MATERIAL GROUP
Controlled-expansion alloys
Controlled-expansion alloys serve components where dimensional changes with temperature matter. They provide different expansion characteristics for precision measurement and glass-to-metal seals.
The lowest expansion is not always the aim
A measuring instrument may need dimensions to stay as stable as possible as temperature changes. A metal part joined to glass instead needs to expand by a similar amount to the glass. Invar 36, Alloy 42, Ni48 and Kovar therefore address different needs: each has its own pattern of dimensional change with temperature.
From precision devices to sealed connections
Sensor bodies, electronic packages and measuring components are important applications. Matching the expansion of a metal to the glass or ceramic around it reduces thermally induced stress in the joint. The value of the alloy lies not just in strength but in how it works alongside the surrounding materials.
Expansion and magnetic properties
Some nickel–iron alloys appear in both expansion and magnetic applications. Similar composition does not establish the same functional performance. Material defined for magnetic shielding and material intended for a precision dimensional component emphasise different properties. For example, expansion matched to glass matters in a sensor package, while the ability to guide magnetic flux matters in its shield.
Grades in this group
Grade designations, organised by material group. Designations from different systems do not always imply identical specification requirements.
| Controlled-expansion alloys4 grades | ||||
|---|---|---|---|---|
| Grade / Alloy | EN / W.Nr. | AISI / SAE | UNS | Grade page |
| Alloy 42Controlled thermal expansion | 1.3917 | — | K94100 | |
| Ni48Iron-nickel · Controlled expansion | 1.3922 | — | — | |
| KovarExpansion matching with glass and ceramic | 1.3981 | — | K94610 | |
| Alloy 52Special iron-nickel expansion alloy | 2.4478 | — | N14052 | |
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