Particle acceleration and deformation on cold spraying of alpha-beta and metastable beta titanium alloys

Cold spray additive manufacturing (CSAM), a solid-state materials deposition technique and an emerging technology currently employed to fabricate and repair components made with high-performance alloys. However, their deformation and bonding mechanisms in relation to the crystal structure of the feedstock materials are poorly explored. The application of CSAM to manufacture components using a wide range of alloys plays a critical role to increase the number of application areas or industries for the technology. This work aims to investigate, for the first time, the potential of metastable beta titanium alloys that offer high mechanical strength and ductility for structural applications via CSAM. The particle acceleration, impact phenomena, and bonding characteristics of Ti-5553 metastable beta and Ti-64 alpha-beta (α-β) titanium alloys during cold spraying were investigated. Computational Fluid Mechanics and Finite element simulations along with swipe tests and in-flight particle velocity measurements were all employed to investigate the critical velocities of these two alloys. The alloy compositions and microstructure influenced the impact and deformation behavior during cold spraying and consequently, their critical velocities. This study critically evaluates and provides a better understanding of the deformation behaviour of metastable beta titanium alloy under ultrahigh strain-rate deformation during cold spraying.