Alnico permanent-magnet alloy Alnico

spore: profile
id: alnico
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Alnico permanent-magnet alloy
abbreviation: Alnico
role: permanent magnet
category: metals
type: magnet-alloys
summary: |
  Alnico is an iron alloy of aluminium, nickel and cobalt, cast or sintered into permanent magnets. Its magnetic output barely changes with temperature: Eclipse says Alnico has the best temperature coefficients of any magnet type, and Arnold quotes a reversible change of 0.02% per degree centigrade. Electron Energy's typical Alnico 5 remanence is 1.28 T, with a Curie temperature of 860 degC and a rated maximum of 525 degC. Its weakness is low coercivity: the typical intrinsic coercivity of cast Alnico 5 is 50.9 kA/m, so it can be demagnetised by its own circuit or by a neighbouring magnet, and it needs a long length-to-diameter ratio. Above about 538 degC the loss of strength is not recovered by remagnetization.
best_for: Magnetic output that stays steady across a wide temperature range, up to 525 to 550 degC (Eclipse and Electron Energy rated maximums)
weakest_at: Low coercivity (Alnico 5 about 50.9 kA/m, Electron Energy typical) so it demagnetises easily, and irreversible loss above about 538 degC
identity:
  formula: Iron-aluminium-nickel-cobalt alloy (Fe, Al, Ni, Co), with copper and titanium in some grades
  source: wikipedia-alnico
  where: 'Lead section, composition sentence: 8-12% Al, 15-26% Ni, 5-24% Co, up to 6% Cu, up to 1% Ti, rest Fe'
tags:
  environments: []
  stresses:
    - extreme-heat
  applications:
    - electronics-and-chips
    - mechanisms
properties:
  - benchmark: remanence_br
    label: Remanence Br, Alnico 5 (cast)
    value: 1.28
    unit: T
    scope: material
    conditions:
      grade: Alnico 5, cast
      value_type: typical, for reference only (not a specification)
    method: Typical value in the Electron Energy Corporation Alnico sell sheet
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 5, column Residual Induction Br (T)
  - benchmark: remanence_br
    label: Remanence Br, Alnico 8 (cast)
    value: 0.82
    unit: T
    scope: material
    conditions:
      grade: Alnico 8, cast
      value_type: typical, for reference only (not a specification)
    method: Typical value in the Electron Energy Corporation Alnico sell sheet
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 8, column Residual Induction Br (T)
  - benchmark: remanence_br
    label: Remanence Br, Alnico 9 (cast)
    value: 1.06
    unit: T
    scope: material
    conditions:
      grade: Alnico 9, cast
      value_type: typical, for reference only (not a specification)
    method: Typical value in the Electron Energy Corporation Alnico sell sheet
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 9, column Residual Induction Br (T)
  - benchmark: max_energy_product
    label: Maximum energy product (BH)max, Alnico 5 (cast)
    value: 43.8
    unit: kJ/m3
    scope: material
    conditions:
      grade: Alnico 5, cast
      value_type: typical, for reference only
    method: Typical value in the Electron Energy Corporation Alnico sell sheet (printed as 5.5 MGOe)
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 5, column (BH)max kJ/m3
  - benchmark: max_energy_product
    label: Maximum energy product (BH)max, Alnico 9 (cast)
    value: 71.6
    unit: kJ/m3
    scope: material
    conditions:
      grade: Alnico 9, cast
      value_type: typical, for reference only
    method: Typical value in the Electron Energy Corporation Alnico sell sheet (printed as 9.0 MGOe)
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 9, column (BH)max kJ/m3
    note: The Dexter AC900 table prints 10 MGOe for a cast grade of the same name. The two sources differ, so this row uses the Electron Energy figure.
