Publication Date:
2016-05-27
Description:
Molecular dynamics simulations were performed to investigate dynamic evolution in metallic glass-forming liquids during quenching from high temperature above melting point down to supercooled region. Two crossover temperatures T A and T S ( T A 〉 T S ) are identified, and their physical meanings are clarified. T A and T S are found to be not only the sign of dynamic crossover phenomena but also the manifestation of two key structure correlation lengths ξ s . As temperature decreases below T A , ξ s goes beyond the nearest-neighbor distance, resulting in the Arrhenius-to-non-Arrhenius transition of structural relaxation time and the failure of Stokes-Einstein (SE) relation. As T S is traversed, the increase rate of ξ s reaches the maximum, leading to the simultaneous appearance of dynamical heterogeneity and fractional SE relation. It is further found that structure correlation increases much faster than dynamic correlation, playing a role of structural precursor for dynamic evolution in liquids. Thus, a structural link is established for deeper understanding dynamic crossover phenomena.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
