Atomistic simulation of the deformation mechanism during nanoindentation of gamma titanium aluminide

In this paper we present a large-scale molecular dynamics simulation that describes the deformation mechanism of an ordered intermetallic compound (TiAl) during a nanoindentation procedure. Using a totally rigid spherical indenter we were able to address the question on which mechanism underlies its plastic deformation, namely homogeneous defect nucleation followed by the expansion of dislocation loops. By means of the calculated local pressure, local shear stress and spatial rearrangements of atoms beneath the indenter, it was possible to quantify the indentation damage on the crystalline structure. Our results show that both emission and interaction of dislocations are mediated by expansion of glide loops on the {1 1 1} planes resulting in the formation of prismatic loops. Moreover, through the load-penetration depth response we estimated the elastic modulus and hardness values of the system, which are in good agreement with experimental results.