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity Hci, Alnico 5 (cast)
    value: 50.9
    unit: kA/m
    scope: material
    conditions:
      grade: Alnico 5, cast
      value_type: typical, for reference only
    method: Typical value in the Electron Energy Corporation Alnico sell sheet (printed as 0.64 kOe)
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 5, column Intrinsic Coercivity iHC (kA/m)
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity Hci, Alnico 8 (cast)
    value: 148.1
    unit: kA/m
    scope: material
    conditions:
      grade: Alnico 8, cast
      value_type: typical, for reference only
    method: Typical value in the Electron Energy Corporation Alnico sell sheet (printed as 1.86 kOe)
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 8, column Intrinsic Coercivity iHC (kA/m)
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity Hci, Alnico 9 (cast)
    value: 119.4
    unit: kA/m
    scope: material
    conditions:
      grade: Alnico 9, cast
      value_type: typical, for reference only
    method: Typical value in the Electron Energy Corporation Alnico sell sheet (printed as 1.50 kOe)
    status: ground
    source: eec-alnico-sheet
    where: Magnetic Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 9, column Intrinsic Coercivity iHC (kA/m)
  - benchmark: curie_temperature
    label: Curie temperature, Alnico 5 (cast)
    value: 860
    unit: degC
    scope: material
    conditions:
      grade: Alnico 5, cast
    method: Value in the Electron Energy Corporation Alnico sell sheet (printed as 1580 degF)
    status: ground
    source: eec-alnico-sheet
    where: Mechanical Properties of Alnico Magnets, Cast Alnico Magnets, row Alnico 5, column Curie Temperature (degC)
  - benchmark: curie_temperature
    label: Curie temperature, cast Alnico (Dexter range)
    value: 760
    value_high: 860
    bound: range
    unit: degC
    scope: material
    conditions:
      material: cast Alnico, typical range across the Dexter cast grades
    method: Range printed in the Dexter typical physical properties table for cast Alnico
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Curie Temperature
  - benchmark: max_service_temp
    label: Maximum working temperature, Alnico 5
    value: 525
    unit: degC
    scope: material
    conditions:
      grade: Alnico 5
      note: maximum recommended temperature; the supplier says the application affects the performance available
    method: Value in the Eclipse Magnetics maximum working temperature table
    status: ground
    source: eclipse-alnico
    where: Max Working Temperature table, row Alnico 5
    note: Electron Energy prints 525 degC for Alnico 5 and 540 degC for Alnico 8 and 9. Eclipse prints 550 degC for Alnico 8 and 9 and is used here.
  - benchmark: max_service_temp
    label: Maximum working temperature, Alnico 8
    value: 550
    unit: degC
    scope: material
    conditions:
      grade: Alnico 8
      note: maximum recommended temperature; the supplier says the application affects the performance available
    method: Value in the Eclipse Magnetics maximum working temperature table
    status: ground
    source: eclipse-alnico
    where: Max Working Temperature table, row Alnico 8
  - benchmark: max_service_temp
    label: Maximum working temperature, Alnico 9
    value: 550
    unit: degC
    scope: material
    conditions:
      grade: Alnico 9
      note: maximum recommended temperature; the supplier says the application affects the performance available
    method: Value in the Eclipse Magnetics maximum working temperature table
    status: ground
    source: eclipse-alnico
    where: Max Working Temperature table, row Alnico 9
  - benchmark: temp_coeff_br
    label: Reversible temperature coefficient of Br, Alnico 5 (alpha)
    value: -0.02
    unit: '%/degC'
    scope: material
    conditions:
      grade: Alnico 5, cast and sintered
      range: not printed in the table
    method: Value in the Eclipse Magnetics temperature-coefficient table (alpha, induction)
    status: ground
    source: eclipse-alnico
    where: Temperature coefficients table, Rev. Temp. Coef. of Induction (Br) alpha, entry Alnico 5
  - benchmark: temp_coeff_br
    label: Reversible temperature coefficient of Br, Alnico 8 (alpha)
    value: -0.025
    unit: '%/degC'
    scope: material
    conditions:
      grade: Alnico 8, cast and sintered
      range: not printed in the table
    method: Value in the Eclipse Magnetics temperature-coefficient table (alpha, induction)
    status: ground
    source: eclipse-alnico
    where: Temperature coefficients table, Rev. Temp. Coef. of Induction (Br) alpha, entry Alnico 8
  - benchmark: temp_coeff_br
    label: Reversible temperature coefficient of Br, Alnico 9 (alpha)
    value: -0.025
    unit: '%/degC'
    scope: material
    conditions:
      grade: Alnico 9, cast and sintered
      range: not printed in the table
    method: Value in the Eclipse Magnetics temperature-coefficient table (alpha, induction)
    status: ground
    source: eclipse-alnico
    where: Temperature coefficients table, Rev. Temp. Coef. of Induction (Br) alpha, entry Alnico 9
  - benchmark: density
    label: Density, cast Alnico (Dexter range)
    value: 6.9
    value_high: 7.3
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      material: cast Alnico, typical range
    method: Range printed in the Dexter typical physical properties table for cast Alnico
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Density (g cm-3)
  - benchmark: density
    label: Density, Alnico (SDS range)
    value: 6.8
    value_high: 7.4
    bound: range
    unit: g/cc
    scope: material
    conditions:
      material: Alnico 2 to 9 and sub-grades, as stated in the supplier SDS
    method: Range printed in the supplier safety data sheet, physical properties section
