High-coercivity sintered Nd14.5Dy1.5Fe68Co5Al1.5Cr2B7.5 permanent magnet

Effect of 1.5 at.% Al and 2.0 at.% Cr additions on microstructure, magnetic properties, thermal stability and corrosion resistance of (Nd,Dy)-(Fe,Co)-B sintered magnet have been studied. It is shown that simultaneous substitution of these elements for Fe in (Nd,Dy)-(Fe,Co)-B magnet causes significant improvement in coercivity and thermal stability; maximum operating temperature up to 473 K may be possible. The corrosion resistance in acid solution and atmospheric environment is also significantly improved by blocking the selective oxidation of the Nd-rich phase owing to the formation of (Nd,Dy)-(Co,Al,Fe)and (Nd,Dy))-(Fe,Cr,Co) phases. (C) 1998 Elsevier Science S.A.