A comparative study of flow instability criteria in the processing map of AlFeCoNiMo0.2 high-entropy alloys

High-entropy alloys (HEAs) were studied via hot compression experiments using a Gleeble-3800 thermal simulation tester. The hot deformation behaviour of an AlFeCoNiMo0.2 HEA and the physical significance of the associated parameters were analyzed according to the Prasad, Gegel, Malas, and Murty instability criteria. Processing maps of different instability criteria under different conditions were constructed. The domain corresponding to a temperature range of 1070°C–1150°C with a strain rate range of 0.001–0.1 s−1 and average power dissipation rates of >40% did not feature flow instability; thus, this domain is appropriate for the AlFeCoNiMo0.2 HEA deformation process. Through microstructure analysis, it was determined that the deformation mechanism in the optimal forming region is dynamic recrystallization.