Hot-end components in today's aero turbofan engines are made from materials known as superalloys, typically based on Ni-Cr, Ni-CR-FE or Co-Cr systems. In the fifty years or so that have elapsed since the first superalloys were introduced, the temperature capability of the materials has increased by approximately 500-degrees and the power output of aero gas turbines has risen from approximately 20 kN of thrust to the 250 kN achievable today. The materials and their development are described.