Creep behavior under isothermal and non-isothermal conditions of AM3 single crystal superalloy for different solutioning cooling rates

Isothermal and non-isothermal creep experiments are performed using AM3 Ni-based single crystal samples which were cooled from the solutioning temperature during heat treatment with different cooling rates. Cooling rates from the solution temperature influenced the precipitate size and distribution and influenced creep properties, with creep lifetimes increasing and secondary creep rates decreasing with faster cooling rates. Up to a cooling rate of about 100 °C/min, the microstructure is very inhomogeneous and the γ׳-particles exhibit an irregular shape and are partially large in size. For the fastest cooling rate (300 °C/min), the microstructure consists of ordered cubic γ׳-precipitates surrounded by narrow γ-channels. According to Orowan stress calculations, the investigated creep properties under both isothermal and non-isothermal conditions seem to be mainly controlled by the resistance to dislocation bowing in the γ-channels.