Permalloy 80 Ni-Fe-Mo

spore: profile
id: permalloy
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Permalloy 80
abbreviation: Ni-Fe-Mo
role: magnetic shield
category: metals
type: magnet-alloys
summary: |
  Permalloy 80 is a soft nickel-iron alloy with about 80 % nickel, used to shield sensitive electronics and to make low-loss transformer, relay and sensor parts. This profile covers the molybdenum-bearing grade, sold as Moly Permalloy (Hamilton Precision Metals, 80.0 % Ni and 4.8 % Mo nominal) and as Magnifer 7904 (VDM, 80 Ni and 4.9 Mo typical). It is ASTM A753 Alloy 4, the same class as mu-metal. The VDM datasheet gives a saturation induction of 0.8 T and a density of 8.7 g/cm3, and the Matthey datasheet gives a DC permeability of 470,000 for 1.00 mm strip. Its strength is modest: 170 N/mm2 yield and 450 N/mm2 tensile after the final anneal (VDM). The original Bell Labs nickel-iron permalloy of about 80 % Ni and 20 % Fe has no molybdenum and is not covered by these values.
best_for: Shielding sensitive electronics from static and slowly varying magnetic fields, and relay, stepper-motor and sensor parts; DC permeability of 470,000 for 1.00 mm strip (Matthey) and a saturation induction of 0.8 T (VDM)
weakest_at: 'Strength and mass: 170 N/mm2 yield after the final anneal (VDM), 8.7 g/cm3 density, and the permeability falls after plastic deformation, so a formed or shocked part must be handled with care'
identity:
  formula: Nickel-iron-molybdenum soft magnetic alloy, nominal 80.0 % Ni, 4.8 % Mo, 0.50 % Mn and 0.35 % Si, balance Fe (Moly Permalloy); Magnifer 7904 typical 80 Ni, 4.9 Mo, 0.5 Mn, 0.3 Si, 0.02 C, balance Fe (VDM)
  source: hpmetals-moly-permalloy
  where: 'Nominal Composition table: Nickel 80.0%, Molybdenum 4.8%, Manganese 0.50%, Silicon 0.35%, Iron Balance'
  designations:
    - system: UNS
      code: N14080
      source: matthey-permimphy
      where: 'Header table, UNS column: N14080 Type 4'
    - system: ASTM
      code: A753
      note: Alloy 4
      source: vdm-magnifer-7904
      where: Standards and specifications table, row ASTM A753-97, Alloy 4
    - system: EN
      code: '2.4545'
      source: vdm-magnifer-7904
      where: Standards and specifications table, row DIN 17745, Material no. 2.4545
    - system: JIS
      code: C 2531
      note: type PC
      source: vdm-magnifer-7904
      where: Standards and specifications table, row JIS C 2531, PC
    - system: Trade name
      code: Moly Permalloy
      source: hpmetals-moly-permalloy
      where: Product name in page title and Nominal Composition table
    - system: Trade name
      code: Magnifer 7904
      source: vdm-magnifer-7904
      where: 'Datasheet title: VDM Magnifer 7904'
    - system: Trade name
      code: Permimphy
      source: matthey-permimphy
      where: 'Datasheet title: Permimphy N14080 type 4'
tags:
  environments: []
  applications:
    - electronics-and-chips
properties:
  - benchmark: saturation_induction
    label: Saturation induction, typical
    value: 0.8
    unit: T
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      temperature: not stated
      unit_in_source: 8000 G
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Saturation induction
  - benchmark: saturation_induction
    label: Saturation induction at 20 °C
    value: 0.8
    unit: T
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temperature: 20 °C
    method: Value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Physical properties table, row Saturation induction at 20ºC
  - benchmark: permeability_dc
    label: DC permeability at 5 mOe, typical, 1.00 mm strip
    value: 470000
    unit: '-'
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      thickness: 1.00 - 0.04 mm
      field: 5 mOe (about 0.4 A/m)
      treatment: rings annealed at 1170 °C in dry pure hydrogen, cooling rate not critical
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Magnetic properties table, DC row, thickness 1.00 - 0.04 mm, Permeability column
  - benchmark: permeability_dc
    label: DC permeability at 5 mOe, typical, 0.34 mm strip
    value: 520000
    unit: '-'
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      thickness: 0.34 - 0.0134 mm
      field: 5 mOe (about 0.4 A/m)
      treatment: rings annealed at 1170 °C in dry pure hydrogen, cooling rate not critical
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Magnetic properties table, DC row, thickness 0.34 - 0.0134 mm, Permeability column
  - benchmark: permeability_initial
    label: Initial permeability, 50 Hz, tape-wound cores
    value: 160000
    value_high: 380000
    bound: range
    unit: '-'
    scope: material
    conditions:
      grade: Magnifer 7904
      frequency: 50 Hz
      sample: toroidal tape-wound cores of 0.065 mm strip
      treatment: after appropriate heat treatment
    method: Range printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: General magnetic properties, first paragraph (initial permeability mu4)
  - benchmark: permeability_max
    label: Maximum permeability, 50 Hz, tape-wound cores
    value: 320000
    value_high: 480000
