Molybdenum Mo

spore: profile
id: molybdenum
spore_version: 0.2
family: refractory-metals
name: Molybdenum
abbreviation: Mo
role: refractory structural and alloying metal
category: metals
type: refractory-metals
summary: |
  Molybdenum is the element Mo, a refractory metal with a melting point of 2623 °C (PubChem record) and a density of 10.22 g/cm3 at 20 °C (Plansee). Most of it goes into steel, cast iron and superalloys. In air it is not easily oxidised at ordinary temperature, but above 400 °C it forms the volatile trioxide MoO3 (PubChem). A laboratory rod made from electron-beam-melted 99.97 % molybdenum and annealed 1 h at 1315 °C had a yield strength of 265 MPa and a tensile strength of 411 MPa at 25 °C (NASA TM X-2576).
best_for: 'High-temperature strength and heat conduction: 2623 °C melting point and 142 W/(m·K) thermal conductivity at 20 °C, in vacuum or inert service'
weakest_at: Oxidation in air above about 400 °C, where it forms volatile MoO3, and toughness at room temperature in as-rolled sheet (ductile-brittle transition above 25 °C in the NASA study)
identity:
  formula: Mo (element, atomic number 42), unalloyed body-centred cubic metal
  cas: 7439-98-7
  source: pubchem-mo
  where: Other Identifiers, CAS entry 7439-98-7 in the PubChem record for molybdenum (CID 23932)
  designations:
    - system: UNS
      code: R03610
      note: isotropic pure molybdenum, ASTM B1024 grades 1 and 2 (unalloyed monolithic forms)
      source: astm-b1024
      where: Scope sections 1.2 and 1.3, Grade 1 (UNS R03610) and Grade 2 (UNS R03610)
    - system: ASTM
      code: B1024
      note: isotropic pure molybdenum, monolithic forms
      source: astm-b1024
      where: 'Title: Standard Specification for Isotropic Pure Molybdenum'
    - system: ASTM
      code: B387
      note: bar, rod and wire; unalloyed Molybdenum 360, 361 and 365 are listed in the scope
      source: astm-b387
      where: Title and scope section 1.1, unalloyed grades 360, 361 and 365
    - system: ASTM
      code: B386
      note: plate, sheet, strip, foil and ribbon; unalloyed Molybdenum 360, 361 and 365 are listed in the scope
      source: astm-b386
      where: Title and scope section 1.1, unalloyed grades 360, 361 and 365
tags:
  applications:
    - structures
    - electronics-and-chips
    - thermal-control
properties:
  - benchmark: density
    label: Density of pure molybdenum at 20 °C
    value: 10.22
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
      form: pure molybdenum metal, no grade stated
    method: Value printed on the manufacturer material page
    status: ground
    source: plansee-mo
    where: Facts table, row Density, condition 20 °C
  - benchmark: melting_point
    label: Melting point of molybdenum
    value: 2623
    unit: °C
    scope: material
    conditions:
      unit_in_source: 4752 °F (NIOSH, 2024) and 2622 °C, 2617 °C from other entries
      pressure: not stated
    method: Value printed in the Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-mo
    where: Chemical and Physical Properties, Experimental Properties, Melting Point, entry 2623 °C
  - benchmark: boiling_point
    label: Boiling point of molybdenum
    value: 4639
    unit: °C
    scope: material
    conditions:
      pressure: 760 mmHg
      unit_in_source: 8717 °F at 760 mmHg (NIOSH, 2024)
    method: Value printed in the Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-mo
    where: Chemical and Physical Properties, Experimental Properties, Boiling Point, entry 4639 °C @760 [mm Hg]
  - benchmark: thermal_conductivity
    label: Thermal conductivity of pure molybdenum at 20 °C
    value: 142
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 20 °C
      form: pure molybdenum metal, no grade stated
    method: Value printed on the manufacturer material page
    status: ground
    source: plansee-mo
    where: Facts table, row Thermal conductivity, condition 20 °C
  - benchmark: cte
    label: Coefficient of thermal expansion of pure molybdenum at 20 °C
    value: 5.2
    unit: ppm/K
    scope: material
    conditions:
      temperature: 20 °C
      unit_in_source: 5.2 × 10-6 m/(m·K), equal to ppm/K
    method: Value printed on the manufacturer material page
    status: ground
    source: plansee-mo
