Superalloys are built to function well in high-temperature applications. Some of the components that use superalloys include gas turbine engines, rocket motors, nuclear reactors, submarines, and petroleum equipment.
Kovar (UNS K94610 / Alloy K / ASTM F15) is a nickel-iron-cobalt controlled-expansion alloy containing 29% nickel. Its coefficient of expansion, which decreases with rising temperature to the inflection point, matches the expansion rate of borosilicate glasses and alumina ceramics. Kovar (UNS K94610 / Alloy K / ASTM F15) is used for glass-to-metal seals in applications requiring high reliability or resistance to thermal shock. Kovar (UNS K94610 / Alloy K / ASTM F15) is used for high-power transmitting valves, transistor leads and headers, integrated-circuit lead frames, and photography flashbulbs.