Invar Alloy
Invar, otherwise known as FeNi36 (64FeNi in the US), is a nickel-iron alloy known for its consistent thermal expansion coefficient (α or CTE). Its name, Invar, signifies its resistance to temperature-
Invar, otherwise known as FeNi36 (64FeNi in the US), is a nickel-iron alloy known for its consistent thermal expansion coefficient (α or CTE). Its name, Invar, signifies its resistance to temperature-
Like other nickel/iron compositions, Invar is a solid solution; that is, it is a single-phase alloy. In one commercial version it consists of approximately 36% nickel and 64% iron. Common grades of Invar have a coefficient of thermal expansion (denoted α, and measured between 20 °C and 100 °C) of about 1.2 × 10−6 K−1 (1.2 ppm/°C), while ordinary steels have values of around 11–15 ppm/°C. Extra-pure grades (<0.1% Co) can readily produce values as low as 0.62–0.65 ppm/°C. Some formulations display negative thermal expansion (NTE) characteristics. Though it displays high dimensional stability over a range of temperatures, it does have a propensity to creep.
Applications:
- Composite molds for the aerospace industry
- Bimetal thermostats
- Clock balance wheels
- Containers and transfer lines for LNG tankers
- Echo boxes and filters for mobile telephones
- Electrical circuit breakers & transformers
- Electron gun components
- High voltage transmission lines
- Laser components
- Magnetic shielding
- Radar and microwave cavity resonators
- Scientific instruments
