Synergistic Enhancement of the Strength and Ductility of High-Entropy Alloy at High Temperatures via Multiple Heterogeneous Microstructure Modulation

• • At ambient temperature, the HEA achieves an ultimate tensile strength of 1700 MPa with 15.9% elongation, surpassing conventional FCC-based HEAs that typically exhibit yield strengths below 500 MPa, enabling weight-critical structural components without ductility trade-offs. • • In the 650–750 °C intermediate temperature range, the alloy maintains a yield strength of 1 GPa and tensile strain above 14%, directly mitigating the ITB failure mode that causes premature fracture in conventional HEAs and superalloys. • • The coherent L1₂ phase stabilizes grain boundaries against oxygen diffusion and crack propagation, eliminating brittle grain boundary phases that degrade performance in legacy alloys such as ATI 718Plus under similar conditions. • • The heterogeneous microstructure modulation—combining grain size variation and L1₂ precipitate heterogeneity—delivers a strength-ductility synergy that outperforms homogeneous precipitation-strengthened alloys, offering a scalable design route for safety engineering applications.