High Entropy Materials (HEMs): An Overview

Abstract

AbstractAlloys, the greatest gift of humans, have affected the material world to the greatest extent. The alloy world has evolved from very simple binary solid solution to complex one, consisting of 5 or more components. The beginning of the current century saw a paradigm shift in the alloy design principal leading to discovery high entropy materials (HEMs). Brian Cantor and Jien-Wei Yeh have independently reported the discovery of quinary equiatomic CoCrFeMnNi FCC alloy to start the research activity in HEMs. These are believed to be stabilized by higher entropy of mixing. The properties of HEMs are also significantly affected by enthalpy of mixing, atomic size differences of the components, and valence electron concentration, permitting only suitable alloying elements to increase the strength, ductility, and other physical properties of these alloys. Interestingly, the HEMs can be bought under the broad category of complex concentrated alloys which do not necessarily lead to formation of complex phase and microstructure. Recently, the discovery of entropy-stabilized ceramics has expanded the scope of this novel concept, leading to development of novel multicomponent ceramics.KeywordsMulticomponent alloysHigh entropy alloys (HEMs)High entropy materials (HEMs)Core effects