High-entropy alloys (HEAs) are substances that are constructed with equal or nearly equal quantities of five or more metals. These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties. Prior to the existence of these substances, alloys consisted of only one or two base metals. For example, additional elements can be added to iron to improve its properties, thereby creating an iron based alloy. Hence, high entropy alloys are a novel material.
Furthermore, research indicates that some HEAs have considerably better strength-to-weight ratios, with a higher degree of fracture resistance, tensile strength, as well as corrosion and oxidation resistance than conventional alloys. Although HEAs have existed since before 2004, research substantially accelerated in the 2010.
Source: https://en.wikipedia.org/wiki/High_entropy_alloys