広域X線吸収微細構造法で見るミディアムエントロピー合金CrCoNiの局所構造

抄録

The high-entropy alloys/medium-entropy alloys（HEA/MEA）have a great deal of attention, since they have exceptional mechanical properties. In order to clarify the mechanism, we investigated the local structure in the prototype equiatomic alloy CrCoNi by the measurement of the extended x-ray absorption fine structure. The structural disorder is larger in the Cr sites than those in other constituent elements, which is consistent with the larger atomic displacement of the Cr atoms predicted by the first-principles calculations. The Cr atom has a solute-type characteristic in the 3d transition metal atoms that enhances the local disorder. If the sample is annealed in the intermediate temperature range, the difference in the local disorder among the constituent elements decreases.