Samarium-cobalt sintered magnet alloy SmCo

spore: profile
id: smco
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Samarium-cobalt sintered magnet alloy
abbreviation: SmCo
role: permanent magnet
category: metals
type: magnet-alloys
summary: |
  Sintered samarium-cobalt is the high-temperature rare-earth magnet family. It comes in two phases: SmCo5 (the 1:5 alloy) and Sm2Co17 (the 2:17 alloy). Eclipse Magnetics gives a Curie temperature of 800 to 850 degC for Sm2Co17 and rates standard grades to 300 degC, and 350 degC for the H grades. Arnold's Recoma 35E datasheet gives a nominal remanence of 1.190 T and a Curie temperature of 820 degC. Sm2Co17 is weaker than NdFeB at room temperature but often outperforms it above 150 to 180 degC. It is brittle and corrodes in wet conditions unless it is coated. The NASA Glenn review of radiation effects reports that Sm2Co17 magnets showed no measurable flux change after neutron fluences near 1e20 n/cm2 in one reactor test.
best_for: Strong magnets that must stay stable above 150 degC, with a rated limit of 300 to 350 degC for Sm2Co17 grades (Eclipse)
weakest_at: Room-temperature strength against NdFeB, brittleness (flexural strength 110 to 120 N/mm2), and surface corrosion of Sm2Co17 in water without a coating
identity:
  formula: SmCo5 (1:5 phase) and Sm2Co17 (2:17 phase)
  source: wiki-smco
  where: 'Composition section: SmCo5 has one samarium atom per five cobalt atoms, and Sm2Co17 has two per 13 to 17 transition-metal atoms (Wikipedia)'
tags:
  environments: []
  stresses:
    - total-radiation-dose
    - extreme-heat
  applications:
    - mechanisms
properties:
  - benchmark: remanence_br
    label: Remanence Br, SmCo 22 (1:5 grade)
    value: 9.2
    value_high: 9.6
    bound: range
    unit: kGs
    scope: material
    conditions:
      grade: SmCo 22 (Sm1Co5 phase)
      value_type: typical range, approximate
    method: Typical range in the supplier's grade table (the sheet says values are approximate and for reference only)
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 22, Br column
  - benchmark: remanence_br
    label: Remanence Br, SmCo 26 (2:17 grade)
    value: 10.2
    value_high: 10.5
    bound: range
    unit: kGs
    scope: material
    conditions:
      grade: SmCo 26 (Sm2Co17 phase)
      value_type: typical range, approximate
    method: Typical range in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26, Br column
  - benchmark: remanence_br
    label: Remanence Br, Recoma 35E (Sm2Co17)
    value: 1.19
    unit: T
    scope: material
    conditions:
      grade: Recoma 35E
      value_type: nominal (minimum 1.170 T)
    method: Value listed in the manufacturer datasheet (11,900 Gauss nominal)
    status: ground
    source: arnold-recoma35e
    where: Magnetic Properties table, Br Residual Induction, nominal column
  - benchmark: coercivity_hcb
    label: Normal coercivity HcB, SmCo 26
    value: 9.4
    value_high: 10
    bound: range
    unit: kOe
    scope: material
    conditions:
      grade: SmCo 26
      value_type: typical range, approximate
    method: Typical range in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26, HcB column
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity HcJ, SmCo 26 (standard)
    value: 18
    bound: lower
    unit: kOe
    scope: material
    conditions:
      grade: SmCo 26
      value_type: minimum
    method: Minimum listed in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26, HcJ column
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity HcJ, SmCo 26H (high-coercivity grade)
    value: 25
    bound: lower
    unit: kOe
    scope: material
    conditions:
      grade: SmCo 26H
      value_type: minimum
    method: Minimum listed in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26H, HcJ column
  - benchmark: coercivity_hcj
    label: Intrinsic coercivity HcJ, Recoma 35E (Sm2Co17)
    value: 1800
    unit: kA/m
    scope: material
    conditions:
      grade: Recoma 35E
      value_type: nominal (minimum 1710 kA/m)
    method: Value listed in the manufacturer datasheet
    status: ground
    source: arnold-recoma35e
    where: Magnetic Properties table, HcJ Intrinsic Coercivity, nominal column
  - benchmark: max_energy_product
    label: Maximum energy product (BH)max, SmCo 26
    value: 24
    value_high: 26
    bound: range
    unit: MGOe
    scope: material
    conditions:
      grade: SmCo 26
      value_type: typical range, approximate
    method: Typical range in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26, BH Max column
  - benchmark: max_energy_product
    label: Maximum energy product (BH)max, Recoma 35E
    value: 265
    unit: kJ/m3
    scope: material
    conditions:
      grade: Recoma 35E
      value_type: nominal (minimum 255 kJ/m3)
    method: Value listed in the manufacturer datasheet
    status: ground
    source: arnold-recoma35e
    where: Magnetic Properties table, BHmax Maximum Energy Product, nominal column
  - benchmark: curie_temperature
    label: Curie temperature, Sm1Co5 phase
    value: 700
    value_high: 750
    bound: range
    unit: degC
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Curie Temperature Sm1Co5, Tc
  - benchmark: curie_temperature
    label: Curie temperature, Sm2Co17 phase
    value: 800
    value_high: 850
    bound: range
    unit: degC
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Curie Temperature Sm2Co17, Tc
  - benchmark: curie_temperature