    where: Facts table, row Coefficient of linear thermal expansion, condition 20 °C
  - benchmark: specific_heat
    label: Specific heat of pure molybdenum at 20 °C
    value: 0.25
    unit: J/(g·K)
    scope: material
    conditions:
      temperature: 20 °C
      form: pure molybdenum metal, no grade stated
    method: Value printed on the manufacturer material page
    status: ground
    source: plansee-mo
    where: Facts table, row Specific heat, condition 20 °C
  - benchmark: electrical_resistivity
    label: Specific electrical resistance of pure molybdenum at 20 °C
    value: 0.056
    unit: Ω·mm²/m
    scope: material
    conditions:
      temperature: 20 °C
      form: pure molybdenum metal, no grade stated
    method: Value printed on the manufacturer material page
    status: ground
    source: plansee-mo
    where: Facts table, row Specific electrical resistance, condition 20 °C
  - benchmark: yield_strength
    label: Yield strength, 0.2 percent offset, annealed rod at 25 °C
    value: 265
    unit: MPa
    scope: material
    conditions:
      material: electron-beam-melted molybdenum, 99.97 % Mo, laboratory ingot (not a standard product)
      form: rod, swaged
      temper: annealed 1 h at 1315 °C (2400 °F)
      temperature: 25 °C (75 °F)
      unit_in_source: MN/m2 (38.4 ksi)
    method: Value printed in a NASA table of tensile results for electron-beam-melted molybdenum
    status: ground
    source: nasa-tm-x2576
    where: Table IV, rod group, 1315 °C anneal row, test temperature 25 °C, column 0.2-percent offset yield strength
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, annealed rod at 25 °C
    value: 411
    unit: MPa
    scope: material
    conditions:
      material: electron-beam-melted molybdenum, 99.97 % Mo, laboratory ingot (not a standard product)
      form: rod, swaged
      temper: annealed 1 h at 1315 °C (2400 °F)
      temperature: 25 °C (75 °F)
      unit_in_source: MN/m2 (59.6 ksi)
    method: Value printed in a NASA table of tensile results for electron-beam-melted molybdenum
    status: ground
    source: nasa-tm-x2576
    where: Table IV, rod group, 1315 °C anneal row, test temperature 25 °C, column ultimate tensile strength
  - benchmark: recrystallization_temperature
    label: Recrystallization temperature of unalloyed molybdenum sheet, 100 percent in 1 hour
    value: 925
    unit: °C
    scope: material
    conditions:
      material: electron-beam-melted unalloyed molybdenum sheet
      cold_work: 81 to 92 percent
      time: 1 hour
      unit_in_source: 1700 °F
    method: Value stated in the recrystallization section of a NASA technical memorandum
    status: ground
    source: nasa-tm-x2576
    where: Recrystallization and Grain Growth section, text on unalloyed molybdenum sheet, and Table VII
  - benchmark: vapor_pressure
    label: Vapour pressure of molybdenum (solid)
    value: 1
    unit: Pa
    scope: material
    conditions:
      temperature: 2469 °C (solid)
      unit_in_source: 1 Pa at 2469 °C (solid)
    method: Value listed in the Vapor Pressure section of the PubChem record
    status: ground
    source: pubchem-mo
    where: Chemical and Physical Properties, Experimental Properties, Vapor Pressure, entry 1 Pa at 2469 °C (solid)
  - benchmark: heat_of_vaporization
    label: Heat of vaporization of molybdenum
    value: 491
    unit: kJ/mol
    scope: material
    conditions:
      basis: not stated in the record
    method: Value listed in the Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-mo
    where: Chemical and Physical Properties, Experimental Properties, Heat of Vaporization, entry 491 kJ/mol
  - benchmark: molar_heat_capacity
    label: Molar heat capacity of molybdenum at 25 °C
    value: 24.06
    unit: J/(mol·K)
    scope: material
    conditions:
      temperature: 25 °C
      pressure: 100 kPa (760 mm Hg)
    method: Value listed in the Other Experimental Properties section of the PubChem record
    status: ground
    source: pubchem-mo
    where: Chemical and Physical Properties, Experimental Properties, Other Experimental Properties, molar heat capacity entry
corrosion:
  - environment: Air at ordinary temperature
    headline: Molybdenum is not easily oxidised by air or water at ordinary temperature.
