Hot Compression Behavior of a Novel High Entropy Alloy

Abstract

In this study, the flow behavior of a novel high entropy alloy, (FeNi)67Cr15Mn10Al5Ti3, was investigated through isothermal compression performed at temperature range of 980–1100 °C using strain rates of 0.01 s−1 and 0.1 s−1. The alloy was mainly composed of a face-centered cubic (FCC) phase and a small amount of body-centered cubic (BCC) phase. During deformation, the alloy exhibited typical single-peak type flow curve at all testing conditions. The stress exponent was determined to be ~5.5 with an apparent activation energy of ~426 kJ/mol, which indicated that dislocation creep was the rate-controlling process. Metallurgical inspection revealed that due to the plastic incompatibility of the two phases, the deformation is non-uniform especially at lower temperature and higher strain rate. Continuous dynamic recrystallization (CDRX) intensively occurred in both phases, but the recrystallization seemed to be much easier in the BCC phase. Dense low angle grain boundaries (LAGBs) were produced as a consequence of CDRX. At a lower strain rate, the LAGB ratio was evidently decreased with the increasing temperature. The sub-grain size was sensitive to the deformation parameter especially at a high temperature and low strain rate. A low temperature and high strain rate were beneficial for grain refinement but a much higher straining was required.