Preparation of Thick Amorphous Alloy Sheets in Multicomponent Fe-based Systems and Their Thermal and Magnetic Properties

Thick amorphous sheets with thickness up to about 200μm were formed for the Fe_Al_5Ga_2P_C_6B_4Si_1 alloy with a wide supercooled liquid region of 58 K before crystallization. The glass transition temperature (T_g), crystallization temperature (T_x) and supercooled liquid region ΔT_x(=T_x-T_g) remain unchanged in the entire thickness range. However, the heat of structural relaxation decreases from 2.2 kJ/mol for the 22μm thick ribbon to 0.48 kJ/mol for the 160μm thick ribbon, accompanying the increase in T_c from 597 K to 619 K. In comparison with the other amorphous alloy ribbons in the same Fe-(Al, Ga)-(P, C, B, Si) system, there is a clear tendency for the maximum sample thickness for glass formation (t_) to increase with increasing ΔT_x. The Fe-Al-Ga-P-C-B-Si amorphous sheets have high saturation magnetization of about 180x10^ Wbm/kg and low coecivity of about 5 A/m in the annealed state and their values remain unchanged in the thickness range up to 200μm. The permeability (μ_e) at 1 kHz shows the high values of 12000 for the 30μm thick ribbon and decreases to about 7000 for the 200μm thick ribbon. It is to be noticed that the good soft magnetic properties of 5 A/m for H_c and 7000 for μ_e as well as the wide supercooled liquid region of 58 K are obtained for the thick amorphous sheets with thickness of 150 to 200μm. These characteristics for the thick amorphous ribbons have not been obtained for Fe-based amorphous alloys previously reported. It is therefore expected that the thick amorphous ribbons cause a further extension of the application fields of ferromagnetic amorphous alloys