    status: ground
    source: allstar-alnico-sds
    where: Section 9.1 Basic Physical and Chemical Properties, row Density
  - benchmark: melting_point
    label: Melting point, Alnico (SDS range)
    value: 1200
    value_high: 1450
    bound: range
    unit: degC
    scope: material
    conditions:
      material: Alnico family, as stated in the supplier SDS
    method: Range printed in the supplier safety data sheet, physical properties section
    status: ground
    source: allstar-alnico-sds
    where: Section 9.1 Basic Physical and Chemical Properties, row Melting Point
  - benchmark: cte
    label: Coefficient of thermal expansion, cast Alnico (Dexter range)
    value: 11
    value_high: 13
    bound: range
    unit: 1e-6 per degC
    scope: material
    conditions:
      material: cast Alnico, typical range
    method: Range printed in the Dexter typical physical properties table for cast Alnico
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Coefficient of Thermal Expansion (x 10-6 degC-1)
  - benchmark: electrical_resistivity
    label: Electrical resistivity, cast Alnico (Dexter range)
    value: 45
    value_high: 75
    bound: range
    unit: uohm cm
    scope: material
    conditions:
      material: cast Alnico, typical range
    method: Range printed in the Dexter typical physical properties table for cast Alnico (printed as uOhm.cm)
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Electrical Resistivity
  - benchmark: vickers_hardness
    label: Vickers hardness, anisotropic cast Alnico
    value: 520
    value_high: 700
    bound: range
    unit: Hv
    scope: material
    conditions:
      material: anisotropic cast Alnico, typical range
    method: Range printed in the Eclipse Magnetics typical physical characteristics table
    status: ground
    source: eclipse-alnico
    where: Physical Characteristics (Typical), Anisotropic Cast Alnico, row Vickers Hardness
  - benchmark: rockwell_c_hardness
    label: Rockwell C hardness, cast Alnico (Dexter range)
    value: 45
    value_high: 55
    bound: range
    unit: HRC
    scope: material
    conditions:
      material: cast Alnico, typical range
    method: Range printed in the Dexter typical physical properties table for cast Alnico
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Rockwell C Hardness
  - benchmark: compressive_strength
    label: Compression strength, anisotropic cast Alnico
    value: 300
    value_high: 400
    bound: range
    unit: N/mm2
    scope: material
    conditions:
      material: anisotropic cast Alnico, typical range
    method: Range printed in the Eclipse Magnetics typical physical characteristics table
    status: ground
    source: eclipse-alnico
    where: Physical Characteristics (Typical), Anisotropic Cast Alnico, row Compression Strength
  - benchmark: flexural_strength
    label: Transverse modulus of rupture, cast Alnico (Dexter range)
    value: 0.05
    value_high: 0.3
    bound: range
    unit: kN/mm2
    scope: material
    conditions:
      material: cast Alnico, typical range
      test: transverse modulus of rupture as printed
    method: Range printed in the Dexter typical physical properties table for cast Alnico
    status: ground
    source: dexter-alnico
    where: Typical Physical Properties, Cast, row Transverse Modulus of Rupture
corrosion:
  - environment: Ordinary dry indoor air, as cast or machined
    headline: Alnico has very good to excellent corrosion resistance for most applications.
    effect: Eclipse says Alnico is regarded as having very good to excellent corrosion resistance for most applications. Arnold says Alnico magnets are inherently corrosion resistant.
    rating: low
    conditions:
      basis: general statement from two suppliers; no corrosion rate given
    source: eclipse-alnico
    where: Corrosion Resistance box
  - environment: Prolonged exposure to water, uncoated
    headline: Iron in the alloy can rust in prolonged water exposure.
    effect: Eclipse says that because iron exists within the Alnico alloy, corrosion may be seen during prolonged exposure to water. Alnico can be coated or painted, but Eclipse notes that this is often only for appearance.
    rating: moderate
    conditions:
      exposure: prolonged water exposure, uncoated
      duration: not stated
    source: eclipse-alnico
    where: Corrosion Resistance box
  - environment: Strong acids and mineral acids, or corrosive metals in contact with the magnet
    headline: The SDS lists strong and mineral acids as incompatible, and they can make hydrogen.
    effect: The supplier SDS says corrosive substances in contact with metals may produce flammable hydrogen gas. No corrosion rate is given.
    rating: unknown
    conditions:
      basis: incompatibility statement, no test
    source: allstar-alnico-sds
    where: Section 10.5 Incompatible Materials and Section 7.2
risks:
  hazards:
    - text: 'Solid Alnico magnet (Allstar SDS, Rev 1.0, 2024): not classified under GHS-US and no label elements apply. The SDS says the solid is not considered flammable, and that the hazards arise in processing: powders, flakes, welding and molten metal.'
      ghs: []
      source: allstar-alnico-sds
      where: Sections 2.1, 2.2 and 2.3
    - text: 'Dust, chips and ribbons (Allstar SDS): these can be ignited more easily by an ignition source or by improper machining, and finely divided damp dust can ignite spontaneously. Dust clouds suspended in air can be explosive.'
      ghs: []
      source: allstar-alnico-sds
      where: Sections 5.2 and 7.1
    - text: 'Fumes during processing (Allstar SDS): inhaling fumes may cause lung inflammation, and molten material may release toxic and irritating fumes. Flakes or powder irritate the respiratory tract, eyes and skin.'
