Niobium-titanium NbTi

spore: profile
id: nb-ti
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Niobium-titanium
abbreviation: NbTi
role: ductile superconducting alloy drawn into wire for MRI and magnet coils
category: metals
type: magnet-alloys
summary: |
  NbTi is a ductile niobium-titanium alloy with about 46 to 48 wt% titanium, drawn into multifilament wire embedded in copper. Its critical temperature is about 9 to 10 K and its upper critical field is about 14.5 to 15.4 T at low temperature, which is why it carries current in strong magnets cooled with liquid helium. Wikipedia says most MRI systems use Nb-Ti. The figures differ between sources because of composition, measurement method and temperature, so the properties below keep each one with its own conditions.
best_for: 'Superconducting magnet wire at 4.2 K up to about 10 T: a manufacturer gives up to 3000 A/mm2 at 4.2 K (Bruker), and Wikipedia gives practical magnet fields up to about 10 teslas'
weakest_at: Critical temperature of about 9 to 10 K, so it must be cooled with liquid helium, and no corrosion or space-environment test was found for the alloy
identity:
  formula: NbTi, a Nb-Ti alloy with 46 to 48 wt% Ti (SAMaterials wire page); the Furukawa booklet says 50 wt% Ti is usual and 46.5 wt% is used for high-field work
  source: samaterials-nbti-wire
  where: Niobium Titanium Alloy Wire Specifications, Chemical Composition row; the Furukawa booklet composition paragraph for the 46.5 wt% figure
tags:
  environments: []
  stresses:
    - extreme-cold
  applications: []
properties:
  - benchmark: critical_temperature
    label: Critical temperature, NbTi alloy (review value)
    value: 10
    unit: K
    scope: material
    conditions:
      composition: NbTi alloy, Nb:Ti ratio not stated
      basis: value printed for the NbTi alloy in the review
    method: Value printed in a 2025 open-access review of bcc high-entropy superconductors, which cites reference 92 (Slimani and Hannachi) for it
    status: ground
    source: arxiv-hea-review
    where: Section 7, sentence beginning The Tc and mu0 Hc2(0) values of the NbTi alloy
  - benchmark: critical_temperature
    label: Critical temperature, commercial NbTi at ambient pressure
    value: 9.6
    unit: K
    scope: material
    conditions:
      pressure: ambient, the baseline before pressure was applied
      composition: commercial niobium-titanium alloy, Nb:Ti ratio not stated
    method: Ambient-pressure baseline printed in the abstract of a high-pressure study on a commercial NbTi alloy
    status: ground
    source: arxiv-1808-07215
    where: Abstract, sentence stating that the transition temperature increases to about 19.1 K from about 9.6 K
  - benchmark: critical_temperature
    label: Critical temperature, three commercial NbTi wires (range)
    value: 9.1
    value_high: 9.35
    bound: range
    unit: K
    scope: material
    conditions:
      wires: three commercial NbTi wires from three manufacturers
      basis: characterization of the commercial wires
    method: Range printed in the abstract of a Brazilian characterization of commercial NbTi wires
    status: ground
    source: ufscar-nbti
    where: Abstract, sentence giving Tc between 9.10 and 9.35 K
  - benchmark: critical_temperature
    label: Critical temperature, NbTi wire (vendor FAQ)
    value: 9.2
    unit: K
    scope: material
    conditions:
      product: NbTi wire, composition not stated
    method: Vendor FAQ answer on a product page, which prints the same figure in Celsius as -263.95 °C
    status: ground
    note: Vendor value, below the 9.6 K and 10 K figures above, so treat it as approximate. The Furukawa booklet gives 9.2 K for elemental niobium, which is the same figure.
