There is significant interest in the use of intermetallic alloys, such as titanium aluminide, in Thermal Protection Systems (TPS) on next-generation low orbit and re-entry space vehicles, based on their good mechanical performance at elevated temperatures, resistance to oxidation and low specific density. However, actual applications of titanium aluminides have been limited due to their low ductility at ambient temperature and difficulty in shaping the alloys using traditional metalworking practices such as machining, cold working, casting, etc. Ultra-lightweight, porous titanium aluminide alloys are being fabricated based on technologies being developed at the Fraunhofer Institute and Fraunhofer USA Centers for Manufacturing and Advanced Materials, located in Dresden, Germany and Newark, DE, USA, respectively. Powder metallurgy processing routes are being utilized to fabricate hollow metal spheres and reaction sintered TiAl and TiAl_3 intermetallics. The processing, microstructures, and selected properties of these controlled-porosity materials are presented, along with a discussion of potential application as thermal protection systems.
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