Enhancing Ω Phase Thermal Stability in Al Alloys through Interstitial Ordering.

Scandium (Sc) can orderly occupy interstitial sites within the Ω phase of aluminum alloys, forming a new phase that significantly enhances the thermal stability of the alloy. However, Sc is relatively expensive and rare. In this work, we employ first-principles calculations to delve into the physical essence interstitial ordering of Sc in enhancing thermal stability at the electronic level, thereby revealing the crucial factors responsible for this improvement. By computationally screening all potential metallic elements across the periodic table, we uncover that, in addition to Sc, a diverse range of elements including lithium (Li), calcium (Ca), strontium (Sr), and some of rare earth elements (Sm, Ce, Y), possess the potential to contribute to thermal stability enhancement through interstitial ordering mechanisms in aluminum alloys. This study deepens our understanding of microstructural thermal stability and offers novel strategies for designing improved thermally stable Al alloys.