Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings
The as-cast microstructure, alloying element segregation, solidification behavior, and thermal stability of model superalloys based on Inconel 740 with various Al/Ti ratios (0.7, 1.5, 3.4) and Ta (2.0, 3.0, 4.0 wt%) concentrations were investigated via ThermoCalc simulations, scanning and transmissi...
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MDPI AG
2022-05-01
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| Online Access: | https://www.mdpi.com/1996-1944/15/9/3296 |
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| author | Małgorzata Grudzień-Rakoczy Łukasz Rakoczy Rafał Cygan Konrad Chrzan Ondrej Milkovič Zenon Pirowski |
| author_facet | Małgorzata Grudzień-Rakoczy Łukasz Rakoczy Rafał Cygan Konrad Chrzan Ondrej Milkovič Zenon Pirowski |
| author_sort | Małgorzata Grudzień-Rakoczy |
| collection | DOAJ |
| description | The as-cast microstructure, alloying element segregation, solidification behavior, and thermal stability of model superalloys based on Inconel 740 with various Al/Ti ratios (0.7, 1.5, 3.4) and Ta (2.0, 3.0, 4.0 wt%) concentrations were investigated via ThermoCalc simulations, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, dilatometry, and differential scanning calorimetry. The solidification of the superalloys began with the formation of primary γ dendrites, followed by MC carbides. The type of subsequently formed phases depended on the superalloys’ initial Al/Ti ratio and Ta concentration. The results obtained from solidification simulations were compared to the obtained microstructures. For all castings, the dendritic regions consisted of fine γ′ precipitates, with their size mainly depending on the initial Al/Ti ratio, whereas in the interdendritic spaces, (Nb, Ta, Ti)C carbides and Nb-rich Laves phase precipitates were present. In high Al/Ti ratio superalloys, β-NiAl precipitates, strengthened by η and α-Cr phases, were observed. Based on dilatometric results, the dissolution of γ′ precipitates was accompanied by a substantial increase in the coefficient of thermal expansion. The end of the dilatation effect took place around the γ′ solvus temperature, as determined via calorimetry. Moreover, the bulk solidus temperature was preceded by the dissolution of the Laves phase, which may be accompanied by local melting. |
| first_indexed | 2024-03-10T03:58:40Z |
| format | Article |
| id | doaj.art-94726e5c900848f2942d90e7a29a20af |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T03:58:40Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-94726e5c900848f2942d90e7a29a20af2023-11-23T08:41:11ZengMDPI AGMaterials1996-19442022-05-01159329610.3390/ma15093296Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy CastingsMałgorzata Grudzień-Rakoczy0Łukasz Rakoczy1Rafał Cygan2Konrad Chrzan3Ondrej Milkovič4Zenon Pirowski5Łukasiewicz Research Network-Krakow Institute of Technology, Zakopianska 73, 30-418 Krakow, PolandFaculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, PolandConsolidated Precision Products Corporation, Investment Casting Division, Hetmańska 120, 35-078 Rzeszow, PolandŁukasiewicz Research Network-Krakow Institute of Technology, Zakopianska 73, 30-418 Krakow, PolandInstitute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, SlovakiaŁukasiewicz Research Network-Krakow Institute of Technology, Zakopianska 73, 30-418 Krakow, PolandThe as-cast microstructure, alloying element segregation, solidification behavior, and thermal stability of model superalloys based on Inconel 740 with various Al/Ti ratios (0.7, 1.5, 3.4) and Ta (2.0, 3.0, 4.0 wt%) concentrations were investigated via ThermoCalc simulations, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, dilatometry, and differential scanning calorimetry. The solidification of the superalloys began with the formation of primary γ dendrites, followed by MC carbides. The type of subsequently formed phases depended on the superalloys’ initial Al/Ti ratio and Ta concentration. The results obtained from solidification simulations were compared to the obtained microstructures. For all castings, the dendritic regions consisted of fine γ′ precipitates, with their size mainly depending on the initial Al/Ti ratio, whereas in the interdendritic spaces, (Nb, Ta, Ti)C carbides and Nb-rich Laves phase precipitates were present. In high Al/Ti ratio superalloys, β-NiAl precipitates, strengthened by η and α-Cr phases, were observed. Based on dilatometric results, the dissolution of γ′ precipitates was accompanied by a substantial increase in the coefficient of thermal expansion. The end of the dilatation effect took place around the γ′ solvus temperature, as determined via calorimetry. Moreover, the bulk solidus temperature was preceded by the dissolution of the Laves phase, which may be accompanied by local melting.https://www.mdpi.com/1996-1944/15/9/3296Inconel 740phase transformationinvestment castingsuperalloysolidification |
| spellingShingle | Małgorzata Grudzień-Rakoczy Łukasz Rakoczy Rafał Cygan Konrad Chrzan Ondrej Milkovič Zenon Pirowski Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings Materials Inconel 740 phase transformation investment casting superalloy solidification |
| title | Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings |
| title_full | Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings |
| title_fullStr | Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings |
| title_full_unstemmed | Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings |
| title_short | Influence of Al/Ti Ratio and Ta Concentration on the As-Cast Microstructure, Phase Composition, and Phase Transformation Temperatures of Lost-Wax Ni-Based Superalloy Castings |
| title_sort | influence of al ti ratio and ta concentration on the as cast microstructure phase composition and phase transformation temperatures of lost wax ni based superalloy castings |
| topic | Inconel 740 phase transformation investment casting superalloy solidification |
| url | https://www.mdpi.com/1996-1944/15/9/3296 |
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