Kovar® is a nickel-iron-cobalt alloy with a coefficient of thermal expansion like that of hard glass. 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. 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).
ASTM | F15 |
UNS | K94610 |
AMS | I-23011 CL1 |
Ni | Co | Fe | Mn | Si | C |
29 | 17 | Balance | 0.5 | 0.2 | 0.04 |
Density g/cm³ | 8.26 | |
Curie Temp | °F 815 | °C 435 |
Melting Point | °F 2640 | °C 1449 |
Modulus of Elasticity at 20°C | MPa | 207 |
Specific Heat | J/g- °C | 0.11 |
Thermal Conductivity at 20°C | W/m.k | 17.3 |
Thermal Expansion | W.m-¹°C | 0.17 |
Electrical Resistivity | mm²/m | 49 |
Poisson's coefficient | 0.317 |
Material is mainly used in bars or as wire. Various dimensions are available upon request.
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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.
Kovar Chemical Composition (Basic Density 8.36) | |||||||||||||
Weight % | Ni | Fe | Co | C | Mn | Si | Al | Cr | Mg | Zr | Ti | Cu | Mo |
Alloy K Kovar |
29.0 | 53.0 | 17.0 | 0.04 max | 0.50 max | 0.20 | 0.10 max | 0.20 max | 0.10 max | 0.10 max | 0.10 max | 0.20 max | 0.20 max |
Material | Condition | Yield Strength (0.1% Offset) | Tensile Strength | Elongation % | ||
psi | MPa | psi | MPa | |||
Alloy K Kovar |
Annealed | 49,000 | 340 | 75,000 | 520 | 42 |
Alloy K / Kovar is available (further details) in Bar, Rod, Tube, Sheet, Strip, Coil, Plate and Wire. For all stock availability contact Sales for further availability.
UNS K94610
Werkstoff Nr 1.3981
DIN 17745
ASTM F 15
AMS 7726 Wire
AMS 7727 Bars and Forgings
AMS 7728 Sheet, Strip and Plate
MIL-I-23011 class 1
AFNOR NF A54-301
S.E.W 385
DILVER P
Kovar ®
Nicoseal ®
Nicosel ®
Rodar ®
Telcoseal ®
Sealvar ®
Alloy 29-17 ®
Nilo K ®
Dilver ®
Pernifer 29-18 ®