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New titanium high-strength engine components

June 25, 2003

Gamma titanium aluminides belong to the most predestined high-temperature lightweight materials offering an alternative to conventional heat-resistant steels and superalloys applied in high-performance automotive and aircraft engines. Investigations of the German Max-Planck-Institut für Eisenforschung GmbH (MPIE) aim at improving titanium aluminides and titanium base alloys that are particularly appropriate for near net shape forming operations of engine parts. Improved material workability and optimized processing technology offer great potential for reducing production cost and time of high quality engine components made of Ti(Al) based alloys. On the 10th World Conference on Titanium (13th-18th July 2003, Hamburg, Germany), researchers of the MPIE will lecture on their latest results

The German MPIE's titanium research activities are focusing on the development and characterization of high-strength microcrystalline titanium base alloys and titanium aluminides. Comprehensive investigations had been carried out for determining the effects of ternary alloying elements of transition metals, in particular Cr, Mo, Nb and Cu, on lattice parameters, phase morphology and microstructures. Advanced intermetallic Ti-46Al-(Cr,Cu,Mo,Si) alloys of enhanced ductility and strength are presently under investigation.

Titanium aluminide alloys having attractive properties for being applied under high thermal and mechanical load - e.g. low specific weight, good oxidation and burn resistance at temperatures of up to 800°C, high elastic stiffness and enhanced high temperature strength. Due to a lower melt viscosity, alloying modifications of Cu ensure better castability and exhibit extremely fine-grained solidification microstructures. Improved strength of 800 to 1070 MPa and a rather high room temperature ductility of up to 4.8 % have been demonstrated for TiAl(Cu,Mo,Si) alloys. Enhanced ductility is attributed to decreased stacking fault energy and twinning is one major deformation mechanism in these alloys.

Manufacturing processes for producing TiAl automotive engine parts based on centrifugal casting, near-net shape quasi-isothermal forging or superplastic die forming have been developed in cooperative projects of industry and research institutes. Together with the German Institut für Werkzeugmaschinen und Fabrikbetrieb, TU Berlin it is investigated on how conventional machining influences the microstructure and mechanical properties of TiAl based alloys. The machining process of intermetallic alloys is often characterized by micro-crack formation at the component surface, or the TiAl-based alloy must be locally warmed up above the brittle-to-ductile transition temperature (between 600 °C and 800 °C). There will be a further investigation on the micro-structural influence of the machining tool and internal stress states of the work-piece material for better optimizing the cutting parameters. Improved machining parameters and tool technology are among the key aspects for decreasing the production costs of lightweight components made of titanium aluminides.

The 10th World Conference on Titanium (13th - 18th July 2003, Hamburg, Germany) will deal with all titanium aspects covering the complete production route from ore to finished products, all application areas, new alloys, advanced materials and microstructure / property evaluation. Researchers and experts from all over the world - for example the German Max-Planck-Institut für Eisenforschung (MPIE), the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt), EADS Airbus, Rolls Royce Deutschland, Lufthansa Technik, Volkswagen, Deutsche Titan and many high ranking universities - will lecture on their latest projects and results. The participation of the seven major titanium countries (USA, CIS, Japan, UK, France, China and Germany) in the International Organizing Committee guarantees extensive coverage of all new interesting areas of research & development and the application of titanium.

Deutsche Gesellschaft - Materialkunde e.V. (DGM)