Factors governing static properties and fatigue, fatigue crack growth, and fracture mechanisms in cold spray alloys and coatings/repairs: A review

Abstract

Cold spray is a powder-based additive manufacturing process that leverages the high kinetic energy of particles accelerated at supersonic speeds to create bulk depositions and coatings, with effective metallurgical and mechanical bonding. As a solid-state process, cold spray offers many advantages over conventional thermal spray techniques, including low processing temperatures, the generation of beneficial compressive residual stresses, and desirable properties. Due to the increased utilization of this technology both for 3D manufacturing and repair of structurally critical components, a literature review that comprehensively discusses the state-of-the-art in cold spray materials and their properties is necessary for the adoption and implementation of the technology. Special emphasis is given to the effects of feedstock powder and processing conditions on the resulting microstructure, porosity, and residual stress, and how these affect hardness, static properties, and fatigue and fracture characteristics. The review also addresses important aspects related to the adhesion at the cold spray coating-substrate interface, which is a critical consideration for coating optimization and application of this process to the repair of fatigue-critical components. Future research directions in cold spray are also discussed in this context.