Element dependence of local disorder in medium-entropy alloy CrCoNi

Abstract

The medium-entropy alloy CrCoNi is known to have exceptional mechanical properties. To clarify its local structure, we performed extended x-ray absorption fine structure measurement of CrCoNi. The structural disorder is larger in Cr sites than in other constituent elements, which is consistent with the larger atomic displacement of the Cr atoms predicted by previous first-principles calculations. The Cr atom has a solute-type characteristic that induces local disorder. The differences in local disorder among the constituent elements decrease as the annealing time increases in the temperature range in which a short-range order develops.