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Material World
Element · Re

Rhenium

One of the rarest elements in the crust, and the reason jet engines can run as hot as they do.

Rhenium was the last stable element to be discovered, in 1925, because it forms no ore of its own — it is dispersed thinly and recovered almost entirely as a by-product of molybdenum roasting from copper porphyry deposits.

It has the second-highest melting point of any element and, unusually, keeps its strength across an enormous temperature range without the ductile-to-brittle transition that limits tungsten. That combination is rare enough that rhenium has no real substitute in its main application.

Uses

Nickel superalloy turbine blades are the dominant use. A few per cent rhenium lets a jet engine blade run at a higher temperature, and engine efficiency rises with combustion temperature, so rhenium content translates fairly directly into fuel economy. Single-crystal blades for the hottest stages contain the most.

Rhenium is also a petroleum reforming catalyst, used with platinum to raise the octane rating of petrol, and rhenium-tungsten alloys make thermocouples and filaments for high-temperature measurement.

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 sourced from

  • Molybdenum — element · recovered from the flue dusts of molybdenum roasting; rhenium forms no ore of its own

is used as

  • Catalysis — application · with platinum, raises the octane rating of petrol

is produced by

  • Roasting — process · recovered from the flue dusts of molybdenite roasting; it forms no ore of its own

is a component of

  • Nickel superalloy — alloy · 0–6% · two or three per cent, and essentially the only use rhenium has — most of world consumption goes into turbine blades

is used in

  • Turbine blade — object · two or three per cent of the alloy, because it slows diffusion and therefore creep — and blade alloys take most of world rhenium production for it

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
  • NIST — National Institute of Standards and Technology
    United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Rhenium 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

  • Rhenium → is sourced from (recovered from the flue dusts of molybdenum roasting; rhenium forms no ore of its own) → Molybdenum → is produced by (reduced from the oxide that roasting molybdenite produces) → 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
  • Rhenium → is produced by (recovered from the flue dusts of molybdenite roasting; it forms no ore of its own) → Roasting → takes as input (a copper sulfide; roasting drives off the sulfur that would otherwise prevent reduction) → Chalcopyrite
  • Rhenium → is produced by (recovered from the flue dusts of molybdenite roasting; it forms no ore of its own) → Roasting → takes as input (roasted for its sulfur as much as for its iron) → Pyrite
  • Rhenium → is produced by (recovered from the flue dusts of molybdenite roasting; it forms no ore of its own) → Roasting → takes as input (roasted to the oxide, the sulfur going to an acid plant rather than the air) → Galena
  • Rhenium → is produced by (recovered from the flue dusts of molybdenite roasting; it forms no ore of its own) → Roasting → takes as input (roasted to zinc oxide before reduction or electrolytic winning) → Sphalerite
  • Rhenium → is produced by (recovered from the flue dusts of molybdenite roasting; it forms no ore of its own) → Roasting → takes as input (roasted in air; the mercury leaves as vapour rather than staying behind as an oxide) → Cinnabar

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

Downstream — what it becomes

  • Rhenium → is a component of (two or three per cent, and essentially the only use rhenium has — most of world consumption goes into turbine blades) → Nickel superalloy → is used in (cast as a single crystal, because at temperature and sustained load the failure mode is creep along grain boundaries — so the boundaries are removed entirely) → Turbine blade → is associated with (the jet engine created the superalloy industry, because no existing material survived the turbine inlet — and turbine temperature has risen about 500 °C since, almost entirely on the blade) → The wartime materials programmes complete chain
  • Rhenium → is used in (two or three per cent of the alloy, because it slows diffusion and therefore creep — and blade alloys take most of world rhenium production for it) → Turbine blade → is associated with (the jet engine created the superalloy industry, because no existing material survived the turbine inlet — and turbine temperature has risen about 500 °C since, almost entirely on the blade) → The wartime materials programmes complete chain
  • Rhenium → is used as (with platinum, raises the octane rating of petrol) → Catalysis
  • Rhenium → is a component of (two or three per cent, and essentially the only use rhenium has — most of world consumption goes into turbine blades) → Nickel superalloy → is associated with (the jet engine created the industry, because no existing material survived the turbine inlet) → The wartime materials programmes complete chain
  • Rhenium → is a component of (two or three per cent, and essentially the only use rhenium has — most of world consumption goes into turbine blades) → Nickel superalloy → is used as (the turbine blade carries its own centrifugal load at four fifths of its melting point, which is structural engineering under the hardest conditions anybody attempts) → Structural engineering
  • Rhenium → is a component of (two or three per cent, and essentially the only use rhenium has — most of world consumption goes into turbine blades) → Nickel superalloy → is used in (the turbine hot section, which runs above the alloy's own melting point and only works because of internal cooling and ceramic coating) → Aerospace manufacture

These are the most distinct paths onward. Rhenium ends up in others besides.