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Alloy Portfolio

Low Expansion Alloys

Designations Equivalent Specifications Major Elements Chemical Compositions(%) Properties Applications
ASTM JIS Ni Cr Mo Cu Fe Other Elements
36Ni-Fe(Invar) -
- 36.0 - - - bal - A nickel-iron low-expansion alloy containing 36% nickel. It maintains nearly constant dimensions over the range of normal atmospheric temperatures, and has a low coefficient of expansion from cryogenic temperatures to about 500°F (260°C). The alloy also retains good strength and toughness at cryogenic temperatures. Used for standards of length, measuring devices, laser components, bi-metal thermostat strips, thermostat rods, and tanks and piping for storing and transporting liquefied gases.
42Ni-Fe(Glass Sealing Alloy) - - 42.0 - - - bal - A nickel-iron controlled-expansion alloy containing 42% nickel. It has a low and nominally constant coefficient of thermal expansion from room temperature to about 570°F (300°C). envelopes of electric bulbs, radio valves, television tubes, and fluorescent lights. Used for semiconductor lead frames in integrated circuits, bi-metal thermostat strip, thermostat rods, for ceramic-to-metal seals with alumina ceramics, and various glass-to-metal seals such as thecore of copper-clad wire for sealing into glass
KOVAR(Glass Sealing Alloy) - - 29.0 - - - 53.0 Co 17.0 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. lead frames, and photography flash bulbs. Used for high-power transmitting valves, transistor leads and headers, and integrated circuit

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