Role of Free Volume on Mechanical Properties of Cu-Zr Based Metallic Glasses-A Molecular Dynamics Study

摘要

In this thesis the investigation is being carried out on mechanical properties of Cu50-Zr50 based metallic glass obtained at different cooling rates using Molecular Dynamics (MD) simulation techniques. Metallic glasses or an amorphous material has pulled in extensive consideration because of their remarkable mechanical properties such as better strength, wear, corrosion resistance and it is twice as solid as titanium. And it is harder and more flexible than ceramics. Because of their enhanced properties over crystalline metals have made them adaptable engineering material for many engineering applications..All the MD simulations are coded in LAMMPS. A box of dimension 50 × 100 × 50 Å3containing 21952 number of atoms of Cu50-Zr50are created and then the crystalline alloy is quenched at different cooling rates (1011K/s-1014 K/s). The different cooling rates induce different free volume content and are found to have a significant effect on the mechanical properties. With increasing cooling rate the free volume of the material increases. With higher free volume material will extend effortlessly under low stress. The samples are then subjected to uniaxial tensile and compressive deformation at different strain rates and at temperatures (300K, 200K, 100K, 50K and 10K). The effect of strain rates, temperatures and excess free volume of the mechanical properties such as yield strength, young’s modulus and ultimate tensile strength is investigated from the stress-strain plots. Inter atomic forces are calculated by using the embedded atom method (EAM). The changes in the atomic structure and deformation can be observed with the help of Ovito snap shots. It is found that strength increases with increase in strain rates and decrease of temperatures.