HARD MAGNETIC-PROPERTIES OF FE-ND-B ALLOYS CONTAINING INTERGRANULAR AMORPHOUS PHASE

Fe-rich Fe-Nd-B amorphous alloys containing 88 to 90 at% Fe annealed for 60-300 s at 923-1023 K have the nanostructure consisting of bcc-Fe, Fe14Nd2B and remaining amorphous phases, and exhibit rather good hard magnetic properties, i.e., remanence (Br) of 1.28 T, coercive field (iHc) of 252 kA/m and maximum energy product ((BH)(max)) of 146 kJ/m(3) for Fe89Nd7B4. The nanoscale Fe14Nd2B particles with a size of about 30 nm are surrounded by the bcc-Fe and amorphous phases which act as a magnetic exchange-coupled medium. The nanoscale coexistence of the three ferromagnetic phases is important for the achievement of the rather good hard magnetic properties. The simultaneous achievement of the high Br and (BH)(max) values and the residual existence of the amorphous phase for the Fe-rich alloys containing about 90 at% Fe has significant engineering importance because of the expectations of high deformability and low cost.