Investigation of bonding features and residual stress in the cold-sprayed single angular titanium particle

Understanding stress evolution and bonding features during the early stages of cost-effective angular particle impact in cold spray deposition is crucial for ensuring mechanical integrity and optimizing the performance of deposited materials. This study investigates the impact dynamics of a single angular titanium particle on a titanium substrate during cold spray deposition, focusing on residual stress evolution, thermal softening, and bonding mechanisms. Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) is employed to investigate the interface region of an angular single titanium splat. Furthermore, the finite element model is used to systematically evaluate the influence of impact velocities (550–950 m/s) on stress distribution, strain evolution, and thermal effects. The results show that maximum tensile residual stress develops at the angular particle/substrate interface due to the combined effects of adiabatic shear instability and stored elastic strain energy, which can lead to the formation of interfacial gaps and jetting, as observed experimentally. These stresses intensify as velocity increases, and a greater volume of the angular titanium particle experiences tensile stresses at higher impact speeds. In contrast, the titanium substrate exhibits compressive residual stresses within a few microns beneath the interface, dominated by peening mechanisms. As a result of peening mechanisms, these compressive stresses increase in both magnitude and depth with rising impact velocities in the titanium substrate. Furthermore, the study demonstrates that thermal softening resistance decreases as velocity increases.