Atomic simulation of void effect on the microstructure evolution and internal stress transmission in nanoindentation

The void effect on the microstructure evolution and internal stress transmission of single crystal copper in nanoindentation are investigated using molecular dynamics simulation. The result indicates that the void can block the dislocation movement and absorb the internal stress during the indentation process. And the indentation-induced strain continuously accumulates beneath the indenter and leads to a significant plastic deformation at the top of the void, forming a “partial-collapse”, and then forming a “full-collapse”. The above results can be generalized to investigate the plastic deformation mechanism of the materials with irregular voids.