Switzerland (Guillaume worked at the International Bureau of Weights and Measures near Paris) · Invar announced 1896; Elinvar announced 1919–1920
Invar and Elinvar Alloys
VerifiedElinvar and its later refinements (Nivarox and similar proprietary alloys) underpin virtually all mass-produced mechanical balance springs made since the mid-twentieth century.
Guillaume discovered that certain nickel-steel alloys have a near-zero coefficient of thermal expansion (Invar) or a near-zero thermoelastic coefficient (Elinvar), the latter directly applicable to balance springs that barely change elastic modulus with temperature.
Elinvar balance springs greatly reduced the need for separate bimetallic compensation balances, simplifying and improving watch regulation; Guillaume received the 1920 Nobel Prize in Physics substantially for this work.
Background
Swiss physicist Charles Édouard Guillaume discovered nickel-iron alloys in 1895 that exhibited anomalous thermal properties. He developed Invar, which has a near-zero coefficient of thermal expansion, to improve the precision of instruments such as clock pendulums. Guillaume subsequently invented Elinvar, an alloy of iron, nickel, and chromium, to address the issue of temperature-induced elasticity changes in watch balance springs.
Ordinary steel springs lost elasticity as temperatures rose, causing watches to lose time and necessitating complex temperature-compensated balances. The use of Elinvar, with its invariable elasticity, allowed for simpler, more accurate timekeeping by rendering the compensation balance obsolete. Guillaume received the Nobel Prize in Physics in 1920 for his work on these nickel steel anomalies and their contributions to precision measurements.
Written from the encyclopedia entries listed under Sources; each statement was checked against the cited text.
How it works
- Invar 36 is composed of approximately 36% nickel and 64% iron.
- Elinvar is composed of approximately 52% iron, 36% nickel, and 12% chromium.
- Elinvar is largely non-magnetic, which provides an additional advantage for antimagnetic timepieces.
Later history
- The Riefler regulator clock of 1898 was among the first instruments to employ an Invar pendulum.
- Subsequent alloys such as Nivarox have followed the development of Elinvar.
How to verify this yourself
Guillaume's original scientific papers were published through the Bureau International des Poids et Mesures and the Comptes Rendus of the French Academy of Sciences; corresponding patents, where filed, should be sought in the French and Swiss patent registers under Guillaume's name rather than assumed from secondary sources.
Manufacturers known to have used it
- Most Swiss manufacturers via licensed or derivative alloys (e.g. Nivarox)
- Hamilton (Elinvar Extra)
Photographs
Photographs are illustrative examples of the type, not necessarily the exact object described. Verify details against the source file page.
Sources & references
- Invar, Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
- Elinvar, Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
- Charles-Édouard Guillaume, Wikipedia (English), retrieved 2026-10-28 (text CC BY-SA 4.0)
- Nobel Prize official biography of Charles Édouard Guillaume (nobelprize.org)
- Comptes Rendus de l'Académie des Sciences, Guillaume's published papers (existence noted)
Where sources disagree, the disagreement is stated rather than resolved silently.