Creep property and rafting kinetics of Co-based monocrystal superalloys with antiphase boundaries of ?' phase

The precipitation strengthened Co-based superalloys show the great potential for the next generation superalloys of aerospace engine, their mechanical properties are associated with the morphology stability of L12-& gamma;' phase under high temperature and loading state. The antiphase boundaries (APBs) formed by different variants of the ordered fcc-L12-& gamma;'-Co3(Al, W) phase, affect creep morphologies and the high-temperature properties of Co-based superalloys. By coupling with the Kim-Kim-Suzuki (KKS) model and crystal plasticity model, the directional rafting and evolution kinetics of the & gamma;' phase are studied during the creep of Co-10Al-10W (at.%) superalloy. Creep rafting under high temperature and low stress is a process of stress-induced directional coarsening, rafting is affected by the APBs on hindering the directional element diffusion. In the early stage of creep, the increasing number of APBs leads to a lower creep strain. Higher temperature accelerates the rafting and reduces the & gamma;' area fraction. Furthermore, under tensile stress and compressive stress, the APBs show the hindering effect on both Ptype rafting and N-type rafting. This study reveals the effects of APBs on the rafting behaviors and creep properties, the findings are theoretically important for the microstructure optimization of Co-based superalloys.