Microstructure and soft magnetic properties of rapidly solidified FeAl alloys

Abstract

An attempt has been made to investigate the microstructure and soft magnetic properties of FeAl alloys produced by a rapid solidification technique, with the aim of estimating their aptitude as core elements in rotating machinery. Examinations by optical and transmission electron microscopy revealed that the specimen containing aluminium up to about 23 at.% consists of ductile ferrite, whereas further addition of aluminium gives rise to embrittlement by the formation of an ordered b.c.c. compound. Furthermore, the rapidly solidified alloys exhibited high saturation induction values, more than 1.88 T in the alloys with aluminium content below 10 at.%. For the coercivity behaviour and core loss at 50 Hz, notable improvement was achieved after annealing at elevated temperatures. It was thus concluded that the present alloys have potential for practical use as magnetic core materials in rotating machinery.