An overview of microstructure, mechanical properties and processing of high entropy alloys and its future perspectives in aeroengine applications

Modern engineering applications continually strive to develop light weight mechanical components with good microstructural stability, improved mechanical properties, corrosion resistance and decreased cost of repairing and maintenance. This necessitates the broad use of advanced high performance materials like high entropy alloys (HEAs). These alloys are created by combining five or more alloying elements in equal or substantial amount. About 5 to 35 at. % of the alloying element is present. It is characterized primarily by greater entropy, slow diffusion, severe lattice deformation, and cocktail effects. Due to its advanced microstructural stability throughout a larger temperature span and for longer length of time, it demonstrates improved mechanical characteristics at ambient temperature, cryogenic temperature, and extreme temperature. The diversity of elemental contents and significantly higher mixing entropy of HEAs make them mechanically superior to classic metals and alloys. It also shows better strength to weight ratio. Hence, it qualifies as a possible structural material and functional material for aeroengine applications. In this work, the studies on the HEAs are briefly reviewed. A basic explanation of the four core effects of HEAs is given. Discussion is held on microstructure and mechanical properties of HEAs. The processing routes of HEAs are presented briefly. The influence of heat treatment on mechanical behavior and microstructure of HEAs is presented. The future scope for research and development in HEAs is briefed.