Potential of Co-base Superalloys: Hierarchical Microstructures and Nanomechanical Properties of Co3(Al,W)

• Applicant: Dr.-Ing. Florian Vogel
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2016 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 317532718

• Final Report Year: 2024

Final Report Abstract

The project focused on the formation, stability, and mechanical properties of hierarchical microstructures in Co-based superalloys and alternative alloy systems. Initially, research centered on the Co-Al-W-8Cr alloy, described in the literature as promising for forming hierarchical microstructures. Despite extensive heat treatments and compositional adjustments, the desired microstructure could not be reproduced. Instead, unexpected segregation phenomena and secondary phase formations impeded further research on this system. To achieve the project’s goals, alternative systems such as Ni-Al-Ti, Ni-Si-Fe, and Fe-Si-V were investigated. While these showed intriguing microstructural features, challenges in sample preparation and limited technological relevance necessitated another pivot. Ultimately, the high-entropy superalloy HESA-Y1 was chosen as the primary focus. It demonstrated a reproducible hierarchical microstructure with cubic γ' precipitates and finely distributed spherical γ particles, making it suitable for high-temperature applications. High-resolution techniques such as transmission electron microscopy (TEM), atom probe tomography (APT), and in situ synchrotron X-ray diffraction (XRD) were used for characterization. APT analyses revealed clear chemical partitioning mechanisms between γ and γ' phases and γ particles, while XRD measurements showed a low lattice misfit of approximately 0.2%, contributing to microstructural stability. TEM confirmed the cubic morphology of γ' precipitates and the homogeneous distribution of γ particles within the precipitates. Nanomechanical tests on freestanding γ' cubes of the HESA-Y1 alloy exhibited brittle deformation behavior, characterized by elastic response, sudden failure, and high variability in strength values. These results aligned with prior simulations indicating no strengthening effect from hierarchical microstructures in isolated γ' cubes. However, the tests underscored the need for application-specific experiments on bulk samples that better replicate engineering conditions. The project provided critical insights into the chemical interactions, stability mechanisms, and mechanical properties of complex alloy systems. HESA-Y1 emerged as a promising candidate for hightemperature applications, offering a solid foundation for future research and technological advancements.

Publications

• Dresden Fraunhofer Cluster Nanoanalysis, European Advanced Training Course – Nano-scale Materials, “3D atomic structures in nanoscale materials: Atom probe tomography”, Dresden, Germany, August 2018 (invited)
  Florian Vogel
  
• Tracing the three-dimensional nanochemistry of phase separation in an inverse Ni-based superalloy. Acta Materialia, 157, 326-338.
  Vogel, F.; Ngai, S.; Fricke, K.; McKechnie, M.; Wanderka, N.; Hentrich, T.; Banhart, J. & Thompson, G.B.
  
• Chinese Atom Probe Tomography (APT) Technology Forum, “High Temperature Superalloys and Hierarchical Microstructures”, December 2019, Beijing, China (invited)
  Florian Vogel
  
• Hierarchical phase separation behavior in a Ni-Si-Fe alloy. Acta Materialia, 195, 327-340.
  Zaiser, E.; Zhou, X.Y.; Manzoni, A.M.; Haas, S.; Glatzel, U.; Zhang, X.P.; Thompson, G.B.; Li, W. & Vogel, F.
  
• 2022 The Third International Conference on Advanced Materials and Intelligent Manufacturing, “From Micrometers to Atoms – How High-Resolution Characterization Enables New Materials”, July 2022, Guangzhou, China (invited keynote)
  Florian Vogel
  
• Formation and evolution of hierarchical microstructures in a Ni-based superalloy investigated by in situ high-temperature synchrotron X-ray diffraction. Journal of Alloys and Compounds, 919, 165845.
  Vogel F.; Cheng J.; Liang S.B.; Ke C.B.; Cao S.S.; Zhang X.P.; Zizak I.; Manzoni A.M.; Yu J.M.; Wanderka N. & Li W.
  
