Cobalt-iron and cobalt intermetallic alloys (Co-Fe, Co-Ti, Co-W, Co-Al) CoFe / Co-W / Co-Ti / Co-Al

spore: profile
id: cobalt-iron-alloys
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Cobalt-iron and cobalt intermetallic alloys (Co-Fe, Co-Ti, Co-W, Co-Al)
abbreviation: CoFe / Co-W / Co-Ti / Co-Al
role: soft magnetic alloys and high-temperature intermetallic strengtheners
category: metals
type: magnet-alloys
summary: |
  This profile covers the cobalt-iron soft magnetic grades other than Hiperco 50 and Permendur (49 % Co), together with the cobalt intermetallic phases that are studied as strengtheners for cobalt-based alloys. For the cobalt-iron family, VACUUMSCHMELZE prints a 17 % cobalt grade, VACOFLUX X1, with a saturation polarization of 2.22 T, a coercivity of 50 A/m, a density of 7.90 g/cm3 and a Curie temperature of 940 C. Its maker groups the lower-cobalt grades (9 to 27 % Co) as cost optimized alloys. For the cobalt-tungsten and cobalt-titanium systems, the sourced values are phase stabilities and compositions, plus first-principles elastic moduli for Co3W and Co7W6. The only measured hardness values in this file belong to a ternary Co-W-Al alloy, not a binary one.
best_for: Cobalt-iron soft magnetic parts where a cheaper grade than 49 % cobalt-iron still needs high saturation (VACOFLUX X1, 17 % Co, per VACUUMSCHMELZE)
weakest_at: No sourced corrosion, failure or cold-service data for any grade in this file; the cobalt-tungsten and cobalt-titanium values are calculated or phase data, not tested alloy parts
identity:
  formula: Fe-Co alloy with 17 % Co (VACOFLUX X1); lower-cobalt Fe-Co grades at 9 to 27 % Co (VACOFLUX 9 CR, 17, 18 HR, 27); Co-W, Co-Ti and Co-Al intermetallic phases (Co3W, Co7W6, Co3Ti, CoTi, B2 CoAl)
  source: vac-vacoflux-x1
  where: Title and Material Properties table on the VACOFLUX X1 product page; family grade list on the 9 to 27 % Cobalt Iron VACOFLUX page
tags:
  environments: []
  stresses: []
  applications:
    - mechanisms
    - structures
properties:
  - benchmark: saturation_polarization
    label: Saturation polarization Js, VACOFLUX X1 (17 % Co-Fe)
    value: 2.22
    unit: T
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron, VACUUMSCHMELZE
      form: product material properties table, typical values
    method: Value printed in the Material Properties table of the VACUUMSCHMELZE VACOFLUX X1 product page
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Saturation polarization JS [T]
  - benchmark: max_permeability
    label: Maximum permeability, VACOFLUX X1
    value: 10000
    bound: lower
    unit: '-'
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
      form: product material properties table
    method: Printed as greater than 10,000 in the Material Properties table
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Maximum permeability µmax (value printed as > 10,000)
  - benchmark: coercivity
    label: Coercivity Hc, VACOFLUX X1
    value: 50
    unit: A/m
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
      form: product material properties table, field and heat treatment not printed on the page
    method: Printed value in the Material Properties table of the VACOFLUX X1 product page
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Coercivity HC [A/m]
  - benchmark: electrical_resistivity
    label: Electrical resistivity, VACOFLUX X1
    value: 0.3
    unit: µΩm
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
      unit_in_source: µΩm
    method: Printed value in the Material Properties table of the VACOFLUX X1 product page; the unit is printed as µΩm
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Electrical resistivity ρel [µΩm]
  - benchmark: density
    label: Density, VACOFLUX X1
    value: 7.9
    unit: g/cm3
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
    method: Printed value in the Material Properties table of the VACOFLUX X1 product page
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Density ρ [g/cm3]
  - benchmark: saturation_magnetostriction
    label: Saturation magnetostriction, VACOFLUX X1
    value: 25
    unit: ppm
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
      sign: positive, printed as +25
    method: Printed value in the Material Properties table of the VACOFLUX X1 product page
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Saturation magnetostriction λS [ppm]
  - benchmark: curie_temperature
    label: Curie temperature, VACOFLUX X1
    value: 940
    unit: °C
