D022 precipitates strengthened W-Ta-Fe-Ni refractory high-entropy alloy

Authors：Li, Tong; Chen, Jin -Xi; Liu, Tian-Wei; Chen, Yan; Luan, Jun-Hua; Jiao, Zeng-Bao; Liu, Chain-Tsuan; Dai, Lan -Hong^*

Source：JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY, 2024, 177: 85-95.

DOI：10.1016/j.jmst.2023.07.069

• Refractory high entropy alloy
• Multi-phase structure
• D0(22) superlattice
• Precipitation strengthening

Refractory high-entropy alloys have recently emerged as promising candidates for high-temperature structural applications. However, their performance is compromised by the trade-off required between strength and ductility. Here, a novel W30Ta5(FeNi)(65) refractory high-entropy alloy with an outstanding combination of strength and plasticity at both room and elevated temperatures is designed, based on the multi-phase transitions design strategy. The alloy comprises a body-centered cubic dendrite phase, a topologically close-packed mu rhombohedral phase, and a high-density coherent nano-precipitate gamma '' phase with the D0(22) structure (Ni3Ta type) embedded in a continuous face-centered cubic matrix. Owing to precipitation strengthening of D0(22), the yield stress of the alloy is determined as high as 1450 MPa, which is a significant improvement (similar to 100%) in comparison with the D0(22)-free alloy, without a loss of ductility. This alloy exhibits an excellent high-temperature strength, with the yield strengths of 1300 MPa at 600 degrees C and 320 MPa at 1000 degrees C. Detailed microstructural characterization using transmission electron microscopy, high-angle annular dark-field imaging, and three-dimensional atom probe tomography analyses indicated that this superior strength-plasticity combination stems from the synergy of a multiple-phase structure. These results provide a new insight into the design of RHEAs and other advanced alloys.

• Institution
  中国科学院研究生院