Effect of atomic configuration and liquid stability on the glass-forming ability of Ca-based metallic glasses

In the present study, we report a Ca-Mg-Ni alloy exhibiting significantly improved glass-forming ability (GFA). The Ca60 Mg25 Ni15 bulk metallic glass (BMG) with a diameter of 13 mm is successfully fabricated by a conventional copper mold casting method in air atmosphere. The Δ Tx, Trg, K, and γ parameters exhibit very poor correlation with the GFA. However, the γ parameter exhibits a far better correlation with GFA, indicating that the liquid phase stability and atomic size mismatch dominantly affect the GFA of Ca-based ternary BMGs. The GFA of alkaline-earth-metal-based ternary BMGs such as Ca- and Mg-based BMGs cannot be described properly only by considering thermodynamic and/or kinetic criterion (Δ Tx, Trg, K, and γ parameters), but can well be described by considering atomic configuration criterion as well as thermodynamic criterion (γ parameter).