The influence of the powder densification temperature on the microstructure and magnetic properties of anisotropic NdFeB magnets aligned by hot deformation

摘要

The relation between the temperature for the initial powder densification and the structure and magnetic properties of anisotropic magnets, oriented by means of die-upset forging is reported. It was found that, from the viewpoint of the efficiency of the orientation process, there is an optimum temperature for the densification. For the Magnequench MQP-A powder used in the study, this temperature is about 650 °C. At this temperature the isotropic densified precursor has the most suitable structure, characterized by small grains and a density close to the theoretical value. The use of precursors with a favourable structure resulted in anisotropic magnets with the following properties: remanence J_r approx= 1.41 T, coercivity _JH_c = 780 kA/m and maximum energy product (BH)_(max) = 390 kJ/m~3.