Design and Characterization of Hierarchically-Strengthened, Cast Al-Ce-Ni-Mn-Sc-Zr Alloys for High-Temperature Applications

We characterize the microstructureMicrostructure and mechanical propertiesMechanical properties of cast Al-Ce-Ni-Mn-Sc-Zr alloysAlloys designed for structural use above 300 °C. We first report on the effect of Ni on the as-cast phase formationPhase formation, where all alloysAlloys consist of fine Al11Ce3 and Ni-rich eutectic phases, but the identity of the Ni-rich phase varies with Ni content. Furthermore, these alloysAlloys contain four coarsening-resistant strengthening phases as determined from SEM and APT investigations: (i) Al11Ce3 and (ii) Ni-rich micron-scale platelets formed during eutectic solidificationSolidification, (iii) L12-Al3(Sc,Zr) nanoprecipitates formed during secondary agingAging, and (iv) Mn solute in the α-Al matrix. The Al-Ce-Ni-Mn-Sc-Zr alloyAlloys possesses higher microhardnessMicrohardness and creep resistance than compositionally simpler alloysAlloys containing fewer of the strengthening phases, indicating that these strengthening mechanisms synergize to provide increased ambient- and elevated-temperature strength.