Evolution of the Phase Composition of the Cantor CoCrFeNiMn Alloy during Prolonged Annealing

The thermal stability of the Cantor high-entropy CoCrFeNiMn alloy fabricated by mechanical alloying of metal powders in a planetary mill has been studied after a 30-day annealing in the 873–1273 K temperature range. X-ray diffraction and microstructural analysis have shown that the phase composition of the alloy changes during isothermal annealing. Annealing at 873 and 1073 K resulted in the precipitation of an intermetallic chromium-rich σ-phase from the fcc solid solution. Annealing at 1073 and 1273 K resulted in the decomposition of the homogeneous fcc solid solution and the formation of solid solutions that retain their initial fcc structure but differ in their elemental compositions.