Phase evolutions during mechanical alloying and annealing of CrMnFeCoNi high-entropy alloy

The synthesis and phase evolutions of the CrMnFeCoNi high-entropy alloy (HEA) during mechanical alloying and subsequent annealing were critically examined. Mechanical alloying produced a mixture of FCC, α ' -martensite, and ε-martensite phases, attributed to severe plastic deformation inducing martensitic transformation. Complete alloying was achieved after ∼30 h of milling, while a homogeneous nanostructured HEA powder formed after ∼90 h due to progressive grain refinement. The aim of this study is to analyze the time-resolved phase evolution during milling with annealing by combining differential scanning calorimetry (DSC), interrupted heat treatments, and post-annealing X-ray diffraction (XRD), allowing direct identification of the reaction responsible for the DSC peak. The reversion of α ' -martensite to a fully austenitic microstructure, accompanied by minor grain growth was detected.