The N alloys are the Nilo range of controlled-expansion iron-nickel sealing alloys. Nilo is the Special Metals designation for the same materials other producers sell as Invar, Pernifer, Magnifer or SUPRA — the chemistry is fixed by the UNS number and ASTM F30 or F1684, not by the brand. That means Alloy 36 and Alloy 42 here are UNS K93600 and UNS K94100: the same two materials already covered under I Alloys, and those cards below link straight to their existing datasheets rather than duplicating them. Alloy 48 and Alloy 52 are the two grades in this list that appear nowhere else on the site, and both have full pages. Across the family, rising nickel raises the expansion coefficient but widens the range over which it stays constant — which is the actual basis for choosing between them.
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As nickel rises from 32% to 52%, two things move together: the expansion coefficient rises, and the temperature range over which it stays constant extends. Alloy 32-5 gives 0.63 µm/m·°C but only from −55 to 95°C. Alloy 36 gives 1.4 to about 260°C. Alloy 42 gives 5.3 to about 300°C. Alloy 48 gives 8.5 with a Curie point near 471°C, and Alloy 52 gives roughly 10 and holds it flat to about 565°C. You are matching the alloy to the glass, ceramic or semiconductor it has to seal against, across the range the joint will actually see.
Two handling points apply across the family. Cold work and machining stress distort the expansion coefficient — for Alloy 52 the published guidance says outright that cold working is not recommended — so the annealing or stabilising treatment must be done at finish size. And none of these alloys is stainless: chromium is capped at 0.25% as a residual, so they rust like plain carbon steel and need plating, or a controlled surface oxide where they are to be glass sealed.
With sealing alloys the processing route is part of the specification, not just a way of reaching a shape. Residual stress from machining, drawing or thread rolling shifts the expansion coefficient, so the sequence matters more than the cutting parameters — Exotic Alloy completes all machining first and anneals the finished component. For Alloy 52 this is stricter still, because cold working is not recommended for that grade at all. These alloys cut much like the austenitic stainless steels: they work-harden, give stringy chips and need sharp tooling, rigid setups and generous coolant. Much of the material moves as fine wire, thin strip and small-bore tube rather than machined bar.
The full controlled-expansion ladder, including the two I Alloy grades that are the same materials.
| Grade | Nilo / Other Names | UNS | Specification | Nominal Ni | Expansion | Constant To | Full Datasheet |
|---|---|---|---|---|---|---|---|
| Alloy 32-5 | Super Invar 32-5 | K93500 | ASTM F1684 | 32% + 5.5% Co | 0.63 µm/m·°C | 95°C | I Alloy 32-5 → |
| Alloy 36 | Nilo 36 / Invar 36 | K93600 | ASTM F1684 | 35–37% | 1.4 µm/m·°C | 260°C | I Alloy 36 → |
| Alloy 42 | Nilo 42 / FeNi42 | K94100 | ASTM F30 | 41–42.5% | 5.3 µm/m·°C | 300°C | I Alloy 42 → |
| Alloy 48 | Nilo 48 / SUPRA 50 | K94800 | ASTM F30 / DIN 17745 | 48% | 8.5 µm/m·°C | Curie 471°C | N Alloy 48 → |
| Alloy 52 | Nilo 52 / Pernifer 50 | N14052 | ASTM F30 / AMS-I-23011 | 50.5% nom. | ~10 µm/m·°C | 565°C | N Alloy 52 → |
Alloy 32-5 is included for comparison and is not part of the N Alloy list. Published nickel contents for Alloy 52 differ between sources — 50.5%, 51% and 52% are all quoted — so the controlling range should come from ASTM F30 or the mill certificate. Nilo is a trademark of the Special Metals Corporation group, Pernifer and Magnifer are VDM Metals trademarks, and Invar is a registered trademark originating with Imphy Alloys; Exotic Alloy is an independent manufacturer and is not affiliated with or endorsed by any of them.
We are committed to delivering zero-defect controlled-expansion and sealing components. All products undergo rigorous testing including PMI (Positive Material Identification), annealing at finish size, dimensional inspection, and material traceability with EN 10204 3.1 certification. Dilatometry is available where the expansion coefficient is contractual.
Exotic Alloy exports controlled-expansion and sealing components to electronics, lighting, lamp, instrument and semiconductor clients worldwide. Our dedicated logistics team ensures secure export packaging and timely deliveries by sea and air freight with full customs documentation support.