    label: Curie temperature, Recoma 35E (Sm2Co17)
    value: 820
    unit: degC
    scope: material
    conditions:
      grade: Recoma 35E
    method: Value listed in the manufacturer datasheet
    status: ground
    source: arnold-recoma35e
    where: Thermal Properties, row Curie Temperature Tc
  - benchmark: max_service_temp
    label: Maximum recommended temperature, Sm1Co5
    value: 250
    unit: degC
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
      condition: maximum recommended working temperature
    method: Value listed in the manufacturer datasheet (Max Working Temperature box)
    status: ground
    source: eclipse-smco
    where: Max Working Temperature box, row Sm1Co5 (1:5)
  - benchmark: max_service_temp
    label: Maximum recommended temperature, Sm2Co17 standard grades
    value: 300
    unit: degC
    scope: material
    conditions:
      phase: Sm2Co17 (2:17), standard grades
      note: L grades +250 degC, H grades +350 degC
    method: Value listed in the manufacturer datasheet (Max Working Temperature box)
    status: ground
    source: eclipse-smco
    where: Max Working Temperature box, row Sm2Co17 (2:17), +250 (L) / +300 / +350 (H)
  - benchmark: max_service_temp
    label: Maximum working temperature, SmCo 26H (Sm2Co17 H grade)
    value: 350
    unit: degC
    scope: material
    conditions:
      grade: SmCo 26H
    method: Value listed in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 26H, Max Temp column
  - benchmark: max_service_temp
    label: Max recommended use temperature, Recoma 35E
    value: 300
    unit: degC
    scope: material
    conditions:
      grade: Recoma 35E
    method: Value listed in the manufacturer datasheet
    status: ground
    source: arnold-recoma35e
    where: Thermal Properties table, row Max. Recommended Use Temperature
  - benchmark: temp_coeff_br
    label: Reversible temperature coefficient of Br, SmCo 22 (1:5 grade)
    value: -0.045
    unit: '%/degC'
    scope: material
    conditions:
      grade: SmCo 22 (Sm1Co5 phase)
      value_type: approximate, reference only
    method: Value listed in the supplier's grade table
    status: ground
    source: allstar-smco-tech
    where: Magnetic Properties of Samarium Cobalt table, row SmCo 22, alpha Br column
  - benchmark: temp_coeff_br
    label: Reversible temperature coefficient of Br, Recoma 35E (Sm2Co17)
    value: -0.035
    unit: '%/degC'
    scope: material
    conditions:
      grade: Recoma 35E
      range: 20 to 200 degC
    method: Value listed in the manufacturer datasheet (note 1)
    status: ground
    source: arnold-recoma35e
    where: Other Properties table, row Reversible Temperature Coefficient of Induction alpha(Br), note 1
  - benchmark: temp_coeff_hcj
    label: Reversible temperature coefficient of coercivity, Recoma 35E (Sm2Co17)
    value: -0.25
    unit: '%/degC'
    scope: material
    conditions:
      grade: Recoma 35E
      range: 20 to 200 degC
    method: Value listed in the manufacturer datasheet (note 1)
    status: ground
    source: arnold-recoma35e
    where: Other Properties table, row Reversible Temperature Coefficient of Coercivity alpha(Hcj), note 1
  - benchmark: density
    label: Density, Sm1Co5 phase
    value: 8.2
    value_high: 8.4
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Density Sm1Co5
  - benchmark: density
    label: Density, Sm2Co17 phase
    value: 8.3
    value_high: 8.5
    bound: range
    unit: g/cm3
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Density Sm2Co17
  - benchmark: cte
    label: Thermal expansion parallel to the c axis, Sm2Co17
    value: 8
    value_high: 10
    bound: range
    unit: 1e-6 per degC
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
      direction: parallel (C//)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Coefficient of Thermal Expansion Sm2Co17, C//
  - benchmark: cte
    label: Thermal expansion perpendicular to the c axis, Sm2Co17
    value: 11
    unit: 1e-6 per degC
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
      direction: perpendicular (C perp)
    method: Value listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Coefficient of Thermal Expansion Sm2Co17, C perpendicular
  - benchmark: thermal_conductivity
    label: Thermal conductivity, SmCo magnet alloy
    value: 11.6
    value_high: 12.8
    bound: range
    unit: W/m degC
    scope: material
    conditions:
      material: samarium cobalt magnet alloy
      temperature: not stated
    method: Range listed in the supplier's physical-properties table (approximate)
    status: ground
    source: allstar-smco-tech
    where: Physical Properties of Samarium Cobalt table, row Thermal Conductivity
  - benchmark: specific_heat
    label: Specific heat, SmCo magnet alloy
    value: 370
    unit: J/(kg degC)
    scope: material
    conditions:
      material: samarium cobalt magnet alloy
      temperature: not stated
    method: Value listed in the supplier's physical-properties table (approximate)
    status: ground
    source: allstar-smco-tech
    where: Physical Properties of Samarium Cobalt table, row Specific Heat
  - benchmark: vickers_hardness
    label: Vickers hardness, Sm2Co17 phase
    value: 450
    value_high: 500
    bound: range
    unit: Hv
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
      load: D.P.N. (diamond pyramid number)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Vickers Hardness Sm2Co17, Hv D.P.N.
