Microstructure modification and coercivity enhancement of sintered NdFeB magnet by vacuum diffusion 70Tb–20Cu–10Ga (at%) alloys

In this work, the eutectic Tb70Cu20Ga10 alloy was applied to high magnetic performance NdFeB magnet. The coercivity of magnets effectively improved of 60.61% without reduction in maximum energy product and remanence after diffusion. The magnetic vector potential of magnet was analyzed by general finite element method. The diffusion mechanism of eutectic had been discussed at various diffusion depth. The Tb diffuses into the magnet formation continuous Tb-rich shells and thin grain boundary phase, which strongly enhance coercivity. The Cu, Ga and O enrich into grain boundary form thin RE2(Fe, CuGaO)3 phases, which increase diffusion channel and recover microcrack near surface of magnet. This Tb70Cu20Ga10 diffusion alloys has a promising potential to develop high magnetic performance and low cost sintered NdFeB magnet.