Effects of Y and Hf Addition on Soft Magnetic Property and Ductility Improvement of Fe–6.9 Wt% Si Alloy

Abstract

Fe–6.9 wt% Si alloy is superior to conventional electrical steels containing 3 wt.%Si in terms of soft magnetic performance at high frequencies but its lack of ductility results in large restriction on workability and shaping. In present investigation, Y-Hf-containing oxides (Y2Hf2O7) in Fe–6.9 wt% Si alloy with Y and Hf addition, caused the preferential nucleation advantage of λ oriented grains in the nucleation process and hindered the development of γ-fiber recrystallization textures during final annealing. Benefiting from the suppression of brittle ordered phases and the change of dislocation configuration, the fracture strain of alloy increased from 6.7% to 9.0% in 6.9Si–0.03Y sheet and showed an excellent ductility value of 11.4% after Hf doping. Meanwhile 6.9Si–0.03Y–0.2Hf sheet exhibited the characteristics of the higher magnetic induction and the lower iron loss because of optimal grain size and stronger λ texture. Y and Hf complex doping provides an effective approach for improving the ductility without sacrificing soft magnetic properties of Fe–6.9 wt%Si alloy.

Keywords: Fe-6.9 wt% Si alloy, Y, Hf, Texture, Ductility