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 (Delta T-x), defined by the difference between crystallization temperature (T-x) and glass transition temperature (T-g), and soft magnetic properties were investigated for Fe70Al5Ga2P12.65-xC5.75B4.6Six(x = 0-4) and Fe77Al2.14Ga0.86P11-xC5B4Six (x = 0-3) glassy alloys. The thermal stability, glass forming ability and effective permeability (mu(e)) at 1 kHz are improved with the replacement of P by 1-3 at. % Si for Fe70Al5Ga2P12.65-xC5.75B4.6Six and by 1-2.6 at. % Si for Fe77Al2.14Ga0.86P11-xC5B4Six. The Delta T-x and the maximum thickness for glass formation (t(max)) reach maximum values of 60 K and 280 mu m, respectively, for Fe70Al5Ga2P12.65-xC5.75B4.6Six and 34 K and 220 mu m, respectively, for Fe77Al2.14Ga0.86P11-xC5B4Six at Si(at. %)/(Si(at. %) + P(at. %)) = 0.24. Core losses for Fe77Al2.14Ga0.86P8.4C5B4Si2.6 glassy alloy is much lower than that for amorphous Fe-Si-B alloy at the sheet thickness more than 70 mu m. 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, (C) 1998 American Institute of Physics. [S0021-8979(98)47211-6].