Effects of Zn addition on the improvement of glass forming ability and plasticity of Mg–Cu–Tb bulk metallic glasses

The effects of Zn addition on the glass forming ability and mechanical properties of Mg65Cu25−xZnxTb10 (x = 0, 2.5, 5, and 7.5) have been investigated. We show that small amounts of Zn addition improve the glass forming ability, strength, and ductility of the Mg–Cu–Tb bulk metallic glass. For the best glass forming composition, amorphous rods of Mg65Cu20Zn5Tb10 with a diameter of at least 7 mm have been prepared by a conventional copper mold casting method. Additionally, this composition exhibits obvious yielding and plastic deformation upon quasi-static compressive loading. The fracture strength, total strain to failure, and the plastic strain of the Mg65Cu20Zn5Tb10 bulk metallic glass reaches 1025 MPa, 2.05% and 0.15%, respectively. This is significantly superior compared to that exhibited by the original Zn-free Mg–Cu–Tb amorphous alloy.