The high-temperature rheological behavior, around the glass transition temperature, of a Zr₄₈Cu₃₄Ag₈Al₈Pd₂ metallic glass was investigated by strain rate jump experiments. The results show that the plastic deformation behavior and apparent viscosity strongly depend on temperature and strain rate. The high temperature rheology can be interpreted within the framework of the free volume model. The relative defect concentration deduced from the free volume model depends on temperature and strain rate and it explains the evolution of apparent viscosity within testing conditions, which is inversely correlated with the defect concentration. The stress overshoot is found to be a characteristic feature of the high-temperature rheological behavior. The origin of the stress overshoot is analyzed based on the physical meaning of the parameters in the free volume model. The results demonstrate that the strength of the stress overshoot is determined by the time of change from non-equilibrium to equilibrium defect concentrations. This study highlights the link between the stress overshoot phenomenon and the initial structural state, examining the influence of physical aging and stress relaxation on the high-temperature deformation process of metallic glasses.

Zr ₄₈ Cu ₃₄ Ag ₈ Al ₈ Pd ₂在玻璃化转变温度附近的高温流变行为通过应变率跳跃实验研究了金属玻璃。结果表明，塑性变形行为和表观粘度强烈依赖于温度和应变速率。高温流变学可以在自由体积模型的框架内进行解释。从自由体积模型推导出的相对缺陷浓度取决于温度和应变率，它解释了测试条件下表观粘度的演变，与缺陷浓度成反比。发现应力超调是高温流变行为的特征。根据自由体积模型中参数的物理意义分析应力超调的来源。结果表明，应力超调的强度取决于从非平衡到平衡缺陷浓度的变化时间。本研究强调了应力超调现象与初始结构状态之间的联系，考察了物理老化和应力松弛对金属玻璃高温变形过程的影响。