      ghs: []
      source: allstar-alnico-sds
      where: Section 4.2
    - text: 'Cobalt metal (PubChem CID 104730), aggregated notifications from 2768 company reports: signal word Danger. Notified hazards include H317 (above 99.9%), H334 (above 99.9%), H341 (65.8%), H350 (64.5%), H360Fd (61.6%), H302 (65.2%) and H413 (54.9%). This describes the pure metal, not the magnet.'
      ghs:
        - H317
        - H334
        - H341
        - H350
        - H360Fd
        - H302
        - H413
      source: pubchem-cobalt
      where: GHS Classification, aggregated information
    - text: 'Nickel metal (PubChem CID 935), aggregated notifications from 4778 company reports: signal word Danger. Notified hazards include H317 (99.9%), H372 (99.7%), H351 (72.9%), H350 (22.5%), H412 (47.2%), H360F (18%) and H341 (13.5%). This describes the pure metal, not the magnet.'
      ghs:
        - H317
        - H372
        - H351
        - H350
        - H412
        - H360F
        - H341
      source: pubchem-nickel
      where: GHS Classification, aggregated information
    - text: 'Exposure limits printed in the Allstar SDS: cobalt OSHA PEL 0.1 mg/m3, NIOSH REL 0.05 mg/m3, ACGIH TWA 0.02 mg/m3; nickel OSHA PEL 1 mg/m3, NIOSH REL 0.015 mg/m3, ACGIH TWA 1.5 mg/m3. The SDS also lists nickel and cobalt in IARC group 2B.'
      ghs: []
      source: allstar-alnico-sds
      where: Section 8.1 Control Parameters and Section 11.1 Carcinogenicity
  failure_risks:
    - mode: Demagnetisation by heat above the grade limit
      trigger: Heating above about 538 degC (1000 degF)
      consequence: Arnold says that at temperatures above 1000 F (538 C) a metallurgical change reduces magnetic strength rapidly, and that this change will not be recovered by remagnetization. Lower-temperature losses are usually less than 5% and can be recovered by remagnetization.
      severity: high
      source: arnold-alnico
      where: Stability section
    - mode: Demagnetisation by the circuit
      trigger: Low length-to-diameter ratio, strong fields from other magnets or electromagnets, or two magnets pushed together in repulsion
      consequence: Eclipse says an L/D ratio of at least 4 or 5 is a rule-of-thumb guide, that external magnets and electromagnets can demagnetise it, and that pushing two Alnico magnets in repulsion can weaken their output. The working point must stay above the knee of the intrinsic curve.
      severity: moderate
      source: eclipse-alnico
      where: Additional Information
    - mode: Rust in water
      trigger: Prolonged exposure to water with an uncoated surface
      consequence: Corrosion may be seen, because the alloy contains iron. Coating or painting is an option.
      severity: low
      source: eclipse-alnico
      where: Corrosion Resistance box
    - mode: Chips and slivers
      trigger: Cutting, grinding or impact
      consequence: Slivers may be generated, which could cause mechanical irritation or injure the eye.
      severity: moderate
      source: allstar-alnico-sds
      where: Section 4.2 Symptoms after eye contact
    - mode: Dust ignition or dust explosion
      trigger: Fine dust or powder, damp finely divided dust, or dust deposits in air
      consequence: Dust can ignite, and dust clouds in air can be explosive. The SDS advises keeping dust off surfaces and removing ignition sources.
      severity: moderate
      source: allstar-alnico-sds
      where: Sections 5.2 and 7.1
  side_effects:
    - text: Molten Alnico can release toxic and irritating fumes during melting or casting.
      affects: Foundry and processing operators
      source: allstar-alnico-sds
      where: Section 4.2
  handling:
    - text: Avoid creating or spreading dust. Clean up by sweeping or shovelling into a suitable container. A vacuum must have a HEPA filter, and only non-sparking tools and explosion-proof equipment should be used during clean-up.
      source: allstar-alnico-sds
      where: Sections 6.3 and 7.1
    - text: Store in a dry, cool place away from strong acids and mineral acids.
      source: allstar-alnico-sds
      where: Section 7.2
    - text: Wear eye protection. Safety glasses are advised during metal processing.
      source: allstar-alnico-sds
      where: Sections 6.1.1 and 8.2
    - text: Handle with care. Eclipse notes that pushing two Alnico magnets together in repulsion can weaken their output, and that careful handling restores it quickly.
      source: eclipse-alnico
      where: Additional Information
  mitigations:
    - text: Use a length-to-diameter ratio of at least 4 or 5 to resist demagnetisation.
      source: eclipse-alnico
      where: Additional Information
    - text: Alnico 8 is recommended for applications exposed to strong demagnetizing fields, or where space dictates a short magnetic length.
