Formation, thermal stability and mechanical properties of Ca-based bulk glassy alloys

Abstract

New bulk glassy alloys were formed in the Ca-Mg-Cu system by the copper mold casting method. The maximum rod diameter (dmax) for the formation of a glassy phase was 2 mm for Ca67Mg19Cu14 and above 4 mm for Ca57Mg19Cu24. The glass transition temperature (Tg), crystallization temperature (Tx), supercooled liquid region (ΔTx = Tx - Tg) and reduced glass transition temperature (Tg/Tm) 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 dmax to increase with increasing ΔTx and Tg/Tm. 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.