Characterization of dynamic recrystallization and development of a processing map during hot deformation of FeCoCrNi high-entropy alloy
Seyyed Ali Sajadi, Mohammad Reza Toroghinejad, Ahmad Rezaeian
Abstract
The hot deformation behavior of a FeCoCrNi high-entropy alloy was delved through hot compression tests within the temperature range of 800–1200 ◦ C and at strain rates ranging from 0.001 to 1 s -1 . Microstructural characterization under various deformation conditions was performed using optical microscopy and scanning electron microscopy equipped with electron backscatter diffraction. An Arrhenius-type equation was developed using the data obtained by analyzing stress-strain curves to evaluate the hot deformation behavior of the alloy and provide the constitutive equation. It was observed that the hot deformation of the alloy was carried out with an activation energy of about 508 kJmol -1 , which was primarily governed by the lattice diffusion of Cr element. Findings further revealed that discontinuous dynamic recrystallization occurred along initial grain boundaries during hot deformation as the main restoration phenomenon. In addition, it was suggested that the grain boundary migrating and dislocation climbing were identified as the main active mechanisms. A processing map was constructed using energy consumption efficiency ( η ) and flow instability. The results indicated that instable flow within the temperature range of 1100–1200 ◦ C and different strain rates can be directly attributed to grain growth under this condition.