Rationally selecting the chemical composition of the Nd–Fe–B magnet for high-efficiency grain boundary diffusion of heavy rare earths

Higher diffusion efficiency of Tb was found in Nd–Fe–B than in Pr–Nd–Fe–B sintered magnets. This is because the reactive Pr brings more intergranular oxides, which blocks the diffusion channel for Tb and consumes Tb at the triple-junction phase.