High-entropy alloys (HEAs) are an exciting new class of alloys, defined as metallic materials with high entropy of mixing in their disordered state. HEAs are also known as multicomponent alloys with at least five major elements. Their final microstructures are not complicated although their compositions are not like conventional alloys with one or two major elements. They can be single phase or multi-phase. They can be crystalline or amorphous. They can be produced by using ingot metallurgy, powder metallurgy, single-crystal, or coating techniques. The concept of HEAs can be extended to high-entropy ceramics (carbides nitrides, borides, or oxides), and high-entropy polymers. Recent advances in HEAs have led to the development of several new and advanced materials, which may potentially overcome the property limits for many advanced applications. An understanding of HEAs have led to the use of novel tools for more detailed study, inluding Bridgman solidification techniques, arc melting, sputter deposition films, pulse laser deposition (PLD), compression/tensile/fracture toughness tests, serration and crackling noise behavior, diffusion barrier, high temperature and very low temperature properties, high energy X-rays synchrotron, neutron diffraction, focus ion beam (FIB), density functional theory modeling (DFT), CALPHAD, and ab initio molecular dynamics (AIMD) modeling.

Original research articles as well as review articles that will stimulate the continuing efforts to understand the structure, phase formation rules, thermodynamics, kinetics, processing, and properties underlying the development strategies and the evaluation of outcomes are encouraged. Also of particular interest are articles describing the new technologies applied for fabricating the materials and characterizing the structural change in the micro- and nanoscale by in situ observations.