Entropy-Engineered Aluminum-Based Superalloys with Superior High-Temperature Mechanical Properties

Abstract

In the quest for lightweight high-performance metallic materials in transportation, the limitations of high-strength Al-based alloys in high-temperature (HT) applications have posed a significant challenge. To overcome this long-standing bottleneck, an innovative design strategy, combining entropy-driven compositional design and rapid solidification processing, to develop “Al-based superalloys” with a γ/γ′ duplex microstructure reminiscent of Ni-based superalloys is presented. By incorporating multirefractory elements (Ti, Zr, Hf, Nb, and Ta) into the alloy design, a high-volume fraction of thermally stable coherent γ′ phase for strengthening the Al-rich face-centered cubic matrix from room temperature (RT) to temperatures close to the melting point is achieved. The developed Al-based superalloys exhibit exceptional specific yield strength and specific Young's modulus, surpassing aerospace aluminum, cobalt, nickel, and titanium alloys from RT to HT. Moreover, our ultra-strong alloys demonstrate deformability and exhibit fine-dimpled fracture behavior. The versatility of our fundamental research on Al-based superalloys demonstrates their potential and can inspire further research in this field. This work opens new possibilities for the development of next-generation lightweight alloys with novel microstructures and outstanding mechanical properties.