Rapidly quenched metals for permanent magnet materials (invited)

Abstract

When magnetically soft amorphous metals are annealed until crystallization occurs, coercive forces sometimes arise that are high enough to suggest the possibility of permanent magnet materials. This paper begins with a brief review of results in alloys not containing rare earths. Then earlier results on rare-earth-modified Fe-B alloys and on Fe-R alloys quenched at intermediate rates are reviewed. Recent experiments indicate that intrinsic coercive forces of many kOe combined with high Ms and Mr are possible in rapidly quenched alloys containing only iron, light rare earths, and glass formers. Recent work and our current results in these alloys are presented and discussed, including effects of composition, quenching rate, annealing, and etching, as well as thermomagnetic effects and phase identification.