Investigation of stress relaxation behavior of amorphous alloy based on a fractional-order model

Amorphous alloys exhibit unique mechanical and physical properties due to their long-range atomic disorder microstructure. Amorphous alloys are widely studied in solid mechanics and condensed matter physics. Stress relaxation is a typical mechanical behavior that can reflect the structural evolution and energy dissipation processes within amorphous materials. Therefore, it is crucial for understanding their deformation mechanisms. Although the classic Maxwell model is widely used to describe viscoelastic response, it fails to accurately capture the nonlinear relaxation behavior of amorphous alloys, which strongly depends on time and temperature. The generalized Maxwell model improves fitting performance by increasing the number of elements. However, this approach presents challenges such as excessive parameters and unclear physical meaning. The introduction of fractional calculus provides a new method for constructing constitutive models with clear physical representations and concise parameters. In this study, stress relaxation of the Pd20Pt20Cu20Ni20P20 amorphous alloy was conducted by the dynamic mechanical analyzer. Based on fractional calculus, the classic Maxwell model was modified to establish a constitutive model that can accurately describe the stress relaxation behavior of amorphous alloys. Experimental results demonstrate that this model accurately captures the stress relaxation process with only a few parameters, which can significantly improve fitting accuracy. Further analysis of the model’s response characteristics under different temperature conditions revealed the influence of temperature on stress relaxation dynamics. This research provides a new perspective and methodological support for understanding the structural evolution behavior of amorphous alloys under thermal-mechanical coupling.