||The mechanical and structural properties of Ti60Zr10Ta15Si15 bulk metallic glasses have been investigated by molecular dynamics (MD) simulation. In order to simulate the Ti-Zr-Ta-Si systems, two potential functions were employed. The tight binding (TB) potential was used to model the interactions between metallic elements (Ti,Zr,Ta) and the Ta-Si pair which showed less covalency based on the electron density analysis. The modified Tersoff potential was used to model the interactions between Si-Zr, Si-Ti and Si-Si pairs. All parameters of TB and modified Tersoff potentials were fitted on the basis of several reference data including the binding energies, atomic forces of structures at equilibrium, elastic constants of pure Zr, Ti, Si, the binary intermetallic compound structures. These reference data were obtained from DFT calculations and experimental results, and the fitted parameters can reflect the properties of all reference data. |
These parameters of TB and modified Tersoff were further applied in generating the structure of Ti60Zr10Ta15Si15 bulk metallic glass and then the molecular dynamic simulation was performed to do the tension test and get the stress-strain profiles. According to stress-strain profiles, Ti60Zr10Ta15Si15 bulk metallic glass is ductile and the estimated Young’s modulus is about 93GPa which is close to the experimental value. Local strain distribution was used for analyzing the deformation mechanism, and results show that shear band develops homogeneously which enhances the plasticity.
The Voronoi tessellation analysis and HA index were used for further investigating the plastic/elastic deformation mechanism. The results show that icosahedral local structure and the structure around Si atoms undergo a severe variation during the tension process.
Keywords: Bulk metallic glasses, Molecular dynamics, Density Functional Theory, mechanical properties,Tight-Binding potential, Tersoff potential