Chemical evolution-induced strengthening on AlCoCrNi dual-phase high-entropy alloy with high specific strength

Quaternary AlCoCrNi alloy was designed by removing the heavy constituent of Fe from the dual-phase AlCoCrFeNi high-entropy alloy to achieve low density with good mechanical properties. The AlCoCrNi alloy exhibited a nano-scale dual-phase structure consisted of Cr-rich A2 and Ni(Co)-Al-rich B2 phases with a high degree of coherence in both dendritic and interdendritic regions. In particular, the Ni(Co)-Al-rich B2 phase revealed the non-stoichiometric composition between the Ni and the Al, which deviated with the Ni-Al-rich B2 phase with a stoichiometric composition in the previous AlCoCrFeNi high-entropy alloy. The chemical evolution in the constituent phases strongly affected the mechanical properties of the dual-phase high-entropy alloy. Based on these microstructural features of the AlCoCrNi alloy, the mechanical properties were systematically investigated at wide temperature ranges.