Bulk Glassy Fe-Ga-P-C-B Alloys with High Saturation Magnetization and Good Soft Magnetic Properties Synthesized by Fluxing Treatment and Copper Mold Casting

Abstract

The effect of fluxing treatment on the glass-forming ability for the Fe₇₅Ga₅P₁₂C₄B₄ glassy alloy was investigated. The fluxing treatment was found to be effective for the elimination of heterogeneous nucleation sites. The glass transition temperature (T_g), crystallization temperature (T_x), supercooled liquid region (ΔT_x) and reduced glass transition temperature (T_g⁄T_m) are all increased by fluxing treatment. The T_g, T_x, ΔT_x and T_g⁄T_m values for Fe₇₅Ga₅P₁₂C₄B₄ glassy alloy are 731 K, 768 K, 37 K and 0.610 respectively before fluxing treatment, increase to 749 K, 805 K, 56 K and 0.625 respectively after fluxing treatment. Bulk glassy Fe₇₅Ga₅P₁₂C₄B₄ alloy rods with high saturated magnetization (I_s) of 1.27 T and good soft magnetic properties of 1.6 A/m for coercive force (H_c) were prepared with diameters range up to 2.5 mm by the copper mold casting method of fluxed alloy melt. The glass synthesis consists of preparing the alloy ingot by induction melting, thermal cycling and purifying the melt in B₂O₃ flux inside a silica tube and then casting the purified alloy into a copper mold. The size of 2.5 mm in diameter of the rod is not an upper limit.