Fictive stress model calculations of viscoelastic behaviors in a Zr-based glassy alloy

Viscoelastic behaviors of a Zr-based glassy alloy in the glass transition region were investigated with uni-axial compression tests. The transition between the linear and the nonlinear viscoelasticity was observed just as it was observed in other glassy materials. The transition is considered to be due to a structural change in the glassy structure. Using the relationship taken from experimental results between the steady-state flow stress and their relaxation time at various temperatures, we make the steady-state flow stress, which is named fictive stress, stand for the flow structure during deformation. Based on the hypothesis of the stress-induced structure change and the concept of the fictive stress, we succeeded in demonstrating various characteristic viscoelastic behaviors. The model calculations agreed fairly well with the experimental results. The condition under which the transition occurs and the mechanism of the transition itself in various deformations of a Zr-based glassy alloy were demonstrated by this model calculation.