    scope: material
    conditions:
      grade: VACOFLUX X1, 17 % cobalt-iron
    method: Printed value in the Material Properties table of the VACOFLUX X1 product page
    status: ground
    source: vac-vacoflux-x1
    where: Material Properties table, column Curie temperature TC [°C]
  - benchmark: elastic_modulus
    label: Young modulus, Co3W L12 phase (first principles)
    value: 440.004
    unit: GPa
    scope: material
    conditions:
      phase: Co3W, L12 structure
      basis: density functional theory (VASP, PBE-GGA); calculated, not measured
    method: Calculated elastic modulus printed in Table 2 of the first-principles study of Co3W and Co7W6 phases
    status: calculated
    source: yang2021-co-w
    where: Table 2, Young modulus E, Co3W L12 column
  - benchmark: elastic_modulus
    label: Young modulus, Co7W6 mu phase (first principles)
    value: 397.264
    unit: GPa
    scope: material
    conditions:
      phase: Co7W6, mu (topologically close-packed) structure
      basis: density functional theory; calculated, not measured
    method: Calculated elastic modulus printed in Table 2 of the first-principles study of Co3W and Co7W6 phases
    status: calculated
    source: yang2021-co-w
    where: Table 2, Young modulus E, Co7W6 mu column
  - benchmark: bulk_modulus
    label: Bulk modulus, Co7W6 mu phase (first principles)
    value: 309.871
    unit: GPa
    scope: material
    conditions:
      phase: Co7W6, mu structure
      basis: density functional theory; calculated, not measured
    method: Calculated bulk modulus printed in Table 2 of the first-principles study of Co3W and Co7W6 phases
    status: calculated
    source: yang2021-co-w
    where: Table 2, Bulk modulus B, Co7W6 mu column
  - benchmark: hardness_vickers
    label: Microhardness, eutectic structure, Co-W-Al alloy
    value: 439
    unit: HV 0.1
    scope: material
    conditions:
      alloy: Co70W12Al15 (wt.%) prepared by aluminothermic reaction; ternary, not a binary Co-W alloy
      phase: eutectic structure
      load: HV 0.1
    method: Mean microhardness with standard deviation printed in the paper (439.0 ± 34.5 HV 0.1)
    status: ground
    source: pmc8779428
    where: Section 3.3 and Table 3, eutectic structure hardness
  - benchmark: hardness_vickers
    label: Microhardness, solid solution A, Co-W-Al alloy
    value: 669
    unit: HV 0.1
    scope: material
    conditions:
      alloy: Co70W12Al15 (wt.%) prepared by aluminothermic reaction; ternary, not a binary Co-W alloy
      phase: solid solution A
      load: HV 0.1
    method: Mean microhardness with standard deviation printed in the paper (669.0 ± 80.5 HV 0.1)
    status: ground
    source: pmc8779428
    where: Section 3.3 and Table 3, solid solution A hardness
  - benchmark: hardness_vickers
    label: Microhardness, solid solution B, Co-W-Al alloy
    value: 524.4
    unit: HV 0.1
    scope: material
    conditions:
      alloy: Co70W12Al15 (wt.%) prepared by aluminothermic reaction; ternary, not a binary Co-W alloy
      phase: solid solution B
      load: HV 0.1
    method: Mean microhardness with standard deviation printed in the paper (524.4 ± 88.4 HV 0.1)
    status: ground
    source: pmc8779428
    where: Section 3.3 and Table 3, solid solution B hardness
corrosion: []
risks:
  hazards:
    - text: 'Cobalt dust and fume (as Co): NIOSH recommended exposure limit 0.05 mg/m3 as an 8-hour TWA, OSHA PEL 0.1 mg/m3 as an 8-hour TWA, IDLH 20 mg/m3 as Co. Symptoms listed include cough, wheezing, weight loss, dermatitis and asthma. These limits apply to cobalt dust and fume, not to bulk solid alloy.'
      ghs: []
      source: niosh-cobalt
      where: Exposure Limits (IDLH, NIOSH REL, OSHA PEL) and Symptoms sections
  failure_risks: []
  side_effects: []
  handling:
    - text: NIOSH lists strong oxidizers and ammonium nitrate as incompatible with cobalt metal.
      source: niosh-cobalt
      where: Incompatibilities and Reactivities section
    - text: Keep cobalt dust down and prevent skin contact; the NIOSH limit is 0.05 mg/m3 as an 8-hour TWA.
      source: niosh-cobalt
      where: Exposure Limits section
  mitigations: []
uses:
  - application: mechanisms
    device: Electric motor laminations and stamped stacks for high-power-density motors
    example: VACUUMSCHMELZE says motors built with its 17 % cobalt-iron VACOFLUX X1 can be considerably better performing than electrical steel and considerably cheaper than designs based on 49 % cobalt-iron.
