Deformation behaviours of TiZrCuNiBe bulk metallic glass in supercooled liquid region

In this work, the deformation behaviours of the Ti33Zr30Cu9Ni5.5Be22.5 bulk metallic glass (BMG) in the supercooled liquid region (SLR) were explored through a series of uniaxial compression experiments with a Gleeble 3500 thermal simulator at different strain rates. Results showed two main deformation modes in the SLR: plastic flow and brittle fracture. With increasing temperature and decreasing strain rate during the plastic flow process, the stress overshoot gradually disappeared, and the steady flow stress decreased. At 648 K, a transition from Newtonian flow to non-Newtonian flow was observed while the strain rate exceeded 1 x 10(-3) s(-1). The morphologies of the deformed BMG specimens changed with increasing temperature and consequently exhibited three profiles: asymmetric deformation, upright drum shape and uniformly flattened column shape. Studies of fracture behaviours showed that as the temperature increased from 618 K to 638 K, the critical strain rate of the fracture increased from 3 x 10(-3) s(-1) to 6 x 10(-3) s(-1). Moreover, the fracture angles increased from 46 degrees to 57 degrees due to the change in cohesive strength according to the Mohr-Coulomb criterion. Unlike the condition at room temperature, unique fracture morphologies, including fishbone-like characteristics and a large area of viscous flow layers, were formed under the high-temperature condition. (C) 2020 Elsevier B.V. All rights reserved.