====== Elinvar ======
**Elinvar** is an alloy of nickel and iron with a uniform thermal expansion characteristics. It was used for [[hairspring]]s and other [[spring]]s since its commercialization in [[1920]], though most hairsprings today use a related alloy known as [[Nivarox]].

Elinvar was discovered by Charles-Edouard Guillaume in [[1896]]. The discovery played a part in his winning the Nobel Prize for Physics in [[1920]]. Guillaume's alloy was commercialized by [[Fabriques de Spiraux Réunies|Fabriques de Spiraux Réunies (SR)]], a collective of Swiss hairspring manufacturers founded in [[1895]], and [[Société des Spiraux Francais]], founded in [[1919]]. Similar materials were also used at the time by competing manufacturers, including **Invar**.

[[Straumann, Reinhard|Reinhard Straumann]] discovered a superior [[balance spring]] material in [[1931]] in collaboration with the German firm [[Heraeus]]. This was commercialized by Straumann's company [[Nivarox SA]] as a competitor to Elinvar and Invar.

Elinvar was also used for [[balance wheel]]s until [[Glucydur]] was popularized and for [[anti-shock]] settings.

In [[1984]], [[Fabriques d'Assortiments Réunies|Fabriques d'Assortiments Réunies (FAR)]], SR, and Nivarox were merged to become [[Nivarox-FAR]]. Today's balance springs use [[Nivarox]] and related alloys based on Straumann's work or modern materials like [[silicon]].

===== See Also =====
  * [[Fabriques de Spiraux Réunies|Fabriques de Spiraux Réunies (SR)]]
  * [[Nivarox]]


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