Hot Deformation Behavior and Microstructure Evolution of Single-Phase Body-Centered Cubic Lightweight High-Entropy Alloys

Lightweight high-entropy alloys (LHEAs) have attracted significant attention due to their excellent mechanical properties. Understanding their hot deformation behavior is crucial for the preparation of large-scale ingots. However, many LHEAs reported to date exhibit limited hot workability owing to their high required hot-working temperatures. In this study, single-phase body-centered cubic (BCC) Ti-Zr-V-Nb-Al-Mo LHEA were employed as a model system to establish the stress–strain relationship over a temperature range of 800-1100 °C and strain rates from 10⁻³ to 1 s⁻¹. Through calculation of the hot deformation activation energy and construction of a hot processing map, it was found that the single-phase BCC LHEAs possess a relatively low activation energy (219 kJ·mol ⁻¹) and a lower instability temperature, resulting in a broader hot-processing window. Microstructural analysis of the deformed samples reveals that the single-phase BCC LHEAs exhibit reduced resistance to dislocation slip during high-temperature deformation, which promotes grain-boundary bulging and sliding and tends to induce discontinuous dynamic recrystallization. These mechanisms effectively lower the deformation resistance of the alloys. The findings provide valuable insights into the hot deformation behavior and hot workability of LHEAs and may inform the processing of other alloy systems.