Cold spray deposition of blended and milled AlCoCrFeNi onto hard substrate

The conventional method for producing high entropy alloy (HEA) coatings involves the processing/design/alloying of HEA particles, followed by deposition through physical or chemical methods. In cold spray (CS), the HEA coatings are fabricated by inducing high particle plastic deformation under high-speed impacts with a substrate surface. The inherent properties of both the impacting material and the substrate, such as hardness, significantly influence the deposition process, leading to various interfacial bonding mechanisms, including metallurgical, mechanical, or a combination thereof. In this study, as-blended and milled equiatomic AlCoCrFeNi particles were cold-sprayed onto hard substrates, titanium and steel, respectively, and the interfacial bonding and deposit properties have been compared and examined. The interactions between individual HEA particle elements and between the particle constituents and substrate were systematically investigated. EDS results revealed the dominant presence of Fe, Al, and Cr elements, with particle deformation for each element highlighted. Notably, the mechanical properties and crystallinity of the particles were retained post-deposition, as evidenced by the nano-scale hardness measurements ranging from 53 HV to 832 HV and the XRD patterns and EBSD images of the resulting coatings.