Formation and Thermal Stability of Ca-Mg-Ag-Cu Bulk Glassy Alloys

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Calcium-based bulk glassy alloys in Ca–Mg–Ag and Ca–Mg–Ag–Cu systems were produced by a metallic mold casting method. The maximum rod diameter (d_max) for the formation of a glassy phase was 4 mm for Ca₆₀Mg₂₀Ag₂₀ and 7 mm for Ca₆₀Mg₂₀Ag₁₀Cu₁₀. The glass transition temperature (T_g), crystallization temperature (T_x), temperature interval of supercooled liquid region (ΔT_x=T_x−T_g) and melting temperature (T_m) were 401 K, 435 K, 35 K and 654 K, respectively, for the former alloy and 398 K, 428 K, 30 K and 624 K, respectively, for the latter alloy. The simultaneous addition of Ag and Cu in the Ca–Mg–(Ag, Cu) system causes a steep decrease in T_m and an increase in the reduced glass transition temperature (T_g⁄T_m), leading to an increase in the glass-forming ability.