The Effect of Tb80Fe20/Al Co-adding on Coercivity and Thermal Stability in Sintered Nd–Fe–B Magnets

The influence of Tb80Fe20/Al co-adding on coercivity and temperature stability of sintered Nd–Fe–B magnets was studied. Compared with the Tb80Fe20 added samples, the coercivity of the Tb80Fe20/Al co-added samples enhances with the increase of Al contents. The excellent magnetic properties are acquired in the 1 wt% Tb80Fe20/0.2 wt% Al co-added magnets. The coercivity (Hcj) is enhanced from 14.33 to 19.08 kOe, and the remanence (Br) decreases slightly by introducing 1 wt% Tb80Fe20/0.2 wt% Al alloy. Meanwhile, the reversible temperature coefficients of coercivity (β) of the Nd–Fe–B magnets are increased from − 0.598 to − 0.579%/°C at 20–140 °C. Moreover, the irreversible flux magnetic loss (hirr) of the Tb80Fe20/Al co-added magnets is obviously reduced with the addition of Al. Further analysis of the microstructure reveals that a modified microstructure, i.e., continuous and clear Nd-rich grain boundary (GB) layers, is acquired in the sintered magnets by introducing Tb80Fe20/Al alloy. In addition, the average grain size decreases to 3.7 from 4.5 μm, which indicates that Tb80Fe20/Al co-adding provides an effective way to prepare for the excellent-performance of sintered Nd–Fe–B magnets.