Investigations on magnetization reversal processes in oriented sintered Nd-Fe-B alloys

Calculations of the magnetic domain structure (domain wall energy density, domain wall thickness, domain width and critical diameter of single domain particles) in Nd2Fe14B have been made by using its intrinsic parameters (lattice constants, magnetic moments of the atoms, Curie temperature, spontaneous magnetization and magneto-crystalline anisotropy constant). The four stages of magnetization reversal processes in oriented sintered Nd-Fe-B magnet after saturation magnetization along its easy direction are studied in detail in this paper. The results show that the nucleation of the reverse-magnetization nuclei in the surface layer of the grains of hard magnetic phase Nd2Fe14B, as well as the irreversible domain wall motion from the surface to the inside of the grains are dominant factors controlling the intrinsic coercivity of the Nd-Fe-B alloy.