WL Kovar alloy

Kovar is a vacuum melted, iron-nickel-cobalt, low expansion alloy whose chemical composition is controlled within narrow limits to assure precise uniform thermal expansion properties. A glass and ceramic sealing alloy, extensive quality controls are employed in its manufacture to ensure uniform physical and mechanical properties for ease in deep drawing, stamping and machining.

Kovar alloy is a nickel-iron-cobalt, controlled expansion alloy. It's expansion characteristics match both borosilicate (or Pyrex) glasses and alumina ceramics. This alone ensures it is a highly popular controlled expansion alloys for hermetic sealing applications (also known as Glass to Metals Sealing). 

Glass sealing of metal components or lead wires, into hard glass or ceramic devices

In applications where low expansion with temperature change is an essential characteristic e.g. integrated circuits packaging

Scientific instruments

Microwave tubes

Hybrid packages

Power tubes

Transistors

Diodes

AMS 7726

AMS 7727

AMS 7728

ASTM F15

MIL I-23011 Class 1