  - benchmark: vickers_hardness
    label: Vickers hardness, Sm1Co5 phase
    value: 500
    value_high: 600
    bound: range
    unit: Hv
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
      load: D.P.N. (diamond pyramid number)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Vickers Hardness Sm1Co5, Hv D.P.N.
  - benchmark: flexural_strength
    label: Flexural strength, Sm2Co17 phase
    value: 110
    unit: MPa
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
      unit_as_printed: N/mm2
      test: not stated
    method: Value listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Flexural Strength Sm2Co17
  - benchmark: flexural_strength
    label: Flexural strength, Sm1Co5 phase
    value: 120
    unit: MPa
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
      unit_as_printed: N/mm2
      test: not stated
    method: Value listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Flexural Strength Sm1Co5
  - benchmark: elastic_modulus
    label: Young's modulus, Sm2Co17 phase
    value: 1.2
    unit: 10^11 N/m2
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
    method: Value listed in the manufacturer physical-properties table (printed as 1.2 x 10^11 N/m2)
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Young's Modulus Sm2Co17
  - benchmark: elastic_modulus
    label: Young's modulus, Sm1Co5 phase
    value: 1.6
    unit: 10^11 N/m2
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
    method: Value listed in the manufacturer physical-properties table (printed as 1.6 x 10^11 N/m2)
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Young's Modulus Sm1Co5
  - benchmark: poissons_ratio
    label: Poisson's ratio, SmCo magnet alloy
    value: 0.27
    unit: '-'
    scope: material
    conditions:
      material: samarium cobalt magnet alloy
      temperature: not stated
    method: Value listed in the supplier's physical-properties table (approximate)
    status: ground
    source: allstar-smco-tech
    where: Physical Properties of Samarium Cobalt table, row Poisson's Ratio
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Sm2Co17 phase
    value: 80
    value_high: 90
    bound: range
    unit: uohm cm
    scope: material
    conditions:
      phase: Sm2Co17 (2:17)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Electrical Resistivity Sm2Co17
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Sm1Co5 phase
    value: 5
    value_high: 6
    bound: range
    unit: uohm cm
    scope: material
    conditions:
      phase: Sm1Co5 (1:5)
    method: Range listed in the manufacturer physical-properties table
    status: ground
    source: eclipse-smco
    where: Physical characteristics table, row Electrical Resistivity Sm1Co5
corrosion:
  - environment: Humid or wet conditions, uncoated Sm2Co17
    headline: Sm2Co17 can rust at the surface in water. A NiCuNi coating is the usual remedy.
    effect: The low free iron content in Sm2Co17 makes it technically prone to a little surface corrosion when in water. The supplier recommends a NiCuNi coating for wet environments. Its corrosion resistance is rated good to very good, far superior to NdFeB, in most applications.
    rating: moderate
    conditions:
      phase: Sm2Co17 (2:17)
      exposure: wet environments; no quantified corrosion rate in the source
    source: eclipse-smco
    where: Corrosion Resistance panel
  - environment: Humid applications, Sm1Co5 (no iron)
    headline: Sm1Co5 has excellent corrosion resistance because it contains no iron.
    effect: The supplier says Sm1Co5 contains no iron and has excellent corrosion resistance, and that SmCo magnets can usually be used in humid applications without a protective coating. No humidity test result is given.
    rating: low
    conditions:
      phase: Sm1Co5 (1:5)
      exposure: humid applications; no test duration or humidity level stated
    source: eclipse-smco
    where: Corrosion Resistance panel
  - environment: Acidic, alkaline or electrically conductive liquids, and powder in air
    headline: Acids release hydrogen from the magnet material. Powder oxidises in air.
    effect: The safety data sheet says hydrogen is released in contact with acid and can cause explosive gas mixtures. It says to avoid exposing powdered magnet material to air or oxygen, and to avoid acidic, alkaline or electrically conductive liquids. No corrosion rate is given.
    rating: unknown
    conditions:
      exposure: contact with acid; powder exposed to air; no quantified rate
    source: allstar-smco-sds
    where: Section 10 Stability and Reactivity, items 10.3 to 10.5
risks:
  hazards:
    - text: 'Cobalt (PubChem CID 104730): signal word Danger. Notified hazards include H317 (over 99.9% of notifications), H334 (over 99.9%), H341 (65.8%), H350 (64.5%), H360Fd (61.6%) and H413 (54.9%). PubChem says 1 of 2768 reports does not meet GHS criteria. Cobalt is also listed by the supplier as IARC 2B (possibly carcinogenic).'
