Load relaxation behavior of a Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass

Abstract

The load relaxation behavior within the supercooled liquid region of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass has been investigated. To explain the relationship between normalized stress and relaxation time, two different stress relaxation modes such as a Kohlrausch-Williams-Watts (KWW) behavior and a simple power law were applied to the short and long relaxation time regimes, respectively. The apparent activation energy for stress relaxation is 126 +/- 10 kJ/mol. Flow curves were obtained by converting load-displacement data into a flow stress-strain rate relation, resulting in three different deformation characteristics through a wide strain rate region interpreted in terms of strain rate sensitivity. A prediction of hot workability has also been attempted by constructing a power dissipation map based on a dynamic materials model. (C) 2007 Elsevier B.V. All rights reserved.