Characterization of surface deformation around Vickers indents in monocrystalline materials

The deformation surrounding Vickers indents on copper and MoSi₂ monocrystals has been characterized for two orientations of the indenter diagonals using optical, electron, and scanning probe microscopy. The surface topography around the indents was characterized using atomic force microscopy (AFM), whereas orientation imaging microscopy (OIM) was used to map the local crystallographic orientation of the surface surrounding one indent on copper and measure lattice rotations due to plastic strain. The results indicate that sink-in and pile-up behavior depend on in-plane crystallographic orientations rather than the orientation of the indenter. Regions with multiple slip show larger lattice rotations and sink-in, whereas regions with lower slip density have smaller lattice rotations and show pile-ups. Strains outside one indent were obtained from OIM data using kinematical relations for single-crystal plasticity. A von Mises strain of 29 pct next to the middle of indent edge on the surface of the sample was deduced from the analysis. This agrees well with the characteristic strain reported for Vickers indents.