Solute segregation at the Al/θ′-Al2Cu interface in Al-Cu alloys

A recent investigation has confirmed that solute atoms segregated to the interfaces between aluminum and θ′-Al2Cu can extend the stability of metastable θ′ to higher temperatures. Herein, we present an extensive first-principles database of the segregation energies of 34 elements to the Al/θ′ interface and identify key descriptors that can guide the design of higher temperature Al-Cu alloys. We find that the segregation energies are strongly correlated with the size and volume of solute atoms and their solubilities within θ′. We provide a physical/chemical basis to the experimentally observed elemental hierarchy in terms of the ability of individual elements to stabilize the Al/θ′ interface. Finally, we suggest a new microalloying strategy that offers opportunities to further increase the critical temperature limit of Al-Cu alloys.