Lattice Distortions in the FeCoNiCrMn High Entropy Alloy Studied by Theory and Experiment
Local lattice distortions have, however, only rarely been investigated in these multi-component alloys.
We, therefore, employ a combined theoretical electronic structure and experimental approach to study the atomistic distortions in the FeCoNiCrMn high entropy (Cantor) alloy by means of density-functional theory and extended X-ray absorption fine structure spectroscopy. Particular attention is paid to element-resolved distortions for each constituent. The individual mean distortions are small on average, <1%, but their fluctuations (i.e., standard deviations) are an order of magnitude larger, in particular for Cr and Mn. Good agreement between theory and experiment is found.
Fig (a) Projection of one of the employed special quasi-random structure (SQS) supercells onto the (100) plane. The black arrows indicate the nearest neighbor bonds for the Mn atoms that are used to extract the distribution of the local bond distortions as shown in (b). In (b), the first-principles computed lattice distortion histogram of Mn-bonds in FeCoNiCrMn is based on 1500 evaluated Mn-bonds. The theoretical data are further analyzed by Gaussian fits (see the text for details).
The experimentally-measured averaged distortion is indicated by the red solid line. Although the mean distortion is rather small (<0.5%), the range of local distortions at the standard deviation is significant (ca. 2%), as indicated in (b).