THE ROLE OF OXYGEN FOR IMPROVING MAGNETIC-PROPERTIES AND THERMAL-STABILITY OF SINTERED (ND,DY)(FE,CO)B MAGNETS

Oxygen has traditionally been thought of as being detrimental to rare earth permanent magnet properties, even though it was shown to increas e the corrosion resistance of NdFeB magnets. In this study, we have sy stematically investigated the effect of oxygen on the magnetic propert ies of various types of NdFeB magnets. The addition of appropriate amo unts of oxygen to a NdDyFeB magnet system containing cobalt causes inc reases in the remanence and intrinsic coercivity. The temperature coef ficient of coercivity and irreversible temperature losses are also imp roved (reduced). In alloy systems not containing cobalt, oxygen doping causes a reduction in intrinsic coercivity.