Achieving exceptional wear resistance in severely deformed cost-effective AlCrFeNi high-entropy alloys through cyclic closed-die forging technique

Herein, the correlation between microstructural refinement and mechanical properties, particularly wear performance, of cost-effective AlCrFeNi_3.1 and AlCrFe₂Ni_2.1 high-entropy alloys (HEAs) processed through cyclic closed-die forging (CCDF) technique was investigated. It was found that both alloys, before and after the CCDF process, exhibited a dual-phase structure consisting of NiAl-rich and CrFeNi-rich phases. Significant grain refinement, the formation of broken CrFeNi-rich dendrite fragments, and their efficient distribution within the matrix were demonstrated by implementing the CCDF technique. However, the microstructure of the AlCrFe₂Ni_2.1 alloy turned out to be finer than that of the AlCrFeNi_3.1 alloy. The CCDF-processed AlCrFe₂Ni_2.1 alloy exhibited the highest microhardness (∼ 719 HV) and the lowest wear rate (∼ (1.3 ± 0.1) × 10^–5 mm³.N⁻¹.m⁻¹), whereas those for the AlCrFeNi_3.1 alloy were 428 HV and (1.8 ± 0.1) × 10^–5 mm³.N⁻¹.m⁻¹, respectively. Finally, the resistance against plastic deformation through reducing the depth of grooves, the degree of delamination, and adhesive wear in the CCDF-processed alloys was clearly revealed compared to the as-homogenized state, specifically for the AlCrFe₂Ni_2.1 alloy. The findings of this study support the suggestion that combining the design of HEAs from inexpensive alloying elements with CCDF processing has the potential to develop economically viable materials without compromising performance.