      ghs:
        - H317
        - H334
        - H341
        - H350
        - H360Fd
        - H413
      source: pubchem-cobalt
      where: GHS Classification section
    - text: 'Samarium (PubChem CID 23951): signal word Danger. Notified hazards are H228 flammable solid (91%) and H261 in contact with water releases flammable gas (94.1%). PubChem says 6 of 255 reports (2.4%) do not meet GHS criteria.'
      ghs:
        - H228
        - H261
      source: pubchem-samarium
      where: GHS Classification section
    - text: 'Finished SmCo magnet (Allstar SDS, Rev 1.0, 09 Feb 2024): classification GHS-US is ''Not Applicable''; the sheet says semi-finished and finished products are articles under REACH with no obligation to classify, and no label applies. The sheet''s classifications for samarium and cobalt apply to powder form only.'
      ghs: []
      source: allstar-smco-sds
      where: Sections 2.1, 2.2 and 3.2
    - text: 'Dust and powder: the SDS says dry mechanical processing is allowed only under special precautions, because dusts can self-heat or be pyrophoric, and that dust clouds in air can be explosive. Wet grinding can form hydrogen at room temperature.'
      ghs: []
      source: allstar-smco-sds
      where: Sections 5.2 and 7.1.1 to 7.1.2
  failure_risks:
    - mode: Demagnetisation by heat
      trigger: Use above the grade's maximum recommended temperature, or heating toward the Curie temperature (700 to 750 degC for Sm1Co5, 800 to 850 degC for Sm2Co17)
      consequence: Loss of magnetisation. The rated limits are 250 degC for Sm1Co5, 300 degC for Sm2Co17 and 350 degC for H grades. Eclipse notes that SmCo performs very similarly to N30 at ambient temperature but better above 150 to 180 degC.
      severity: high
      source: eclipse-smco
      where: Max Working Temperature box and opening paragraphs
    - mode: Demagnetisation by high-energy particles
      trigger: Proton beams and high-energy particle fields
      consequence: In an earlier French study cited by the NASA review, about 1e16 per cm2 (about 1e9 rad) of 400 GeV protons caused nearly complete demagnetisation of similar SmCo alloys. The review says radiation energy and magnet chemistry both matter, and that Sm2Co17 was more stable than SmCo5 under 500 MeV protons.
      severity: high
      source: bowman-2013
      where: Hard Magnetic Materials and Radiation section
    - mode: Brittleness
      trigger: Mechanical impact and handling
      consequence: Flexural strength is 110 N/mm2 for Sm2Co17 and 120 N/mm2 for Sm1Co5 (Eclipse). The supplier says NiCuNi plating is claimed by some to limit chipping, but this is rarely done.
      severity: moderate
      source: eclipse-smco
      where: Physical characteristics table; Corrosion Resistance panel
    - mode: Surface corrosion of uncoated Sm2Co17
      trigger: Exposure to water or a wet environment
      consequence: Light surface rust on Sm2Co17, which the supplier says can be avoided with a NiCuNi coating.
      severity: moderate
      source: eclipse-smco
      where: Corrosion Resistance panel
  side_effects:
    - text: Magnetic fields from packed magnets can attract magnetisable material and can interfere with pacemakers and other implanted devices; the SDS says people with heart pacemakers must keep away from magnetic fields.
      affects: Handling and shipping of magnetised parts
      source: allstar-smco-sds
      where: Section 7 Handling and Storage and Section 14 Transport
  handling:
    - text: Keep the magnets dry and in a place free of corrosive atmosphere, and keep them away from iron, cobalt and nickel objects and high magnetic fields.
      source: allstar-smco-sds
      where: Section 7.2 Storeroom and Receptacle Requirements
    - text: 'For processing: provide filtered ventilation. Cobalt has a 0.1 mg/m3 OSHA permissible exposure limit as Co for metal dust and fume. The SDS recommends a P3 respirator where limits are exceeded.'
      source: allstar-smco-sds
      where: Section 8 Exposure Controls
    - text: Avoid elevated temperatures above 150 degC for powdered magnet material (the SDS lists this as a condition to avoid). The grade ratings in the properties apply to solid magnets.
      source: allstar-smco-sds
      where: Section 10.4 Conditions to Avoid
    - text: Wear gloves when handling magnetised parts or parts with sharp edges, and wear safety glasses during metal processing.
      source: allstar-smco-sds
      where: Section 8.2 Exposure Controls
  mitigations:
    - text: 'Sm2Co17 in wet conditions: a NiCuNi coating is recommended by the supplier to avoid surface corrosion.'
      source: eclipse-smco
      where: Corrosion Resistance panel
    - text: Higher-temperature grades (H grades, +350 degC) and low-temperature-coefficient grades are available; the LTC versions have less variation in output with temperature.
      source: eclipse-smco
      where: Opening paragraphs and Max Working Temperature box
    - text: The NASA review suggests keeping the bulk temperature of irradiated permanent magnets below 50% of the Curie temperature as a design guideline. For Sm2Co17 this is about 400 to 425 degC (half of the 800 to 850 degC Eclipse range; computed here).
      source: bowman-2013
      where: Hard Magnetic Materials and Radiation section; Summary and Conclusions
uses:
  - application: mechanisms
    device: Linear alternator in a Stirling space power convertor (nuclear fission power system)
    example: NASA Glenn reviewed how radiation affects the magnets in the linear alternator of a Stirling power convertor, for nuclear-powered space missions.
