Comparative Study of Mechanical and Corrosion Behaviors of Cost-Effective AlCrFeNi High Entropy Alloys

AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) has attracted significant interest among researchers due to unprecedented mechanical properties compared with single-phase solid solution high entropy alloys; however, the high content of cobalt element limits its engineering applications. In this paper, the mechanical and corrosion behaviors of cost-effective AlCrFeNi3.1 and AlCrFe2Ni2.1 HEAs were systematically studied by tensile tests and electrochemical methods; meanwhile, the results were compared with AlCoCrFeNi2.1 EHEA. The results indicated that all the studied HEAs showed dual phase microstructure composed of FCC and BCC/B2 phases. Due to the hetero-deformation induced strengthening, all the studied HEAs showed an excellent combination of strength and ductility with fracture strength over 1 GPa and fracture strain exceeding 17%, indicating that substituting the cobalt element of AlCoCrFeNi2.1 EHEA by nickel or iron element is feasible from the perspective of mechanical properties. As for the corrosion behaviors in 3.5 wt.% NaCl solution, AlCrFeNi3.1 HEA exhibited the best corrosion resistance due to the high volume fraction of the corrosion resistant FCC phases and low Al/Cr ratio of BCC/B2 phases, while AlCrFe2Ni2.1 HEA showed the worst corrosion resistance owing to the high Al/Cr ratio of BCC/B2 phases.

Automated summary

This paper systematically studied the mechanical and corrosion behaviors of AlCrFeNi3.1 and AlCrFe2Ni2.1 HEAs, and compared the results with AlCoCrFeNi2.1 EHEA. The results showed excellent strength and ductility in these HEAs, indicating the feasibility of substituting cobalt element and AlCrFeNi3.1 HEA exhibited the best corrosion resistance.