Thermal Stability of Thermal-sprayed AlCoCrFe-M High Entropy Alloy Coatings

High entropy alloys (HEAs) have attracted significant interest due to their outstanding mechanical and corrosion-resistant properties. Among them, AlCoCrFe-based HEAs demonstrate great potential for various applications in sustainable energy production and storage. This study focuses on assessing the viability of thermal-sprayed coatings made from AlCoCrFe-based HEAs doped with Mo, V, W, and Zr for high-temperature applications. This work first calculates the pseudo-binary diagrams of isopleths of H4M systems (H4 = AlCoCrFe, M = Mo, V, W, and Zr) with the Calphad approach to explore the compositions of these HEA candidates. The H4M coatings are then fabricated using flame spray and cold spray techniques. A series of heat treatments and pre-oxidation are performed to evaluate the phase stability and characteristics of the thermally grown oxides. This is essential for determining if the coatings are suitable for high-temperature applications where resistance to oxidation and phase transformation is crucial.