Solidification Pathway, Phase Stability, and High-Temperature Deformation Mechanisms of a Dual-Phase High-Entropy Alloy

High-entropy alloys (HEAs) offer a platform for designing microstructures suited to extreme conditions. Dual-phase HEAs show promising strength-ductility combinations at high temperatures, but maintaining phase stability above 800°C remains challenging. This study introduces a novel dual-phase HEA (FCC + BCC) with microstructural evolution driven by spinodal decomposition and intermetallic stabilization. The alloy transitions from initial FCC to mixed FCC-BCC laths, with spinodal nanophases in the BCC matrix. Coarse σ (FeCr-type) and NiZr-rich intermetallics form at phase boundaries, enhancing stability. Post-solidification analysis shows σ phase consuming spinodal BCC at high temperatures, while retained nanoscale BCC spinodal contributes to strain incompatibility and HDI hardening. This interplay balances phase stability and mechanical performance. Compressive tests at 800-1000°C (strain rate 1/s) reveal phase stability and deformation mechanisms. Behavior is governed by lamellar morphology and σ/α-Cr ↔ B2 interactions. Retained GNDs and enhanced twinning sustain work hardening up to 900°C. At 1000°C, FCC-dominated strain localization triggers rapid softening via dynamic recrystallization. These findings deepen understanding of high-temperature deformation in dual-phase HEAs, offering pathways for optimizing alloy design in extreme environments.