Hot-extruded AlCoCrFeNi high-entropy alloy with ultra-high strength and large ductility

Abstract

An equimolar AlCoCrFeNi high-entropy alloy (HEA) with trade-off properties between strength and ductility is prepared by hot extrusion for the first time. Compared with the HEAs prepared by casting and heat treatments, hot-extruded AlCoCrFeNi HEA not only contains uniform elements and phase distributions but also finer grains and microstructures. The average diameter of the homogeneous equal-axis fine grains is less than 5 µm. The compressive yield strength and ultimate compressive strength of the hot-extruded AlCoCrFeNi HEA reach 1450 and 3500 MPa respectively, while the compressive strain reach 42%. These excellent mechanical properties are attributed to the fine microstructure. In addition, the uniform dispersed network phase structures, ultrafine sub-grains, high density dislocations and blunted cracks in the deformed AlCoCrFeNi HEA are all the important factors affecting the strength and plasticity of the HEA. Hot-extruded AlCoCrFeNi HEA with excellent mechanical properties confirms a great prospect for the preparation of high-strength HEAs.