Plasma sprayed high entropy alloys: Microstructure and properties of AlCoCrFeNi and MnCoCrFeNi

High Entropy Alloys (HEAs) are a new class of alloys with multi-principle elements in equi-atomic ratio that present novel phase structures. HEAs are known to for their high temperature microstructural stability, enhanced oxidation and wear resistance properties. Apart from bulk material consolidation methods such as casting and sintering, HEAs can also be deposited as a surface coating. In this work, thermal sprayed HEA coatings are investigated as an alternative bond coat material for a thermal barrier coating system. Nanostructured HEAs that were based on AlCoCrFeNi and MnCoCrFeNi were prepared by ball milling and then plasma sprayed. Splat studies were assessed to optimise the appropriate thermal spray parameters and spray deposits were prepared. Subsequently, the microstructure and mechanical properties of both type of HEAs coatings were characterized and compared to conventional plasma spray NiCrAlY bond coats.