    source: bowman-2013
    where: Introduction
  - application: mechanisms
    device: Motors, sensors, loudspeakers and military systems
    example: The Eclipse datasheet says SmCo magnets are ideal for aerospace, automotive, sensor, loudspeaker, motor and military applications.
    source: eclipse-smco
    where: Opening paragraph
supply:
  - subject: Cobalt
    abundance: World mine production was 310,000 t of cobalt content in 2025 (302,000 t in 2024). Congo (Kinshasa) mined 230,000 t, Indonesia 44,000 t and Russia 7,700 t in 2025. Shares are computed by Space Mushroom from the table (Congo about 74.2%, Indonesia about 14.2%, Russia about 2.5%). World reserves are 12,000,000 t. USGS's own text gives Congo as 73% of the world total.
    producers:
      - country: Congo (Kinshasa)
        share_percent: 74.2
        year: 2025
      - country: Indonesia
        share_percent: 14.2
        year: 2025
      - country: Russia
        share_percent: 2.5
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (cobalt named)
        listed: true
      - list: EU critical raw materials 2023 (cobalt listed)
        listed: true
    recycling: Cobalt content of purchased scrap was 25% of estimated US cobalt consumption in 2025 (USGS).
    substitutes:
      - 'USGS: potential substitutes in magnets include barium or strontium ferrites, and neodymium-iron-boron alloys (USGS).'
    source: usgs-mcs2026-cobalt
    where: Salient Statistics (US), Recycling line, World Mine Production and Reserves table, Substitutes
  - subject: Samarium and other rare earths
    abundance: 'World rare-earth mine production was 390,000 t of rare-earth oxide equivalent in 2025 (380,000 t in 2024). Shares are computed by Space Mushroom from the 2025 column: China 270,000 t (about 69.2%), United States 51,000 t (about 13.1%), Australia 29,000 t (about 7.4%), Burma 22,000 t (about 5.6%). Reserves in China are 44,000,000 t. USGS does not report samarium mine output separately.'
    producers:
      - country: China
        share_percent: 69.2
        year: 2025
      - country: United States
        share_percent: 13.1
        year: 2025
      - country: Australia
        share_percent: 7.4
        year: 2025
      - country: Burma
        share_percent: 5.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (rare earth elements and samarium named)
        listed: true
      - list: EU critical raw materials 2023 (light and heavy rare earth elements listed; samarium not named on the EC page)
        listed: true
    recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.'
    substitutes:
      - 'USGS: substitutes are available for many applications but generally are less effective.'
    source: usgs-mcs2026-rare-earths
    where: Salient Statistics, World Mine Production and Reserves table (2025 column), Recycling, Substitutes
  - subject: Samarium export controls and stockpile
    abundance: In April 2025 China tightened export controls to cover alloys, compounds, metals and oxides of samarium, gadolinium, terbium, dysprosium and other elements. In November China suspended its October expansion for one year, while the April controls remained in effect, and began issuing general export licences to selected exporters. For FY 2025 the US government's potential stockpile acquisitions included 60 t of samarium-cobalt alloy.
    critical_lists: []
    recycling: No recycling rate for samarium-cobalt magnets is given in the sources read.
    substitutes: []
    source: usgs-mcs2026-rare-earths
    where: Events, Trends, and Issues; Government Stockpile
  - subject: Heavy rare earths (EU supply)
    abundance: The European Commission page states that China provides 100% of the EU's supply of heavy rare earth elements.
    critical_lists:
      - list: 'EU critical raw materials 2023: heavy rare earth elements'
        listed: true
    source: ec-crm
    where: Fifth list of critical raw materials (2023) and supply concentration statement
documents:
  - title: 'Eclipse Magnetics Technical Data Sheet: Samarium Cobalt Magnets (SmCo)'
    type: datasheet
    url: https://www.eclipsemagnetics.com/site/assets/files/19544/eclipsemagnetics_smco_datasheet.pdf
  - title: Allstar Magnetics Samarium Cobalt Technical Data (ASM 09-23-2023)
    type: datasheet
    url: https://allstarmagnetics.com/wp-content/uploads/2024/09/Samarium-Cobalt-Technical-Data-ASM-09-23-2023.pdf
    year: 2023
  - title: Arnold Magnetic Technologies Recoma 35E sintered samarium cobalt datasheet (Rev. 160204a)
    type: datasheet
    url: https://www.arnoldmagnetics.com/wp-content/uploads/2017/10/Recoma-35E-160205-final.pdf
    year: 2016
  - title: 'Allstar Magnetics Safety Data Sheet: Samarium Cobalt (SDS SMC Rev 1.0, 09 Feb 2024)'
    type: sds
    url: https://allstarmagnetics.com/wp-content/uploads/2024/10/Samarium-cobalt-SDS.pdf
    year: 2024
  - title: 'NASA Glenn: Design Issues for Using Magnetic Materials in Radiation Environments at Elevated Temperature (NTRS 20130010718)'
    type: paper
    url: https://ntrs.nasa.gov/api/citations/20130010718/downloads/20130010718.pdf
    year: 2013
  - 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: Rare Earths'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
  - title: 'USGS: About the 2025 List of Critical Minerals'
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: 'European Commission: Critical raw materials'
    type: report
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    year: 2024
  - title: 'PubChem compound records: samarium (CID 23951) and cobalt (CID 104730), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23951
    year: 2026
gaps:
  - No flight, vacuum-outgassing, thermal-cycling or space-qualification result for samarium-cobalt magnets was found in an opened source. The NASA review says no verified models or experimental data exist for predicting magnet behaviour in space power applications.
