Tribological Properties of High Entropy Materials

Friction and wear are inevitable for operating mechanical systems, resulting in the deterioration of critical transmission components and even the breakdown of mechanical equipment. With further exploration of the extremely harsh service environment of equipment, such as the high load, wide temperature change, and strong irradiation, increasingly higher performance requirements were put forward on material properties. High entropy materials (HEMs), containing multi-principal alloying elements, have superior advantages over conventional metallic materials in terms of hardness, strength, toughness, wear resistance, and thermal stability, endowing them with huge potential applications as wear resistance and friction reduction materials. In this chapter, the properties and development status of HEMs for tribological applications were reviewed to gain a better understanding of their advantages and limitations obtained by various preparation methods. Moreover, the influencing factors on tribological behaviors, such as crystal structure of the phases, grain size, formation of an oxide layer, and wear mechanisms, are outlined. Finally, the future trend of tribology application of HEM and the key problems to be solved are prospected.