Magnetic properties and thermal stability of sintered Nd-Fe-B magnet with Dy-Ni additive

A sintered (Nd_0.8Pr_0.2)_30.7FebalB_0.98Cu_0.2 magnet with 3% intergranular Dy₈₅Ni₁₅ additive is prepared to study the magnetic properties and thermal stability of the Nd-Fe-B magnet. The results show that the magnet with or without additive obtains its optimum comprehensive magnetic properties at the sintering temperature of 1 030 °C and 1 040 °C, respectively. The maximum coercivity of the magnet with additive reaches 15.16 kOe, while that of the magnet without additive is just 11.88 kOe. Further investigation on microstructure indicates that the grains of the magnet with additive form a modified “core shell” structure. Adding Dy₈₅Ni₁₅ can significantly enhance the coercivity of Nd-Fe-B magnet and thus decrease its coercivity temperature coefficient.