spore: profile
id: metglas-2705m
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: METGLAS 2705M
abbreviation: Co-based amorphous ribbon
role: magnetic shield and high-frequency core alloy
category: metals
type: magnet-alloys
summary: |
  METGLAS 2705M is a cobalt-based amorphous metal ribbon made by Metglas, Inc. Its technical bulletin gives a density of 7.80 g/cm3, a saturation induction of 0.77 T and a Curie temperature of 365 °C. In a 2011 University of Kentucky test, a human-size cylindrical shield made from the ribbon measured DC shielding factors of 267 axial and 1500 transverse in the Earth's magnetic field.
best_for: Flexible magnetic shields and high-permeability cores, where the ribbon is used without annealing (the manufacturer's product page makes this claim)
weakest_at: 'Ground data only: no corrosion rate, no long-term ageing data above the 90 °C continuous service temperature, and no vacuum or flight result were found in the sources read'
identity:
  formula: 'Cobalt-based amorphous metal ribbon, Co-Fe-Ni-Mo-B-Si: cobalt 75 to 85, silicon 3 to 7, boron 1 to 5, iron 1 to 5, molybdenum 1 to 5 and nickel 1 to 5 (weight %, SDS ranges)'
  crystal_system: amorphous (no crystal lattice)
  source: metglas-2705m-sds
  where: Section 2, Composition table (weight %)
  designations:
    - system: Trade name
      code: 2705M
      source: metglas-2705m-datasheet
      where: Title block, Magnetic Alloy 2705M (cobalt-based)
    - system: Trade name
      code: 2705M Cobalt Base Magnetic Alloy
      source: metglas-2705m-sds
      where: Title block on every page, METGLAS 2705M Cobalt Base Magnetic Alloy
tags:
  environments: []
  stresses: []
  applications:
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, as printed in the technical bulletin
    value: 7.8
    unit: g/cm3
    scope: material
    conditions:
      grade: METGLAS 2705M ribbon
      condition: as printed in the physical properties table
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Density (g/cm3) = 7.80
  - benchmark: saturation_induction
    label: Saturation induction
    value: 0.77
    unit: T
    scope: material
    conditions:
      grade: METGLAS 2705M ribbon
      condition: as printed in the magnetic properties table
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Saturation Induction (T) = 0.77
  - benchmark: dc_permeability
    label: Maximum DC permeability, annealed
    value: 600000
    unit: '-'
    scope: material
    conditions:
      heat_treatment: annealed
      printed_unit: none
    method: Value printed in the technical bulletin; the bulletin prints no unit, so the value is entered as a dimensionless number
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Maximum D.C. Permeability, Annealed = 600,000
  - benchmark: dc_permeability
    label: Maximum DC permeability, as cast
    value: 290000
    unit: '-'
    scope: material
    conditions:
      heat_treatment: as cast
      printed_unit: none
    method: Value printed in the technical bulletin; the bulletin prints no unit, so the value is entered as a dimensionless number
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Maximum D.C. Permeability, As Cast = 290,000
  - benchmark: saturation_magnetostriction
    label: Saturation magnetostriction
    value: 0.5
    bound: upper
    unit: ppm
    scope: material
    conditions:
      printed_as: <0.5 ppm
      condition: as printed in the magnetic properties table
    method: Upper limit printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Saturation Magnetostriction (ppm) = <0.5
  - benchmark: electrical_resistivity
    label: Electrical resistivity
    value: 136
    unit: μΩ.cm
    scope: material
    conditions:
      grade: METGLAS 2705M ribbon
      temperature: not stated
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Electrical Resistivity (μΩ.cm) = 136
  - benchmark: curie_temperature
    label: Curie temperature, technical bulletin
    value: 365
    unit: °C
    scope: material
    conditions:
      grade: METGLAS 2705M ribbon
      condition: as printed in the magnetic properties table
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Magnetic Properties table, Curie Temperature (°C) = 365
  - benchmark: curie_temperature
    label: Curie temperature, safety data sheet
    value: 365
    unit: °C
    scope: material
    conditions:
      printed_as: 689 °F (365 °C)
      grade: METGLAS 2705M Cobalt Base Magnetic Alloy
    method: Value printed in the manufacturer's safety data sheet
    status: ground
    note: The bulletin and the safety data sheet give the same Curie temperature.
