High Cycle Fatigue Cracking of Meso- and Micromechanical Testpieces of Aluminide Intermetallics, with in situ Nanoscale Strain Mapping

Projektbeschreibung

Optimierung von Legierungen für Anwendungen in der Luft- und Raumfahrt

Aluminide bezeichnen intermetallische Verbindungen, die für verschiedene rotierende und luftgestützte technische Anwendungen äußerst vorteilhaft sind. Sie können jedoch oft spröde sein, insbesondere im Zusammenhang mit Materialermüdung. Ziel des EU-finanzierten Projekts FracTAlS ist es, zu untersuchen, wie durch Verformungen bei hochzyklischen Dauerbeanspruchungen leichter, struktureller intermetallischer Aluminide Risse entstehen. Mithilfe einer Kombination neu entwickelter Verfahren zur Dehnungsabbildung im Nanobereich sollen demzufolge die Auswirkungen von Verformungen auf die Ermüdungsbelastung erforscht werden. Im Laufe der Jahre sind bei den Ermüdungseigenschaften von intermetallischen Gamma-Titanaluminiden und Magnesiumaluminiden keine Verbesserungen erzielt worden. So könnten Erstere eine deutlich höhere Treibstoffeffizienz in Großserienindustrien bieten, während Letztere ideale Kandidaten für die Strukturbauteile von morgen und umweltfreundlichere Luftantriebstechnologien sind.

Ziel

The aim of FracTAlS is to increase the understanding of the deformation mechanisms leading to and mediating cracking in high cycle fatigue loading of lightweight, structural aluminide intermetallics, in order to better direct microstructural and alloy development. Such materials are highly desirable for many rotating and airborne engineering applications but often suffer from prohibitive brittleness, particularly in fatigue. The project applies a combination of nanoscale strain mapping techniques recently developed by the host institution, and by Dr. Edwards, on novel in-situ meso- and micro-mechanical fatigue testing setups, to study deformation behaviour upon fatigue loading. Currently, the European hub plays a central role in the research and development of advanced gamma titanium aluminide alloys, such as for improved processability, and the large-scale production of γ-TiAl components. However, no significant improvements have been made to the fatigue properties of the lightweight γ-TiAl alloys in the past few decades, effectively limiting their widespread application in higher volume industries where they could result in considerable increases in fuel efficiency. Similarly, Mg aluminides, such as the γ-Mg17Al12 phase, possess outstanding strength to weight properties; given sufficient improvements to their toughness and fatigue performance, they would be excellent candidates for structural components in future, more ecologically friendly, aero-propulsion technologies where the operational temperatures are lower than gas turbine engines (e.g. electric and hybrid-electric). This project is closely aligned with EU policy on climate action and sustainable development as it targets reduced emissions through reduced hydrocarbon fuel consumption; its success will serve to increase the European confidence and knowledge-base in these material systems and, through further interaction with European industry, the extent of their use.