Dynamic precipitation of σ-phase and element partitioning in equiatomic CoCrFeMnNi high-entropy alloy

Abstract

We studied the development and element partitioning for σ-phase precipitation during hot compression of the CoCrFeMnNi HEA. The σ-phase mainly observed in the necklaced area (NA), where dynamic recrystallization (DRX) occurred but did not occur in the deformed area (DA). The σ-phase increases the hardness and elastic modulus measured by nanoindentation in NA, compared to that of DA. Several defects are transferred by the interface reaction of the crystal grains accompanied by the partitioning of the Cr and Ni elements. This results in the accelerated dynamic precipitation of the Cr-rich σ-phase.