    source: metglas-2705m-sds
    where: Section 9, Physical and chemical properties, Curie temperature
  - benchmark: crystallization_temperature
    label: Crystallization temperature, technical bulletin
    value: 520
    unit: °C
    scope: material
    conditions:
      grade: METGLAS 2705M ribbon
      condition: as printed in the physical properties table
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Crystallization Temperature (°C) = 520
  - benchmark: crystallization_temperature
    label: Crystallization temperature, safety data sheet
    value: 520
    unit: °C
    scope: material
    conditions:
      printed_as: 968 °F (520 °C)
      grade: METGLAS 2705M Cobalt Base Magnetic Alloy
    method: Value printed in the manufacturer's safety data sheet
    status: ground
    source: metglas-2705m-sds
    where: Section 9, Physical and chemical properties, Crystallization temp
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, as printed in the technical bulletin
    value: 1
    value_high: 2
    bound: range
    unit: GPa
    scope: material
    conditions:
      form: ribbon
      heat_treatment: not stated in the bulletin
      printed_as: 1-2 (GPa)
    method: Range printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Tensil Strength (GPa) = 1-2
  - benchmark: elastic_modulus
    label: Elastic modulus, as printed in the technical bulletin
    value: 100
    value_high: 110
    bound: range
    unit: GPa
    scope: material
    conditions:
      form: ribbon
      printed_as: 100-110 (GPa)
    method: Range printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Elastic Modulus (GPa) = 100-110
  - benchmark: lamination_factor
    label: Lamination factor
    value: 75
    bound: lower
    unit: '%'
    scope: material
    conditions:
      printed_as: '>75 (%)'
      form: ribbon
    method: Lower limit printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Lamination Factor (%) = >75
  - benchmark: cte
    label: Coefficient of thermal expansion
    value: 12.1
    unit: ppm/°C
    scope: material
    conditions:
      temperature_range: not printed in the bulletin
      grade: METGLAS 2705M ribbon
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Thermal Expansion (ppm/°C) = 12.1
  - benchmark: max_service_temp
    label: Continuous service temperature
    value: 90
    unit: °C
    scope: material
    conditions:
      basis: continuous service temperature as printed
      grade: METGLAS 2705M ribbon
    method: Value printed in the manufacturer's technical bulletin
    status: ground
    source: metglas-2705m-datasheet
    where: Physical Properties table, Continuous Service Temp. (°C) = 90
  - benchmark: shielding_factor
    label: DC axial magnetic shielding factor, single-shell cylinder
    value: 267
    unit: '-'
    scope: material
    conditions:
      assembly: single-shell open-ended cylinder of 2705M ribbon, 0.61-m diameter and 1.83-m long
      thickness_total: 122 µm (6 foil layers)
      field: DC, Earth's magnetic field
      shaking: not used
    method: Measured by the authors of a 2011 University of Kentucky paper on large Metglas shields
    status: ground
    source: arxiv-1107-malkowski
    where: Abstract
  - benchmark: shielding_factor
    label: DC transverse magnetic shielding factor, single-shell cylinder
    value: 1500
    unit: '-'
    scope: material
    conditions:
      assembly: single-shell open-ended cylinder of 2705M ribbon, 0.61-m diameter and 1.83-m long
      thickness_total: 122 µm (6 foil layers)
      field: DC, Earth's magnetic field
      shaking: not used
    method: Measured by the authors of a 2011 University of Kentucky paper on large Metglas shields
    status: ground
    source: arxiv-1107-malkowski
    where: Abstract
  - benchmark: thickness
    label: Ribbon thickness, as printed in the 2011 paper
    value: 20.3
    unit: µm
    scope: material
    conditions:
      form: ribbon foil
      width: 5.08-cm wide
    method: Value printed in the abstract of a 2011 university paper that tested the ribbon
    status: ground
    source: arxiv-1107-malkowski
    where: Abstract, ribbon description
corrosion:
  - environment: Moisture and corrosive materials (storage and incompatibilities)
    headline: The SDS says the product can be attacked by moisture and corrosive materials.
    effect: Section 10 lists moisture and corrosive materials as incompatible, and Section 7 asks that the product not be exposed to moisture or any other substance. The SDS gives no corrosion rate, test or exposure time.
