A molecular dynamic study of the effects of high pressure on the structure formation of liquid metallic Ti62Cu38 alloy during rapid solidification

Abstract

In this study, the effects of high pressure ranging from 0 to 100 GPa on the structural evolution of liquid metallic Ti62Cu38 alloy during rapid cooling have been extensively investigated by using classical molecular dynamics simulation with embedded atom method at a cooling rate of 5 × 1010 K s−1. To investigate the first order phase transition during the solidification of the system and to determine the crystallization and glass transition temperatures, the temperature-dependent change in the curves of thermodynamic properties such as average volume per atom, specific heat and enthalpy are examined. Structural properties are expressed by using pair distribution functions, structure factors and atomic configuration. The microstructural atomic order in the system are characterized by using Honeycutt-Andersen pairs and Voronoi tessellation analysis methods. The results provide convincing evidence that the applied pressure during rapid cooling has a strong effect on determining whether the metallic liquid Ti62Cu38 will transform into a crystal-like structure or a glassy structure. The critical pressure for the glass formation are predicted to be approximately 10 GPa. While the simulated crystallization and glass transition temperatures increase linear with a slope of 11.11 K GPa−1 within the range of 0–9 GPa and with a slope of 12.10 K GPa−1 within the range of 10–100 GPa, respectively. While crystal-like clusters are dominant in the system up to 10 GPa, icosahedral-like clusters representing a short range order at 10 GPa become dominant in the system. The amount of dominant icosahedral-like clusters remains basically stable with pressure increase from 10 to 100 GPa. Also, as the pressure is applied, the calculated bond lengths for all bond pairs decrease.