High energy NdFeB permanent magnets with nanocrystalline structure

Experimental studies of remanence enhancement and the effect of quenching conditions on rapid solidification of undercooling NdFeB melts with composition near the Nd/sub 2/Fe/sub 14/B phase was investigated by melt spinning technic. Nanocrystalline alloys and nanocomposites Nd/sub 2/Fe/sub 14/B//spl alpha/Fe have been synthesized by melt-spinning a Nd rich alloy, Nd/sub 30/FeB/sub 0.9/ (%weight) and Fe rich alloy Nd/sub 12.6/FeB/sub 3.88/ (% weight) at the wheel speed in the range up to 25-40 m/s. Microstructural and magnetic studies have showed that is an corresponding rapid solidification and wheel speed for to obtain a uniform nanocrystalline as well amorphous microstructure. Lower speed appearance larger grains for both Nd/sub 2/Fe/sub 14/B and Fe phases, while higher speed leads to appearance of an amorphous phase, which will result in a Nd/sub 2/Fe/sub 14/B//spl alpha/Fe, with lower dimension grains, after subsequent crystallization annealing treatment. Refinement of the mean Nd/sub 2/Fe/sub 14/B crystallites diameter below /spl sim/50 nm for melt spun NdFeB alloys leads to enhancement of the remanence above that predicted by Stoner Wohlfarth theory. Increasing the Fe:Nd ratio promotes the formation of nanocomposite Nd/sub 2/Fe/sub 14/B//spl alpha/Fe structure which leads to a further enhancement Jr, owing to interphase, with higher saturation, /spl alpha/Fe phase.