High Entropy Alloys: Development and Applications

Traditional commercial alloys have been used for decades. The design of these alloys is based on selecting a main component otherwise known as a principal element depending on anticipated properties. The principal element would thus form the matrix. Commercially available alloy systems are either aluminium based, copper based, iron based or nickel based in the case of super alloys. However, this limits the number of alloys that can be made from these traditional alloy systems. New alloys have been developed at the turn of the new millennium referred to as High Entropy alloys. These alloys have been achieved through equiatomic substitution, by replacing individual components with multicomponent equiatomic or near-equiatomic mixtures of chemically similar species. Although vast information about the behaviour of binary systems is available, little knowledge is available about these multi-component systems. This paper reviews the development of high entropy alloys, their properties and characteristics and present and future applications.