The effect of chromium and cobalt segregation at dislocations on nickel-based superalloys

• Published in: Scripta materialia Vol. 145; pp. 76 - 80
• Main Authors: Kontis, Paraskevas, Li, Zhuangming, Collins, David M., Cormier, Jonathan, Raabe, Dierk, Gault, Baptiste
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2018; Elsevier
• Subjects: Acoustics; Atom probe tomography; Automatic; Biomechanics; Chemical Sciences; Dissolution; Electric power; Electromagnetism; Engineering Sciences; Fluid mechanics; Material chemistry; Materials and structures in mechanics; Mathematical Physics; Mechanics; Physics; Pipe diffusion; Polymers; Quantum Physics; Rafting; Reactive fluid environment; Recrystallisation; Thermics; Vibrations; Recrystallisation; Rafting; Dissolution; Atom probe tomography; Pipe diffusion
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2017.10.005

The segregation of solutes at dislocations in a polycrystalline and a single crystal nickel-based superalloy is studied. Our observations confirm the often assumed but yet unproven diffusion along dislocations via pipe diffusion. Direct observation and quantitative, near-atomic scale segregation of chromium and cobalt at dislocations within γ' precipitates and at interfacial dislocations leading to the partial or complete dissolution of γ' precipitates at elevated temperatures is presented. Our results allow us to elucidate the physical mechanism by which pipe diffusion initiates the undesirable dissolution of γ' precipitates. [Display omitted]