Compositional dependence of thermal stability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloys

Structure, glass forming ability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloy system were investigated in the compositional range of Fe from 69 to 78 at%, (Al+Ga) from 2 to 12 and (P+C+B) from 17 to 28. The saturation magnetization (sigma(s)) rises gradually with increase of Fe concentration. The maximum value of 70K for supercooled liquid region (Delta T-x=T-x-T-g, T-x: crystallization temperature, T-g: glass transition temperature) and the maximum thickness of 180 mu m for glass formation (t(max)) are found in the composition range around Fe=70at% and (Al+Ga)=7at%. The highest permeability (mu(e)) of 20,000 at 1kHz and the lowest coercive force (H-c) of 2 A/m at the sample thickness of 30 mu m can be also obtained at this composition. It was ascertained that the composition regions to yield the maximum glass forming ability and lowest magnetostriction were in agreement with that in which the most excellent soft magnetic properties were yielded. This results allow us to assume that the excellent soft magnetic properties for this glassy alloy system in the limited composition range are presumably due to high structural homogeneity resulting from significantly high glass-forming ability.