Analysis of the influence of abnormally grown grains on demagnetization behavior of FeNdB sintered magnets

This study investigates the influence of abnormally grown grains on the magnetic properties of FeNdB sintered magnets. Specifically, the local demagnetization process caused by abnormally grown grains in the microstructure was analyzed by dynamic Kerr microscopy. The demagnetization process starts in large grains and has a strong influence on the surrounding microstructure. In a process similar to that described for non-magnetic inclusions or pores, the stray field of the already-demagnetized grain forms two areas with differing magnetic properties. A demagnetizing effect is found on the front faces of these grains while a stabilizing effect is found on the side faces. The negative influence of abnormal grain growth on the magnetic properties is also visualized.