Evolution of Ni-based superalloys for single crystal gas turbine blade applications

The chemistry of the Ni-based superalloys designed for single crystal gas turbine blades has significantly evolved since the development of the first generation of alloys derived from columnar grained materials. The overall performance of the second and third generations has been significantly improved by the addition of increasing amounts of rhenium. However, the problems of increased density, grain defects and microstructural stability have also become more and more acute and render necessary to carefully control the level of the various alloying elements in order to effectively benefit from the high potential of the most recently developed third generation alloys.