The rheological behavior and thermoplastic deformation of Zr-based bulk metallic glasses

In this paper, the rheological behavior and thermoplastic deformation of Zr61.88Cu18Ni10.12Al10 bulk metallic glasses (BMGs) in the supercooled liquid region (SCLR) were studied by high temperature compression tests and a processing map was constructed. The results indicated that the flow stress of present alloy in the SCLR is very sensitive to temperature and strain-rate. The flow stress decreases with increasing temperature and decreasing strain-rate. The viscosity coefficient of the present alloy ranges from 1011 Pa.s to 109 Pa.s and decreases with increasing temperature and strain-rate. When the strain-rate is greater than 5 × 10−3 s−1, the Zr61.88Cu18Ni10.12Al10 alloy undergoes a transition from Newtonian fluid to non-Newtonian fluid. The surface profile exhibited a similar shape of the letter 'N' after high temperature compression in the deeply SCLR. The optimum hot processing region of Zr61.88Cu18Ni10.12Al10 alloy is 688 K-708 K with a low strain-rate and 708 K-723 K with a high strain-rate.