Microstructural investigation of the deformed volume beneath quasi-static and dynamic indentation in Ni single crystal

The deformed volume beneath the Ni (100) single crystal after quasi-static (<10¹ s⁻¹) and dynamic indentation (>10³ s⁻¹) tests were comparatively investigated. The lattice rotation and microstructure were explored using on-axis TKD and TEM methods. The results show that quasi-static indentation induces symmetrical lattice rotation and uniformly distributed sub-grains, while dynamic indentation shows asymmetrical crystal rotation and severe plasticity localization close to the edge of indenter. The observed difference is well interpreted by the dislocation rearrangement and dislocation emission mechanism in quasi-static and dynamic indentation respectively. The heterogeneity of plasticity in dynamic indentation can be attributed to the higher contact stress and pre-existing surface defect on the edge of indenter leading to the concentrated dislocation emission.