Astonishing Science. Spectacular museum.
A European Space Agency project has its sights set high – taking materials science into space. Experiments carried out on board space-bound rockets are helping scientists develop the materials of the future. These two new types of material are intermetallics – compounds of metals with some extraordinary properties.
This 'Texus sounding rocket' is loaded with experimental kit and launched from the Arctic Circle.
Titanium aluminide is incredibly strong, even at extreme temperatures, so is ideal for making jet-engine parts which have to withstand great heat and huge forces. This intriguing material has extraordinary properties which promise to cut the weight of jet-engine parts – an application with enticing environmental benefits.
This is an ingot of Titanium aluminide. This extremely strong material maintains its strength even when the temperature soars to above 700 °C.
Strength is a crucial property in turbine blades. Inside a Rolls-Royce jet engine, the force on a turbine blade is about the same as a weight of 10 tonnes – equivalent to hanging a double-decker bus from it.
In this diagram of a jet engine, the titanium aluminide turbine blades would be on the right.
Titanium aluminide turbine blades are half as dense as the nickel alloy blades currently used in jet engines. Reducing the density and so the weight of an aircraft engine has huge environmental benefits.
Lighter engines mean lighter planes that require less fuel. Lower fuel consumption by aircraft will result in lower production of polluting gases such as carbon dioxide. Jet-engine emissions contain greenhouse gases which affect Earth’s climate. Reducing them will reduce the impact of aviation on climate change.
Resembling an alloy, titanium aluminide is a compound of metals, but has a much more ordered structure. This ordered structure gives this material its unique properties. Until now, it had been very difficult to cast titanium aluminide into moulds and scientists were unable to take advantage of its superior properties.
But thanks to the space-based experiments, scientists have new data describing the properties of titanium aluminide. Now they understand better how gravity affects the casting process. Armed with this knowledge, materials scientists are developing new casting techniques, leading to the successful production of prototype titanium aluminide blades.
Two turbine blades, one made from titanium aluminide, the other a traditional nickel alloy.
The titanium aluminide turbine blade is built to withstand the intense heat and stresses generated inside a jet engine. Titanium aluminide’s low density means that a turbine blade made from it has about half the weight of a blade made from a traditional nickel alloy. The strength of the blade is a result of both the properties of titanium aluminide and the sophisticated techniques used to cast it.
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