Unique High Temperature Deformation Behavior of a Harmonic Structured High Entropy CrMnFeCoNi Alloy

The Harmonic Structure (HS) design was applied to a high entropy CrMnFeCoNi alloy with two different ultrafine-grained (UFG) fractions. The high-temperature deformation behavior of the alloy with those kinds of HS compacts, as well as a homogeneous (Homo) compact, was studied by compression tests at a strain rate of 0.01/s at 1073 K. The stress-strain curves of the Homo and HS compacts exhibited strikingly disparate characteristics, rendering them quite distinctive. The Homo compact exhibited a steady state deformation following the onset of yielding, whereas the two types of HS compacts demonstrated a softening behavior with increasing strain. It is notable that the HS compacts exhibited the formation of a smaller misoriented grain concentration at the UFG network structure, designated as the “Shell,” at the initial stage of deformation. Conversely, the Homo compact exhibited a comparable microstructural alteration only following the occurrence of a substantial strain region. It can thus be posited that the process of dynamic recrystallization occurred at an earlier stage in the HS compacts in comparison to the Homo compacts. In other words, a selective dynamic crystallization occurs at the Shell in the HS compacts at high temperature deformation.