The effects of the heat treatments on the soft magnetic properties of the Sendust alloys

The effects of heat treatments on the soft magnetic properties and the temperature dependency of the properties of the Sendust alloys (Fe-9∼10wt%Si-5∼7 wt%A1 ternary alloys) were investigated. The quenching from the various temperatures(400°C∼800°C) was performed on the samples control-cooled(100°C/h) after homogenization(1100°C × 5h). It is found that the quenching temperature considerably affected the soft magnetic properties, and that the quenching temperature giving the good properties was varied with the alloy composition. The obtained highest initial permeability at 20°C was 380 000 for an Fe-9.7wt%Si-5.4wt%A1 alloy when it was quenched from 400°C. This value is about ten times higher than that of conventional Sendust alloys, and superior to 220 000 of Permalloy (Fe-79wt%Ni-5wt%Mo).