• 2023 National Seminar on High-Temperature Corrosion and Protection, “Exploring avenues for tailoring the thermal stability of hierarchical microstructures in Ni-based superalloys via phase targeted alloy design“, November 2023, Guangzhou, China (invited)
  Florian Vogel
  
• Atom Probe Tomography & Microscopy (APT&M 2023), “Exploring Avenues for Tailoring the Thermal Stability of Hierarchical Microstructures in Ni-Based Superalloys via Phase Targeted Alloy Design”, August 2023, Belgium
  Florian Vogel
  
• Chinese Atom Probe Tomography (APT) Technology Forum, “Exploring avenues for tailoring the thermal stability of hierarchical microstructures in Ni-based superalloys via phase targeted alloy design“, December 2023, Shanghai, China (invited, organizing committee member)
  Florian Vogel
  
• The 10th International Conference on Advanced Manufacturing Technology and Materials Engineering (AMTME 2023), “From Micrometers to Atoms – How High-Resolution Characterization Enables New Materials”, March 2023, Zhuhai, China (invited)
  Florian Vogel
  
• The 8th Electron Microscopy Network Conference (iCEM 2023), “Phase Stability and Strengthening Mechanisms in Next-Generation High-Temperature Structural Materials with Hierarchical Microstructures”, June 2023, China (invited)
  Florian Vogel
  
• The 9th National Conference on the Preparation/Processing and Application Technology of Non-Ferrous Structural Materials, “Tailoring the Stability of Hierarchical Microstructures in Ni- Based Superalloys”, April 2023, Wuhan, China
  Florian Vogel
  
• Tracking maze-like hierarchical phase separation behavior in a Fe-Si-V alloy. Journal of Alloys and Compounds, 968, 172157.
  Vogel, F.; Ngai, S.; Zhou, X.Y.; Zaiser, E.; Manzoni, A.M.; Wu, Y.; Zheng, W.W.; Zhang, P. & Thompson, G.B.
  
• Chinese Atom Probe Tomography (APT) Technology Forum, “Advanced Analytical Microscopy and Tomography: Unveiling Critical Insights for Modern Engineering Materials and Industrial Applications”, November 2024, Shanghai, China (invited)
  Florian Vogel
  
• Effect of γ forming element additions on the homogenization behavior and formation of hierarchical microstructures in Ni-based superalloys. Journal of Alloys and Compounds, 975, 172929.
  Huang, Mingshuai; Ma, Yiqin; Wu, Yuan; Zheng, Weiwei; Pavel, Michael J.; Weaver, Mark L.; Meng, Wenxing; Long, Yan; Ngai, Sieglind; Wang, Xiaojian; Zhang, Peng; Li, Wei & Vogel, Florian
  
• Influence of the Nb–Al ratio on homogenization behavior and hierarchical microstructures in high-entropy superalloys. Intermetallics, 172, 108380.
  Ma, Yiqin; Ji, Qiuying; Ngai, Sieglind; Li, Jingzhen; Pavel, Michael J.; Weaver, Mark L.; Zhang, Peng; Li, Wei; Wu, Yuan & Vogel, Florian
  
• National Conference on Electron Microscopy, “Advanced Analytical Microscopy and Tomography: Unveiling Critical Insights for Modern Engineering Materials and Industrial Applications”, October 2024, Dongguan, China (invited)
  Florian Vogel
  
• The First International Forum on Material Microstructures and Editorial Board Meeting of the Journal "Microstructure", “Beyond Imaging: The Role of Three-Dimensional Atom Probe Tomography in Microstructure Characterization and Analysis”, January 2024, Haikou, China (invited keynote)
  Florian Vogel
  
• Elucidating hierarchical microstructures in high entropy superalloys: An integrated multiscale study. Materials Characterization, 220, 114642.
  Zaiser, Erika; Fantin, Andrea; Manzoni, Anna M.; Hesse, René; Többens, Daniel M.; Hsu, Wei-Che; Murakami, Hideyuki; Yeh, An-Chou; Pavel, Michael J.; Weaver, Mark L.; Zhu, Huihui; Wu, Yuan & Vogel, Florian