    rating: unknown
    source: metglas-2705m-sds
    where: Section 10, Incompatibilities; Section 7, Storage recommendations
  - environment: Heating above the continuous service temperature (thermal ageing)
    headline: The bulletin gives 90 °C as the continuous service temperature and prints no ageing data above it.
    effect: The bulletin prints a crystallization temperature of 520 °C and a continuous service temperature of 90 °C. No property change after long heating at intermediate temperatures was found in the sources read.
    rating: unknown
    source: metglas-2705m-datasheet
    where: Physical Properties table, Continuous Service Temp. and Crystallization Temperature
risks:
  hazards:
    - text: The SDS says the primary hazard as shipped is the sharp edges of the product. Some individuals may develop allergic skin reactions after repeated handling.
      ghs: []
      source: metglas-2705m-sds
      where: Section 3, Emergency overview
    - text: The SDS gives a WHMIS classification of D2B (sensitizer) for the product as shipped. Vapors and fumes from grinding, sanding, cutting or welding are harmful if inhaled.
      ghs: []
      source: metglas-2705m-sds
      where: Section 3, Inhalation; Section 15, WHMIS classification
    - text: The SDS lists cobalt as IARC group 2b (possible carcinogen) and says cobalt and nickel, and their compounds, should be treated as possible carcinogens.
      ghs: []
      source: metglas-2705m-sds
      where: Section 3, Delayed effects and carcinogen table
    - text: 'PubChem''s record for the element cobalt (the alloy''s main constituent, not the alloy itself) lists these EU CLP statements: H317, H334, H341, H350, H360F and H413.'
      ghs:
        - H317
        - H334
        - H341
        - H350
        - H360F
        - H413
      source: pubchem-cobalt
      where: Safety and Hazards, GHS Classification, reference 71 (Regulation (EC) No 1272/2008)
  failure_risks:
    - mode: Fire or melting of the ribbon
      trigger: Melting or burning in a structural fire
      consequence: The SDS says the product may burn in a structural fire, and toxic and irritating vapors may be released if it melts or burns.
      severity: moderate
      source: metglas-2705m-sds
      where: Section 3 and Section 5, Special fire fighting precautions
    - mode: Operation above the continuous service temperature
      trigger: Use above 90 °C
      consequence: The bulletin gives 90 °C as the continuous service temperature. No property data above that limit were found in the sources read, so the effect of longer exposure is not documented.
      severity: low
      source: metglas-2705m-datasheet
      where: Physical Properties table, Continuous Service Temp.
  handling:
    - text: The edges are very sharp. Wear cut-resistant gloves and safety glasses when grinding, sanding, cutting or welding.
      source: metglas-2705m-sds
      where: Section 7, Normal handling; Section 8, Personal protective equipment
    - text: Use mechanical ventilation when cutting, grinding, sanding or welding the ribbon.
      source: metglas-2705m-sds
      where: Section 8, Engineering controls
    - text: Store the ribbon in a facility that protects it from physical damage, moisture and other contamination.
      source: metglas-2705m-sds
      where: Section 7, Storage recommendations
  mitigations:
    - text: The manufacturer says the alloy can be annealed for square or linear permeability.
      source: metglas-magnetic-page
      where: 2705M section, Benefits
uses:
  - application: electronics-and-chips
    device: Flexible electromagnetic shielding (human-size cylindrical shield)
    example: A 2011 University of Kentucky paper built a single-shell, open-ended cylinder of 2705M ribbon, 0.61-m diameter and 1.83-m long, and measured DC shielding factors of 267 axial and 1500 transverse in the Earth's magnetic field.
    source: arxiv-1107-malkowski
    where: Abstract
  - application: electronics-and-chips
    device: Internal magnetic shield in a cryogenic neutron electric dipole moment experiment (laboratory use, not flown)
    example: A 2017 paper on a neutron electric dipole moment experiment used six layers of Metglas 2705M as the internal shield, because the alloy keeps high permeability from room temperature to cryogenic temperatures.
    source: arxiv-1701-slutsky
    where: Description of the internal Metglas shield (the paragraph citing Metglas, Inc.)
