Creep Behavior of a Ru-Free Nickel-Based Single Crystal Superalloy at Medium Temperatures

Le résumé fourni par la source

By means of creep curves measurement and diffraction contrast analysis of dislocation configurations, the creep behavior and effect factors of a Ru-free nickel-based single crystal superalloy within the temperature range of 740~780°C are investigated. Results indicated that, the cubical γ′ phase transformed into the bunch-like structure. During creep at 760°C/750Mpa, no rafted features of γ′ phase is detected, but the degree of distortion of the cubic γ′ phase near fracture regions is increased. During creep, more super-dislocations shearing into γ′ phase of Ru-free alloy are decomposed on {111} plane to form the partials plus stacking fault, which is attributed to the interaction of the elements to decrease the stacking fault energy of the alloy. Moreover, the screw dislocations shearing into γ' phase of Ru-free alloy during creep at 760 °C may cross-slip from {111} to {100} planes for decomposing to form the configuration of the K-W locks, which is attributed to the higher alloying extent for decreasing the diffusion rate of elements. And the dislocation configuration may restrain the slipping of them to improve the creep resistance of alloy due to the non-plane core structure of them.

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