Thermal stability and magnetic properties of (Fe, Co)–Ga–(P, C, B, Si) bulk glassy alloys

The replacement effect of Co for Fe on the glass-forming ability (GFA) and magnetic properties in the (Fe, Co)–Ga–(P, C, B, Si) systems were investigated. The glass-forming ability of (Fe1−xCox)73Ga4P11C5B4Si3 (numbers indicate at.%) alloys increased significantly by the addition of an optimum amount of Co. The maximum diameter of the glassy alloy rod (dmax) was 3.0 mm for Fe73Ga4P11C5B4Si3 and increased to 5 mm for (Fe0.8Co0.2)73Ga4P11C5B4Si3. However, the glass-forming ability of this alloy system decreases with further increasing Co content. The saturation magnetization was 1.26 T for (Fe0.8Co0.2)73Ga4P11C5B4Si3 and 1.40 T for (Fe0.85Co0.15)77Ga2P10C5B3.5Si2.5. The dmax for the latter alloy was 3 mm. The high GFA of (Fe, Co)–Ga–P–C–B–Si alloys seems to result from the necessity of the redistribution of Co for the progress of crystallization.