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Material World
Alloy

Nichrome

Nickel and chromium, which glows red hot for years without oxidising away — the wire in every electric heater, toaster and kiln.

Electrical conductor

A heating element has to do something no ordinary conductor does: resist current enough to get hot, and then survive being hot in air indefinitely. Most metals fail the second requirement long before the first becomes interesting — iron wire glowing red simply oxidises until it breaks.

Nichrome does not, and the reason is chromium. At temperature it forms a thin, tight chromium oxide layer that seals the surface and stops further oxidation, and that layer re-forms if it is damaged. The wire underneath is protected by a scale a few atoms thick.

Uses

Toasters, hair dryers, electric ovens, industrial furnaces, kiln elements, soldering irons, hot-wire foam cutters, and the igniters in a great many things that need to start a fire electrically.

It also has a second life in the laboratory. A nichrome loop is the standard tool for flame tests, because the alloy does not colour a flame itself and does not corrode in the reagents being tested — which is a requirement almost nothing else meets.

Almost uniquely among conductors it is chosen for resistance rather than in spite of it, and its resistivity barely changes with temperature, so an element behaves the same cold as hot.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is composed of

  • Nickel — element · 55–80% · the base metal, and what carries the current
  • Chromium — element · 15–25% · the whole point: it forms the tight oxide skin that stops the wire burning away at red heat, and re-forms if it is damaged

is used as

  • Electrical conduction — application · as a deliberately poor one: nichrome is chosen for its resistance, not despite it

is produced by

Sources

  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • Material World
    Our own writing

Questions this page answers

Where it comes from, and what it becomes

Follow Nichrome back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Nichrome → is composed of (the whole point: it forms the tight oxide skin that stops the wire burning away at red heat, and re-forms if it is damaged) → Chromium → is produced by (as ferrochrome, reduced from chromite and added to steel without ever being separated as the pure metal) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Nichrome → is composed of (the base metal, and what carries the current) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Nichrome → is produced by (melted and drawn to wire, the drawing being the harder half) → Alloying and melting → takes as input (the base metal of both brass and bronze) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation
  • Nichrome → is composed of (the whole point: it forms the tight oxide skin that stops the wire burning away at red heat, and re-forms if it is damaged) → Chromium → is produced by (as ferrochrome, reduced from chromite and added to steel without ever being separated as the pure metal) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Nichrome → is composed of (the whole point: it forms the tight oxide skin that stops the wire burning away at red heat, and re-forms if it is damaged) → Chromium → is produced by (as ferrochrome, reduced from chromite and added to steel without ever being separated as the pure metal) → Smelting → takes as input (reduced with carbon to metallic tin) → Cassiterite
  • Nichrome → is composed of (the whole point: it forms the tight oxide skin that stops the wire burning away at red heat, and re-forms if it is damaged) → Chromium → is produced by (as ferrochrome, reduced from chromite and added to steel without ever being separated as the pure metal) → Smelting → takes as input (reduced with coke in a blast furnace) → Hematite

These are the most distinct paths back. Nichrome can be traced through others besides.

Downstream — what it becomes