This study investigates microstructural alterations in copper powder during cold spraying. A highly nonhomogeneous structure was observed with average strains of almost 50% close to the interface. Large strains and high strain rates resulted in significant grain refinement and the formation of sub 100-nm grains. Deformation occurred by slip and twinning, the latter promoted by impurities in the copper feedstock. Thin foils from the deposits were studied by TEM analysis and cross-sections of deformed particles were made and examined using FIB-SEM techniques.

Titanium is widely used in aerospace, highly corrosive environments and implants due to unique properties such as high strength to weight ratio and excellent corrosion resistance. Cold gas dynamic spray (cold spray) technology in contrast to current fabrication technologies has provided the potential for titanium to be utilised in broader industrial applications and at lower cost. Particle velocity is the most important parameter in cold spray process that leads to successful deposition of titanium at supersonic speeds. In this study, particle image velocimetry (PIV) is used to determine particle velocities for a commercially pure (CP) titanium powder in respect to cold spray parameters such as temperature and pressure. The results show the significance of flow field measurements using PIV in optimization of the nozzle configuration to achieve the maximum velocity for particles. Further more, PIV results can be used to validate the current models developed for cold spray process.