A Fictive Stress Model Calculation of Nonlinear Viscoelastic Behaviors in a Zr-Based Glassy Alloy: Stress Growth and Relaxation

Abstract
Nonlinear viscoelastic behaviors of a Zr55Al10Ni5Cu30 glassy alloy are investigated experimentally and by theoretical modeling, based on the hypothesis of stress-induced structural relaxation and the concept of fictive stress. The model calculation curves agree well quantitatively with the experimental results. Structural changes of the nonlinear viscoelasticity during complex-step tests are expressed directly by the fictive stress. In addition, the critical condition under which the transition from linear to nonlinear viscoelasticity occurs is clarified on the basis of this model.