Turbine of the times

Due to the extraordinary temperature and forces they must withstand, turbine blades in the hot sections of jet engines are manufactured from a class of materials known as superalloys.

Although such superalloys have been successfully used for more than 50 years due to their outstanding mechanical properties, materials scientists are still working to improve their characteristics, enabling design engineers to develop jet engines that can operate at even higher temperatures and hence use fuel more efficiently. Even as they do so, a new class of intermetallic materials is emerging that may replace superalloys entirely.

Superalloys used in today’s aero-engine blades are metallic alloys based on nickel, the high-temperature strength of which is enhanced by adding aluminium at the melt-processing stage. As the alloys are cooled from high temperatures, a microstructure is created that consists of two main equilibrium phases – a gamma phase, as the matrix, and a gamma-prime phase as the precipitate. It is the precipitate that is largely responsible for the elevated temperature strength of the material, its resistance to creep deformation and its high oxidation resistance.