High Entropy Materials

For more than 5000 years, metals and alloys have been formed in roughly the same way-propelling civilization from the Bronze Age to the industrial revolution and the advanced materials age. Now there is a new technique on the horizon that could help us take another big leap forward. This chapter describes high entropy materials (HEM) such as high entropy alloys (HEA), high entropy ceramics (HEC), high entropy polymer (HEP), and high entropy hybrids (HEH). These are the new class of materials that can extract strength from its single phase. For better understanding, an extensive description of various associated key concepts and mechanisms of high entropy alloys are described here. Various core effects such as high entropy effect, lattice distortion effect, sluggish diffusion effect, cocktail effect describe the strengthening process of the materials. Liquid-, solid- and gas-state route, electrochemical process, and additive manufacturing provide direction to synthesis the high entropy materials. High-entropy superalloys, high-entropy bulk metallic glasses, high-entropy flexible materials, and high-entropy coatings have been discussed. Various properties of HEA have been discussed with the example of current fabricated multi-materials. Emerging applications, of HEA such as in automobile, aero-vehicle, machinery, nuclear reactors, electrical and electronics, biomedical, and other applications, have been discussed here.