    bound: range
    unit: '-'
    scope: material
    conditions:
      grade: Magnifer 7904
      frequency: 50 Hz
      sample: toroidal tape-wound cores of 0.065 mm strip
      treatment: after appropriate heat treatment
    method: Range printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: General magnetic properties, first paragraph (maximum permeability)
  - benchmark: coercive_force
    label: Static coercive force, typical, upper bound
    value: 1
    bound: upper
    unit: A/m
    scope: material
    conditions:
      grade: Magnifer 7904
      sample: toroidal tape-wound cores after heat treatment
    method: Typical value stated in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: General magnetic properties, first paragraph (static coercive force Hc)
  - benchmark: curie_temperature
    label: Curie temperature, Magnifer 7904
    value: 410
    unit: °C
    scope: material
    conditions:
      grade: Magnifer 7904
      unit_in_source: 830 °F
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Curie temperature
  - benchmark: curie_temperature
    label: Curie temperature, Permimphy N14080 type 4
    value: 420
    unit: °C
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
    method: Value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Physical properties table, row Curie temperature
  - benchmark: curie_temperature
    label: Curie temperature, Moly Permalloy
    value: 455
    unit: °C
    scope: material
    conditions:
      grade: Moly Permalloy
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Curie Temperature
  - benchmark: density
    label: Relative density, typical
    value: 8.7
    unit: g/cm3
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      unit_in_source: 0.316 lb/in3
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Relative density
  - benchmark: density
    label: Density, Moly Permalloy
    value: 0.315
    unit: lbs/cu.in
    scope: material
    conditions:
      grade: Moly Permalloy
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Density
  - benchmark: melting_point
    label: Melting point, approximate
    value: 1450
    unit: °C
    scope: material
    conditions:
      grade: Moly Permalloy
      basis: approximate, printed as Melting Point (Approx.)
    method: Approximate value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Melting Point (Approx.)
  - benchmark: thermal_conductivity
    label: Thermal conductivity, typical
    value: 0.32
    unit: W/cm K
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      temperature: not stated
      unit_in_source: 134 (BTU in)/(ft hr °F)
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Thermal conductivity
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C
    value: 19
    unit: W/m °K
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temperature: 20 °C
    method: Value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Physical properties table, row Thermal conductivity at 20°C
  - benchmark: thermal_conductivity
    label: Thermal conductivity at room temperature
    value: 34.6
    unit: W/m·K
    scope: material
    conditions:
      grade: Moly Permalloy
      temperature: room temperature
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Thermal Conductivity at R.T.
  - benchmark: cte
    label: Mean coefficient of thermal expansion, 20 to 100 °C
    value: 12
    unit: 10-6/K
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      temperature: 20 to 100 °C
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Mean coefficient of thermal expansion
  - benchmark: cte
    label: Thermal expansion coefficient, 25 to 200 °C
    value: 12.7
    unit: 10-6/°C
    scope: material
    conditions:
      grade: Moly Permalloy
      temperature: 25 to 200 °C
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Thermal Expansion Coefficient
  - benchmark: elastic_modulus
    label: Modulus of elasticity, soft strip
    value: 190
    value_high: 221
    bound: range
    unit: kN/mm2
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temper: not stated
    method: Range printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Physical properties table, row Modulus of elasticity
  - benchmark: elastic_modulus
    label: Modulus of elasticity in tension, annealed
    value: 32
    unit: 10^6 psi
    scope: material
    conditions:
      grade: Moly Permalloy
      temper: annealed
      unit_in_source: 32 X 10 6 PSI
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Moly Permalloy mechanical properties table, row Modulus of Elasticity (Tension), annealed column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength after final anneal
    value: 450
    unit: N/mm2
    scope: material
    conditions:
      grade: Magnifer 7904
      temper: after final anneal
      product_form: typical
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 3, Mechanical properties, row Tensile strength Rm, column after final anneal
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, soft annealed temper R500
    value: 500
    value_high: 700
    bound: range
    unit: N/mm2
