Deposition behavior and bonding mechanism during cold spraying of Ti6Al4V on different substrates

In this study, single Ti6Al4V (hereafter referred to as "Ti64 ") particles were deposited onto various substrates (Al, Cu, 304 stainless steel (SS), and Ti64) by cold spraying to investigate the contact interaction and bonding mechanisms between the particle and substrate. The results showed that deformation occurred only on the Al substrate when impacted by the Ti64 particle, whereas both, the Ti64 particle and Cu substrate, were deformed upon impact. In the case of Ti64/SS and Ti64/Ti64, the particles underwent deformation, whereas the substrates were not severely deformed. Transmission electron microscopy analysis of the interfacial microstructure of Ti64/ Al showed an interfacial oxide layer between the particle and substrate, which prevented the adhesion of the cold-sprayed Ti64 particle. However, localized metallurgical bonding occurred because of the transformation of the oxide layer into an amorphous phase. In contrast, for Ti64/SS, the deformation of both, the particle and substrate, led to grain refinement caused by dynamic recrystallization at the interface. The constituents of the substrate and particle were fully intermixed at the interface and formed a strong metallurgical bond.