Strain rate dependence of deformation behavior in Zr-based bulk metallic glasses in the supercooled liquid region

Zr-based bulk metallic glasses (BMG) have superior mechanical properties such as high strength, elastic strain limit and fracture toughness. However, the application fields of bulk metallic glasses have been limited because of their small size and lack of workability. In order to improve the workability using superplastic behavior, it is important to investigate the deformation behavior of BMGs in the supercooled liquid region. In this study, the strain rate dependence of the deformation behavior in a Zr55Al10Ni5Cu30 bulk metallic glass under tensile loading at temperatures between 680 K and 720 K were investigated. The flow behavior exhibited significant strain rate dependence, and the flow stress became lower with lowering strain rates. The crystallization of glass phase of the alloy occurred during testing at low strain rates and higher temperature in the supercooled liquid region, and eventually, shortened the elongation expected at lower strain rates.