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temper: R500 soft annealed
      product_form: strip
    method: Range printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Mechanical properties of strips table, row R500 soft annealed, column Rm
  - benchmark: ultimate_tensile_strength
    label: Ultimate tensile strength, annealed
    value: 90000
    unit: psi
    scope: material
    conditions:
      grade: Moly Permalloy
      temper: annealed
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Moly Permalloy mechanical properties table, row Ultimate Tensile Strength, annealed column
  - benchmark: yield_strength
    label: Yield strength Rp0.2 after final anneal
    value: 170
    unit: N/mm2
    scope: material
    conditions:
      grade: Magnifer 7904
      temper: after final anneal
      measure: Rp0.2
      product_form: typical
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 3, Mechanical properties, row Yield stress Rp0.2, column after final anneal
  - benchmark: yield_strength
    label: Yield strength Rp0.2 soft annealed temper R500
    value: 200
    value_high: 450
    bound: range
    unit: N/mm2
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temper: R500 soft annealed
      measure: Rp0.2
      product_form: strip
    method: Range printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Mechanical properties of strips table, row R500 soft annealed, column Rp0.2
  - benchmark: yield_strength
    label: Yield strength 0.2 % offset, annealed
    value: 35000
    unit: psi
    scope: material
    conditions:
      grade: Moly Permalloy
      temper: annealed
      measure: 0.2 % offset
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Moly Permalloy mechanical properties table, row Yield Strength (0.2% Offset), annealed column
  - benchmark: elongation
    label: Elongation A5 after final anneal
    value: 30
    unit: '%'
    scope: material
    conditions:
      grade: Magnifer 7904
      temper: after final anneal
      gauge_length: A5
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 3, Mechanical properties, row Elongation A5, column after final anneal
  - benchmark: elongation
    label: Elongation A50mm soft annealed temper R500, minimum
    value: 25
    bound: lower
    unit: '%'
    scope: material
    conditions:
      grade: Permimphy N14080 type 4
      temper: R500 soft annealed
      gauge_length: 50 mm
    method: Minimum value printed in a manufacturer datasheet
    status: ground
    source: matthey-permimphy
    where: Mechanical properties of strips table, row R500 soft annealed, column A50mm (min.)
  - benchmark: elongation
    label: Elongation in 2 inch, annealed
    value: 30
    unit: '%'
    scope: material
    conditions:
      grade: Moly Permalloy
      temper: annealed
      gauge_length: 2 in
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Moly Permalloy mechanical properties table, row Elongation in 2 inch, annealed column
  - benchmark: electrical_resistivity
    label: Electrical resistivity, typical
    value: 55
    unit: µΩcm
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      temperature: not stated
      unit_in_source: 349 ohm circ mil/ft
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Electrical resistivity
  - benchmark: electrical_resistivity
    label: Electrical resistivity at room temperature
    value: 59
    unit: Microhm·cm
    scope: material
    conditions:
      grade: Moly Permalloy
      temperature: room temperature
    method: Value printed on a manufacturer web page
    status: ground
    source: hpmetals-moly-permalloy
    where: Physical Properties table, row Electrical Resistivity @ R.T.
  - benchmark: saturation_magnetostriction
    label: Saturation magnetostriction, typical
    value: 0.000001
    unit: '-'
    scope: material
    conditions:
      grade: Magnifer 7904, typical value
      unit_in_source: + 1 · 10 -6
    method: Typical value printed in a manufacturer datasheet
    status: ground
    source: vdm-magnifer-7904
    where: Table 2, Physical properties, row Saturation magnetostriction
corrosion:
  - environment: Uncoated, in ordinary air
    headline: The high nickel content is given as the reason the alloy needs no corrosion-resistant coating.
    effect: Matthey says the high nickel content allows use of this material without the need of a corrosion resistant coating. No corrosion rate, humidity test or salt-spray result is printed in the sources read.
    rating: low
    conditions:
      grade: Permimphy N14080 type 4
      exposure: not stated
      basis: manufacturer statement, no test data
    source: matthey-permimphy
    where: Main technical properties and features, first paragraph
risks:
  hazards:
    - text: PubChem's GHS record for nickel (CID 935) lists H317 (may cause an allergic skin reaction), H351 (suspected of causing cancer) and H372 (causes damage to organs through prolonged or repeated exposure), with signal word Danger. These classes are for nickel metal; the alloy is about 80 % nickel and is not separately classified in the sources read.
