Segregation-sandwiched stable interface suffocates nanoprecipitate coarsening to elevate creep resistance

We demonstrate a strategy to stabilize nanoprecipitates in Al-Cu alloys, based on computational design that identifies synergistic solutes (Sc and Fe) that simultaneously segregate to the theta '-Al2Cu/Al interface and strongly bond to one another. Furthermore, Sc and Fe are predicted to each segregate into a separate atomic plane, forming a sandwiched structure reinforcing the interface. This interfacial architecture was realized through a simple heat treatment in a Sc-Fe-Si triple-microalloyed Al-Cu model alloy. Such a back-to-back layered interface, thermodynamically stable and kinetically robust, is found to suffocate nanoprecipitate coarsening at 300 degrees C, enabling a dramatic reduction in creep rate. IMPACT STATEMENT The segregant architecture of synergistic solute at theta '-Al2Cu/Al interface was guided by computational calculations and artificially realized at atomic scale to achieve an ultra-high thermal stability of theta '-Al2Cu, leading to a high creep resistance at 300 degrees C.