Beyond Ni-based superalloys: Development of CoRe-based alloys for gas turbine applications at very high temperatures

High temperature material development is mainly driven by gas turbine needs. Today, Ni-based superalloys are the dominant material class in the hot section of turbines. Material development will continue to push the maximum service temperature of Ni-superalloys upwards. However, this approach has a fundamental limit and cannot be sustained indefinitely, as the Ni-superalloys are already used very close to their melting point. Within the framework of a DFG Forschergruppe program (FOR 727) – “Beyond Ni-base Superalloys” – CoRe based alloys are being developed at the Technische Universität Braunschweig as a new generation of high temperature materials that can be used at + 100 °C above single crystal Ni-superalloys. Two main strengthening concepts, namely precipitation hardening by MC carbides and composite hardening by Co Re -type σ phase are being explored in CoRe alloy development. Selected results of microstructural characterizations, including in-situ measurements by synchrotron and neutron scattering are presented.