    effect: 'The PubChem record quotes a source: the metal is not easily oxidised by air or water at ordinary temperature, and it has poor oxidation resistance at higher temperature.'
    rating: low
    conditions:
      temperature: ordinary temperature (not stated numerically)
    source: pubchem-mo
    where: Spectral Information, Other Spectra entry
  - environment: Air above 400 °C
    headline: Above 400 °C molybdenum forms a highly volatile trioxide, MoO3, and above 700 °C the oxidation becomes so severe that it needs a protective coating.
    effect: The PubChem record says that when heated above 400 °C molybdenum yields a highly volatile trioxide (MoO3), and above 700 °C oxidation is so severe that use is possible only if the metal is protected by a covering layer of an oxidation-resistant metal, an alloy, or a silicon deposit.
    rating: severe
    conditions:
      temperature: above 400 °C in air
      unit_in_source: 400 °C and 700 °C as printed
    source: pubchem-mo
    where: Spectral Information, Other Spectra entry
  - environment: Acids and water
    headline: Molybdenum is insoluble in water and is attacked by hot concentrated sulphuric or nitric acid.
    effect: The PubChem record gives insoluble in water, soluble in nitric acid and sulphuric acid, slightly soluble in hydrochloric acid, and insoluble in hydrofluoric acid and dilute sulphuric acid. The record also says it reacts with nitric acid, hot concentrated sulphuric acid, and fused potassium chlorate or nitrate.
    rating: moderate
    conditions:
      basis: solubility statements as printed, no rate given
    source: pubchem-mo
    where: Experimental Properties, Solubility entries
risks:
  hazards:
    - text: PubChem aggregates ECHA C&L notifications for molybdenum (1523 company reports). Among the notifications, H228 flammable solid is given for 30 % of reports that gave codes, H361 suspected of damaging fertility or the unborn child for 29.5 %, and H225 for 11.6 %. The record says 874 of 1523 reports (57.4 %) do not meet GHS criteria. The notified classification is not specific to form, so it is not a rating for solid metal.
      ghs:
        - H228
        - H361
        - H225
      source: pubchem-mo
      where: Safety and Hazards, GHS Classification, GHS Hazard Statements and ECHA C&L Notifications Summary
    - text: Other PubChem notifications give H315 (causes skin irritation), H319 (causes serious eye irritation) and H335 (may cause respiratory irritation), signal word Warning.
      ghs:
        - H315
        - H319
        - H335
      source: pubchem-mo
      where: Safety and Hazards, GHS Classification, second notification block
    - text: 'The PubChem record gives the NIOSH Pocket Guide excerpt: dust and fumes irritate the eyes and respiratory tract. Exposure routes are inhalation, ingestion and skin or eye contact. Target organs are the eyes, respiratory system, liver and kidneys.'
      ghs: []
      source: pubchem-mo
      where: Safety and Hazards, Health Hazards, NIOSH excerpt
  failure_risks:
    - mode: Oxide loss in hot air
      trigger: Metal heated above 400 °C in air
      consequence: Molybdenum forms the volatile trioxide MoO3, so the metal is lost from the part. Above 700 °C a protective coating is needed.
      severity: critical
      source: pubchem-mo
      where: Spectral Information, Other Spectra entry
    - mode: Softening of cold-worked sheet
      trigger: Cold-worked unalloyed sheet (81 to 92 percent cold work) held 1 hour at 925 °C
      consequence: The sheet recrystallises fully, so it loses the strength it gained from cold work. The source gives the temperature only and does not measure the strength after annealing.
