Deformation Behavior of Zr-based bulk metallic glass in an undercooled liquid state under compressive loading

Abstract

High temperature deformation behavior of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk amorphous alloy has been studied in a temperature range between 355 and 460 degreesC under compressive loading after rapid heating. A transition of flow behavior, viz. from a Newtonian to a non-Newtonian flow, has been reported by many researchers as the temperature is decreased at a given strain rate. In the present study, two different theoretical relations based on a viscous flow model and a transition state theory have been applied to analyze the transition behavior of deformation in terms of viscosity and flow stress. An experimental deformation map was then constructed to specify the boundaries between Newtonian and non-Newtonian flow, based on the relationship between the flow stress and strain rate in an undercooled liquid state. It has further been confirmed that the stress overshoot phenomena can be observed mostly in a non-Newtonian flow regime appearing in an intermediate temperature and strain rate region in this deformation map.