Titanium aluminides are intermetalic alloys with titanium and aluminium as mean alloying elements. Titanium aluminides are promising materials for high temperature and structural applications of the future. Due to their low density from 3.9 g/cm³ to 4.1 g/cm³ along with an excellent high temperature strength these materials are predestine for usage in stationary and aeronautic gas turbines as well as for valves and turbo chargers in cars.
Technically relevant alloys show different microstructures depending on composition and thermo-mechanical treatment influencing the mechanical properties. For example, the globular Near-γ-microstructures are showing an improved ductility while lamellar microstructures are showing a higher toughness.
Conventional titanium alloys can be used up to 550°C while titanium aluminides are intended for service temperatures of 700°C at least. Thus they are competing with established heat resistant steel and nickel alloys – along with a drastically reduced density.
The Institute of Materials research is collaborating with well-known German aeroengine companies for the optimisation and understanding of titanium aluminides. The research work is concentrated on microstructural characterisation und the relationship of microstructure and mechanical properties, such as fatigue, crack propagation, and damage tolerance.
A special research topic conducted at DLR is the impact testing of blade-like specimens followed by determination of the residual fatigue life. The impact tests are carried out in close collaboration with the Institute of Structures and Design. A further speciality of the research work at DLR is the interaction of materials modelling with experimental characterisation.