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. •Al0.25Ti0.75CoCrFeNi high entropy alloy (HEA) consists of a chi (χ) phase matrix with L21 ordered second phase.•A third nano-twinned phase with fcc crystal structure also forms.•Hardness of the matrix bcc chi (χ) phase is 1090 Hv ±14 and of the L21 phase is 570 Hv ± 9.•Ascast alloy offers low sliding coefficient of friction (∼0.3) and low wear rate (∼1.2 x 10-5 mm3/N·m).