Grain boundary diffusion (GBD) is an interface composition technology which makes heavy rare earth elements enter the grain boundary to enhance partial anisotropy field and thus improve the intrinsic coercivity and thermal stability of the material while remanence is basically unchanged. Unlike conventional metallurgy process, grain boundary diffusion elements do not require to enter the main phase and minimizes the heavy rare earth usage which is favorable for improving cost performance. Even GBD technology can create new grade with higher remanence and intrinsic coercivity that were previously unattainable with conventional process, but it should be noted that the feasibility of the GBD technology tends to vary according to the detailed shape and grade.