      severity: moderate
      source: nasa-tm-x2576
      where: Recrystallization and Grain Growth section and Table VII
    - mode: Brittleness at room temperature in as-rolled sheet
      trigger: Sheet used as rolled, not annealed
      consequence: The NASA table gives an approximate ductile-brittle transition above 25 °C (more than 75 °F) for as-rolled sheet, so the sheet can break in a brittle way near room temperature. The table is an OCR scan, so this value should be checked against the page image.
      severity: moderate
      source: nasa-tm-x2576
      where: Table IV, row 100 Mo sheet (a) as rolled, not annealed, last column
  side_effects: []
  handling:
    - text: Keep dust and fumes out of breathing zones and off the eyes. The PubChem record cites the NIOSH Pocket Guide for irritation of the eyes, nose and throat in animals and for liver and kidney effects at high exposure.
      source: pubchem-mo
      where: Health Hazards, NIOSH excerpt
    - text: Use an oxidation-resistant coating or a vacuum or inert atmosphere for hot service, because the metal oxidises to a volatile oxide above 400 °C in air.
      source: pubchem-mo
      where: Spectral Information, Other Spectra entry
  mitigations: []
uses:
  - application: structures
    device: Alloying agent in steel, cast iron and superalloys
    example: The USGS says molybdenum is used principally as an alloying agent in cast iron, steel and superalloys, and that in 2025 U.S. apparent consumption was estimated at 34,000 tons of molybdenum content.
    source: usgs-mcs2026-molybdenum
    where: Domestic Production and Use paragraph and Salient Statistics table, row Apparent consumption
  - application: electronics-and-chips
    device: Conductive metal layers in thin-film transistors
    example: The PubChem record says molybdenum is found in some electronic applications as the conductive metal layers in thin-film transistors (TFTs).
    source: pubchem-mo
    where: Use and Manufacturing, Uses section
  - application: thermal-control
    device: Resistance elements in electric furnaces
    example: The PubChem record lists resistance elements for electric furnaces among molybdenum uses. The USGS lists graphite, tantalum and tungsten as potential substitutes for molybdenum in refractory materials for high-temperature electric furnaces.
    source: pubchem-mo
    where: Use and Manufacturing, Uses section; USGS Substitutes paragraph
supply:
  - subject: Molybdenum (mine production, molybdenum content)
    producers:
      - country: China
        share_percent: 37.3
        year: 2025
      - country: Chile
        share_percent: 16.2
        year: 2025
      - country: United States
        share_percent: 15.4
        year: 2025
      - country: Peru
        share_percent: 15
        year: 2025
      - country: Mexico
        share_percent: 6.5
        year: 2025
    critical_lists: []
    recycling: The USGS says molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap, and that recycled molybdenum may be as much as 30 % of apparent supply. There is no separate recovery process for secondary molybdenum from its alloys.
    substitutes:
      - 'USGS: little substitution in steels and cast irons; boron, chromium, niobium and vanadium in alloy steels; tungsten in tool steels; graphite, tantalum and tungsten for refractory materials in high-temperature electric furnaces.'
    source: usgs-mcs2026-molybdenum
    where: World Mine Production and Reserves table, mine production 2025e (world total 260,000 tons; shares calculated by Space Mushroom from the country values 97,000; 42,000; 40,000; 39,000; 17,000). Substitutes and Events, Trends and Issues paragraphs. The top five producers sum to 90 % of world production, as the USGS also states.
