Investigation of magnetic domain evolutions and microstructural changes in Pr–Dy–Cu modified Nd–Fe–B magnets

The enhancement of coercivity in Nd–Fe–B sintered magnets modified by Pr₅₈Dy₁₀Cu₃₂ alloy was investigated through scanning electron microscope (SEM) and in-situ magneto-optic Kerr effect (MOKE) microscopy. The modification treatment resulted in the formation of a smooth and continuous weakly magnetic grain boundary layer and the (Nd,Pr,Dy)₂Fe₁₄B main phase with a high magnetocrystalline anisotropy field, leading to an increased coercivity of 23 kOe. MOKE observations revealed that the dynamic evolution of the maze domain area under an external magnetic field varied significantly between the original and modified magnets. Compared with the original magnets, the modified magnets exhibited a slower decrease in maze domain area during magnetization and a slower increase during reverse magnetization, contributing to the observed coercivity enhancement.