Ultrahigh Coercivity and Excellent Thermal Stability of Hot-Deformed Nd-Fe-B Magnets by the Diffusion of (Pr,Nd)-Dy-Cu-Al

The effects of the addition of (Pr0.25Nd0.75)10Dy80Cu5Al5 alloy powders on the magnetic properties and microstructure of the hot-deformed Nd-Fe-B magnets were investigated in this work. Through the addition of (Pr0.25Nd0.75)10Dy80Cu5Al5, an ultrahigh coercivity of 3.14 T was obtained in a 6-mm-thick hot-deformed magnet, and the temperature coefficient of coercivity and remanence were improved from −0.475 %/℃ and −0.145 %/℃ to −0.383 %/℃ and −0.110 %/℃ at 20−180 ℃, respectively, showing the excellent thermal stability. Microstructure observations indicated that the formation of thick nonferromagnetic intergranular phase, the reduction of grain size and aspect ratio and the formation of the (Nd,Dy)2Fe14B main phase were achieved after the addition of (Pr0.25Nd0.75)10Dy80Cu5Al5, which were the main reasons for the enhancement of coercivity and thermal stability.