The effect of PrCuGa grain boundary diffusion on the magnetic properties and microstructure of sintered Nd-La-Y-Fe-B magnet

Committed to acquiring cost-effective Nd-Fe-B based permanent magnets, commercial Nd-La-Y-Fe-B magnets had been grain boundary diffused with PrCuGa as the diffusion source. The optimized magnetic properties had been obtained when the magnet was annealed at 930 celcius. The Hcj and (BH)max increased from 13.6 kOe, 32.2 MGOe to 18.3 kOe, 33.2 MGOe respectively. The results show that the concentration of Pr in the grain boundary phase increases after the diffusion of PrCuGa, and the characteristic peak of the matrix magnet shifts to a large angle from the XRD pattern. Both Hcj and (BH)max are improved because Pr partially replaces La to from (Pr,Nd,La, Y)2Fe14B with higher intrinsic properties. In addition, Cu and Ga elements improve the continuity of the grain boundary phases and isolate the short-range exchange coupling between the main phase grains, contributing to the increased Hcj.