The Invar is a Alliage of Fer (64  %) and of Nickel (36  %) with a little Carbon and Chromium. This invention is due to the Suisse Charles Edouard Guillaume (Nobel Prize of physique 1920).

Thanks to its weak thermal dilation coefficient (approximately 10^-6  K ^-1 in length; certain nuances have negative dilation coefficients), it is used to produce precision instruments:

• Clock industry
• Topography
• detecting measuring devices physique of laboratory
• of seismic activity
• frameworks Shadow mask
• valves of engines
• lining of the cisterns of Methane tanker
• printed circuits electronics