A high-temperature nanostructured Cu-Ta-Li alloy with complexion-stabilized precipitates

We present a bulk nanocrystalline copper alloy that can operate at near-melting temperatures with minimal coarsening and creep deformation. The thermal stability of the Cu-3Ta-0.5Li atomic % (at %) alloy is attributed to coherent, ordered L1₂ Cu₃Li precipitates surrounded by a tantalum-rich atomic bilayer phase boundary complexion. Adding 0.5 at % lithium to the immiscible Cu-Ta system changes the morphology of the nanoscale precipitates from spherical to cuboidal while simultaneously tailoring the phase boundary. The resultant complexion-stabilized nanoscale precipitates provide excellent thermal stability, strength, and creep resistance. The underlying alloy design principles may guide the development of next-generation copper alloys for high-temperature applications such as heat exchangers.