Orientation dependence of nanoindentation pile-up patterns and of nanoindentation microtextures in copper single crystals

Abstract

We present a study about the dependence of nanoindentation pile-up patterns and of microtextures on the crystallographic orientation using high purity copper single crystals. Experiments were conducted on a Hysitron nanoindentation setup using a conical indenter in order to avoid symmetries others than those of the crystal structure. Orientation measurements were conducted using a high resolution electron back-scatter diffraction technique for the automated acquisition of texture mappings around the indents. Simulations were carried out by means of a 3D elastic–viscoplastic crystal plasticity finite element method which takes full account of crystallographic slip and orientation changes during indentation. The experiments as well as the simulations show that the pile-up patterns on the surfaces of (0 0 1)-, (0 1 1)- and (1 1 1)-oriented single crystals have four-, two-, and sixfold symmetry, respectively. The different pile-up patterns can be explained in terms of the strong crystallographic anisotropy of the out-of-plane displacements around the indents. Pronounced accumulation of material entailing characteristic pile-up patterns occurs along the intersection vectors between the primary crystallographic slip planes and the indented surface planes.