Defects and their elemental distributions in a crept co-al-w-ti-ta single crystal superalloy

Abstract

The structure of defects and their elemental distributions is the decisive factor to metal’s mechanical properties. The γ/γ′ structure Co-Al-W-based superalloy is a potential replicable alloy to Ni-based superalloys that have been used for a long time. Revealing the microstructure of a defect induced by high-temperature crept provides direct clues for the alloy development. Our work revealed the high-resolution, high-angle annular dark field images and corresponding elemental distributions on crept defects. Defects in the γ phase mainly contain dislocation networks, while the γ' phase contains lots of stacking faults and anti-phase boundaries. The results indicate that dislocation networks and stacking faults contain more weight elements than the base γ′ phase, while anti-phase boundaries contain more light elements. Disclosing atomic structure and its elemental distributions gives direct evidence for alloy design and further high-temperature mechanical improvement.