Effects of Alloying Elements on the Thermal Stability and Corrosion Resistance of an Fe-based Metallic Glass with Low Glass Transition Temperature

The effects of alloying elements on the thermal stability, glass-forming ability (GFA), corrosion resistance, and magnetic and mechanical properties of a soft magnetic Fe₇₅P₁₀C₁₀B₅ metallic glass with a low glass transition temperature (T _g) of 723 K (450°C) were investigated. The addition of Mo, Ni, and Co significantly increased the stabilization of supercooled liquid, GFA, and corrosion resistance in the H₂SO₄ solution. The maximum critical diameter (d _c) of 4 mm for glass formation was obtained for the Fe₅₅Co₁₀Ni₅Mo₅P₁₀C₁₀B₅ alloy, which shows the largest supercooled liquid region (ΔT _x ) of 89 K (89 °C). The substitution of Cr for Mo further enhanced the corrosion resistance of the Fe₅₅Co₁₀Ni₅Mo₅P₁₀C₁₀B₅, while the ΔT _x and d _c decreased. The (Fe, Ni, Co)₇₀(Mo, Cr)₅P₁₀C₁₀B₅ bulk metallic glasses showed low T _g of 711 K to 735 K (438 °C to 462 °C), wide ΔT _x of 67 K to 89 K, high saturation magnetization of 0.79 to 0.93 T, low coercive force of 2.36 to 6.61 A m⁻¹, high compressive yield strength of 3271 to 3370 MPa, and plastic strain of 0.8 to 2.3 pct. In addition, the mechanism for enhancing stability of supercooled liquid was discussed in terms of the precipitated phases during crystallization.