Minnert, Christian (2022)
Assessment of thermally activated dislocation mechanisms via novel indentation approaches.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00021976
Dissertation, Erstveröffentlichung, Verlagsversion
Kurzbeschreibung (Abstract)
The efficiency of gas turbines and jet engines used for energy generation and transportation can be increased by raising their combustion temperature. However, this is often limited by the materials used. For the development of new high-temperature materials, knowledge of the local mechanical properties of, for instance, individual phases in Ni-based superalloys is therefore of great importance. These properties are largely unknown, as they are not accessible with conventional macroscopic test methods.
In the present work, the depth-sensing indentation testing technique was applied to assess the thermally activated deformation mechanisms on a local scale. For this purpose, a new in-situ indentation device was developed, which for the first time allows dynamic indentation experiments to be carried out on a small scale at temperatures of up to 1100 °C. Furthermore, a new indentation creep loading protocol was developed using a constant contact pressure approach similar to conventional uniaxial creep experiments. For indentation testing at high temperatures, a new step load method has been presented that allows a significant reduction of the contact time, thus minimizing the wear of the indenter tips. The method is suitable for the investigation of transients in material behavior at high to medium strain rates. In addition, a new approach for determining the brittle-ductile-transition temperature of body centered cubic metals was presented. In this approach, the change in the temperature-dependent activation volume was used to determine an intersection temperature that agrees well with the brittle-to-ductile-transition temperature from conventional Charpy pendulum impact tests.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2022 | ||||
Autor(en): | Minnert, Christian | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Assessment of thermally activated dislocation mechanisms via novel indentation approaches | ||||
Sprache: | Englisch | ||||
Referenten: | Durst, Prof. Dr. Karsten ; Michler, Prof. Dr. Johann | ||||
Publikationsjahr: | 2022 | ||||
Ort: | Darmstadt | ||||
Kollation: | 162 Seiten in verschiedenen Seitenzählungen | ||||
Datum der mündlichen Prüfung: | 28 Juli 2022 | ||||
DOI: | 10.26083/tuprints-00021976 | ||||
URL / URN: | https://tuprints.ulb.tu-darmstadt.de/21976 | ||||
Kurzbeschreibung (Abstract): | The efficiency of gas turbines and jet engines used for energy generation and transportation can be increased by raising their combustion temperature. However, this is often limited by the materials used. For the development of new high-temperature materials, knowledge of the local mechanical properties of, for instance, individual phases in Ni-based superalloys is therefore of great importance. These properties are largely unknown, as they are not accessible with conventional macroscopic test methods. In the present work, the depth-sensing indentation testing technique was applied to assess the thermally activated deformation mechanisms on a local scale. For this purpose, a new in-situ indentation device was developed, which for the first time allows dynamic indentation experiments to be carried out on a small scale at temperatures of up to 1100 °C. Furthermore, a new indentation creep loading protocol was developed using a constant contact pressure approach similar to conventional uniaxial creep experiments. For indentation testing at high temperatures, a new step load method has been presented that allows a significant reduction of the contact time, thus minimizing the wear of the indenter tips. The method is suitable for the investigation of transients in material behavior at high to medium strain rates. In addition, a new approach for determining the brittle-ductile-transition temperature of body centered cubic metals was presented. In this approach, the change in the temperature-dependent activation volume was used to determine an intersection temperature that agrees well with the brittle-to-ductile-transition temperature from conventional Charpy pendulum impact tests. |
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Alternatives oder übersetztes Abstract: |
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Status: | Verlagsversion | ||||
URN: | urn:nbn:de:tuda-tuprints-219766 | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 600 Technik, Medizin, angewandte Wissenschaften > 600 Technik 600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften und Maschinenbau |
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Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Physikalische Metallkunde |
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Hinterlegungsdatum: | 25 Aug 2022 12:04 | ||||
Letzte Änderung: | 26 Aug 2022 06:05 | ||||
PPN: | |||||
Referenten: | Durst, Prof. Dr. Karsten ; Michler, Prof. Dr. Johann | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 28 Juli 2022 | ||||
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