  - 'The Naval Postgraduate School paper (bremsstrahlung irradiation of rare-earth magnets, which the search result describes as ranking Sm2Co17 above SmCo5 above NdFeB) could not be opened: the repository page returned no full text. The ranking is therefore not stated in this profile.'
  - Radiation values in the NASA review are quoted from earlier experiments (Brown 1982, Coninckx, Blackmore, Chen). None were re-measured, and the SmCo5 versus Sm2Co17 comparison is qualitative only in the sources read.
  - The NASA review's neutron fluences (about 1e18 n/cm2 with negligible loss in Brown et al., and about 1e20 n/cm2 with imperceptible change in Chen et al.) are printed with superscript exponents that the PDF text does not keep, so they appear in the story and risk text only, not as numeric properties.
  - Eclipse's Sm2Co17 Hci coefficient (-0.20) and Sm1Co5 Br coefficient (-0.050) print trailing zeros that the value check could not match; the Arnold (Sm2Co17) and Allstar (SmCo 22) rows that print the same number exactly are used instead.
  - No quantified humidity, salt-spray or coating-specific corrosion data for uncoated or NiCuNi-coated SmCo were found in an opened source.
  - Manufacturing route (powder metallurgy, pressing, sintering and ageing) was not read in a fetched source, so no process entry is given.
  - Compressive strength, the Recoma 35E specific heat and thermal conductivity values, and the Recoma 35E electrical resistivity (its unit symbol is lost in the PDF text) were not included because the PDF layout is ambiguous for those rows.
  - 'Property names not in spores/property-canon.yaml and used here as snake_case: remanence_br, coercivity_hcb, coercivity_hcj, max_energy_product, temp_coeff_br, temp_coeff_hcj, vickers_hardness, neutron_fluence_no_loss.'
  - Atomic weights are PubChem values printed to a few decimals (Sm 150.4, Co 58.93319). No IUPAC table value was read.
  - Samarium production is not reported separately by USGS; the rare-earth shares are for all rare earths combined. Cobalt and rare-earth shares were computed by this profile from USGS tables.
  - The composition of a typical commercial SmCo magnet (about 35% Sm and 65% Co by weight) comes from one supplier SDS; grade-by-grade compositions were not read.
  - The Eclipse table layout is ambiguous in places, so grade-level Eclipse rows for the 2:17 alloy were not used; the Allstar grade table is used for grade values.
composition:
  - grade: Typical SmCo magnet (supplier SDS)
    Sm: '35'
    Co: '65'
    unit: wt.%
    method: approximate values stated in the SDS mixture table
    source: allstar-smco-sds
    where: Section 3.2 Mixture
  - basis: SmCo5 (1:5 alloy), per Wikipedia
    Sm: about 36
    Co: balance
    unit: wt.%
    source: wiki-smco
    where: Composition section
  - basis: Sm2Co17 (2:17 alloy), per Wikipedia
    Sm: about 25
    note: Cu, Hf and/or Zr, sometimes Pr, and Fe are also present
    unit: wt.%
    source: wiki-smco
    where: Composition section
  - basis: Sm1Co5 contains no iron; Sm2Co17 contains Cu, Hf and/or Zr, sometimes Pr, and Fe
    source: eclipse-smco
    where: Opening paragraphs
review:
  status: draft
  method: assistant
  checked_values: 34
  unreachable: 1
  caveats: 4
  note: 'Written by an AI assistant on 2026-10-26 from sources read in this run: Eclipse and Allstar SmCo datasheets, Arnold Recoma 35E datasheet, Allstar SmCo SDS, NASA NTRS 20130010718 (Bowman 2013), USGS MCS 2026 cobalt and rare-earth chapters, USGS 2025 critical-mineral page, EC critical raw materials page, PubChem samarium and cobalt records, and Wikipedia (composition only). The Naval Postgraduate School paper could not be opened. Eclipse and Allstar values are approximate, supplier reference values, not measured data. Producer shares and the 50% Curie-temperature figure are computed by this profile.'
story:
  recipe:
    line: Samarium-cobalt alloys are intermetallic compounds of samarium and cobalt. SmCo5 is the older 1:5 phase, with one samarium atom per five cobalt atoms. Sm2Co17 is the stronger 2:17 phase, with two samarium atoms per seventeen cobalt atoms. Sm2Co17 magnets also contain copper, hafnium and/or zirconium, sometimes praseodymium, and iron. Commercial magnets are sintered, and the Allstar SDS gives a typical mix of about 35% samarium and 65% cobalt by weight. The sintering route itself was not read in a fetched source.
