Enhancement of plastic deformation in ultrasound-assisted cold spray of tungsten: a molecular dynamics study
Tungsten (W) is widely valued for its exceptional thermal stability, mechanical strength, and corrosion resistance, making it an ideal candidate for high-performance military and aerospace applications. However, its high melting point and limited room-temperature plasticity pose significant challenges for processing W using additive manufacturing (AM). Cold spray (CS), a solid-state AM process that relies on high-velocity particle impact and plastic deformation, offers a promising route for additive manufacturing of W, yet conventional CS fails to induce sufficient plastic deformation for effective bonding. In this study, we employ atomistic simulations to investigate the effect of ultrasonic perturbation in enhancing plastic deformation during CS of W, with a focus on acoustoplasticity-driven deformation mechanism. We show that ultrasonic perturbation leads to pronounced acoustic softening and promotes transient temperature elevation at the particle-substrate and particle-particle interfaces, thereby enhancing plastic deformation compared to non-ultrasound-assisted CS. Additionally, our results show that the coupled effects of acoustic softening and enhanced transient thermal activation lead to substantial improvements in interfacial bonding across a wide range of impact velocities, particle sizes, and ultrasonic parameters. Finally, we analyze the feasibility of ultrasound-assisted CS for manufacturing heterogeneous interfaces consisting of an equimolar Vanadium (V)-Tungsten (W) coating on a W substrate. Simulations reveal distinct mechanical behavior and dislocation densities compared to the homogeneous W on W CS configurations. Overall, this work highlights the potential of ultrasound-assisted cold spray as an effective strategy for manufacturing uniform coatings and engineered alloys, thereby addressing critical limitations in the additive manufacturing of refractory metals.