Controlled Expansion Alloys

Controlled expansion alloys (nickel-iron alloys such as Kovar® and alloy 52) provide reliable results for applications requiring materials with predictable rates of expansion and contraction over given temperature ranges. Primary applications include creating hermetically sealed environments, matched expansion joints, and glass-to-metal seals. For more information on how Leading Edge's nickel-iron alloys can add value to your application, contact one of our material specialists.


Composed of iron, nickel and cobalt, Kovar®1 has thermal expansion characteristics similar to hard glass, making it an excellent choice for glass-to-metal hermetic seals. Kovar® is widely used in the electronics industry.

Alloy 52

Alloy 52 is a nickel-iron alloy with a thermal expansion rate similar to soft glasses and ceramics. Typical applications include voltage regulators, conductors, and glass-to-metal hermetic seals.

LE Alloy 49

In addition to excellent glass-to-metal sealing capabilities, nickel-iron alloys with slightly higher iron content provide increased magnetic shielding. LE alloy 49 is used for applications such as solenoid components, glass-to-metal hermetic seals, transformers and power transducers.

  1. Carpenter Technology Corporation
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