Improved plasticity of a ZrCuAlAg bulk metallic glass by controlling the casting condition.

A series of Zr50.75Cu35.75Al8.5Ag5 bulk metallic glasses (BMGs) were prepared by controlling the cooling rate and over-heating temperature. The plastic deformation behavior of the BMGs was examined. The plasticity was enhanced when the BMG was prepared at a high cooling rate and low over-heating temperature. The plasticity of the Zr-based BMGs prepared under different casting conditions was discussed based on the amount of free volume. The structural heterogeneity of the BMGs prepared with different over-heating temperatures was examined using a high-resolution transmission electron microscope and mapped by using an energy dispersive x-ray spectroscope. The results showed that a low over-heating temperature could increase the degree of heterogeneity, but an extremely low over-heating temperature could lead to nanocrystallization. The difference in the heterogeneous structures caused the distinct plastic performance of the Zr50.75Cu35.75Al8.5Ag5 BMGs prepared with different over-heating temperatures. [ABSTRACT FROM AUTHOR]