High-entropy alloys (HEAs) are alloys with five or more principal elements. Due to the distinct design concept

these alloys often exhibit unusual properties. Thus

there has been significant interest in these materials

leading to an emerging yet exciting new field. This paper briefly reviews some critical aspects of HEAs

including core effects

phases and crystal structures

mechanical properties

high-temperature properties

structural stabilities

and corrosion behaviors. Current challenges and important future directions are also pointed out.