Enhanced plasticity of Zr56Co24Ag4Al16 and Zr56Co22Cu6Al16 bulk metallic glasses by controlling the casting temperature

The influence of casting temperature on the compressive plasticity of Zr56Co24Ag4Al16 and Zr56Co22Cu6Al16 bulk metallic glasses (BMGs) fabricated via copper mold suction casting was studied through the varying electric discharge current, including (100%, 90%, 80% and 70%). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate the glassy alloys structure. In addition, the compression test, microhardness test, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were utilized to discuss the possible mechanisms involved in the enhanced plasticity achievement. The results demonstrated that the samples subjected to the 80% casting current exhibit the highest compressive plasticity. The plastic strain increased dramatically from 4% to 10.7% for the Ag-containing samples and from 5.7% to 12% for the Cu-containing samples as the casting current decreased from 100% to 80%, and then the plastic strain decreased to 8.4% for the Ag-containing sample and to 9.4% for the Cu-containing sample at 70% of the casting current. The effect of casting temperature on the mechanical properties was explored by focusing mainly upon the effects of structure evolution such as those of free-volume content variations.