Formation, Thermal Stability and Mechanical Properties of Ca-Based Bulk Glassy Alloys

抄録

New bulk glassy alloys were formed in the Ca–Mg–Cu system by the copper mold casting method. The maximum rod diameter (d_max) for the formation of a glassy phase was 2 mm for Ca₆₇Mg₁₉Cu₁₄ and above 4 mm for Ca₅₇Mg₁₉Cu₂₄. The glass transition temperature (T_g), crystallization temperature (T_x), supercooled liquid region (ΔT_x=T_x−T_g) and reduced glass transition temperature (T_g⁄T_m) are 387 K, 407 K, 20 K and 0.60, respectively, for the former alloy and 404 K, 440 K, 36 K and 0.64, respectively, for the latter alloy. There is a tendency for d_max to increase with increasing ΔT_x and T_g⁄T_m. Young’s modulus (E) and compressive fracture strength are 38 GPa and 545 MPa, respectively, for the Ca₅₇Mg₁₉Cu₂₄ alloy rod with a diameter of 2 mm. The success of synthesizing bulk glassy alloys in the simple metal (Ca) base system makes it important as a basic alloy system for examining fundamental chemical and physical properties of bulk glassy alloys.