Characterization of beta-solidifying gamma-TiAl alloy variants using advanced in- and ex-situ investigation methods

Laura Melanie Drössler

Characterization of beta-solidifying gamma-TiAl alloy variants using advanced in- and ex-situ investigation methods

Titel in Übersetzung: Charakterisierung von beta-erstarrenden gamma-TiAl Legierungsvarianten anhand von in- und ex-situ Untersuchungsmethoden

Laura Melanie Drössler

Lehrstuhl für Metallkunde (420)

Publikation: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Diplomarbeit

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Abstract

Internationale Forschungstätigkeiten im Bereich der gamma-TiAl Basislegierungen nahmen in den letzten Jahrzehnten stark zu. Dieser intermetallische Strukturwerkstoff zeigt ein hohes Potential für Hochtemperaturanwendungen bis zu 800°C. Aufgrund seiner geringen Dichte und der hohen spezifischen Festigkeit sind diese Werkstoffe viel versprechende Kandidaten für Anwendungen der Luft- und Raumfahrt sowie der Automobilindustrie. Im Rahmen dieser Diplomarbeit wurde eine neu entwickelte gamma-TiAl Basislegierung, eine so genannte TNM-Legierung, mit den Legierungselementen Nb, Mo und B charakterisiert. Diese Legierung weist ausgezeichnete mechanische Eigenschaften für die Anwendung in den genannten Gebieten auf sowie gute Verformbarkeit bei erhöhten Temperaturen und kann mit nahezu konventionellen Methoden geschmiedet werden. Quantitative Analysen an rasterelektronenmikroskopischen Aufnahmen an Proben in unterschiedlichen Wärmebehandlungszuständen wurden durchgeführt. Um die Entstehung des Gefüges detaillierter zu beschreiben wurden EBSD Messungen an Proben in verschiedenen Stadien der mikrostrukturellen Umwandlung, der zellularen Reaktion, durchgeführt. Zur Bestimmung der Phasenübergänge und der Ordnungstemperaturen wurden Synchroton und Neutronenbeugungs Experimente durchgeführt. Basierend auf transmissionselektronenmikroskopischen (TEM) Aufnahmen und Röntgenbeugungsmessungen (XRD) wurde, zusammen mit den Ergebnissen aus Härtemessungen, ein Modell erstellt, das eine Verbindung zwischen Gefüge und mechanischen Eigenschaften herstellt.

Titel in Übersetzung	Charakterisierung von beta-erstarrenden gamma-TiAl Legierungsvarianten anhand von in- und ex-situ Untersuchungsmethoden
Originalsprache	Englisch
Qualifikation	Dipl.-Ing.
Betreuer/-in / Berater/-in	Clemens, Helmut, Betreuer (intern)
Datum der Bewilligung	19 Dez. 2008
Publikationsstatus	Veröffentlicht - 2008

Bibliographische Notiz

gesperrt bis null

Schlagwörter

intermetallische Materialien Titanaluminide Gefüge- und Phasenanalyse in-situ Beugungsexperimente mit Neutronen- und Synchrotronstrahlung

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abstract = "Research interests on intermetallic gamma-TiAl based alloys have been increasing over the last decades. Gamma-TiAl alloys are structure materials that can be applied up to service temperatures of 800°C. Due to their low density of about 4 g/cm3 and their high specific strength they are promising candidates for high temperature applications in aeroengines and the automotive industry. Apart from their excellent high temperature properties TiAl alloys are very brittle at room temperature. The characterization of a recently developed TiAl alloy (TNM alloy) containing Nb, Mo and B was the task of the present work. This alloy exhibits appropriate mechanical properties as well as good workability at elevated temperatures and can be forged at near conventional conditions. Quantitative metallographic analyses were conducted to describe the appearing phases and their dependence on temperature. To study the evolution of the microstructure more thoroughly, electron backscatter diffraction (EBSD) measurements were conducted on samples which show different stages of cellular reaction. For the determination of phase transformation temperatures and ordering temperatures within the alloy both synchrotron and neutron diffraction experiments were performed. A model of the lamellae formation based on TEM- and XRD-measurements is proposed which gives a connection between microstructure and mechanical properties of the multiphase material.",

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AB - Research interests on intermetallic gamma-TiAl based alloys have been increasing over the last decades. Gamma-TiAl alloys are structure materials that can be applied up to service temperatures of 800°C. Due to their low density of about 4 g/cm3 and their high specific strength they are promising candidates for high temperature applications in aeroengines and the automotive industry. Apart from their excellent high temperature properties TiAl alloys are very brittle at room temperature. The characterization of a recently developed TiAl alloy (TNM alloy) containing Nb, Mo and B was the task of the present work. This alloy exhibits appropriate mechanical properties as well as good workability at elevated temperatures and can be forged at near conventional conditions. Quantitative metallographic analyses were conducted to describe the appearing phases and their dependence on temperature. To study the evolution of the microstructure more thoroughly, electron backscatter diffraction (EBSD) measurements were conducted on samples which show different stages of cellular reaction. For the determination of phase transformation temperatures and ordering temperatures within the alloy both synchrotron and neutron diffraction experiments were performed. A model of the lamellae formation based on TEM- and XRD-measurements is proposed which gives a connection between microstructure and mechanical properties of the multiphase material.

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