Hot deformation behavior and constitutive modeling of a cost-effective Al8Cr12Mn25Ni20Fe35 high-entropy alloy
Ahmed W. Abdelghany, Matias Jaskari, Atef Hamada, Antti Jarvenpää, Hassan El-Hofy, Akihiko Chiba, Mohamed Abdel-Hady Gepreel
Abstract
In this study, a new non-equiatomic and cost-effective high-entropy alloy (HEA), Al8Cr12Mn25Fe35Ni20, was designed using thermodynamic parameters and prepared by arc melting. The alloy was subjected to homogenization at 1200 °C and a hot-rolling reduction of 50%. The hot deformation behavior and deformation mechanism were studied at varying strain rates ranging from 0.01 to 10 s−1 and temperatures ranging from 900° to 1100°C via plane strain compression tests using a Gleeble 3800 thermo-mechanical simulator. The phase structure of the rolled alloy was studied using electron backscattered diffraction (EBSD), X-ray diffraction, and differential thermal analysis to detect phase transformation. The constitutive model was implemented to predict the high-temperature flow stress using the Zener-Holloman parameter (Z), which correlated well with the experimental values. The studied HEA exhibited a relatively high activation energy for hot deformation of 389.5 kJ.mol−1, i.e., comparable to those of equiatomic HEAs in the literature. The hot-deformed microstructural features and deformation mechanism were studied using EBSD, which revealed discontinuous dynamic recrystallization as the main softening mechanism. Dynamic recrystallization (DRX) showed the formation of fine grains along the initial grain boundaries, accompanied by Al-Ni-rich B2 precipitates at the recrystallized grain boundaries.