Extrusion formability and deformation behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass in an undercooled liquid state after rapid heating

Abstract

Deformation behavior of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass (BMG) has been investigated under compressive loading after rapid heating to an undercooled liquid state. A homogeneous plastic flow has been observed at the intemediate initial strain rate and temperature range of undercooled liquid state. In this homogeneous flow regime. the Newtonian flow was observed to become a non-Newtonian flow as the temperature at a given strain rate was decreased. An empirical deformation map could fie constructed from the result of compression tests to provide the boundary between the Newtonian and non-Newtonian flow regimes in terms of strain rates and test temperatures, Considering the efficiency of power dissipation and instability condition based on the dynamic materials model (DMM), a processing map could also be constructed. The macroscopic formability of this BMG alloy has also been examined through an extrusion test in a laboratory scale within undercooled liquid state. From the results of macroscopic extrusion formability test, both the deformation map and processing map are found to present an adequate optimal forming condition. (c) 2005 Elsevier B.V. All rights reserved.