Development of Dy-Free Nd-Fe-B-Based Sintered Magnet Through Grain Boundary Engineering Using Pr-Cu Alloys

Dy-free sintered magnets were fabricated by mixing Nd-Fe-B powder with various amounts of Pr-Cu powder followed by the common procedures for making Nd-Fe-B-based sintered magnets. With the Pr-Cu addition increasing from 0 to 10 wt%, the obtained magnets' H-cj increases from the original 14.5-18.6 kOe. The highest maximum energy product (BH)(max) achieved was 35.0 MGOe with 7.5 wt% Pr-Cu. The distribution of the Pr and Cu elements was primarily at grain boundary (GB) and triple junctions, leading to a reduced coupling among grains, thus an enhanced H-cj.