Effect of voids on nanoindentation response of Fe-10% Cr alloys using molecular dynamics simulation

Nanoindentation response of single crystal Fe-10% Cr models has been investigated using Molecular Dynamics (MD) simulation. Defect-free (DF) model and models with voids of various sizes and positioned at various locations from the indenter surface are researched. The load-displacement response of the models with layers of voids (LV) deviates from the response observed in the DF model as dislocations start interacting with voids. The depth at which this transition happens depends on the number of layers as well as the size of the voids. For models with a single void (SV), the transition occurs depending on the location of the void from the indenter surface. For the SV model with a void closer to the indenter surface, the effect of void is removed once the void is collapsed at a sufficiently large indentation depth; whereas, for model with void closer to the center, the effect of the void to the load-displacement curve is minimal. Both hardness and reduced modulus are found to be lower for models with voids when compared to DF model. The results reveal the nucleation of < 001 >, 1/2 < 111 >, and 1/6 < 111 > types of dislocations during indentation. The dislocation lengths and densities have been calculated for various models. The dislocation densities are found to be higher in models with voids as compared to DF model due to the interaction of dislocations with the voids.