Conference Dates
October 4-9, 2015
Abstract
The influence of crystal orientation on elastic and plastic response of WC, β-Si3N4 and ZrB2 ceramic grains is important to understand, model and enhance its composite mechanical properties. In order to investigate this, nanoindentation testing was carried out using Berkovich tip on selected surface areas which were mapped by electron backscatter diffraction (EBSD) prior to the tests. To study the surface morphology after nanoindentation and to characterize the resulted deformation fields around the imprints additional EBSD, atomic force microscopy (AFM) and scanning electron microscopy (SEM) investigations were performed. Considerable elastic and plastic anisotropy was found is WC and β-Si3N4 (Fig. 1a,b) crystals while the orientation dependence of ZrB2 grains exhibited slight influence on hardness and indentation modulus. The measured indentation modulus, as the elastic response, was compared with the model proposed by Vlassak and Nix and our finite element model (FEM) calculations using single crystal elastic constants, as it is shown for β-Si3N4 in Fig. 1c. To explain the obtained hardness anisotropy, as the plastic response, a theoretical model is proposed in which the critical force for slip activation is determined as a function of crystal orientation, based on the possible slip systems of materials. The predictions of the applied models describing both elastic and plastic behaviors are in good agreement with the experimental results, (for β-Si3N4 see in Fig. 1d)
Recommended Citation
Tamas Csanadi, Dusan Nemeth, Alexandra Kovalcikova, and Jan Dusza, "Nanoindentation induced deformation anisotropy in WC, β-Si3N4 and ZrB2 crystals" in "Nanomechanical Testing in Materials Research and Development V", Dr. Marc Legros, CEMES-CNRS, France Eds, ECI Symposium Series, (2015). https://dc.engconfintl.org/nanomechtest_v/42