Microstructure and wear resistance of an intermetallic-based Al0.25Ti0.75CoCrFeNi high entropy alloy

An Al0.25Ti0.75CoCrFeNi high entropy alloy (HEA), consisting of multiple principal elements, forms the uncommonly observed chi-phase, which is a large lattice parameter intermetallic phase based on the body centered cubic crystal structure, as the matrix phase and a L21 phase (ordered Huesler phase, X2YZ-type based on the face-centered cubic structure) as a major secondary phase. Additionally, a face centered cubic phase with a high density of nano-twins is also present in the microstructure as a third phase. The extremely high Vicker's hardness of the matrix chi phase (1090Hv ± 14) and of the L21 phase (570 ± 9 HV) along with low sliding coefficient of friction (∼0.3) and low wear rate (∼1.2 × 10−5 mm3/N m) makes this HEA a promising candidate for mechanical wear-resistant applications.