On the origin of deformation-induced rotation patterns below nanoindents

This study is about the origin of systematic deformation-induced crystallographic orientation patterns around nanoindents (here of single crystalline copper; conical indenter) using the following approach: first, the rotation pattern is investigated in three-dimensions (3D) using a high-resolution 3D electron backscattered diffraction (EBSD) technique (EBSD tomography) which works by a serial sectioning and EBSD mapping procedure in a scanning electron microscopy-focused ion beam cross-beam set-up. Second, the problem is modeled using a crystal plasticity finite element method which is based on a dislocation density-based constitutive model. Third, the results were discussed in terms of a geometrical model which simplifies the boundary conditions during indentation in terms of a compressive state normal to the local tangent of the indent shape. This simplification helps to identify the dominant slip systems and the resulting lattice rotations, thereby allowing us to reveal the basic mechanism of the formation of the rotation patterns. The finite element simulations also predict the pile-up patterning around the indents, which can be related to the dislocation density evolution.