AlCoCrFeNix high-entropy alloy coatings in high-pressure cold spray development

Cold spray (CS) deposition relies on effective particle adherence through kinetic energies. Although high-entropy alloys (HEA) are gaining research attention as a feedstock of interest thanks to their characteristic physio-mechanical properties, the bonding strength between the incoming particles at the interface and follow up splats during CS is becoming prevalent to investigate. CS is a process of solid-state deformation of particles at relatively low temperatures; the microstructural evolution in the coating and substrate interface is expected to be shaped by the particle impact condition. In this research, a mechanically alloyed AlCoCrFeNi_x feedstock family (where x = 0,1 and 2.1) was investigated through high-pressure cold spray (HPCS) deposition on maraging steel and titanium substrates. The goal was to evaluate the effect of adding Ni equiatomic content over a progressive milling regime in the HEA particles by i) identifying the HPCS process parameters; and ii) analyzing resulting microstructure transformation and bonding characteristics at the single pass substrate-deposit interface using experimental/characterization/testing techniques such as scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), electron backscattered diffraction (EBSD), nanoindentation, among others.