Kovar (Nilo®, Alloy K) / 1.3981 / UNS K94610
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).
Material Data Sheet
| ASTM | F15 |
| UNS | K94610 |
| AMS | I-23011 CL1 |
Main fields of application
Kovar is used for:
- Hermetic sealing
- Production of transistors and diodes in electronic industry
- Vacuum systems in chemistry and scientific research
- Electronic tubes (power, microwave, X-Ray)
- Hybrid circuit casings
- Oscillator housings
- Concentrated solar power
- Scientific instruments
Chemical composition of Kovar
| Ni | Co | Fe | Mn | Si | C |
| 29 | 17 | Balance | 0.5 | 0.2 | 0.04 |
Mechanical properties of Kovar
| 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 |
Delivery program
Material is mainly used in bars or as wire. Various dimensions are available upon request.
Material Outlet by Hempel
taashvialloy.com offers buyers a new and uncomplicated procurement channel, which also includes small quantities and materials in special alloys at favourable conditions
Product Count
Coil 
Coil slit strip 
Sheets & plates 
Tubes round 
Full material square-cut 
Tubes quadratic or rectangular 
Hexagon-Shape 
U-Shape 
Wire Coil 
Flat Steel 
Cuts, fittings, other shapes 
Disk 
Round bars 
Ingots "square" Services
Waterjet cutting
Laser cutting
Plasma cutting
Shear cutting
Kovar / Nilo K (ASTM F15)
Technical Data Sheet
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 |
Typical Mechanical Properties
| 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 |
Availability
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.
Specifications
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
Registered Names
Kovar ®
Nicoseal ®
Nicosel ®
Rodar ®
Telcoseal ®
Sealvar ®
Alloy 29-17 ®
Nilo K ®
Dilver ®
Pernifer 29-18 ®