    source: samaterials-nbti-wire
    where: FAQs, question 2
  - benchmark: upper_critical_field
    label: Upper critical field, NbTi alloy at 0 K (review value)
    value: 14.5
    unit: T
    scope: material
    conditions:
      temperature: 0 K, printed as mu0 Hc2(0)
      composition: NbTi alloy, Nb:Ti ratio not stated
    method: Value printed in the same open-access review, which cites reference 92
    status: ground
    source: arxiv-hea-review
    where: Section 7, same sentence as the 10 K critical temperature value
  - benchmark: upper_critical_field
    label: Upper critical field, commercial NbTi at 1.8 K and ambient pressure
    value: 15.4
    unit: T
    scope: material
    conditions:
      temperature: 1.8 K
      pressure: ambient baseline
      composition: commercial niobium-titanium alloy, Nb:Ti ratio not stated
    method: Ambient-pressure baseline printed in the abstract of a high-pressure study
    status: ground
    source: arxiv-1808-07215
    where: Abstract, sentence stating that the critical field at 1.8 K is enhanced to 19 T from 15.4 T
  - benchmark: upper_critical_field
    label: Upper critical field, three commercial NbTi wires (range, Kramer estimate)
    value: 14
    value_high: 17
    bound: range
    unit: T
    scope: material
    conditions:
      temperature: not stated in the abstract
      method_basis: Kramer method, because the equipment could not measure it directly
    method: Range printed in the abstract. It is an extrapolation by the Kramer method, not a direct measurement
    status: ground
    source: ufscar-nbti
    where: Abstract, sentence giving Hc2 between 14 and 17 T
  - benchmark: density
    label: Density, NbTi wire (vendor page)
    value: 6.4
    value_high: 6.5
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      form: wire, as listed in the product specifications
      composition: 46 to 48 % Ti as printed on the same page
    method: Range printed on a supplier product page, with no measurement method given
    status: ground
    note: Vendor value, not from a manufacturer datasheet. The SAMaterials safety data sheet for the powder prints Density N/A. No second density source was found in this run.
    source: samaterials-nbti-wire
    where: Niobium Titanium Alloy Wire Specifications, density row
  - benchmark: melting_point
    label: Melting point, NbTi wire (vendor page, approximate)
    value: 2300
    unit: °C
    scope: material
    conditions:
      form: wire, as listed in the product specifications
      printed: approximate value with a tilde
    method: Approximate value printed on a supplier product page
    status: ground
    note: Approximate and from a vendor page. The SAMaterials safety data sheet prints Melting Point N/A for the powder.
    source: samaterials-nbti-wire
    where: Niobium Titanium Alloy Wire Specifications, melting point row
  - benchmark: critical_current_density
    label: Critical current density, NbTi conductor (manufacturer maximum)
    value: 3000
    unit: A/mm2
    scope: material
    conditions:
      temperature: 4.2 K, the standard operating temperature printed on the page
      field: not stated with the figure
      form: conductor type not specified
    method: Maximum figure printed in the highlights and benefits text of a manufacturer page
    status: ground
    note: A maximum, not a typical value, and no field is given with it. The same page gives operation in magnetic fields up to approx. 9.5 T.
    source: bruker-nbti
    where: Highlights and Benefits text, sentence beginning they carry current densities of up to 3,000 A/mm2
  - benchmark: practical_magnet_field
    label: Practical magnet field range, Nb-Ti wire
    value: 10
    unit: T
    scope: material
    conditions:
      basis: practical magnet field range, as printed in the article
    method: Range printed in the Wikipedia article, in its description of the Nb-Ti wire form
    status: ground
    note: Wikipedia gives up to about 10 teslas. The Bruker page gives up to approx. 9.5 T.
    source: wikipedia-nbti
    where: Article text, description of the Nb-Ti wire form (practical magnet fields up to about 10 teslas)
  - benchmark: critical_temperature
    label: Critical temperature, Nb-Ti (Wikipedia, approximate)
    value: 10
    unit: K
    scope: material
    conditions:
      basis: approximate value printed in the article
    method: Approximate value printed in the Wikipedia article
    status: ground
    source: wikipedia-nbti
    where: Article text, description of Nb-Ti (critical temperature about 10 kelvins)
  - benchmark: upper_critical_field
    label: Maximal critical magnetic field, Nb-Ti (Wikipedia, approximate)
    value: 15
    unit: T
    scope: material
    conditions:
      basis: approximate value printed in the article
    method: Approximate value printed in the Wikipedia article
    status: ground
    source: wikipedia-nbti
    where: Article text, description of Nb-Ti (maximal critical magnetic field about 15 teslas)
corrosion:
  - environment: Air and common chemicals (safety data sheet reactivity statement)
    headline: No corrosion rate was found for NbTi. The safety data sheet lists air and several chemical classes as incompatible.
    effect: The SAMaterials safety data sheet for NbTi lists halogens, halocarbons, mineral acids and oxidizing agents as reactive materials, and air as an incompatible condition. Its hazardous decomposition products are metal oxide fume. It prints no corrosion test, exposure time or rate.
    rating: unknown
    conditions:
      basis: reactivity section of a supplier safety data sheet, with no exposure test
    source: samaterials-nbti-sds
    where: Section 10, Reactivity
risks:
  hazards:
    - text: 'SAMaterials safety data sheet for NbTi, powder form: signal word Danger, with H228 (flammable solid) and H252 (self-heating in large quantities; may catch fire).'
