Molecular dynamics study of dynamic and structural properties of supercooled liquid and glassy iron in the rapid-cooling processes

Molecular dynamics simulations were applied to study the dynamic and structural properties of supercooled liquid and glassy iron in the rapid-cooling processes. The mean-square displacement and the non-Gaussian parameter were used to describe the dynamic properties. The evolution of structural properties was investigated using the pair distribution functions and bond-angle distribution functions. Results for dynamic and structural relaxations indicate that the dynamic features are consistently correlated with the structure evolution, and there are three temperature regions as the temperature decreases: (1) at higher temperatures (1500 K, 1300 K, and 1100 K), the system remains in the liquid characteristics during the overall relaxation process. (2) At medial temperatures (1050 K, 900 K, and 700 K), a fast beta-relaxation is followed by a much slower alpha-relaxation. There is a little change in the structural properties in the beta-relaxation region, while major configuration rearrangements occurred in the alpha-relaxation range and the crystallization process was completed at the end of alpha-relaxation region. (3) At lower temperature (500 K), the system shows glassy characteristics during the overall relaxation process. In addition, the melting temperature, glass transition temperature and diffusion coefficients of supercooled liquid iron are also computed. (C) 2014 Elsevier B.V. All rights reserved