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’
$H_{\mathrm {c}j}$
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
$H_{\mathrm {c}j}$
.