    source: vac-vacoflux-x1
    where: Introduction paragraph and Benefits list of the VACOFLUX X1 product page
  - application: structures
    device: Gamma-prime strengthened cobalt-based high-temperature alloys (research stage)
    example: Co3Ti with the L12 structure is stable at 1473 K in the Co-Ti-W system, and W helps keep the gamma-prime phase stable, according to the isothermal-section study. The paper is a phase-equilibrium study, not a component test.
    source: shi2022-co-ti-w
    where: Abstract and Introduction, Co-Ti-W isothermal sections at 1273 and 1473 K
supply:
  - subject: Cobalt (used in all cobalt-iron and cobalt intermetallic grades listed here)
    producers:
      - country: Congo (Kinshasa)
        share_percent: 73
        year: 2025
      - country: Indonesia
        share_percent: 14
        year: 2025
    critical_lists: []
    recycling: 'USGS: in 2025 cobalt content of purchased scrap was 25 % of estimated cobalt consumption.'
    substitutes:
      - 'USGS: depending on the application, substitution for cobalt could lose performance or raise cost. Potential substitutes in magnets include barium or strontium ferrites, neodymium-iron-boron alloys, or nickel-iron alloys.'
    source: usgs-mcs2026-cobalt
    where: Events, Trends, and Issues (world share of mine production, estimated), Recycling and Substitutes sections
documents:
  - title: VACUUMSCHMELZE, 17 % Cobalt-Iron VACOFLUX X1 product page
    type: datasheet
    url: https://vacuumschmelze.com/products/soft-magnetic-materials-and-stamped-parts/vacoflux-x1
  - title: VACUUMSCHMELZE, 9 to 27 % Cobalt-Iron VACOFLUX product page
    type: datasheet
    url: https://vacuumschmelze.com/products/soft-magnetic-materials-and-stamped-parts/9-to-27-cobalt-iron-vacoflux
  - title: Yang et al., first-principles study of Co3W, Co7W6 and Co3Mo phases (PMC7998609)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC7998609
    year: 2021
  - title: Shi et al., Isothermal Sections of the Co-Ti-W System at 1273 and 1473 K, Frontiers in Materials 9:880143
    type: paper
    url: https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2022.880143
    year: 2022
  - title: Co70W12Al15 alloy by aluminothermic reaction, microhardness study (PMC8779428)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8779428
  - title: Onset of magnetism in B2 transition metal aluminides (arXiv cond-mat/9712321)
    type: paper
    url: https://arxiv.org/pdf/cond-mat/9712321
    year: 1997
  - title: USGS Mineral Commodity Summaries 2026, Cobalt
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
  - title: NIOSH Pocket Guide to Chemical Hazards, Cobalt metal dust and fume (as Co)
    type: database
    url: https://www.cdc.gov/niosh/npg/npgd0146.html
gaps:
  - 'Corrosion and oxidation: no fetched page gave a corrosion or oxidation value for any cobalt-iron or cobalt intermetallic grade in this file. The corrosion section is empty for that reason.'
  - 'Failure risks: no fetched source gave a failure mode for these alloys (no ageing, cold-service or brittleness data for a named grade). The failure_risks list is empty rather than filled from other grades.'
  - 'Cobalt-iron grades other than VACOFLUX X1 (VACOFLUX 9 CR, 17, 18 HR and 27): the family page was read, but its property tables are on tabs that did not load in the browser, so only the X1 values are recorded. The family page lists the grades; its values are not recorded.'
  - 'Co-Al: the B2 CoAl phase is recorded only as a composition range (45 to 58 at.% Al, arXiv cond-mat/9712321). No density, melting point or mechanical value for CoAl was found in any page we could open. The OSTI 1996 CoAl record could not be reached, and no Okamoto assessment page was found.'
  - 'Co-Ti: the congruent melting point of CoTi and the density of Co3Ti were not recorded. The Frontiers paper names the Davydov 2001 CoTi congruent melting point and a Wu 2020 eutectic at 1427 K only in its literature review; both are second-hand and are not recorded as property values.'
  - 'Co-W corrosion: a search snippet described Co-W coatings with better corrosion resistance at 13 to 24 at.% W, but the page was not fetched, so no value is recorded.'
  - 'Cobalt-iron electrical loss and magnetic core loss: not printed on the VACOFLUX X1 page, which lists only the material properties table.'
  - 'Heat treatment of the cobalt-iron grades in this file: the X1 page does not print an anneal, so none is recorded here (the 49 % grade anneal is in the Permendur profile).'
  - 'Designations: no UNS, EN, DIN, JIS, AISI or ASTM code was printed for VACOFLUX X1 or the cobalt intermetallic phases on any fetched page.'
  - 'Critical-minerals listing for cobalt: the USGS 2026 cobalt summary text we read does not print a 2025 critical-minerals list status, so critical_lists is empty.'
