Elinvar is a nickel, iron and chromium alloy with low thermal expansion and good elastic properties (small influence of temperature variations on modulus of elasticity). It was invented in 1919 by Swiss physicist Charles Édouard Guillaume. It originally consisted of 52% iron, 36% nickel and 12% chromium and found use as a material for making hairsprings in watch movements.
Elinvar was one of the first alloys to minimize the problems of previously used steel hairspring, i.e. thermal instability, magnetic susceptibility and low corrosion resistant. Steel has a relatively large influence of temperature variations on the modulus of elasticity. This means that its "elasticity" varies with temperature, necessitating sophisticated and only partially effective thermal compensation in the balance assembly.
Used today Elinvar contains approx. 59% iron, 36% nickel and 5% chromium, and its properties in relation to the steel reduces the susceptibility hairspring for magnetization and improve its thermal stability, a magnetic field acts on the elements of elinvar (draws it) but Elinvar does not permanently magnetize.
Use of Elinvar for making of balance springs has made it possible to high-precision movements without the use of complicated thermal compensation methods and has guaranteed "anti-magnetic" properties for watches.
Charles Édouard Guillaume was awarded the Nobel Prize in 1920 for his discovery of Elinvar.
Notifier: Tomasz Jakubas
Other records: Timeline of Watchmaking Innovations