Influence of Si addition on thermal stability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloys

The thermal stability of the supercooled liquid region (ΔT _x), defined by the difference between crystallization temperature (T_x) and glass transition temperature (T_g), and soft magnetic properties were investigated for Fe₇₀Al₅Ga ₂P_12.65-xC_5.75B_4.6Si _x(x=0-4) and Fe₇₇Al_2.14Ga_0.86P _11-xC₅B₄Si_x(x=0-3) glassy alloys. The thermal stability, glass forming ability and effective permeability (μ_e) at 1 kHz are improved with the replacement of P by 1-3 at. % Si for Fe₇₀Al₅Ga₂P_12.65-xC _5.75B_4.6Si_x and by 1-2.6 at. % Si for Fe ₇₇Al_2.14Ga_0.86P_11-xC ₅B₄Si_x. The ΔT_x and the maximum thickness for glass formation (t_max) reach maximum values of 60 K and 280 μm, respectively, for Fe₇₀Al₅Ga ₂P_12.65-xC_5.75B_4.6Si_x and 34 K and 220 μm, respectively, for Fe₇₇Al_2.14Ga _0.86P_11-xC₅B₄Si_x at Si(at. %)/(Si(at. %)+P(at. %))=0.24. Core losses for Fe₇₇Al _2.14Ga_0.86P_8.4C₅B₄Si _2.6 glassy alloy is much lower than that for amorphous Fe-Si-B alloy at the sheet thickness more than 70 μm. Therefore, it can be said that the Fe-Al-Ga-P-C-B-Si glassy alloys are useful for inductive applications because of their bulky shape and good soft magnetic properties.