Engineering ordered two-dimensional defect phases to strengthen structural alloys

Defects in crystals are usually considered to be consequences of deformation, but they can also be engineered as strengthening features. Planar defects can strengthen structural alloys but usually form only during deformation or service, limiting control over their density, stability, and chemistry. We show that predeformation followed by aging can convert such defects into a designed architecture of ordered defect phases. In a single-crystal cobalt-nickel-based superalloy and a polycrystalline cobalt-chromium-tungsten alloy, this treatment creates dense networks of coherent, atomically thin, ordered defect-confined phases. These increase room-temperature strength by more than 200 megapascals and reduce the superalloy's minimum creep rate by more than threefold. Electron microscopy and simulations show that local chemical ordering amplifies strengthening and that the ordered defect phases remain shearable while impeding slip transmission.