Abstract
The study provided a systematic investigation into the creep behavior of a γ'-strengthened Co-based single crystal superalloy Co-7Al-8W-1Ta-4Ti(at.％)under compressive creep conditions at 1000 ℃ and 137 MPa.Simultaneously,the microstructural changes during thermal exposure at 1000 ℃ were thor-oughly examined.The microstructure analysis of the creep samples revealed the presence of y/y'rafts,twins,stacking faults,and dislocation networks.Statistical analyses were conducted to assess the dimen-sions and volume fractions of γ',alongside Vickers hardness tests and nanoindentation experiments.Re-sults show that γ'dissolution in the creep samples with substantially higher dissolution rates compared to thermal exposure.Localized Co depletion and Ti enrichment in twin is observed in creep sample,po-tentially initiating localized phase transformations.Concurrently,lattice rotation occurred during creep,resulting in a progressive deviation of crystal orientation away from the[001]direction.Stacking faults transitioned from network-like structures to parallel configurations,and twins played a significant role in creep deformation,particularly in samples subjected to 382 h creep.The study also explored the evo-lution of Vickers hardness and the elastic modulus,introducing a systematic linear model to describe Vickers hardness changes during both thermal exposure and creep conditions.
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