Dynamic relaxation in metallic glasses: A unified view from quasi-point defects and fractional viscoelasticity

Y Chen and Y Xiao and GJ Lyu and B Wang and YJ Wang and Y Yang and E Pineda and C Fusco and L Chazeau and J Qiao, INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE, 217, 104394 (2025).

DOI: 10.1016/j.ijengsci.2025.104394

Amorphous solids are ubiquitous in nature, and their non-Debye relaxation behaviors are often modeled using the stretched exponential function or the power-law form. However, these empirical approaches lack a clear physical landscape and direct ties to the underlying microstructure. Dynamic mechanical relaxation is a key metric for understanding the mechanical and physical properties of amorphous solids with viscoelastic characteristics. This study focuses on dynamic mechanical relaxation behavior of Cu50Zr43Al7 metallic glass, a typical representative of amorphous solids. We employ the simplified modified fractional-order model, combining the quasi-point defect theory and the fractional calculus, to investigate the mechanical relaxation spectrum of Cu50Zr43Al7 metallic glass in temperature domain. Our findings demonstrate the convergence between mechanical (simplified modified fractional-order model) and physical (quasi-point defect theory) viewpoints. Molecular dynamics simulations reveal that variations of parameter chi (or alpha) in the models is closely related to changes in icosahedral clusters. Additionally, calculation of local pair entropy S2 for atoms before and after annealing, along with analysis of the "entropy-rising" atoms during annealing, show a strong correlation with the quasi-point defects.

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