Details

Autor(en) / Beteiligte

• Mukhopadhyay, Semanti
• Xue, Fei
• Sriram, Hariharan
• Hayes, Robert W.
• Marquis, Emmanuelle A.
• Wang, Yunzhi
• Mills, Michael J.
• Sudbrack, Chantal
• Jablonski, Paul
• Andersson, Joel
• Liu, Xingbo
• Smith, Tim
• Stockinger, Martin
• Ott, Eric A.
• Wessman, Andrew
• Fahrmann, Michael
• Kirka, Michael
• Bi, Zhongnan
• Bockenstedt, Kevin
• Dempster, Ian
• Nagahama, Daisuke

Titel

Preferential γ′ Precipitation on Coherent Annealing Twin Boundaries in Alloy 718

Ist Teil von

• Proceedings of the 10th International Symposium on Superalloy 718 and Derivatives, p.135-146

Ort / Verlag

Cham: Springer Nature Switzerland

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Early strain localization, parallel and adjacent to annealing twin boundaries (ATBsAnnealing twin boundaries (ATBs)), has been reported in several superalloysSuperalloys. While strain localization is generally attributed to local shear stresses developed near ATBsAnnealing twin boundaries (ATBs) due to elastic anisotropyAnisotropy, the role of local microstructural features near ATBsAnnealing twin boundaries (ATBs) is unclear. Precipitate free zones (PFZ) parallel to ATBsAnnealing twin boundaries (ATBs) in a γʺ–strengthened alloy 945X have been reported and were found to greatly influence strain localization in the alloy. However, it is unclear if such PFZs near ATBsAnnealing twin boundaries (ATBs) occur in other superalloysSuperalloys, potentially influencing strain localization. The present work investigates local microstructuresMicrostructuresnear ATBsAnnealing twin boundaries (ATBs) in a Ni-based superalloyNi-based superalloy—718, which is strengthened by both γʹ and γʺ phases. Based on characterization experiments, this paper reports that Alloy 718Alloy 718 shows a high density of herringbone-like γʹ−γʺprecipitates at ATBsAnnealing twin boundaries (ATBs). However, the ATBsAnnealing twin boundaries (ATBs) exhibit a much higher fraction of γ′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma^\prime$$\end{document} (25.3 ± 2.8%) than γ″\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma^{\prime \prime}$$\end{document} (18.4 ± 2.4%), ultimately causing the coprecipitate fraction at ATBsAnnealing twin boundaries (ATBs) to be as high as 43%. A local HCP phase at the ATBsAnnealing twin boundaries (ATBs) within γ′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma^\prime$$\end{document} precipitates exhibiting Nb segregation and Al depletion is also reported. On the contrary, no appreciable change in the ATBAnnealing twin boundaries (ATBs) composition was observed within γ″\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\gamma^{\prime \prime}$$\end{document}. Finally, a novel mode of heterogeneous precipitationPrecipitationat ATBsAnnealing twin boundaries (ATBs) is proposed.