Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM
The microstructure of a René 108 Ni-based superalloy was systematically investigated by X-ray diffraction, light microscopy, energy-dispersive X-ray spectroscopy, and electron microscopy techniques. The material was investment cast in a vacuum and then solution treated (1200 °C-2h) and aged (900 °C-...
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doaj-2454dff72b8944f5a9d0ce97c4aaed682020-11-25T02:19:30ZengMDPI AGMaterials1996-19442020-10-01134452445210.3390/ma13194452Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEMŁukasz Rakoczy0Bogdan Rutkowski1Małgorzata Grudzień-Rakoczy2Rafał Cygan3Wiktoria Ratuszek4Anna Zielińska-Lipiec5Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, PolandFaculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, PolandŁukasiewicz Research Network-Kraków Institute of Technology, Zakopiańska 73, 30-418 Kraków, PolandInvestment Casting Division, Consolidated Precision Products Corporation, Hetmańska 120, 35-078 Rzeszów, PolandFaculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, PolandFaculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Kraków, PolandThe microstructure of a René 108 Ni-based superalloy was systematically investigated by X-ray diffraction, light microscopy, energy-dispersive X-ray spectroscopy, and electron microscopy techniques. The material was investment cast in a vacuum and then solution treated (1200 °C-2h) and aged (900 °C-8h). The γ matrix is mainly strengthened by the ordered L1<sub>2</sub> γ′ phase, with the mean γ/γ′ misfit, δ, +0.6%. The typical dendritic microstructure with considerable microsegregation of the alloying elements is revealed. Dendritic regions consist of secondary and tertiary γ′ precipitates. At the interface of the matrix with secondary γ′ precipitates, nano M<sub>5</sub>B<sub>3</sub> borides are present. In the interdendritic spaces additionally primary γ′ precipitates, MC and nano M<sub>23</sub>C<sub>6</sub> carbides were detected. The γ′ precipitates are enriched in Al, Ta, Ti, and Hf, while channels of the matrix in Cr and Co. The highest summary concentration of γ′-formers occurs in coarse γ′ surrounding MC carbides. Borides M<sub>5</sub>B<sub>3</sub> contain mostly W, Cr and Mo. All of MC carbides are enriched strongly in Hf and Ta, with the concentration relationship between these and other strong carbide formers depending on the precipitate’s morphology. The nano M<sub>23</sub>C<sub>6</sub> carbides enriched in Cr have been formed as a consequence of phase transformation MC + γ → M<sub>23</sub>C<sub>6</sub> + γ′ during the ageing treatment.https://www.mdpi.com/1996-1944/13/19/4452superalloyHRSTEMSTEM-EDXM<sub>23</sub>C<sub>6</sub>nano-borides |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Łukasz Rakoczy Bogdan Rutkowski Małgorzata Grudzień-Rakoczy Rafał Cygan Wiktoria Ratuszek Anna Zielińska-Lipiec |
spellingShingle |
Łukasz Rakoczy Bogdan Rutkowski Małgorzata Grudzień-Rakoczy Rafał Cygan Wiktoria Ratuszek Anna Zielińska-Lipiec Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM Materials superalloy HRSTEM STEM-EDX M<sub>23</sub>C<sub>6</sub> nano-borides |
author_facet |
Łukasz Rakoczy Bogdan Rutkowski Małgorzata Grudzień-Rakoczy Rafał Cygan Wiktoria Ratuszek Anna Zielińska-Lipiec |
author_sort |
Łukasz Rakoczy |
title |
Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM |
title_short |
Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM |
title_full |
Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM |
title_fullStr |
Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM |
title_full_unstemmed |
Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM |
title_sort |
analysis of γ′ precipitates, carbides and nano-borides in heat-treated ni-based superalloy using sem, stem-edx, and hrstem |
publisher |
MDPI AG |
series |
Materials |
issn |
1996-1944 |
publishDate |
2020-10-01 |
description |
The microstructure of a René 108 Ni-based superalloy was systematically investigated by X-ray diffraction, light microscopy, energy-dispersive X-ray spectroscopy, and electron microscopy techniques. The material was investment cast in a vacuum and then solution treated (1200 °C-2h) and aged (900 °C-8h). The γ matrix is mainly strengthened by the ordered L1<sub>2</sub> γ′ phase, with the mean γ/γ′ misfit, δ, +0.6%. The typical dendritic microstructure with considerable microsegregation of the alloying elements is revealed. Dendritic regions consist of secondary and tertiary γ′ precipitates. At the interface of the matrix with secondary γ′ precipitates, nano M<sub>5</sub>B<sub>3</sub> borides are present. In the interdendritic spaces additionally primary γ′ precipitates, MC and nano M<sub>23</sub>C<sub>6</sub> carbides were detected. The γ′ precipitates are enriched in Al, Ta, Ti, and Hf, while channels of the matrix in Cr and Co. The highest summary concentration of γ′-formers occurs in coarse γ′ surrounding MC carbides. Borides M<sub>5</sub>B<sub>3</sub> contain mostly W, Cr and Mo. All of MC carbides are enriched strongly in Hf and Ta, with the concentration relationship between these and other strong carbide formers depending on the precipitate’s morphology. The nano M<sub>23</sub>C<sub>6</sub> carbides enriched in Cr have been formed as a consequence of phase transformation MC + γ → M<sub>23</sub>C<sub>6</sub> + γ′ during the ageing treatment. |
topic |
superalloy HRSTEM STEM-EDX M<sub>23</sub>C<sub>6</sub> nano-borides |
url |
https://www.mdpi.com/1996-1944/13/19/4452 |
work_keys_str_mv |
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