Kovar (ASTM F15)

UNS K94610 special
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Fe-Ni-Co controlled-expansion alloy with CTE matched to borosilicate glass and certain ceramics. Used for glass-to-metal and ceramic-to-metal hermetic seals in electronics.

Applicable Standards

  • ASTM F15
  • UNS K94610

Composition Ranges (wt %)

Element Min (%) Max (%) Typical Range
Fe 52.0 56.0 ~54.0
Ni 28.5 29.5 ~29.0
Co 16.5 17.5 ~17.0
Mn 0.2 0.6 ~0.4
Si — 0.2 ~0.1
C — 0.02 ~0.01
Fe 52.0–56.0% Ni 28.5–29.5% Co 16.5–17.5% Mn 0.2–0.6% Si 0.0–0.2% C 0.0–0.02%

Typical Applications

  • Glass-to-metal seals
  • Hermetic packages
  • LED housings
  • Transistor cases
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