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
  - title: PubChem compound record for molybdenum (CID 23932), XML view
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/XML
  - title: 'Plansee material page: molybdenum (physical properties, 20 °C)'
    type: datasheet
    url: https://www.plansee.com/en/materials/molybdenum.html
  - title: Klopp and Witzke, Mechanical properties of electron-beam-melted molybdenum and dilute molybdenum-rhenium alloys, NASA TM X-2576 (1972)
    type: report
    url: https://ntrs.nasa.gov/api/citations/19720017873/downloads/19720017873.pdf
    year: 1972
  - title: 'ASTM B1024/B1024M-23: Standard Specification for Isotropic Pure Molybdenum'
    type: standard
    url: https://standards.nimonik.com/products/astm/b1024-b1024m/
    year: 2023
  - title: 'ASTM B387/B387M-23: Standard Specification for Molybdenum and Molybdenum Alloy Bar, Rod, and Wire'
    type: standard
    url: https://store.astm.org/b0387_b0387m-23.html
    year: 2023
  - title: 'Wikipedia: Molybdenum (crystal structure, molybdenite ore, history)'
    type: database
    url: https://en.wikipedia.org/wiki/Molybdenum
    year: 2026
  - title: 'ASTM B386/B386M-25: Standard Specification for Molybdenum and Molybdenum Alloy Plate, Sheet, Strip, Foil, and Ribbon'
    type: standard
    url: https://store.astm.org/b0386_b0386m-25.html
    year: 2025
gaps:
  - No EN, W.Nr., DIN or JIS designation for pure molybdenum was printed in any source opened in this run. UNS R03630 was searched for and not confirmed; the only UNS code found for unalloyed molybdenum is R03610 (ASTM B1024).
  - Young's modulus and Poisson's ratio for pure molybdenum are not recorded. The Wikipedia elastic-properties data page gives 329 GPa and 0.31 at room temperature (CRC), but the brief limits Wikipedia to composition and history, so the value was not used. The Princeton glossary (320 GPa) and matmatch pages were not readable in this run.
  - The Plansee page returned Access Denied to the automated curl check, so the values from it (density, thermal conductivity, CTE, specific heat, electrical resistance) were read with the web-fetch tool in this run but cannot be checked by verify-values. The page prints no modulus, tensile, yield, hardness or recrystallization values.
  - Mechanical data rest on one laboratory rod condition (electron-beam-melted 99.97 % molybdenum, annealed 1315 °C, tested at 25 °C) and one sheet recrystallization figure. No standard-product minimum tensile or yield value from ASTM B386 or B387 was found in the scope pages opened; those pages print scope and grade names only.
  - Hardness of pure molybdenum was not found in a readable source. The Advent RM and aircraftmaterials pages were garbled, and the Elmet page could not be reached.
  - The as-rolled sheet transition temperature (above 25 °C) is read from an OCR table in a NASA scan and should be checked against the page image.
  - Boiling point, heat of vaporization and molar heat capacity come from the PubChem record, whose original sources are not named in the fetched text.
  - Recrystallization temperature is stored under a non-canonical benchmark name (recrystallization_temperature) because no canonical name in property-canon.yaml fits. Boiling point and heat of vaporization are also non-canonical names.
  - The PubChem GHS notifications are not specific to the metal form; the H228 and H361 shares may come from powder or compound notifications, so they are shown as aggregated ECHA data only.
  - The USGS molybdenum summary does not state a critical-minerals list membership, and the 2025 U.S. critical-minerals list was not opened. The critical_lists field is therefore empty.
  - No exposure limits (OSHA PEL, ACGIH TLV) were read; PubChem gives only the OSHA sampling method numbers.
  - Radiation effects, outgassing (NASA total mass loss) and atomic-oxygen erosion of molybdenum were not searched or not found in an accepted source.
  - 'Process steps: the USGS says roasting plants convert molybdenum concentrate to molybdic oxide, from which metal powder is made. The powder-to-ingot route is taken from the NASA laboratory melt, not from a primary production reference.'
  - Electrical conductivity is not recorded; the Plansee page gives 17.9 × 10^6 S/m at 20 °C, which was not converted and is represented by the resistivity line instead.
