Creep property and rafting kinetics of Co-based monocrystal superalloys with antiphase boundaries of γʹ 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 L1 2 -γʹ phase under high temperature and loading state. The antiphase boundaries (APBs) formed by different variants of the ordered fcc-L1 2 -γʹ-Co 3 (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 γʹ 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 γʹ area fraction. Furthermore, under tensile stress and compressive stress, the APBs show the hindering effect on both P-type 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. • Directional diffusion of W is hindered by APBs during creep of Co–Al–W superalloy. • APBs inhibit the rafting of γʹ phase under tensile and compressive creep stress. • APBs improve the creep resistance at the early stage of creep. [ABSTRACT FROM AUTHOR]