Cold Spray High Speed Impact: Bridging Atomic and Macro Scale Phenomena Through Local Dislocation Rosette Visualization Using a Single Crystal Substrate

The fundamental modifications induced by a cold sprayed (CS) particle following its impact onto a substrate surface has yet to be completely experimentally defined. The influence of particle temperature and velocity on its impinging energy and influencing zone, which controls the subsequent atomic bonding process, has not yet been fully analyzed. Up to now, atomic level characterization using transmission electron microscopy has described the atomic order/disorder at the particle/substrate interface, while grain size level characterization focusing on macroscopic features has associated grain refinement, twinning and dynamic recrystallization to the presence of shear instabilities, high stress and high strain rate deformation. However, both scales do not provide further material deformation details, i.e. the size and geometry of the full micro-plasticly deformed zone and characterization of micro-mechanisms (dislocation behavior and activity). To access these features, the current study uses an etch pit technique on a single crystal material to reveal the complete spatial location of dislocations, loading history, generated stress and impact direction generated by cold spray impacts. A finite element model is also used and validated to simulate the single crystal anisotropic high strain rate deformation.