Localization model description of diffusion and structural relaxation in glass-forming Cu-Zr alloys
JF Douglas and BAP Betancourt and XH Tong and H Zhang, JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT, 054048 (2016).
We test the localization model (LM) prediction of a parameter-free relationship between the a-structural relaxation time tau(alpha) and the Debye-Waller factor < u(2)> for a series of simulated glass-forming Cu- Zr metallic liquids having a range of alloy compositions. After validating this relationship between the picosecond ('fast') and long- time relaxation dynamics over the full range of temperatures and alloy compositions investigated in our simulations, we show that it is also possible to estimate the self-diffusion coefficients of the individual atomic species (D-Cu, D-Zr) and the average diffusion coefficient D using the LM, in conjunction with the empirical fractional Stokes- Einstein (FSE) relation linking these diffusion coefficients to tau(alpha). We further observe that the fragility and extent of decoupling between D and tau(alpha) strongly correlate with < u(2)> at the onset temperature of glass-formation T-A where particle caging and the breakdown of Arrhenius relaxation first emerge.
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