      ghs:
        - H228
        - H252
      source: samaterials-nbti-sds
      where: Section 2, Hazards Identification; Section 9 lists the form as powder, sputtering target and custom parts
    - text: The same safety data sheet says the alloy is non-flammable except as a powder, and gives CO2, sand or extinguishing powder for fires, not water.
      ghs: []
      source: samaterials-nbti-sds
      where: Section 5, Firefighting Measures
    - text: The Goodfellow wire product page prints no hazard statement and says a US regulation safety data sheet is available on request.
      ghs: []
      source: goodfellow-nbti-wire
      where: Safety Data Sheet heading
  failure_risks:
    - mode: 'Quench: local heating drives the superconductor normal'
      trigger: Flux jumps, wire movement under electromagnetic forces, or cracking of the brittle epoxy that potts the conductor
      consequence: The temperature rise can take the superconductor above its critical temperature so it turns normal. The booklet says stored electromagnetic energies of 10^7 to 10^8 J/m3 compare with 10^3 to 10^4 J/m3 needed to quench it, and that a small displacement can heat a typical NbTi/Cu composite from 4.2 to 7 K, probably quenching the magnet.
      severity: high
      source: furukawa-nbti
      where: Text on flux jumps and quench, around Fig. 15 (the exponents come from OCR text and were read as 10 to the 7 to 8 and 10 to the 3 to 4)
    - mode: Fire from NbTi powder
      trigger: Handling the alloy in powder form in air
      consequence: The safety data sheet classes the powder as a flammable solid (H228) and as self-heating in large quantities (H252). Water must not be used on it.
      severity: moderate
      source: samaterials-nbti-sds
      where: Section 2 and Section 5
  side_effects: []
  handling:
    - text: Keep the powder away from heat, sparks, open flames and hot surfaces (P210), store it in a cool dry place in a tightly sealed container, and use CO2, sand or powder for fires.
      source: samaterials-nbti-sds
      where: Section 2 precautionary statements; Section 7 Handling and Storage; Section 5
    - text: Keep the alloy away from halogens, halocarbons, mineral acids and oxidizing agents, which the safety data sheet lists as reactive.
      source: samaterials-nbti-sds
      where: Section 10, Reactivity
  mitigations: []
uses:
  - application: radiation-shielding
    device: Alpha Magnetic Spectrometer Nb-Ti coils (built for the mission, later replaced)
    example: Wikipedia says liquid-helium-cooled Nb-Ti coils were built for the Alpha Magnetic Spectrometer mission and were later replaced by non-superconducting magnets. This is the only use on the application list that this profile could source.
    source: wikipedia-nbti
    where: Applications paragraph, Alpha Magnetic Spectrometer entry
supply:
  - subject: Niobium (mine production, the niobium base of NbTi)
    producers:
      - country: Brazil
        share_percent: 93
        year: 2025
      - country: Canada
        share_percent: 5
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Niobium, used to strengthen steel)
        listed: true
    recycling: 'USGS: niobium was recycled when niobium-bearing steels and superalloys were recycled, but scrap recovery for niobium content was negligible.'
    substitutes:
      - 'USGS: ceramic matrix composites, molybdenum, tantalum and tungsten, and in steels molybdenum, tantalum and titanium, may replace niobium, with a performance loss or higher cost.'
    source: usgs-mcs2026-niobium
    where: Events, Trends and Issues (Brazil about 93% of world production and Canada 5%); World Mine Production and Reserves table, 2025e, Brazil 104,000 t, world total 112,000 t; Recycling; Substitutes
  - subject: Titanium (sponge metal, the titanium base of NbTi)
    producers:
      - country: China
        share_percent: 70.3
        year: 2025
      - country: Japan
        share_percent: 14.3
        year: 2025
      - country: Russia
        share_percent: 6.8
        year: 2025
      - country: Kazakhstan
        share_percent: 4.3
        year: 2025
      - country: Saudi Arabia
        share_percent: 3.2
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Titanium, used as a white pigment and in metal alloys)
        listed: true
    recycling: 'USGS: consumption data for titanium scrap for the titanium metal industry were withheld, so no scrap recovery figure is printed.'
    substitutes:
      - 'USGS: aluminum, nickel, specialty steels and zirconium alloys may be substituted for titanium where corrosion resistance is needed.'
