A study of hot compression behavior of an as-cast FeCrCuNi2Mn2 high-entropy alloy

Abstract

In this study, hot deformation behavior of an as-cast FeCrCuNi2Mn2 high-entropy alloy (HEA) was evaluated. For this purpose, hot compression tests were carried out in the temperature range of 600–1000 oC and initial strain rate range of 0.001–0.1 s-1. Flow stresses under different deformation conditions were then friction-corrected. Work hardening rate analysis was used to evaluate the occurrence of dynamic recrystallization. Microstructures of the hot compressed specimens were characterized using optical microscopy. Strain-dependent constitutive equations were developed using the data obtained from the Sellars–Tegart–Garofalo equation. The critical and peak strain and the critical and peak stress, as dynamic recrystallization parameters, were extracted from the work hardening rate versus stress curves. The results indicated that the modeled flow stresses were generally lower than the measured ones, which could be attributed to the impact of friction on the flow stress. Microstructural observations after hot compression tests as well as evaluation of work hardening rate versus stress curves showed typical dynamic recrystallization characteristics under different deformation conditions. In addition, with increase in deformation temperature and decrease in strain rate, more DRX grains were formed along grain boundaries and shear bands, resulting in a decrease in the flow stress. The size of the DRX grains was strongly affected by deformation temperature and increased with increase in temperature. The normalized critical stress and strain for the initiation of DRX were calculated as εc/εp = 0.60 and σc/σp = 0.86, respectively. The activation energy of hot deformation was determined to be 708 kJ/mol. It was noticed that the developed constitutive equations could accurately predict the flow stress behavior of the studied alloy over a wide range of experimental conditions.