Effect of Annealing on the Structure of the High-Entropy Alloy Al_0.5CoCrCuFeNi

A detailed examination of the effect of annealing on the structure of the high-entropy alloy Al0.5CoCrCuFeNi was carried out using different methods of electron microscopy and X-ray structural analysis techniques. Numerical estimates of the dislocation density 5·1015 m-2, the mean size of the ordered (crystalline) domains 18 nm and lattice micro strain 3·10-3 were obtained through Williamson–Hall analysis of XRD patterns. The estimates of the dislocation density was found to correlate with the estimates of the total length of dislocation segments per unit volume which effectively interacts with elastic vibrations of the sample 4·1013 m-2, as determined from acoustic relaxation measurements. This is consistent with the idea that a significant portion of dislocations are concentrated in grain boundaries, and only dislocation segments located inside grains and having a favorable orientation with respect to the direction of sound wave propagation can effectively interact with cyclic deformation of the sample.