    source: usgs-mcs2026-titanium
    where: World Sponge Metal Production table, 2025 (China 260,000, Japan 53,000, Russia 25,000, Kazakhstan 16,000, Saudi Arabia 12,000, world total 370,000 rounded). Shares calculated by Space Mushroom from that table. Substitutes; Salient Statistics, net import reliance 100% in 2025e
documents:
  - title: 'Wikipedia: Niobium-titanium'
    type: database
    url: https://en.wikipedia.org/wiki/Niobium-titanium
    year: 2026
  - title: 'High critical current densities of body-centered cubic high-entropy alloy superconductors: recent research progress, Kitagawa, Mizuguchi and Nishizaki, arXiv:2504.06454 (open access)'
    type: paper
    url: https://arxiv.org/pdf/2504.06454
    year: 2025
  - title: arXiv:1808.07215, high-pressure enhancement of superconductivity in a commercial niobium-titanium alloy
    type: paper
    url: https://arxiv.org/abs/1808.07215
    year: 2018
  - title: Caracterizacao de fios supercondutores comerciais de NbTi (Brazilian characterization of commercial NbTi wires, UFSCar repository)
    type: report
    url: https://repositorio.ufscar.br/handle/ufscar/18650
    year: 2025
  - title: Niobium Titanium Alloy Wire, SAMaterials product specifications and FAQ
    type: datasheet
    url: https://samaterials.com/niobium-titanium-alloy-wire.html
  - title: SAMaterials safety data sheet, Niobium Titanium Alloy (NbTi), product NB7819
    type: sds
    url: https://www.samaterials.com/tds/sc/1783992753-NB7819.pdf
  - title: Fundamentals of niobium based superconductors, Y. Furukawa, Furukawa Electric (technical booklet)
    type: report
    url: https://assets.niobium.tech/-/media/niobiumtech/attachments-biblioteca-tecnica/nt_fundamentals-of-niobium-based-superconductors.pdf
  - title: Bruker EAS niobium-titanium superconductor product page
    type: datasheet
    url: https://www.bruker.com/fr/products-and-solutions/superconductors/superconductors/niobium-titanium-superconductor.html
  - title: Goodfellow niobium-titanium alloy spooled wire Nb52/Ti48 product page
    type: datasheet
    url: https://www.goodfellow.com/usa/niobium-titanium-alloy-spooled-wire-nb52-ti48-group
  - title: 'USGS Mineral Commodity Summaries 2026: Niobium (Columbium)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Titanium and Titanium Dioxide'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
  - title: USGS 2025 final list of critical minerals (about the 2025 list)
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
gaps:
  - No manufacturer datasheet with a printed density, melting point or Tc for NbTi was opened. The density and melting point come from one supplier product page (SAMaterials), and the density has no second source.
  - The critical temperature and upper critical field differ between sources (about 9.1 to 10 K, and about 14 to 17 T). The sources do not state the composition, the temperature or the field for most figures, so the values are kept apart rather than merged.
  - 'Designations: no fetched page printed a UNS, EN, ASTM or AMS code for NbTi itself. The Goodfellow page gives only Nb52/Ti48 and the SAMaterials page gives NbTi, so identity.designations is left empty.'
  - Specific heat, thermal conductivity, thermal expansion, Young's modulus and yield strength of NbTi were not found as printed numbers in the sources read. The Furukawa booklet shows them only in graphs.
  - No corrosion rate, oxidation test or space-environment test (outgassing, atomic oxygen, radiation, vacuum) for NbTi was found in the sources read.
  - 'Property names not in spores/property-canon.yaml: critical_temperature, upper_critical_field, critical_current_density and practical_magnet_field. They are snake_case names as the brief allows. Canonical names would need adding to the canon before import.'
  - The uses list has no terrestrial magnet category. MRI and accelerator magnets are recorded in story.uses only, and the Alpha Magnetic Spectrometer coils are the only top-level use that matches the application list, so there is one top-level use, not two.
  - The EU critical raw materials list was not opened, so the supply lists carry only the USGS 2025 list.
  - Niobium smelting and titanium sponge production process steps were not read from a primary source. The recipe gives only the Furukawa process order for the alloy.
  - Atomic weights for titanium and niobium were not read from a NIST page in this run, so the recipe parts have no atomic_weight.
