Elinvar is the name of a type of metallic alloy with a modulus of elasticity which does not vary with temperature; the name means elastically invariable. The first work in producing it was done by the same man who had invented invar, the alloy of nickel and iron which has a small temperature coefficient of expansion. The initial use of elinvar materials was in watches which required that a mechanical vibration rate not change with temperature changes.

Elinvar consists of 59% iron, 36% nickel, and 5% chromium.

Ferrous alloys