On the anisotropic scratching behavior of single crystalline copper at nanoscale

Anisotropic material behavior raises some difficulties in characterizing and predicting the wear response of crystalline materials. A systematic set of nano-scratch crystal plasticity finite element simulations and experiments is performed to study the effect of crystal orientation and scratching direction on the wear resistance of single crystalline copper. Our results show that the scratching profile and wear volume are significantly influenced by the crystallographic orientation and scratching direction, suggesting a considerable anisotropy in the scratch response of crystalline copper. Quantifying the wear volume using Archard’s wear law shows that this anisotropy results in an orientation and scratching direction dependent wear coefficient. Alternatively, it is shown that a unique wear coefficient can be obtained for crystalline materials when one uses the scratching hardness in Archard’s wear law. This new finding may help to unify discrepant experimental and numerical wear observations and to advance physics-based wear laws without empirical coefficients. •The anisotropic scratching response of single crystalline copper has been studied using both experiments and simulations•The effect of crystalline orientation and scratching direction on the scratch profile and wear volume have been elaborated•Wear coefficient varies by scratching direction and crystallographic orientation•Scratching hardness is a proper material constant to characterize wear volume using Archard’s wear law.