  - Mo-99 and biological roles of molybdenum are outside the scope of this profile.
sources:
  usgs-mcs2026-molybdenum:
    title: Mineral Commodity Summaries 2026, Molybdenum (U.S. Geological Survey, February 2026)
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-mo:
    title: 'PubChem compound record: Molybdenum (CID 23932), including ECHA C&L notifications, NIOSH and vapour pressure entries'
    id: CAS 7439-98-7, UNII 81AH48963U
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23932/XML
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and others
  plansee-mo:
    title: 'Plansee, Molybdenum material page (facts table: physical properties at 20 °C)'
    url: https://www.plansee.com/en/materials/molybdenum.html
    kind: datasheet
    license: Manufacturer web page (cited, not reproduced)
  nasa-tm-x2576:
    title: 'NASA TM X-2576: Mechanical properties of electron-beam-melted molybdenum and dilute molybdenum-rhenium alloys (Klopp and Witzke, Lewis Research Center, 1972)'
    id: NTRS 19720017873
    url: https://ntrs.nasa.gov/api/citations/19720017873/downloads/19720017873.pdf
    year: 1972
    kind: report
    license: public domain (NASA)
  astm-b1024:
    title: ASTM B1024/B1024M-23, Standard Specification for Isotropic Pure Molybdenum
    id: UNS R03610
    url: https://standards.nimonik.com/products/astm/b1024-b1024m/
    kind: standard
    license: Standard summary page (cited, not reproduced)
  astm-b387:
    title: ASTM B387/B387M-23, Standard Specification for Molybdenum and Molybdenum Alloy Bar, Rod, and Wire
    url: https://store.astm.org/b0387_b0387m-23.html
    kind: standard
    license: Standard store page (cited, not reproduced)
  astm-b386:
    title: ASTM B386/B386M-25, Standard Specification for Molybdenum and Molybdenum Alloy Plate, Sheet, Strip, Foil, and Ribbon
    url: https://store.astm.org/b0386_b0386m-25.html
    kind: standard
    license: Standard store page (cited, not reproduced)
  wikipedia-mo:
    title: Molybdenum (Wikipedia), used for crystal structure, ore and history only
    url: https://en.wikipedia.org/wiki/Molybdenum
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-25'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 1
  caveats: 6
  note: 'Values were read by an AI assistant on 2026-10-25 from the pages and PDFs named in each entry. The Plansee page is not readable by the automated check and its values were read through the web-fetch tool. Caveats: no modulus value from an accepted source; mechanical values come from one laboratory rod condition; the as-rolled transition temperature is an OCR table value; the supply shares are calculated from the USGS production table; PubChem GHS notifications are aggregated across forms.'
story:
  risk_groups:
    - title: For people
      lead: The sources describe dust and fumes as irritants, and the aggregated ECHA data for molybdenum carry mixed hazard codes.
      level: 1
      verdict: Mixed notifications
      points:
        - label: Dust and fumes
          line: The NIOSH excerpt in PubChem says dust and fumes irritate the eyes and respiratory tract, and it lists the liver and kidneys as target organs.
        - label: Classification
          line: Of 1523 company reports to the European chemicals agency, 874 said molybdenum does not meet GHS criteria. Among reports that gave codes, H228 (flammable solid) was given for 30 % and H361 (suspected of damaging fertility) for 29.5 %.
    - title: If it fails
      lead: These failure routes are taken from the sources. The oxidation route is a measured observation in the PubChem text, not a rate.
      points:
        - label: Hot air
          line: Above 400 °C molybdenum forms a highly volatile trioxide, and above 700 °C it needs a protective coating.
        - label: Cold-worked sheet
          line: Sheet cold-worked by 81 to 92 percent recrystallises fully in 1 hour at 925 °C, so it loses the strength from cold work.
        - label: As-rolled sheet
          line: The NASA table gives an approximate ductile-brittle transition above 25 °C for as-rolled sheet, so it can break in a brittle way near room temperature.
    - title: Handling and storage
      points:
        - label: Dust control
          line: Keep dust and fumes away from breathing zones and eyes.
