Coercivity mechanism of sintered NdFeB magnets having high coercivities

摘要

The combination of some additions and substitutions to sintered Nd‐Fe‐B magnets was investigated in order to obtain high coercivity and good thermal stability. Some additions (Al,Ga,Nb,W) and a substitution (Dy for Nd) give Nd‐Fe‐B‐based sintered magnets high coercivities without a large remanence loss. Small differences in the amount of additions (Nd,Dy)‐Fe‐(Al,Ga)‐(Nb,W)‐B for sintered magnets show no significant difference in magnetic hysteresis loops at room temperature. Those magnet alloys also have similar good thermal stability. Effects of additions in the high‐coercivity materials are studied by measuring coercivities and anisotropy fields as a function of temperature. The small amount of additions (Nb,W) affects the large influence to the coercivity mechanism.