Developing Thermal Spray High Entropy Alloys for Bond Coat Applications

This thesis explores a new type of metallic alloys called high entropy alloys (HEAs) with enhanced oxidation resistance for application as bond coats in jet engines. Towards this, several compositions of the AlCoCrFeNi family of HEAs were evaluated experimentally and two best compositions were realized. Increased Al , decreased Cr and Fe contents, and optimum microstructure were beneficial to alloy oxidation resistance. Thermal spray coatings of these HEAs were analysed to understand the development of their microstructure as well as oxidation mechanisms. Cold spray was validated as a viable process for coating HEAs for oxygen sensitive high temperature applications. These learnings will aid the development of more efficient turbine engines through blades with longer lifetimes.