Karpstein N, Wu M, Bezold A, Neumeier S, Cormier J, Spiecker E (2024)
Publication Language: English
Publication Type: Conference contribution, Original article
Publication year: 2024
Publisher: Springer Science and Business Media Deutschland GmbH
Pages Range: 502-511
Conference Proceedings Title: Minerals, Metals and Materials Series
Event location: Champion, PA, USA
ISBN: 9783031639364
DOI: 10.1007/978-3-031-63937-1_47
Elemental segregation at stacking faults in the γ′ phase is a crucial part of the stacking-fault-based deformation of superalloys, and the local composition of a stacking fault critically affects the resistance of γ′ to further shearing. Here, the process of elemental segregation at extrinsic stacking faults in γ′ is examined in Ni-base superalloy CMSX-4 and Co-base superalloy ERBOCo-4. By measuring fault compositions not only after deformation, but also after additional load-free annealing steps of different durations and temperatures between 700 and 900 °C, time- and temperature-dependent aspects of the segregation process are revealed. It is shown that elemental segregation continues to evolve toward an equilibrium composition after a fault has formed, indicating that fully formed stacking faults still provide a driving force for segregation processes and that their equilibrium composition can differ from that which they obtain during their formation. As the elemental segregation process is diffusion-based, it is observed to be considerably slower at a lower temperature. In both alloys, the segregation trends observed after annealing depend on the annealing temperature: A lower temperature promotes a more γ-like fault composition associated with γ′ softening; conversely, at higher temperatures, the fault composition tends toward that of the η phase, which is considered beneficial in the context of local phase transformation strengthening. As η-like segregation also involves the enrichment of slowly diffusing tungsten, kinetics likely play a role in the observed temperature dependence.
APA:
Karpstein, N., Wu, M., Bezold, A., Neumeier, S., Cormier, J., & Spiecker, E. (2024). Temperature and Time Dependence of Elemental Segregation at Stacking Faults in Ni- and Co-Base Superalloys. In Jonathan Cormier, Ian Edmonds, Stephane Forsik, Paraskevas Kontis, Corey O’Connell, Timothy Smith, Akane Suzuki, Sammy Tin, Jian Zhang (Eds.), Minerals, Metals and Materials Series (pp. 502-511). Champion, PA, USA, US: Springer Science and Business Media Deutschland GmbH.
MLA:
Karpstein, Nicolas, et al. "Temperature and Time Dependence of Elemental Segregation at Stacking Faults in Ni- and Co-Base Superalloys." Proceedings of the 15th International Symposium on Superalloys, ISS 2024, Champion, PA, USA Ed. Jonathan Cormier, Ian Edmonds, Stephane Forsik, Paraskevas Kontis, Corey O’Connell, Timothy Smith, Akane Suzuki, Sammy Tin, Jian Zhang, Springer Science and Business Media Deutschland GmbH, 2024. 502-511.
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