Optimized Control of Hot-Working Parameters in Hot-Forged (CoCrNi)94Al3Ti3 Medium-Entropy Alloy

It is essential to develop the optimal hot-working process of the (CoCrNi)94Al3Ti3 alloy, a recently developed precipitation-hardened medium-entropy alloy with promising mechanical properties, for its industrial application. In this study, the hot workability of the as-forged (CoCrNi)94Al3Ti3 alloy was investigated over a temperature range of 1000 °C to 1150 °C and a strain rate ranging from 0.001 to 1 s−1 using a Gleeble-1500D thermal simulation machine of Dynamic Systems Inc., USA. As a result, the constitutive relationship was established, and the hot deformation activation energy was calculated as 433.2 kJ/mol, suggesting its well-defined plastic flow behavior under low-energy-input conditions. Hot-processing maps were constructed to identify the stable hot-working regions. Microstructure analysis revealed that the hot-forged (CoCrNi)94Al3Ti3 alloy exhibited continuous dynamic recrystallization (CDRX) behavior under optimal hot-working conditions. Considering the hot-processing maps and DRX characteristics, the optimal hot-working window of hot-forged (CoCrNi)94Al3Ti3 alloy was identified as 1100 °C with a strain rate of 0.1 s−1. This work offers valuable guidance for developing high-efficiency forming processes for (CoCrNi)94Al3Ti3 medium-entropy alloy.