      source: arnold-alnico
      where: Design Considerations and Grade sections
    - text: Alnico can be remagnetised (Eclipse). The loss from heating above about 538 degC is not recovered by remagnetization (Arnold).
      source: eclipse-alnico
      where: Additional Information; Arnold Stability section
uses:
  - application: electronics-and-chips
    device: Traveling wave tubes and electron tubes
    example: Electron Energy lists Traveling Wave Tubes (TWTs) and Electron Tubes among its Alnico application types, alongside high thermal stability.
    source: eec-alnico-sheet
    where: Features and Application Types list
  - application: mechanisms
    device: Generators and magnetic pump couplings
    example: Electron Energy lists Generators and Magnetic Pump Couplings as application types. Eclipse notes that rotating machines and generators using Alnico need careful design, because the air gap varies during rotation.
    source: eclipse-alnico
    where: Additional Information; Electron Energy Application Types list
  - application: electronics-and-chips
    device: Automotive, aerospace and military sensors
    example: Electron Energy lists automotive, aerospace and military sensors as an Alnico application type.
    source: eec-alnico-sheet
    where: Application Types list
supply:
  - subject: Cobalt
    abundance: Cobalt is 5 to 24% of the Alnico alloy by weight (Allstar SDS). Cobalt is a constituent of the alloy at these levels.
    producers:
      - country: Congo (Kinshasa)
        share_percent: 73
        year: 2025
      - country: Indonesia
        share_percent: 14
        year: 2025
    critical_lists:
      - list: 'USGS 2025 List of Critical Minerals: Cobalt, used in batteries and metal alloys used in extreme temperatures'
        listed: true
      - list: EU critical raw materials list, cobalt entry on the European Commission page
        listed: true
    recycling: 'USGS: in 2025 the cobalt content of purchased scrap represented 25% of estimated cobalt consumption.'
    substitutes:
      - 'USGS: potential substitutes in magnets include barium or strontium ferrites, neodymium-iron-boron alloys, or nickel-iron alloys. Substitution could lower product performance or raise cost.'
    source: usgs-mcs2026-cobalt
    where: Events, Trends, and Issues (Congo share and Indonesia share, printed in text); Recycling; Substitutes
  - subject: Nickel
    abundance: Nickel is 14 to 21% of the Alnico alloy by weight (Allstar SDS).
    producers:
      - country: Indonesia
        share_percent: 66.7
        year: 2025
      - country: Philippines
        share_percent: 6.9
        year: 2025
      - country: Russia
        share_percent: 5.1
        year: 2025
    critical_lists:
      - list: 'USGS 2025 List of Critical Minerals: Nickel, used to make high-strength steel and rechargeable batteries'
        listed: true
      - list: 'EU list: nickel is a strategic raw material but does not meet the critical raw material thresholds (European Commission page)'
        listed: true
    recycling: 'USGS: most secondary nickel was in the form of nickel content of stainless-steel scrap.'
    substitutes: []
    source: usgs-mcs2026-nickel
    where: World Mine Production and Reserves table, 2025e; shares are Space Mushroom computations (Indonesia 2,600,000 of 3,900,000 t; Philippines 270,000 t; Russia 200,000 t)
  - subject: Aluminium
    abundance: Aluminium is 8 to 12% of the Alnico alloy by weight (Allstar SDS).
    producers:
      - country: China
        share_percent: 60.8
        year: 2025
      - country: Russia
        share_percent: 5.3
        year: 2025
      - country: Canada
        share_percent: 4.5
        year: 2025
      - country: United Arab Emirates
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: 'USGS 2025 List of Critical Minerals: Aluminum, used in almost all sectors of the economy'
        listed: true
      - list: 'EU critical raw materials list: aluminium and bauxite merged, European Commission page'
        listed: true
    recycling: 'USGS: about 3.6 million tons of aluminum was recovered from purchased scrap in the United States in 2025.'
    substitutes: []
    source: usgs-mcs2026-aluminum
    where: World Smelter Production table, 2025e (China 45,000 of 74,000 kt; Russia 3,900; Canada 3,300; UAE 2,700); shares are Space Mushroom computations; Recycling
documents:
  - title: Electron Energy Corporation Alnico magnets sell sheet (EECFY21)
    type: datasheet
    url: https://www.electronenergy.com/hubfs/Rebrand%20-%20Sell%20Sheets/EECFY21_Alnico%20Sell%20Sheet.pdf
    year: 2021
  - title: Eclipse Magnetics Alnico technical data sheet
    type: datasheet
    url: https://www.eclipsemagnetics.com/site/assets/files/22210/eclipsemagnetics_alnico_data_sheet.pdf
  - title: Dexter Magnetic Technologies Alnico curves and properties table (V101)
    type: datasheet
    url: https://www.dextermag.com/wp-content/uploads/2016/10/Dexter_Alnico_Curves__Properties_Table.pdf
    year: 2010
  - title: Allstar Magnetics SDS, Alnico 2 to 9 and all sub-grades, Rev 1.0 (08Feb2024)
    type: sds
    url: https://allstarmagnetics.com/wp-content/uploads/2024/10/Alnico-SDS.pdf
    year: 2024
  - title: USGS Mineral Commodity Summaries 2026, Cobalt
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Nickel
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Aluminum
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: 'PubChem compound records: cobalt (CID 104730) and nickel (CID 935), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/104730
    year: 2026
gaps:
  - No flight, vacuum, thermal-cycling or space-qualification source was found for Alnico. Electron Energy lists TWTs as an application but gives no space data.
