| Abstract Scope |
Lightweight structural alloys offer a sustainable route to improved energy efficiency. Among them, Al-Li-based ternary alloys with core-shell precipitates exhibit an exceptional combination of high strength-to-weight ratio and superior thermal stability, arising from a size-controlled, coarsening-resistant, and functionally tunable precipitate architecture. However, the fundamental mechanisms governing core-shell precipitate formation remain poorly understood, limiting their application to other alloy systems. This study investigates the influence of core size on shell formation. Our experimental results demonstrate that shell formation occurs only when the core size lies within a critical range. A systematic study of ternary Al-Li-based alloys reveals an upper critical core size beyond which a uniform shell cannot form. As core size increases, shell morphology undergoes a distinct transition, highlighting the role of interfacial energy in governing shell formation. These findings provide mechanistic insights into core-shell precipitate evolution and guide tailoring precipitate architectures for next-generation lightweight, high-performance, sustainable structural alloys. |