  - Abundance and supply of iron, aluminium, tungsten and titanium are not recorded here. Only cobalt supply was read in this run.
  - 'Hazard data: the NIOSH entry covers cobalt metal dust and fume. The PubChem GHS classification could not be read (a browser check blocked the page), so ghs is empty.'
  - 'Non-canonical property names (not in spores/property-canon.yaml, new snake_case names): saturation_polarization, max_permeability, coercivity, saturation_magnetostriction, hardness_vickers.'
  - 'Media: no image with a verified license was fetched in this run.'
sources:
  vac-vacoflux-x1:
    title: VACUUMSCHMELZE, 17 % Cobalt-Iron VACOFLUX X1 product page
    url: https://vacuumschmelze.com/products/soft-magnetic-materials-and-stamped-parts/vacoflux-x1
    kind: datasheet
    license: Manufacturer product page (cited, not reproduced)
  vac-9-27-cofe:
    title: VACUUMSCHMELZE, 9 to 27 % Cobalt-Iron VACOFLUX product page
    url: https://vacuumschmelze.com/products/soft-magnetic-materials-and-stamped-parts/9-to-27-cobalt-iron-vacoflux
    kind: datasheet
    license: Manufacturer product page (cited, not reproduced)
  yang2021-co-w:
    title: First-principles study of Co3W, Co7W6 and Co3Mo phases (Yang et al., Materials, 2021, PMC7998609)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC7998609
    kind: paper
    license: open access (cited, not reproduced)
  shi2022-co-ti-w:
    title: Isothermal Sections of the Co-Ti-W System at 1273 and 1473 K (Frontiers in Materials 9:880143)
    url: https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2022.880143
    kind: paper
    license: CC BY 4.0 (cited, not reproduced)
  pmc8779428:
    title: Co70W12Al15 alloy by aluminothermic reaction, microhardness study (PMC8779428)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC8779428
    kind: paper
    license: open access (cited, not reproduced)
  arxiv-coal:
    title: Onset of magnetism in B2 transition metal aluminides (arXiv cond-mat/9712321)
    url: https://arxiv.org/pdf/cond-mat/9712321
    year: 1997
    kind: paper
    license: arXiv (cited, not reproduced)
  usgs-mcs2026-cobalt:
    title: Mineral Commodity Summaries 2026, Cobalt
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  niosh-cobalt:
    title: 'NIOSH Pocket Guide to Chemical Hazards: Cobalt metal dust and fume (as Co)'
    url: https://www.cdc.gov/niosh/npg/npgd0146.html
    kind: handbook
    license: US government (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 3
  caveats: 4
  note: 'Values read by an AI assistant on 2026-10-26 from the pages named in each entry. Unreachable or gated: OSTI 1996 CoAl record (connection refused), Okamoto Co-Al assessment (not found), Davydov 2001 and Wu 2020 Co-Ti sources (not fetched), PubChem cobalt GHS (browser check). Caveats: only VACOFLUX X1 values are measured on a named grade; the Co-W elastic moduli are first-principles values; the hardness values are for a ternary Co-W-Al alloy; no corrosion or failure data are sourced.'
story:
  risk_groups:
    - title: For people
      lead: The hazard in this family is cobalt dust and fume, not the bulk alloy. The sources read give exposure limits for cobalt metal dust and fume.
      level: 1
      verdict: Cobalt dust limits apply
      points:
        - label: Dust and fume
          line: NIOSH sets a recommended limit of 0.05 mg/m3 as an 8-hour average for cobalt dust and fume, with an IDLH of 20 mg/m3 as Co. OSHA's PEL is 0.1 mg/m3 as an 8-hour average. Symptoms listed include asthma, dermatitis and weight loss.
    - title: If it fails
      lead: No failure mode for these alloys was sourced in this run. The gaps list says what is missing.
      points:
        - label: Not sourced
          line: No fetched page gave a failure mode, ageing change or corrosion result for a named grade in this file.
    - title: Handling and storage
      points:
        - label: Oxidizers
          line: NIOSH lists strong oxidizers and ammonium nitrate as incompatible with cobalt metal.
        - label: Dust
          line: Keep cobalt dust down and prevent skin contact.
  why: The cobalt-iron family is in this file for its magnetic saturation. VACUUMSCHMELZE's 17 % cobalt grade, VACOFLUX X1, prints a saturation polarization of 2.22 T at a lower cobalt content than the 49 % grade. The cobalt intermetallic phases (Co3W, Co7W6, Co3Ti, B2 CoAl) are studied as strengtheners for cobalt-based high-temperature alloys, in the same way that gamma-prime phases strengthen cobalt-based superalloys. The sourced numbers for those phases are first-principles elastic moduli and phase stabilities, not tested alloy strength.
  uses:
    - where: Electric motors
      line: VACUUMSCHMELZE says motors built with VACOFLUX X1 can perform considerably better than electrical steel and cost considerably less than designs based on 49 % cobalt-iron.