  - Radiation tolerance of Alnico (gamma, electron, neutron or proton dose at which flux is lost) was not found in an opened source.
  - 'Normal coercivity Hcb for Alnico 5, 8 and 9 was not added: Dexter prints Hc values for AC500, AC800 and AC900, but it was not included to keep the grades consistent with the Electron Energy values.'
  - 'Sign and size of the coercivity temperature coefficient (beta) were not used: Eclipse prints +0.01 %/degC for Alnico 5, Dexter prints -0.02 %/degC (AC500) and Electron Energy prints -0.015 %/degC near (BH)max. The three sources disagree.'
  - 'Tensile strength was not used: the Electron Energy table gives kPa and kpsi columns that do not agree, and the Eclipse range was printed without a grade.'
  - Thermal conductivity was not found in an opened source.
  - A quantified corrosion rate or salt-spray result for Alnico was not found in an opened source.
  - No safety data sheet for the alloy gave a GHS classification. The PubChem records describe the pure metals cobalt and nickel, not the magnet alloy.
  - Atomic weights are PubChem molecular-weight values printed to two decimals (Fe 55.84, Al 26.981538, Co 58.93319, Ni 58.693, Cu 63.55), not IUPAC table values.
  - Crystal structure, CAS number and UNS or other designation codes for Alnico were not taken from a source we opened.
  - Shares for nickel, aluminium and cobalt are computed from USGS tables (nickel and aluminium) or printed in text (cobalt). Iron and titanium supply were not read.
  - Property names remanence_br, coercivity_hcj, temp_coeff_br, rockwell_c_hardness and compressive_strength are not in spores/property-canon.yaml; they follow the NdFeB profile naming.
  - Electron Energy max operating temperatures (540 degC for Alnico 8 and 9) differ from Eclipse (550 degC); both are noted, Eclipse is used.
composition:
  - basis: Alnico family, supplier SDS ranges
    Fe: 40-70
    Al: 8-12
    Ni: 14-21
    Co: 5-24
    Cu: 0.1-6
    unit: wt.%
    method: Composition table of the Allstar SDS, mixture ranges
    source: allstar-alnico-sds
    where: Section 3.2 Mixture
  - basis: Alnico family, Wikipedia typical ranges
    Al: 8-12
    Ni: 15-26
    Co: 5-24
    Cu: up to 6
    Ti: up to 1
    Fe: balance
    unit: '%'
    method: Typical composition window stated in the lead section
    source: wikipedia-alnico
    where: Lead section (composition)
process:
  - text: Alnico is cast (sand casting gives near-net shape and is cost effective at low and high volume) or sintered (cost effective at medium to high volume, for smaller and simpler shapes). Bonded Alnico is rare. Anisotropic grades get their direction of magnetisation from the casting or sintering process.
    source: eclipse-alnico
    where: Introduction
  - text: The superior magnetic output of the premium grades is produced by crystal orientation from the molten state.
    source: arnold-alnico
    where: Grades section (premium grades text)
  - text: 'History: the development of Alnico began in 1931 when T. Mishima in Japan found that an iron, nickel and aluminium alloy had about double the coercivity of the best magnet steels of the time. Alnico 5 was developed during World War 2.'
    source: wikipedia-alnico
    where: Lead section and Manufacturing process caption
review:
  status: draft
  method: assistant
  checked_values: 25
  unreachable: 0
  caveats: 4
  note: 'Written by an AI assistant from sources opened in this run: the Electron Energy sell sheet, the Eclipse data sheet, the Dexter table, the Allstar SDS, the USGS 2026 cobalt, nickel and aluminium summaries, the PubChem cobalt and nickel records, and the Arnold product page. The Wikipedia page was read for composition and history only. Values were copied as printed, and computed shares are labelled in where. Three sources disagree on some values, and those rows carry notes.'
story:
  recipe:
    line: Alnico is an iron-based alloy of aluminium, nickel and cobalt, named after the initials of those elements. Typical grades carry 8 to 12% aluminium, 15 to 26% nickel, 5 to 24% cobalt, up to 6% copper and up to 1% titanium, with iron as the balance. The supplier SDS gives a narrower nickel range (14 to 21%) and lists iron at 40 to 70%. Eclipse says Alnico can be produced by casting or sintering, and that casting is often used for near-net-shape magnets.