      ghs:
        - H317
        - H351
        - H372
      source: pubchem-ni
      where: GHS Hazard Statements section, PubChem record for CID 935
  failure_risks:
    - mode: Permeability loss from plastic deformation
      trigger: Forming, bending or other mechanical working of the part after the final anneal
      consequence: Matthey says treated parts must be handled with care to avoid all plastic deformation, which will degrade the magnetic properties. Recovery by re-annealing is not stated in the sources read.
      severity: moderate
      source: matthey-permimphy
      where: Heat treatment of finished parts paragraph
    - mode: Oxidation or contamination during the anneal
      trigger: Heat treatment without a protective atmosphere, parts that are not degreased, or inert powder that is not anhydrous
      consequence: Matthey says a protective atmosphere is essential to avoid oxidation, that parts must be degreased and cleaned before annealing, and that the inert powder must be perfectly anhydrous.
      severity: moderate
      source: matthey-permimphy
      where: Heat treatment of finished parts paragraph
  side_effects:
    - text: The VDM datasheet gives a relative density of 8.7 g/cm3 for Magnifer 7904, so shields and cored components add mass.
      affects: Mass of a shield or cored component
      source: vdm-magnifer-7904
      where: Table 2, Physical properties, row Relative density
  handling:
    - text: Matthey recommends a pure dry hydrogen anneal between 800 and 1150 °C, with the parts degreased and cleaned first and the inert powder (alumina or magnesia) kept perfectly anhydrous.
      source: matthey-permimphy
      where: Heat treatment of finished parts paragraph
    - text: The Moly Permalloy page says effective magnetic shielding is provided by annealing at 1900°F or higher, and that joining is by spot welding or tungsten inert gas welding.
      source: hpmetals-moly-permalloy
      where: Handling and Processing text on the product page
  mitigations:
    - text: Anneal in pure dry hydrogen as a protective atmosphere, and degrease the parts before annealing, which Matthey gives as the way to avoid oxidation and contamination.
      source: matthey-permimphy
      where: Heat treatment of finished parts paragraph
uses:
  - application: electronics-and-chips
    device: Magnetic shields and shielding cans for sensitive electronics
    example: The VDM datasheet lists shielding films, shielding cans and spatial shielding arrangements against magnetic interference as typical applications of Magnifer 7904.
    source: vdm-magnifer-7904
    where: Typical applications list, Shieldings bullet
  - application: electronics-and-chips
    device: Relays, stepper motors and magnetic sensors
    example: Matthey says the main applications are relays for ground fault circuit breakers and railway signalling, stepper motors for watches, shielding and magnetic sensors for current, angular position and displacement.
    source: matthey-permimphy
    where: Typical uses paragraph
  - application: electronics-and-chips
    device: Photomultiplier magnetic shield in the DAMPE electromagnetic calorimeter
    example: A cylinder of one-layer permalloy strip is able to reduce the effect of a 3 G magnetic field on the gain of the R5610A-01 photomultiplier to less than 1 percent.
    source: dampe-pmt-shield
    where: Abstract
supply:
  - subject: Nickel (about 80 % of the alloy)
    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: []
    recycling: 'USGS: in 2025 nickel recovered from scrap accounted for approximately 60% of apparent consumption, and most recycled nickel was used to produce new alloys and stainless steel.'
    substitutes: []
    source: usgs-mcs2026-nickel
    where: 'World Mine Production and Reserves table, 2025e column, metric tons of nickel content: Indonesia 2,600,000; Philippines 270,000; Russia 200,000; world total (rounded) 3,900,000. Shares calculated by Space Mushroom from these figures. Recycling paragraph.'
  - subject: Molybdenum (about 4.8 to 4.9 % of the alloy)
    producers:
      - country: China
        share_percent: 37.3
        year: 2025
      - country: Chile
        share_percent: 16.2
        year: 2025
      - country: Peru
        share_percent: 15
        year: 2025
    critical_lists: []
    recycling: 'USGS: molybdenum is recycled as a component of catalysts, ferrous scrap and superalloy scrap, and the molybdenum content of recycled alloys is significant and reused.'
    substitutes:
      - 'USGS: there is little substitution for molybdenum in its major application in steels and cast irons.'
    source: usgs-mcs2026-molybdenum
    where: 'World Mine Production and Reserves table, 2025e column, thousand metric tons: China 97,000; Chile 42,000; Peru 39,000; world total (rounded) 260,000. Shares calculated by Space Mushroom from these figures. Events, Trends and Issues: China, Chile, the United States, Peru and Mexico produced 90 % of world output in 2025.'
