Synergistic Enhancement of the Strength and Ductility of High-Entropy Alloy at High Temperatures via Multiple Heterogeneous Microstructure Modulation
Face-centered cubic (FCC) high-entropy alloys (HEAs) exhibit a critical strength deficiency and intermediate temperature brittleness (ITB) between 650–750 °C, severely limiting their deployment in safety-critical structural applications. This study introduces a coherent FCC/L1₂ HEA engineered through multiple heterogeneous microstructure modulation, incorporating grain size heterogeneity and multimodal L1₂ precipitate distributions. The alloy achieves a tensile strength of 1700 MPa with 15.9% ductility at ambient temperature. In the intermediate temperature regime, yield strength reaches 1 GPa with tensile strain exceeding 14%, effectively suppressing ITB. The primary L1₂ phase stabilizes grain boundaries, inhibiting crack propagation and oxygen diffusion, thereby preventing brittle phase formation at boundaries. This heterogeneous structural strategy provides a validated pathway for designing high-performance HEAs for advanced high-temperature structural applications.