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Controlled Expansion Alloys

Form	Size Range
	3mm – 60mm diameter
	20mm square

Flat also available

We hold a specialist range of low thermal expansion alloys including Alloy 36 (Invar®), Alloy K (Kovar®), Alloy 42 and Alloy 52 (Nilo®). Low expansion alloys are iron-nickel alloys that exhibit an extremely low expansion rate at room temperature. These materials have been utilised in modern applications that require metal to be joined to glass or ceramic, and areas where the thermal expansion rates of the materials must coincide to prevent differential expansion within the joint area. They are used in industries such as electronics, medical (laser and x-ray machines), aerospace engineering, telecommunications and cryogenic components.

Iron and nickel have very similar coefficients of thermal expansion. However, the addition of nickel to iron can result in the creation of an alloy in which the coefficient is reduced by an order of magnitude. Research in the 1920s (by Charles Édouard Guillaume, who won the Nobel Prize in Physics for his discovery) found that an iron-nickel alloy containing around 36% nickel exhibited virtually no thermal expansion at, or close to, room temperature. This type of material became noted for its invariability or lack of expansion and contraction with temperature changes. By modifying the composition of this 36% nickel alloy, metallurgists have created a number of special materials with unique expansion characteristics to suit particular applications.