Indentation properties of Cu-Zr-Al metallic-glass thin films at elevated temperatures via molecular dynamics simulation

Abstract Metallic glasses, also known as amorphous metals, exhibit unique mechanical properties in terms of their strength and ductility. In this work, molecular dynamics simulation techniques were adopted to construct (Cu50Zr50)100−xAlx thin-film glasses, with x being the atomic percentage of aluminum, through simulated sputter deposition processes. The deposition simulations were conducted with a tight-binding interatomic potential, and argon working gas was modeled by the pair-wise Moliere potential. The calculated radial distribution functions of the films show more amorphous microstructures, consisting distorted icosahedral clusters. The as-deposited films were annealed at various temperature with the NPT ensemble, and aluminum clusters were found at temperature T > 800 K. The formation of the aluminum clusters may be due to the system being trapped into a local energy minimum. For their indentation properties at elevated temperatures, a right-angle conical carbon indenter tip was adopted with the NVT ensemble. No aluminum clusters were found with the NVT ensemble at high temperatures. In addition, the hardness and Young’s modulus show strong temperature dependence above the glass transition temperature. Pileup index, viscosity and elastic anisotropy exhibit anomalies around glass transition temperature.