    - where: Cobalt-based high-temperature alloys
      line: In the Co-Ti-W system, Co3Ti with the L12 structure is stable at 1473 K, and W adds to the stability of the gamma-prime phase. The source is a phase study, not a component test.
  can_do:
    - label: High saturation
      value: 2.22 T
      benchmark: saturation_polarization
      line: VACOFLUX X1 prints a saturation polarization Js of 2.22 T. The 17 % cobalt grade is named as optimized for motors.
    - label: Low coercivity
      value: 50 A/m
      benchmark: coercivity
      line: VACOFLUX X1 prints a coercivity Hc of 50 A/m on the material properties table.
    - label: Stays magnetic when hot
      value: 940 °C
      benchmark: curie_temperature
      line: VACOFLUX X1 prints a Curie temperature of 940 °C.
    - label: Stiffness of Co3W (calculated)
      value: 440.004 GPa
      benchmark: elastic_modulus
      line: First-principles calculation gives a Young modulus of 440.004 GPa for the L12 Co3W phase. This is a calculated value, not a test.
  compare: Among the cobalt-iron grades recorded here, VACOFLUX X1 gives up saturation in exchange for lower cobalt content and cost. The X1 page describes the 49 % cobalt-iron family as having high saturation, with a family figure that is not this grade's value, so it is not recorded here. No electrical steel value is recorded, so the maker's power-density claim is not checked.
  compare_rows:
    - label: Saturation polarization
      benchmark: saturation_polarization
    - label: Coercivity
      benchmark: coercivity
    - label: Curie temperature
      benchmark: curie_temperature
  handling:
    - 'Control cobalt dust: the NIOSH limit is 0.05 mg/m3 as an 8-hour TWA (NIOSH).'
    - Keep away from strong oxidizers and ammonium nitrate (NIOSH).
    - No anneal or heat-treatment instruction for these grades was sourced in this run. Use the supplier's instructions.
  good_for:
    - Motor laminations where cost and saturation both matter, per VACUUMSCHMELZE for VACOFLUX X1.
    - Research on Co3W and Co3Ti phases as strengtheners for cobalt-based high-temperature alloys.
  watch_out:
    - The ternary Co-W-Al hardness values are not binary Co-W values.
    - The Co-W elastic moduli are calculated (first principles), not measured.
    - No corrosion or failure data are sourced for any grade in this file.
    - 'Cobalt supply is concentrated: Congo (Kinshasa) mined an estimated 73 % of world cobalt in 2025 and Indonesia 14 % (USGS).'
  verdict: The 17 % cobalt-iron grade VACOFLUX X1 is the only measured magnetic grade in this file. Its values are printed by the maker, with saturation polarization 2.22 T and Curie temperature 940 °C. The cobalt-tungsten and cobalt-titanium values are phase data and calculated moduli. Corrosion, failure modes and binary Co-W or Co-Al mechanical data still need sources.
  recipe:
    line: 'The cobalt-iron grades are iron-cobalt alloys. VACOFLUX X1 is named as 17 % cobalt and the remainder iron (VACUUMSCHMELZE). The cobalt-tungsten, cobalt-titanium and cobalt-aluminium phases are ordered intermetallics: Co3W (L12 or DO19), Co7W6 (mu phase), Co3Ti (L12) and B2 CoAl over 45 to 58 at.% Al (Yang et al., Shi et al., arXiv cond-mat/9712321). The hardness alloy in this file is Co70W12Al15 (wt.%), made by an aluminothermic reaction.'
    parts:
      - name: Cobalt
        symbol: Co
        share_percent: 17
        role: Main element of the 17 % cobalt-iron grade (VACOFLUX X1, product name).
      - name: Iron
        symbol: Fe
        role: Balance of the cobalt-iron grade (VACOFLUX X1 is named as 17 % CoFe).
      - name: Tungsten
        symbol: W
        share_percent: 12
        role: Nominal tungsten in the Co70W12Al15 (wt.%) hardness alloy. In the Co-Ti-W system, W stabilises the L12 gamma-prime phase at 1473 K.
      - name: Aluminium
        symbol: Al
        share_percent: 15
        role: Nominal aluminium in the Co70W12Al15 (wt.%) hardness alloy. B2 CoAl is a separate phase in the same family.