    parts:
      - name: Iron
        symbol: Fe
        share: 40-70 wt.%
        role: Largest part of the alloy by weight (SDS). Iron is why uncoated Alnico can rust in prolonged water exposure (Eclipse).
        source: pubchem-iron
      - name: Aluminium
        symbol: Al
        share: 8-12 wt.%
        role: One of the three main additions named in the alloy's name (Wikipedia). Its share is 8 to 12% (SDS).
        source: pubchem-aluminum
      - name: Nickel
        symbol: Ni
        share: 14-21 wt.%
        role: 'A main addition: 15 to 26% in the Wikipedia range and 14 to 21% in the SDS.'
        source: pubchem-nickel
      - name: Cobalt
        symbol: Co
        share: 5-24 wt.%
        role: A main addition at 5 to 24% (SDS and Wikipedia). USGS notes that cobalt is used in metal alloys used at extreme temperatures.
        source: pubchem-cobalt
      - name: Copper
        symbol: Cu
        share: 0.1-6 wt.%
        role: Present in some grades, up to 6% (Wikipedia), and 0.1 to 6% in the SDS.
        source: pubchem-copper
  why: 'Alnico is a cast or sintered alloy of iron, aluminium, nickel and cobalt, first developed in 1931 (Wikipedia). Its magnetic output hardly changes with temperature, which is its main advantage. Eclipse says Alnico has the best temperature coefficients of any magnet type and is the best choice for extremely high-temperature work. Its Curie temperature is 860 degC for cast Alnico 5 (Electron Energy) and it is rated to 525 to 550 degC. The cost of that stability is low coercivity: a cast Alnico 5 magnet has an intrinsic coercivity of only 50.9 kA/m, so the magnet must be long and the circuit well designed.'
  uses:
    - where: Traveling wave tubes and electron tubes
      line: Electron Energy lists TWTs and electron tubes among its Alnico application types, alongside high thermal stability.
    - where: Generators and magnetic pump couplings
      line: Electron Energy lists generators and magnetic pump couplings as applications. Eclipse adds that rotating machines using Alnico need careful design because the air gap varies during rotation.
    - where: Sensors
      line: Electron Energy lists automotive, aerospace and military sensors as an application type.
  can_do:
    - label: Stable output with heat
      value: 0.02% per degC
      line: Arnold quotes a reversible temperature coefficient of 0.02% per degree centigrade, which it calls the lowest of any standard commercial magnet. Eclipse gives -0.02 %/degC for Alnico 5 and -0.025 %/degC for Alnico 8 and 9.
    - label: Working heat
      value: Rated 525 to 550 degC
      line: Eclipse rates Alnico 5 to 525 degC and Alnico 8 and 9 to 550 degC. Electron Energy rates the grades to 540 degC.
    - label: Remanence
      value: 1.28 T (Alnico 5)
      line: Electron Energy gives a typical remanence of 1.28 T for cast Alnico 5, 0.82 T for cast Alnico 8 and 1.06 T for cast Alnico 9.
    - label: Hardness
      value: 520 to 700 Hv
      line: Eclipse gives a Vickers hardness of 520 to 700 Hv for anisotropic cast Alnico, and Dexter gives 45 to 55 HRC for cast grades.
  compare: Alnico trades strength for stability. Its remanence and energy product are modest, and its coercivity is low for the grades listed. Its output changes little with heat and its Curie temperature is high, which makes it suited to hot environments. USGS lists neodymium-iron-boron alloys among the potential substitutes for cobalt in magnets, and Wikipedia says rare-earth magnets are replacing Alnico in many of its applications.
  compare_rows:
    - label: Remanence (Alnico 5)
      benchmark: remanence_br
    - label: Maximum energy product (Alnico 9)
      benchmark: max_energy_product
    - label: Curie temperature (cast Alnico 5)
      benchmark: curie_temperature
  handling:
    - Avoid dust. Clean up mechanically, using a HEPA-filtered vacuum where a vacuum is needed.
    - Keep it dry, cool and away from strong and mineral acids.
    - Use an L/D ratio of 4 or 5 or more, and keep external magnets and fields away from the working magnet.
  good_for:
    - Output that must stay steady across a wide temperature range, such as sensors and generators in hot environments.
    - Electron tubes and travelling wave tubes, where Electron Energy lists Alnico for high-temperature stability.
  watch_out:
    - 'Low coercivity: an Alnico 5 magnet has only 50.9 kA/m intrinsic coercivity (Electron Energy typical).'
    - Irreversible loss above about 538 degC (Arnold).
    - Rust in prolonged water exposure if uncoated (Eclipse).