  - The Furukawa booklet is OCR text. Only values readable without OCR doubt were used, and exponents in the quench text were read with care.
sources:
  wikipedia-nbti:
    title: Niobium-titanium, Wikipedia (description, uses, production history)
    url: https://en.wikipedia.org/wiki/Niobium-titanium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  arxiv-hea-review:
    title: 'High critical current densities of body-centered cubic high-entropy alloy superconductors: recent research progress, Kitagawa, Mizuguchi and Nishizaki'
    id: arXiv:2504.06454
    url: https://arxiv.org/pdf/2504.06454
    year: 2025
    kind: paper
    license: arXiv (cited, not reproduced)
  arxiv-1808-07215:
    title: High-pressure enhancement of superconductivity in a commercial niobium-titanium alloy
    id: arXiv:1808.07215
    url: https://arxiv.org/abs/1808.07215
    year: 2018
    kind: paper
    license: arXiv (cited, not reproduced)
  ufscar-nbti:
    title: Caracterizacao de fios supercondutores comerciais de NbTi (characterization of commercial NbTi superconducting wires), UFSCar repository
    id: UFSCar repository record 18650
    url: https://repositorio.ufscar.br/handle/ufscar/18650
    year: 2025
    kind: report
    license: repository record (cited, not reproduced)
  samaterials-nbti-wire:
    title: Niobium Titanium Alloy Wire, SAMaterials product specifications and FAQ
    url: https://samaterials.com/niobium-titanium-alloy-wire.html
    kind: datasheet
    license: supplier product page (cited, not reproduced)
  samaterials-nbti-sds:
    title: Safety Data Sheet, Niobium Titanium Alloy, SAMaterials
    id: product NB7819, formula NbTi
    url: https://www.samaterials.com/tds/sc/1783992753-NB7819.pdf
    kind: datasheet
    license: supplier safety data sheet (cited, not reproduced)
  furukawa-nbti:
    title: Fundamentals of niobium based superconductors, Yoshio Furukawa, The Furukawa Electric Company (technical booklet)
    url: https://assets.niobium.tech/-/media/niobiumtech/attachments-biblioteca-tecnica/nt_fundamentals-of-niobium-based-superconductors.pdf
    kind: report
    license: booklet (cited, not reproduced)
  bruker-nbti:
    title: Bruker EAS, niobium-titanium superconductor product page
    url: https://www.bruker.com/fr/products-and-solutions/superconductors/superconductors/niobium-titanium-superconductor.html
    kind: web
    license: manufacturer web page (cited, not reproduced)
  goodfellow-nbti-wire:
    title: Goodfellow, niobium-titanium alloy spooled wire Nb52/Ti48 product page
    url: https://www.goodfellow.com/usa/niobium-titanium-alloy-spooled-wire-nb52-ti48-group
    kind: web
    license: supplier product page (cited, not reproduced)
  usgs-mcs2026-niobium:
    title: Mineral Commodity Summaries 2026, Niobium (Columbium), February 2026
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-titanium:
    title: Mineral Commodity Summaries 2026, Titanium and Titanium Dioxide, February 2026
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 3
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: the Durham NbTi critical current density paper (403), the EPJ ST 2024 NbTi article (403) and the Dublin Durham repository record (connection refused). The NbTi density and melting point come from one supplier page. The critical temperature and upper critical field differ between sources because of composition, method and temperature.'
story:
  recipe:
    line: NbTi is a binary alloy of niobium and titanium. Wire grade uses 46 to 48 wt% titanium (SAMaterials), and the Furukawa booklet says the usual composition is 50 wt% Ti with 46.5 wt% for high-field use. Commercial production arc-melts the two metals into an ingot, makes a copper-clad Nb-Ti composite rod, extrudes it into multifilament rod inside oxygen-free copper, then draws and heat-treats the conductor (Furukawa booklet process list).
    parts:
      - name: Niobium
        symbol: Nb
        share_note: balance of the alloy
        role: The base metal. Niobium carries the superconducting state, and the titanium content sets the alloy's critical properties.
      - name: Titanium
        symbol: Ti
        share_note: 46 to 48 wt% (SAMaterials wire page); 46.5 wt% for high-field use (Furukawa booklet)
        role: The alloying addition that makes the alloy ductile enough to draw into wire and raises its upper critical field.
  risk_groups:
    - title: For people
      lead: The alloy in bulk wire form is not classified in the sources read. The powder is a flammable solid.
      level: 1
      verdict: Flammable as powder, not classified as bulk wire
      points:
        - label: Powder
          line: The SAMaterials safety data sheet classes NbTi powder as H228 (flammable solid) and H252 (self-heating), with the signal word Danger.
