Heterogeneous microstructural evolution in cold sprayed copper coatings using local Zener-Hollomon parameter and strain

Cold spray processing is a solid-state coating technique and an emerging method for additive manufacturing. In this study, we employ a cold spray system to deposit copper coatings over a large temperature range (373 K to 873 K) and we systematically investigate the microstructural evolutions using EBSD and TEM techniques. Diverse microstructures are observed, including recrystallized grains, annealing twins, shear bands, submicron-sized grains, deformation twins, and nanometer-sized grains. We have created the first deformation mechanism map for cold sprayed coatings to interpret and predict the heterogeneous microstructural evolutions in copper using the local Zener-Hollomon (Z) parameter and plastic strain (strain-Z-microstructure map). Such a map can be used to predict and design the microstructures of cold sprayed copper samples based on processing parameters and can also be extended to other severe plastic deformation (SPD) processes, such as cutting, extrusion, solid-phase welding, and other solid-state additive manufacturing processes.