    parts:
      - name: Samarium
        symbol: Sm
        atoms: 1
        atomic_weight: 150.4
        role: One samarium atom per five cobalt atoms in SmCo5, and two per seventeen in Sm2Co17. Samarium supplies the magnetic anisotropy and most of the coercivity.
        source: pubchem-samarium
      - name: Cobalt
        symbol: Co
        atoms: 5
        atomic_weight: 58.93319
        role: The balance of the alloy by weight, about 65% in a typical magnet. Cobalt sets the high Curie temperature and the high-temperature stability.
        source: pubchem-cobalt
  why: Samarium-cobalt (SmCo) is a sintered rare-earth permanent magnet. It was developed in the early sixties by Karl Strnat at Wright-Patterson Air Force Base and Alden Ray at the University of Dayton, according to Wikipedia. Its Curie temperature of 700 to 850 degC and its rated working limits of 250 to 350 degC are the reason it is chosen where heat is the main limit. Its remanence falls by only 0.035% per degC for Sm2Co17. The trade-off is strength at room temperature, where NdFeB is stronger, and brittleness. For radiation, the NASA Glenn review cites Sm2Co17 as the most stable magnet type among those it reports, but it gives no flight data.
  uses:
    - where: Space power conversion (ground review)
      line: NASA Glenn reviewed radiation effects on the magnets in the linear alternator of a Stirling power convertor for nuclear-powered space missions. The review says no verified models or flight data exist for predicting magnet behaviour in space power applications.
    - where: Motors, sensors and loudspeakers
      line: The Eclipse datasheet lists aerospace, automotive, sensor, loudspeaker, motor and military applications for SmCo magnets, and calls them an ideal first choice in mission-critical applications.
    - where: Specialised uses listed by USGS
      line: The USGS 2025 critical-mineral page describes samarium as used in permanent magnets, nuclear reactors and cancer treatments.
  can_do:
    - label: Remanence
      value: 10.2 to 10.5 kGs
      line: SmCo 26 (Sm2Co17) has a remanence of 10.2 to 10.5 kGs, and Recoma 35E has a nominal 1.190 T (Allstar, Arnold).
    - label: Working temperature
      value: 300 degC (350 degC for H grades)
      line: Eclipse rates Sm2Co17 at 300 degC for standard grades and 350 degC for H grades, and Sm1Co5 at 250 degC. Arnold's Recoma 35E is rated to 300 degC.
    - label: Temperature stability
      value: '-0.035 %/degC (Sm2Co17)'
      line: The remanence of Sm2Co17 (Recoma 35E) falls by 0.035% per degC over 20 to 200 degC, against 0.045% per degC for the SmCo 22 (1:5) grade (Allstar).
    - label: Radiation
      value: Imperceptible change up to about 1e20 n/cm2
      line: In a water-moderated reactor test cited by NASA Glenn, Sm2Co17 magnets showed imperceptible flux change after up to about 1e20 n/cm2 of neutrons. Conditions (temperature and magnet shape) are not fully stated, and these are earlier experiments quoted in the review.
    - label: Coercivity
      value: 25 kOe minimum (H grade)
      line: SmCo 26H has an intrinsic coercivity of at least 25 kOe, against 18 kOe for SmCo 26 (Allstar). Coercivity is the field the magnet resists before it loses magnetisation.
  compare: Against NdFeB, SmCo is weaker at room temperature but often performs better above 150 to 180 degC, according to the Eclipse datasheet, which also says it is stable over a wide temperature range. In the NASA review's reactor test, the NdFeB samples had no post-irradiation magnetic flux recorded, while Sm2Co17 magnets showed imperceptible change after up to about 1e20 n/cm2. Within SmCo, Sm2Co17 has the higher remanence and rated temperature, and Sm1Co5 contains no iron and so resists humid corrosion better without coating.
  compare_rows:
    - label: Remanence (SmCo 26)
      benchmark: remanence_br
    - label: Maximum working temperature
      benchmark: max_service_temp
    - label: Curie temperature
      benchmark: curie_temperature
  handling:
    - Keep Sm2Co17 magnets coated with NiCuNi if they will be in wet conditions.
    - 'Do not heat the magnets above the grade''s rating: 250 degC for Sm1Co5, 300 degC for Sm2Co17 and 350 degC for H grades.'
    - Dust from machining is a fire and explosion hazard. Use filtered ventilation and avoid creating dust.
    - Keep pacemaker wearers away from magnetised parts.
  good_for:
    - 'High-temperature magnets: the rated limit is 300 degC for standard Sm2Co17 and 350 degC for H grades, and the Curie point is above 800 degC.'
    - 'Radiation-exposed parts where the NASA review reports little change: Sm2Co17 showed imperceptible flux change after the neutron fluence in the cited reactor test.'
    - Humid applications for Sm1Co5, which contains no iron and does not usually need a coating (Eclipse).
  watch_out:
    - Weaker than NdFeB at room temperature (Eclipse).
    - 'Brittle: flexural strength is 110 to 120 N/mm2 (Eclipse).'
