Nano-Indentation Deformation Studies of Al-Cu Alloy Via Molecular Dynamic Simulation.

Abstract

This thesis is concerned with the modeling and simulation deformation studies of crystalline Al-Cu (Al50-70:Cu30-50) alloys by classical molecular dynamic simulations (MD). Deformation studies were done by nano-indentation by coding in LAMMPS (Large Scale Atomic/Molecular Massively Parallel Simulator) which is a well studied and widely used open source code. In this study the effect of temperature, indenter diameter, loading rate, composition on mechanical properties of alloys have been investigated. The simulated deformation studies were carried out by nano-indentation at room temperature as well as at elevated temperatures (300 K and 500 K). Also the effect of Cu on the deformation behavior was studied by varying copper content in the range of 15-25 at%. The simulation box size of dimension (100 Ǻ×100Ǻ×100 Ǻ) and consisting of 62500 atoms were used for all the alloys. In this study NVT ensemble with periodic boundary conditions along the non-loading directions was used. It has been found that with increase in copper content the strength of the alloy increased. Further, with increase of loading rate from 1 Å/ps to 2 Å/ps the load increases as there is no sufficient time for atomic rearrangements. Also, with increase in indenter diameter from 15 Å to 20 Å hardness increases, this is due to more resistance offered by the atoms of the alloy to indentation. Furthermore, with increasing temperature the hardness of the alloys decreased. The results obtained could lead to better understanding the behavior of the alloys at the macroscopic level.