  - application: electronics-and-chips
    device: Magnetic sensors, high frequency cores and magnetic switches
    example: The manufacturer's 2705M section lists flexible electromagnetic shielding, magnetic sensors, high frequency cores and magnetic switches as applications.
    source: metglas-magnetic-page
    where: 2705M section, Applications list
supply:
  - subject: Cobalt
    producers:
      - country: Congo (Kinshasa)
        share_percent: 73
        year: 2025
      - country: Indonesia
        share_percent: 14
        year: 2025
      - country: Australia
        share_percent: 1.2
        year: 2025
      - country: Philippines
        share_percent: 1.2
        year: 2025
      - country: Russia
        share_percent: 2.5
        year: 2025
    critical_lists:
      - list: 'USGS 2025 List of Critical Minerals (entry: Cobalt, used in batteries and metal alloys used in extreme temperatures)'
        listed: true
      - list: EU critical raw materials list (Cobalt entry, European Commission page)
        listed: true
    recycling: 'USGS: cobalt content of purchased scrap represented 25% of estimated cobalt consumption in 2025.'
    substitutes:
      - 'USGS: substitution for cobalt could result in a loss in product performance or increased cost. Potential substitutes in some magnets include nickel-iron alloys.'
    source: usgs-mcs2026-cobalt
    where: World Mine Production table, 2025 column (world total 310,000 t); the 73% and 14% shares are printed in Events, Trends and Issues; the Australia, Philippines and Russia shares are calculated by Space Mushroom from tonnes (3,700, 3,700 and 7,700 of 310,000 t). Recycling; Substitutes.
documents:
  - title: METGLAS Magnetic Alloy 2705M (cobalt-based) technical bulletin
    type: datasheet
    url: https://metglas.com/wp-content/uploads/2021/06/2705M-Magnetic-Alloy-updated.pdf
    year: 2014
  - title: 'METGLAS 2705M Cobalt Base Magnetic Alloy: Material Safety Data Sheet (FRM 8200.007 Rev. 01)'
    type: sds
    url: https://metglas.com/wp-content/uploads/2016/12/Metglas-Alloy-2705M-Cobalt-Based-Alloy.pdf
    year: 2013
  - title: Technique for high axial shielding factor performance of large-scale, thin, open-ended, cylindrical Metglas magnetic shields (arXiv:1107.2625)
    type: paper
    url: https://arxiv.org/pdf/1107.2625
    year: 2011
  - title: Cryogenic magnetic coil and superconducting magnetic shield for neutron electric dipole moment searches (arXiv:1701.03101)
    type: paper
    url: https://arxiv.org/pdf/1701.03101
    year: 2017
  - title: Mineral Commodity Summaries 2026, Cobalt (USGS)
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
  - title: PubChem compound record, Cobalt (CID 104730), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/104730
gaps:
  - No corrosion rate, humidity test, salt-spray result or exposure time for 2705M was found in the sources read; the only corrosion statement is the SDS line that moisture and corrosive materials can attack the product.
  - No UNS, ASTM, EN, AISI or JIS designation for 2705M was printed in the sources read; only the trade names are listed.
  - Vickers hardness is printed on the technical bulletin without a unit, so it is not recorded as a property.
  - The two permeability values are printed without a unit and are entered as dimensionless numbers, as the bulletin prints them.
  - Saturation induction, crystallization temperature, permeability, magnetostriction, lamination factor, shielding factor and thickness use names outside the canonical list (property-canon.yaml), as no canonical name fits.
  - Composition is given only as weight-percent ranges from the SDS; no atomic-percent composition from a fetched source was found.
  - Crustal abundance and producer shares for nickel, molybdenum, boron and silicon were not read; only cobalt supply is recorded.
  - No long-term thermal ageing data for 2705M above its continuous service temperature were found in the sources read.
  - The technical bulletin is dated 2014 by its copyright range and does not label its table values as typical; no newer datasheet was found in this run.
  - No vacuum, radiation or flight data for 2705M were found; the shielding and cryogenic uses are ground laboratory tests, not flight.
  - The 2011 shield measurements are from one cylinder geometry in the Earth's magnetic field; no other field strength was read for 2705M.
  - The product page lists 2705M for shielding, sensors, high frequency cores and magnetic switches, but gives no numbers for it.
  - The 2017 paper describes cryogenic permeability only qualitatively; no cryogenic permeability value was read.
