EFFECT OF MINOR GRAIN-BOUNDARY ADDITIVES ON THE MAGNETIC-PROPERTIES OF NDFEB MAGNETS

Cobalt has been known as an element to increase the Curie temperature but to decrease the coercivity of (Nd,Dy)FeB magnets. Because of this negative effect, various elements have been added to increase the coer civity but at the expense of remanence and/or Curie temperature. The c ombined addition of cobalt and small amounts of copper to (Nd,Dy)FeB a lloy was found to substantially increase the coercivity without B-r an d T-c reduction. As a result, the temperature stability and corrosion resistance have substantially improved without sacrificing any magneti c performance.