        - label: Hot service
          line: Use a vacuum, an inert gas, or a protective coating when the metal is hot in air.
  why: Molybdenum is a refractory metal, with a melting point of 2623 °C (PubChem) and a density of 10.22 g/cm3 at 20 °C (Plansee). It is used mostly as an alloying agent in steel, cast iron and superalloys, according to the USGS. The pure metal also appears in thin-film transistor layers and in electric-furnace resistance elements, according to the PubChem record.
  uses:
    - where: Steel and superalloys
      line: The USGS says molybdenum is used principally as an alloying agent in cast iron, steel and superalloys, and it estimates U.S. apparent consumption in 2025 at 34,000 tons of molybdenum content.
    - where: Thin-film electronics
      line: The PubChem record says molybdenum is found in some electronic applications as the conductive metal layers in thin-film transistors.
    - where: Furnaces
      line: The PubChem record lists resistance elements for electric furnaces among its uses.
  can_do:
    - label: Stay solid when hot
      value: 2623 °C
      benchmark: melting_point
      line: Molybdenum melts at 2623 °C according to the PubChem record, and boils at 4639 °C at 760 mmHg.
    - label: Carry heat
      value: 142 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity at 20 °C is 142 W/(m·K), as printed by Plansee for pure molybdenum.
    - label: Hold strength when annealed
      value: 265 MPa yield
      line: A laboratory rod of electron-beam-melted 99.97 % molybdenum, annealed 1 h at 1315 °C, had a yield strength of 265 MPa and a tensile strength of 411 MPa at 25 °C.
    - label: Weight
      value: 10.22 g/cm3
      benchmark: density
      line: Density is 10.22 g/cm3 at 20 °C, according to the Plansee page for pure molybdenum.
    - label: Expansion
      value: 5.2 ppm/K
      benchmark: cte
      line: The coefficient of linear thermal expansion is 5.2 ppm/K at 20 °C, as printed by Plansee.
  compare: The USGS names graphite, tantalum and tungsten as potential substitutes for molybdenum in refractory materials for high-temperature electric furnaces, and boron, chromium, niobium and vanadium as alternatives in alloy steels. Molybdenum is hard to replace in steels and cast irons, where the USGS says there is little substitution.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Keep dust and fumes out of the breathing zone and away from the eyes.
    - Protect the metal from air above 400 °C with a coating, a vacuum or an inert gas.
    - If cold work must be kept, hold cold-worked sheet below the 925 °C recrystallisation temperature (100 % recrystallised in 1 hour, NASA TM X-2576).
  good_for:
    - 'High-temperature service in vacuum or inert gas: melting point 2623 °C (PubChem).'
    - 'Steel and superalloy additions: the main end use, according to the USGS.'
    - 'Conducting heat: 142 W/(m·K) at 20 °C (Plansee).'
  watch_out:
    - 'Oxidation: above 400 °C in air molybdenum forms volatile MoO3 (PubChem).'
    - 'Room-temperature brittleness in as-rolled sheet: a transition above 25 °C (NASA, OCR table).'
    - 'Supply: China produced about 37 % of 2025 mine output, and China imposed export controls on molybdenum powders in February 2025 (USGS).'
    - No modulus, hardness, radiation or outgassing data are recorded for this profile.
  verdict: Molybdenum is a refractory metal that melts at 2623 °C and is mostly used to make steel and superalloys stronger. Pure metal conducts heat at 142 W/(m·K) and has a yield strength of 265 MPa in one annealed laboratory rod, but it oxidises to volatile MoO3 above 400 °C in air. The profile lacks a modulus from an accepted source, standard-product mechanical minimums and any space-environment test data.
  recipe:
    line: Molybdenum is a single-element metal (Mo) with a body-centred cubic crystal structure (Plansee; Wikipedia). It is not found as a free metal in nature; the main ore is molybdenite (MoS2), according to Wikipedia, and the USGS says concentrate is roasted to molybdic oxide, from which metal powder is made (PubChem; USGS). In the NASA laboratory route, pressed powder electrodes were electron-beam melted into ingots, extruded, swaged and rolled.
    parts:
      - name: Molybdenum
        symbol: Mo
        atoms: 1
        atomic_weight: 95.94
        role: The whole material. Atomic mass 95.94 g/mol as printed on the Plansee page.