Kovar/UNS K94610/ASTM F15/Nilo K Kovar (Alloy K) 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 (Alloy K) is used for glass-to-metal seals in applications requiring high reliability or resistance to thermal shock. Kovar (Alloy K) is used for high-power transmitting valves, transistor leads and headers, integrated-circuit lead frames, and photography flash bulbs. Since Kovar Alloy is tough and versatile, while employing extensive quality controls throughout UNS K94610 alloy’s manufacturing process to ensure uniform physical and mechanical properties for ease in deep drawing, stamping and machining are consistently achieved. Furthermore, the coefficient of thermal expansion (CTE) of Kovar® is its most dynamic mechanical property.