        - label: Wire
          line: The Goodfellow wire page prints no hazard statement, and the safety data sheet covers the powder and custom parts.
    - title: If it fails
      lead: The main failure in a magnet is a quench, when the wire turns normal and dumps its stored energy as heat.
      points:
        - label: Quench
          line: The Furukawa booklet says flux jumps, wire movement and cracked epoxy can heat the conductor until it turns normal, and that stored energy is far larger than the energy needed to quench it.
        - label: Fire
          line: Powder can catch fire, so fires need CO2, sand or powder extinguishers, not water.
  why: NbTi is the workhorse superconductor for MRI and magnet coils. It is ductile enough to draw into wire, and it carries high current density at 4.2 K. Its critical temperature is about 9 to 10 K and its upper critical field is about 14.5 to 15.4 T at low temperature. Wikipedia says most MRI systems use Nb-Ti, and it was used in the coils of the Alpha Magnetic Spectrometer before that instrument was rebuilt with non-superconducting magnets.
  uses:
    - where: MRI and accelerator magnets
      line: Wikipedia says most MRI systems use Nb-Ti, and the Large Hadron Collider uses Nb-Ti cable. The application list has no terrestrial magnet category, so these uses are recorded here only.
    - where: Fusion and research magnets
      line: Wikipedia says Nb-Ti is used for ITER poloidal field coils, and Wendelstein 7-X is cooled to 4 K to produce a 3 T field.
    - where: Space
      line: Wikipedia says liquid-helium-cooled Nb-Ti coils were built for the Alpha Magnetic Spectrometer and were later replaced by non-superconducting magnets. No flown superconducting use was found.
  can_do:
    - label: Carry current in strong fields
      value: 3000 A/mm2 at 4.2 K
      benchmark: critical_current_density
      line: Bruker says its NbTi conductors carry current densities of up to 3,000 A/mm2 at the standard 4.2 K operating temperature, in magnetic fields up to about 9.5 T.
    - label: Upper field
      value: 14.5 T at 0 K
      benchmark: upper_critical_field
      line: The NbTi alloy has an upper critical field of 14.5 T at 0 K (Kitagawa review). Commercial wires measured in a Brazilian study gave 14 to 17 T by the Kramer method.
    - label: Superconducting transition
      value: 9.6 K at ambient pressure
      benchmark: critical_temperature
      line: A commercial NbTi alloy has a transition temperature of about 9.6 K at ambient pressure, and the same study gives 15.4 T at 1.8 K. Three commercial wires measured 9.10 to 9.35 K in another study.
    - label: Density and melting
      value: 6.4 to 6.5 g/cm3
      benchmark: density
      line: A supplier page lists NbTi wire at 6.4 to 6.5 g/cm3 and an approximate melting point of 2300 °C. These are vendor figures without a stated method.
  compare: NbTi suits magnets that need about 10 T or less at 4.2 K. Its critical temperature of about 9 to 10 K is low, so it needs liquid helium, but it is ductile and can be drawn into wire. The Kitagawa review uses the state-of-the-art Nb-Ti wire used in accelerators as its benchmark for critical current density when it compares bcc high-entropy superconductors. The three rows below compare density, melting point and critical temperature.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Critical temperature
      benchmark: critical_temperature
  handling:
    - Keep the powder away from heat, sparks and open flames, and use CO2, sand or powder for fires, not water.
    - Store the alloy in a cool, dry place in a tightly sealed container, away from halogens, mineral acids and oxidizing agents.
    - Ask the supplier for the Ti content and the Cu to superconductor ratio, since these change the critical values.
  good_for:
    - Magnets at 4.2 K up to about 10 T, where the Bruker page gives up to 3,000 A/mm2 at 4.2 K and Wikipedia gives practical fields up to about 10 teslas.
    - 'Ductile wire: the alloy can be drawn into multifilament wire embedded in copper (Furukawa booklet and Wikipedia).'
  watch_out:
    - Critical temperature of about 9 to 10 K means the magnet needs liquid helium cooling, and the figures vary by source.
    - Quench is the main failure. Stored energy in the conductor far exceeds the energy needed to quench it (Furukawa booklet).
    - Powder is a flammable solid (H228). No corrosion rate and no space-environment test was found for NbTi.
  verdict: NbTi is the standard magnet superconductor for fields up to about 10 T at 4.2 K, and it can be drawn into wire. Its critical temperature of about 9 to 10 K means liquid helium cooling, and its supply rests on Brazil for niobium and China for titanium sponge. No space-environment test was found, so the profile records only ground values.