Revealing the γ′ Evolution During Controlled Cooling in Udimet 720LI by Electron Microscopy with Complementary in-Situ SAXS
Tsankova S, Quadfasel A, Köbrich M, Witulski T, Stark A, Solís C, Neumeier S (2026)
Publication Type: Conference contribution
Publication year: 2026
Publisher: Springer Science and Business Media Deutschland GmbH
Pages Range: 743-754
Conference Proceedings Title: Minerals, Metals and Materials Series
Event location: Pittsburgh, USA
ISBN: 9783032351753
DOI: 10.1007/978-3-032-35176-0_41
Abstract
Understanding the microstructural evolutionMicrostructural evolution of Ni-base superalloysSuperalloy during cooling from solution heat treatmentHeat treatment is essential for optimizing turbine disc performance. In this study, a multi-technique approach was employed to investigate theγ′ precipitation γ′ precipitationPrecipitation behavior of Udimet 720LIUdimet 720LI under controlled continuous coolingContinuous cooling conditions. A series of cooling experiments were conducted using a quenching dilatometer to apply precisely defined cooling rates between 0.7 and 100 °C/s. Selected experiments were complemented by synchrotron-based small-angle X-ray scattering (SAXSSmall-Angle X-ray Scattering (SAXS)) measurements to track the precipitation kineticsPrecipitation kinetics during cooling. Post-cooling microstructural characterization by scanning electron microscopy (SEM) showed that the grain size and primary γ′ precipitates remained unaffected by the cooling rate, whereas the secondary γ′ precipitates exhibited a strong cooling rate sensitivityCooling rate sensitivity. Their average diameter followed a power-law relationship with cooling rate, with an exponent consistent with diffusion-controlled growth. The size distributions were broad at slow cooling and narrow at high cooling rates, in agreement with the nucleation burst theory described in literature. The SAXSSmall-Angle X-ray Scattering (SAXS) analysis showed very good agreement with the SEM results and additionally revealed the presence of fine tertiary γ′ precipitates, with diameters below the SEM resolution limit. These findings highlight the importance of combining SEM with in-situ SAXSSmall-Angle X-ray Scattering (SAXS) to capture the full precipitate population across multiple size scales. By linking in-situ phase transformation kinetics with post-cooling microstructural analysis, this study establishes a framework for quantifying the relationship between cooling rate and γ′ evolution and supports the development of optimized heat treatmentHeat treatment strategies for turbine disc alloys.
Authors with CRIS profile
Svetoslava Tsankova
Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)
Steffen Neumeier
Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)
Involved external institutions
Germany (DE)How to cite
APA:
Tsankova, S., Quadfasel, A., Köbrich, M., Witulski, T., Stark, A., Solís, C., & Neumeier, S. (2026). Revealing the γ′ Evolution During Controlled Cooling in Udimet 720LI by Electron Microscopy with Complementary in-Situ SAXS. In Eric A. Ott, Chantal Sudbrack, Andrew Wessman, Joel Andersson, Zhongnan Bi, Ian Dempster, Martin Detrois, Michael Fahrmann, Michael Kirka, Jonah Klemm-Toole, Daisuke Nagahama, Jérémy Rame, Kevin Severs, Kinga Unocic (Eds.), Minerals, Metals and Materials Series (pp. 743-754). Pittsburgh, USA: Springer Science and Business Media Deutschland GmbH.
MLA:
Tsankova, Svetoslava, et al. "Revealing the γ′ Evolution During Controlled Cooling in Udimet 720LI by Electron Microscopy with Complementary in-Situ SAXS." Proceedings of the 11th International Symposium on Superalloy 718 and Derivatives, ISS 2026, Pittsburgh, USA Ed. Eric A. Ott, Chantal Sudbrack, Andrew Wessman, Joel Andersson, Zhongnan Bi, Ian Dempster, Martin Detrois, Michael Fahrmann, Michael Kirka, Jonah Klemm-Toole, Daisuke Nagahama, Jérémy Rame, Kevin Severs, Kinga Unocic, Springer Science and Business Media Deutschland GmbH, 2026. 743-754.
BibTeX: Download