The effect of atomic concentration on the structural evolution of Zr100-xCox alloys during rapid solidification process

Abstract The effects of the concentration on the glass formation, the crystallization process, and atomic structure of Zr100-xCox (x = 10, 30, 50, 70, and 90) alloys were investigated by classical molecular dynamics simulation based on the embedded atom method during rapid quenching. The structural evolution of these systems was evaluated by analyzing some structural functions and structural characterization methods. The calculated coordination number and structure factor were compared with the experimental data and it was observed that there was a good agreement between the molecular dynamics simulation and experimental results. Simulations performed for this study revealed that the local environment depends on the atomic composition in the Zr Co alloy. The liquid - glass transition was observed for the concentrations of Co in the range of 30–90%, which is consistent with the experimental glass forming range for Zr100-xCox alloys. The Voronoi and Honeycutt–Andersen pair analysis showed that the number of pairs and bonds reflecting the development of the icosahedral short range order increased with increased Co concentration and the Zr30Co70 alloy, having a large number of ideal and distorted icosahedrons with respect to other compositions considered in present study, has the highest fraction of Co-centered full icosahedral ⟨0,0,12,0⟩ clusters. Analysis results showed that in Zr90Co10 alloy, the number of ⟨0,6,0,8⟩ clusters denoting the transition to bcc structure remarkably increased, and ⟨0,3,6,4⟩, ⟨0,5,2,6⟩ and ⟨0,4,4,6⟩ clusters play a key role during the crystallization process.