    - 'Concentrated supply: Congo (Kinshasa) mined an estimated 73% of world cobalt and Indonesia 66.7% of world nickel (USGS; the nickel share is computed from the table).'
  verdict: Alnico is the high-temperature choice among the magnet alloys covered here. It gives up coercivity to get a very small change of output with heat, and it needs a long, well-designed magnetic circuit. The sourced data show good thermal stability and modest magnetic output, and no flight or space-qualification data were found.
  risk_groups:
    - title: For people
      level: 1
      verdict: No safety classification for the solid
      lead: The supplier SDS does not classify the solid magnet under GHS-US. The hazards come from dust, fumes and chips during processing.
      points:
        - label: Dust and fumes
          line: Do not breathe dust or fumes. Molten material and metal processing give off irritating fumes, and nickel and cobalt compounds are on the IARC 2B list in the SDS.
        - label: Chips
          line: Slivers can be produced by cutting or grinding, and they can injure the eye. Wear eye protection.
      gap: No GHS classification for the alloy as a whole; the PubChem entries describe the pure metals.
    - title: If it fails
      level: 3
      verdict: Heat and poor circuit design demagnetise it
      lead: Heating above about 538 degC causes an irreversible loss, and low coercivity makes it sensitive to its circuit.
      points:
        - label: Heat
          line: Above about 538 degC (1000 degF) Arnold says magnetic strength falls rapidly and is not recovered by remagnetization.
        - label: Circuit
          line: Eclipse says a low L/D ratio, strong external fields and magnets pushed together in repulsion can all weaken Alnico.
    - title: Handling and storage
      points:
        - label: Dust
          line: Keep dust off surfaces and clean up mechanically. Fine dust can ignite and dust clouds can be explosive.
        - label: Storage
          line: Store dry and cool, away from strong and mineral acids, which can produce flammable hydrogen.
sources:
  eec-alnico-sheet:
    title: Alnico Magnets, Electron Energy Corporation sell sheet (EECFY21)
    id: EECFY21
    url: https://www.electronenergy.com/hubfs/Rebrand%20-%20Sell%20Sheets/EECFY21_Alnico%20Sell%20Sheet.pdf
    year: 2021
    kind: datasheet
    license: manufacturer sell sheet
  eclipse-alnico:
    title: Technical Data Sheet, Alnico Magnets (Eclipse Magnetics)
    id: eclipsemagnetics_alnico_data_sheet.pdf
    url: https://www.eclipsemagnetics.com/site/assets/files/22210/eclipsemagnetics_alnico_data_sheet.pdf
    kind: datasheet
    license: manufacturer datasheet
  dexter-alnico:
    title: Alnico Curves and Properties Table (Dexter Magnetic Technologies, V101)
    id: Dexter_Alnico_Curves__Properties_Table.pdf
    url: https://www.dextermag.com/wp-content/uploads/2016/10/Dexter_Alnico_Curves__Properties_Table.pdf
    year: 2010
    kind: datasheet
    license: manufacturer datasheet
  arnold-alnico:
    title: Alnico magnets (Arnold Magnetic Technologies product page)
    url: https://www.arnoldmagnetics.com/products/alnico-magnets
    kind: web
    license: supplier web page
  wikipedia-alnico:
    title: Alnico (Wikipedia)
    url: https://en.wikipedia.org/wiki/Alnico
    kind: web
    license: CC BY-SA
  allstar-alnico-sds:
    title: Allstar Magnetics Safety Data Sheet, Alnico 2 to 9 and all sub-grades (Rev 1.0, 08Feb2024)
    id: SDS Alnico, Rev 1.0, 08Feb2024
    url: https://allstarmagnetics.com/wp-content/uploads/2024/10/Alnico-SDS.pdf
    year: 2024
    kind: datasheet
    license: supplier document, linked not reproduced
  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-mcs2026-nickel:
    title: Mineral Commodity Summaries 2026, Nickel
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-aluminum:
    title: Mineral Commodity Summaries 2026, Aluminum
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit-2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals, 6 Nov 2025)
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    kind: web
    license: public domain (USGS)
  eu-crm-page:
    title: Critical raw materials (European Commission)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: EC web page
  pubchem-cobalt:
    title: 'PubChem compound CID 104730, cobalt: GHS classification and molecular weight'
    id: CID 104730
    url: https://pubchem.ncbi.nlm.nih.gov/compound/104730
    kind: database
  pubchem-nickel:
    title: 'PubChem compound CID 935, nickel: GHS classification and molecular weight'
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    kind: database
  pubchem-iron:
    title: 'PubChem compound CID 23925, iron: molecular weight'
    id: CID 23925
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23925
    kind: database
  pubchem-aluminum:
    title: 'PubChem compound CID 5359268, aluminum: molecular weight'
    id: CID 5359268
    url: https://pubchem.ncbi.nlm.nih.gov/compound/5359268
    kind: database
  pubchem-copper:
    title: 'PubChem compound CID 23978, copper: molecular weight'
    id: CID 23978
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23978
    kind: database
license: CC-BY-4.0