Rate dependency of a Zr-based bulk metallic glass: Strength and fracture characteristic

Compressive mechanical response of a Zr-based bulk metallic glass is investigated in the strain rate range of 0.0001/s-9000/s. Negative strain rate dependency of the peak stress is revealed which shows a 30% decrease compared with the static date. Rate dependent melting phenomenon is indicated by measuring the width of vein-like structures on the fracture surface after each compression at different strain rates. The mechanisms of temperature rise localizing in a shear band are explored for analyzing the melting behavior, the reduced viscosity and the resultant stress decrease. The characteristic transition from non-Newtonian to Newtonian flow in the shear bands correlated to the strain rate is addressed. The melting liquid is also involved in the dynamic deformation straining through forming high-density nano-space wrinkle structures for a considerable toughness. (C) 2018 Elsevier B.V. All rights reserved.