Magnetic properties of nanocomposite Nd2(Fe,Co,M)14B/α-Fe-bonded magnets

Nanocomposite Nd12.6Fe69.8-xCo11.6MxB6/α-Fe (M=Al-Cr, V, Cr, Ni, Zr or Mo) powders, with a volume fraction of magnetically soft α-Fe phase of 10 and 37.5%, have been prepared by a high-energy ball-milling (HEBM) and annealing. Enhanced remanent magnetic polarizations up to 1.15 T were obtained. It has been found that addition of a small amount of Al-Cr, Cr, Zr or Mo to Nd12.6Fe69.8-xCo11.6MxB6/α-Fe can improve the intrinsic coercivity and the hysteresis squareness of the Nd2(Fe,Co)14B/α-Fe-base d nanocomposite materials. The improvements may be related to refined grain sizes realized by these additives. Bonded magnets of Jr and JHc ranging from 0.81 T and 840 kA m-1 to 1.10 T and 760 kA m-1 have been produced from Nd12.6Fe67.8Co11.6Cr2B6/α-Fe, with a 10 and 37.5% volume fraction of soft α-Fe phase, respectively. (orig.)