever escalated in recent years. Common techniques for enhancing the coercivity in the Nd-Fe-B-type magnet are the alloying and grain boundary diffusion (GBD) using heavy rare earth (HRE = Tb, Dy). Enhancing coercivity in the die-upset Nd-Fe-B-type magnet has been investigated intensively for high temperature application by taking advantage of the inherently high coercivity due to its fine grain structure. The diffusion technique has also been applied to the die-upset magnet as a means of enhancing coercivity, and various rare earth fluorides (RF₃) have been investigated as a source of rare earth dopant into the flakes. In this study, substitution of Nd in Nd-Fe-B flake by rare earth dopant in the Nd-Fe-B-type hot-pressed magnets doped with various RF₃ and its effect on coercivity were investigated.