Design and fabrication of Nd-Fe-B magnet with excellent thermal stability

A novel Nd-Fe-B type permanent magnet with excellent thermal stability was designed by Co replacing Fe in the main phase and the grain boundary phase. The remanence and coercivity temperature coefficient reach 0.058%/°C and 0.465%/°C in the temperature range from 25 to 100 °C, which are much lower than those of commercial Nd-Fe-B magnet. An enhanced Curie temperature is obtained for the novel magnet due to the Co substitution, which significantly improves the operating temperature. The microstructure result reveals that an amorphous phase exists in the intergranular grains which is probably responsible for the deterioration of intrinsic coercivity. This work can provide a reference for the design and optimization of components of sintered Nd-Fe-B magnets with excellent thermal stability.