한국주조공학회

The effect o f alloy composition on the glass forming ability (GFA) o f the Ca-rich Ca-Mg-Zn alloys has been investigated in C a ^M g ^ Z ^ k and Ca55+xMg15Zn30.x (x=0, 5, 10, 15, 20) alloys. In a wide composition range o f 15-25% Zn and 10-20% Mg bulk metallic glass (BMG) samples with the diameter larger than 6 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the alloys investigated, the Ca65Mg15Zn20 alloy exhibits the hipest GFA enabling to form BMG sample with the diameter o f at least 15 mm. The crystalline phase formed during solidification o f Ca65Mg15Zn20 (Dmax=15 mm) could be identified as a mixture o f Ca3Zn and CaMg2 cause by the redistribution o f the constituent elements on long-range scale. The compressive fracture strength and fracture elongation o f the Ca65Mg15Zn20 BMG are 602 MPa and 2.08% respectively. The a parameter which has been recently proposed for evaluating GFA exhibits better correlation with GFA o f Ca-Mg-Zn alloys than other parameters suggested so far such as ATX, Trg, K , y, and zlT* parameters.

Ca-Mg-Zn, Copper mold casting, Bulk metallic glass, Glass forming ability,