  - Hazard data rest on the 2705M SDS and the PubChem record for the element cobalt, which is not the alloy itself.
sources:
  metglas-2705m-datasheet:
    title: METGLAS Magnetic Alloy 2705M (cobalt-based) technical bulletin
    id: Metglas, Inc. technical bulletin, ref 2705M08202014
    url: https://metglas.com/wp-content/uploads/2021/06/2705M-Magnetic-Alloy-updated.pdf
    year: 2014
    kind: datasheet
    license: manufacturer document, linked not reproduced
  metglas-2705m-sds:
    title: 'Material Safety Data Sheet: METGLAS 2705M Cobalt Base Magnetic Alloy'
    id: FRM 8200.007 Rev. 01; initial release October 2003, revision 01 dated 02/06/13
    url: https://metglas.com/wp-content/uploads/2016/12/Metglas-Alloy-2705M-Cobalt-Based-Alloy.pdf
    year: 2013
    kind: datasheet
    license: supplier document, linked not reproduced
  metglas-magnetic-page:
    title: 'METGLAS Magnetic Materials: 2705M section (Applications and Benefits)'
    id: Metglas, Inc. product page
    url: https://metglas.com/magnetic-materials/
    kind: web
    license: manufacturer web page, linked not reproduced
  arxiv-1107-malkowski:
    title: Technique for high axial shielding factor performance of large-scale, thin, open-ended, cylindrical Metglas magnetic shields
    id: arXiv:1107.2625 (S. Malkowski, R. Adhikari, B. Hona, C. Mattie, D. Woods, H. Yan, B. Plaster; University of Kentucky)
    url: https://arxiv.org/pdf/1107.2625
    year: 2011
    kind: paper
    license: arXiv preprint
  arxiv-1701-slutsky:
    title: Cryogenic magnetic coil and superconducting magnetic shield for neutron electric dipole moment searches
    id: arXiv:1701.03101 (S. Slutsky et al.)
    url: https://arxiv.org/pdf/1701.03101
    year: 2017
    kind: paper
    license: arXiv preprint
  usgs-mcs2026-cobalt:
    title: Mineral Commodity Summaries 2026, Cobalt
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS)
    id: Final 2025 List of Critical Minerals
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials (European Commission, list of critical raw materials)
    id: EU critical raw materials list, Cobalt entry
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: European Commission web page
  pubchem-cobalt:
    title: PubChem compound record, Cobalt (CID 104730), GHS classification
    id: CID 104730
    url: https://pubchem.ncbi.nlm.nih.gov/compound/104730
    kind: database
    license: public domain (NCBI)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 18
  unreachable: 0
  caveats: 3
  note: Read by an AI assistant on 2026-11-01 from the technical bulletin, the SDS, the product page, two arXiv papers, the USGS cobalt chapter and the PubChem record; values copied as printed. Cobalt shares are from USGS tonnes.
story:
  recipe:
    line: METGLAS 2705M is a ribbon of cobalt with smaller amounts of boron, iron, molybdenum, nickel and silicon. The SDS gives weight-percent ranges rather than a fixed composition. The manufacturer says its magnetic materials are made on a proprietary high-speed casting process.
    parts:
      - name: Cobalt
        symbol: Co
        share_percent: 75
        share_high: 85
        role: Main constituent, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
      - name: Silicon
        symbol: Si
        share_percent: 3
        share_high: 7
        role: Alloying element, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
      - name: Boron
        symbol: B
        share_percent: 1
        share_high: 5
        role: Alloying element, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
      - name: Iron
        symbol: Fe
        share_percent: 1
        share_high: 5
        role: Alloying element, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
      - name: Molybdenum
        symbol: Mo
        share_percent: 1
        share_high: 5
        role: Alloying element, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
      - name: Nickel
        symbol: Ni
        share_percent: 1
        share_high: 5
        role: Alloying element, given as a weight-percent range in the SDS.
        source: metglas-2705m-sds
        where: Section 2, Composition table, weight %
  risk_groups:
    - title: For people
      level: 1
      verdict: Sharp edges and fumes from cutting
      lead: The SDS says the sharp edges are the main hazard as shipped. Fumes from grinding, cutting or welding are harmful if inhaled.
      points:
        - label: Edges
          line: The edges are very sharp. The SDS asks for cut-resistant gloves and safety glasses when the ribbon is ground, sanded, cut or welded.
