Based upon nickel, but containing significant amounts of at least ten other elements including chromium and aluminium, the superalloys are high-temperature materials which display excellent resistance to mechanical and chemical degradation at temperatures close to their melting points. Since they first emerged in the 1950s, these alloys have had a unique impact. Consider the aeroengines which power the modern civil aircraft. The superalloys are employed in the very hottest sections of the turbines, under the heaviest of loads, with the utmost importance placed on assuring the integrity of the components fabricated from them. Indeed, the development of the superalloys has been intrinsically linked to the history of the jet engine for which they were designed; quite simply, a modern jet aeroplane could not fly without them. Further improvements in temperature capability are now being actively sought, for example for the engines to power the two-decked Airbus A380 and the Boeing 787 Dreamliner. Superalloys are being employed increasingly in the land-based turbine systems used for generating electricity, since fuel economy is improved and carbon emissions are reduced by the higher operating conditions so afforded. But new developments in superalloy metallurgy are required for the next generation of ultra-efficient power generation systems. Over the next 25 years, the world's installed power generation capacity is expected to double, due to the rapidly growing economies and populations of the developing countries, and because most of the current plant in the developed countries will need to be replaced.