新型钴基高温合金中 W 元素对蠕变组织和性能的影响

γ' precipitate strengthened cobalt-based alloys exhibit superior comprehensive properties and are potential candidates for the anticipated next-generation superalloy. The phase field method, which considers the combined effect of multiple energy fields, effectively elucidates the processing and mechanism of microstructure evolution. By using the ternary elastoplastic phase field model coupled with CALPHAD and crystal plasticity model, the γ' evolution of Co-9Al-xW (x = 8, 9, and 10; atomic fraction, %) alloys during creep processes is simulated herein. The corresponding rafting behaviors and creep properties are evaluated from the perspective of the changes in second-order moment invariant map (SOMIM) and stress/strain fields. The results show that as the W content increases, the volume fraction of the γ' phase increases, the plastic strain in the γ matrix reduces, and rafting occurs with accelerated rate, which enhances the creep property. Further, the SOMIM analysis shows that the raft structure leads to a steady creep behavior in 9W and 10W alloys. In addition, the alloy with a high W content has a high misfit stress in the γ matrix, which leads to a low plastic strain.