        - label: Fumes
          line: Vapors and fumes from grinding, sanding, cutting or welding are harmful if inhaled. The SDS asks for mechanical ventilation during those operations.
        - label: Cobalt
          line: The SDS lists cobalt as IARC group 2b, a possible carcinogen, and says cobalt and nickel, and their compounds, should be treated as possible carcinogens.
    - title: If the ribbon melts or burns
      level: 2
      verdict: Toxic fumes if melted or burned
      lead: These points come from the SDS and are not based on field incidents.
      points:
        - label: Fire
          line: The product may burn in a structural fire. Toxic and irritating vapors may be released if it melts or burns, and the SDS asks for self-contained respiratory protection.
    - title: Handling and storage
      points:
        - label: Storage
          line: The SDS asks that the ribbon be kept from physical damage, moisture and other contamination.
        - label: Incompatibility
          line: The SDS says the product can be attacked by moisture and corrosive materials.
  why: METGLAS 2705M is a cobalt-based amorphous metal ribbon made by Metglas, Inc. Amorphous means the atoms are not arranged in a regular crystal lattice. A 2011 University of Kentucky paper calls the alloy a low-cost, high-permeability cobalt-based magnetic material. The manufacturer lists it for flexible electromagnetic shielding, magnetic sensors, high frequency cores and magnetic switches.
  uses:
    - where: Magnetic shielding
      line: A 2011 University of Kentucky paper built a human-size cylindrical shield from the ribbon. In the Earth's magnetic field, its DC shielding factors were 267 axial and 1500 transverse.
    - where: Cryogenic experiment
      line: A 2017 paper on a neutron electric dipole moment experiment used six layers of 2705M as the internal shield, because the alloy keeps high permeability from room temperature to cryogenic temperatures. This is a laboratory use, not a flight.
    - where: Sensors and cores
      line: The manufacturer's product page lists the alloy for magnetic sensors, high frequency cores and magnetic switches.
  can_do:
    - label: Saturation induction
      benchmark: saturation_induction
      value: 0.77 T
      line: The technical bulletin gives a saturation induction of 0.77 T.
    - label: Permeability
      benchmark: dc_permeability
      value: 600,000 annealed; 290,000 as cast
      line: The bulletin gives a maximum DC permeability of 600,000 when annealed and 290,000 as cast. The bulletin prints no unit for these values.
    - label: Shielding
      benchmark: shielding_factor
      value: 267 axial; 1500 transverse
      line: In the 2011 test of a 0.61-m diameter, 1.83-m long shield of six foil layers, the DC shielding factors in the Earth's magnetic field were 267 axial and 1500 transverse.
    - label: Temperature
      benchmark: max_service_temp
      value: 90 °C
      line: The bulletin gives 90 °C as the continuous service temperature.
    - label: Curie temperature
      benchmark: curie_temperature
      value: 365 °C
      line: The bulletin and the SDS both give a Curie temperature of 365 °C.
  compare: METGLAS 2705M is a cobalt-based ribbon, and its 2705M section on the manufacturer's product page lists it for shielding, sensors and high frequency cores. The sources read do not compare its numbers directly with other magnetic alloys, so the table below shows its own datasheet values for the three properties.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Saturation induction
      benchmark: saturation_induction
    - label: Curie temperature
      benchmark: curie_temperature
  handling:
    - The edges are very sharp. Wear cut-resistant gloves and safety glasses.
    - Ventilate when cutting, grinding, sanding or welding the ribbon.
    - Store it away from moisture and corrosive materials.
    - The bulletin gives 90 °C as the continuous service temperature.
  good_for:
    - Flexible electromagnetic shielding, the first use the manufacturer lists for 2705M.
    - 'Single-shell shielding of a steady field: the 2011 test measured 267 axial and 1500 transverse DC shielding factors.'
  watch_out:
    - The bulletin prints its permeability values without a unit, so they are entered as dimensionless numbers.
    - The continuous service temperature is 90 °C, and the sources read give no data above it.
    - No corrosion rate was found. The SDS only says moisture and corrosive materials can attack the product.
  verdict: METGLAS 2705M is a documented cobalt-based shielding ribbon with datasheet values and one 2011 university shield test. Its corrosion, long-term ageing and flight behaviour are not documented in the sources read.