    - Sm2Co17 rusts at the surface in water without a NiCuNi coating.
    - 'Cobalt is a supply concern: Congo (Kinshasa) mined about 74% of world cobalt in 2025 (computed), and cobalt is on the USGS 2025 critical list.'
    - China's April 2025 export controls cover samarium alloys, compounds, metals and oxides.
  verdict: 'SmCo is the high-temperature rare-earth magnet: its Curie temperature and rated working temperature are well above NdFeB''s, and the NASA review reports little radiation damage for Sm2Co17. Its room-temperature strength is lower than NdFeB''s. A NiCuNi coating covers the Sm2Co17 corrosion risk. No space-flight data were found, so its fitness for spacecraft is not proven by these sources.'
  risk_groups:
    - title: For people
      level: 1
      verdict: Dust and powder are the hazard
      lead: The finished magnet is not classified under GHS-US. Hazards come from powder, dust and processing.
      points:
        - label: Finished magnet
          line: The supplier SDS says the solid magnet is not classified under GHS-US and no label applies.
        - label: Powder and dust
          line: Dust can self-heat, be pyrophoric or form explosive clouds in air. Wet grinding can release hydrogen.
        - label: Cobalt
          line: Cobalt is a skin and respiratory sensitiser (H317, H334 in powder form), and the SDS lists it as IARC 2B.
      gap: Safety data sheets for other suppliers were not read.
    - title: If it fails
      level: 3
      verdict: Heat and particle radiation demagnetise it
      lead: The loss of magnetisation depends on grade, temperature and radiation type.
      points:
        - label: Heat
          line: Above its rated temperature, the magnet loses magnetisation. The rating is 250 degC for Sm1Co5, 300 degC for standard Sm2Co17 and 350 degC for H grades.
        - label: Particles
          line: In an earlier French study cited by NASA Glenn, about 1e16 per cm2 of 400 GeV protons caused nearly complete demagnetisation of similar SmCo alloys.
        - label: Corrosion
          line: Uncoated Sm2Co17 can rust at the surface in water.
    - title: Handling and storage
      points:
        - label: Storage
          line: Keep dry, in a place free of corrosive atmosphere, and away from iron, cobalt and nickel objects.
        - label: Processing
          line: Use filtered ventilation, avoid dust, and keep the powder away from air and acids.
        - label: Temperature
          line: Avoid temperatures above 150 degC for powdered magnet material (SDS).
sources:
  eclipse-smco:
    title: Technical Data Sheet, Samarium Cobalt Magnets (SmCo)
    url: https://www.eclipsemagnetics.com/site/assets/files/19544/eclipsemagnetics_smco_datasheet.pdf
    kind: datasheet
    license: manufacturer datasheet
  allstar-smco-tech:
    title: Samarium Cobalt Technical Data (ASM 09-23-2023)
    url: https://allstarmagnetics.com/wp-content/uploads/2024/09/Samarium-Cobalt-Technical-Data-ASM-09-23-2023.pdf
    year: 2023
    kind: datasheet
    license: supplier datasheet
  arnold-recoma35e:
    title: Recoma 35E Sintered Samarium Cobalt Magnets (datasheet, Rev. 160204a)
    url: https://www.arnoldmagnetics.com/wp-content/uploads/2017/10/Recoma-35E-160205-final.pdf
    year: 2016
    kind: datasheet
    license: manufacturer datasheet
  allstar-smco-sds:
    title: Safety Data Sheet, Samarium Cobalt (SDS SMC, Rev 1.0, 09 Feb 2024)
    url: https://allstarmagnetics.com/wp-content/uploads/2024/10/Samarium-cobalt-SDS.pdf
    year: 2024
    kind: datasheet
    license: supplier document
  bowman-2013:
    title: Design Issues for Using Magnetic Materials in Radiation Environments at Elevated Temperature
    id: NTRS 20130010718 (Nuclear and Emerging Technologies for Space 2013, paper 6801)
    url: https://ntrs.nasa.gov/api/citations/20130010718/downloads/20130010718.pdf
    year: 2013
    kind: report
    license: public domain (NASA)
  usgs-mcs2026-cobalt:
    title: Mineral Commodity Summaries 2026, Cobalt
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cobalt.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-rare-earths:
    title: Mineral Commodity Summaries 2026, Rare Earths
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS)
    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)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    year: 2024
    kind: web
    license: European Commission web page
  pubchem-samarium:
    title: 'PubChem compound CID 23951, samarium: molecular weight and GHS classification'
    id: CID 23951
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23951
    kind: database
    license: public domain (NCBI)
  pubchem-cobalt:
    title: 'PubChem compound CID 104730, cobalt: molecular weight and GHS classification'
    id: CID 104730
    url: https://pubchem.ncbi.nlm.nih.gov/compound/104730
    kind: database
    license: public domain (NCBI)
  wiki-smco:
    title: Samarium-cobalt magnet (Wikipedia), composition and history sections only
    url: https://en.wikipedia.org/wiki/Samarium%E2%80%93cobalt_magnet
    kind: web
    license: CC BY-SA
license: CC-BY-4.0
updated: '2026-10-26'