documents:
  - title: Hamilton Precision Metals, Moly Permalloy product page
    type: datasheet
    url: https://hpmetals.com/products/materials/moly-permalloy
  - title: VDM Metals, Magnifer 7904 material data sheet No. 9004 (August 2000 edition)
    type: datasheet
    url: https://alloy59.de/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_MAG_7904.pdf
    year: 2000
  - title: Lamineries Matthey, Permimphy N14080 type 4 datasheet
    type: datasheet
    url: https://www.matthey.ch/fileadmin/user_upload/downloads/fichetechnique/EN/Permimphy_v22E.pdf
  - title: 'Wikipedia: Permalloy'
    type: report
    url: https://en.wikipedia.org/wiki/Permalloy
  - title: Wang et al., Magnetic shield of PMT used in DAMPE electromagnetic calorimeter (arXiv 1309.7638)
    type: paper
    url: https://arxiv.org/pdf/1309.7638
    year: 2013
  - 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: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
  - title: PubChem compound record for nickel (CID 935), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Nickel
gaps:
  - 'Permalloy 80 in the original sense (about 80 % Ni and 20 % Fe, no molybdenum) is not covered: no datasheet for that composition was opened, and Wikipedia gives only approximate figures. The values here are for the molybdenum-bearing grade.'
  - No flight record for this grade on a named spacecraft was found. The DAMPE paper is a photomultiplier shielding study for the DAMPE calorimeter, read from its abstract and test results.
  - The Moly Permalloy DC magnetic table on the HPM page does not pair its labels with its values, so no permeability or saturation value is taken from it.
  - The Matthey electrical resistivity is printed as 55 with no unit, so it is not entered. The VDM value of 55 µΩcm is used instead.
  - Curie temperature (410, 420 and 455 °C) and thermal conductivity (19, 32 and 34.6 W/m K) differ between the three sources and are kept as separate rows; no single value was chosen.
  - Magnetic benchmark names (saturation_induction, permeability_dc, permeability_initial, permeability_max, coercive_force, saturation_magnetostriction) and hardness are not in spores/property-canon.yaml; short snake_case names are used.
  - The ASTM A753 standard text was not opened. The Alloy 4 designation and its composition range are taken from the VDM and Matthey datasheets; the search result gave the A753 composition ranges only as a snippet and is not used.
  - Iron, the balance element, has no supply source in this run. The USGS iron and steel summary was not read.
  - Critical-mineral lists for nickel and molybdenum were not checked against the 2025 final list, so critical_lists is empty for both.
  - Corrosion rate, salt-spray and humidity data for this grade were not found. The only statement is the Matthey manufacturer claim that no coating is needed.
  - The nickel hazard codes are for nickel metal (PubChem CID 935). No hazard classification for the alloy itself was found.
  - Radiation effects, outgassing, cold welding, thermal cycling and vacuum behaviour were not looked up.
  - The Moly Permalloy and Magnifer 7904 values are typical or nominal, and none is a guaranteed minimum or maximum.
  - No images were checked for this profile, so no media entry was added.
sources:
  hpmetals-moly-permalloy:
    title: Hamilton Precision Metals, Moly Permalloy product page
    url: https://hpmetals.com/products/materials/moly-permalloy
    kind: web
    license: Manufacturer web page (cited, not reproduced)
  vdm-magnifer-7904:
    title: VDM Metals, Magnifer 7904 material data sheet No. 9004
    url: https://alloy59.de/fileadmin/user_upload/Downloads/Data_Sheets/Data_Sheet_VDM_MAG_7904.pdf
    kind: datasheet
    license: Manufacturer data sheet (cited, not reproduced)
  matthey-permimphy:
    title: Lamineries Matthey, Permimphy N14080 type 4 datasheet
    url: https://www.matthey.ch/fileadmin/user_upload/downloads/fichetechnique/EN/Permimphy_v22E.pdf
    kind: datasheet
    license: Manufacturer data sheet (cited, not reproduced)
  wikipedia-permalloy:
    title: 'Wikipedia: Permalloy'
    url: https://en.wikipedia.org/wiki/Permalloy
    kind: web
    license: CC BY-SA (cited, not reproduced)
  dampe-pmt-shield:
    title: Wang et al., Magnetic shield of PMT used in DAMPE electromagnetic calorimeter
    id: arXiv 1309.7638
    url: https://arxiv.org/pdf/1309.7638
    year: 2013
    kind: paper
    license: arXiv (cited, not reproduced)
  usgs-mcs2026-nickel:
    title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: Public domain (USGS)
  usgs-mcs2026-molybdenum:
    title: 'USGS Mineral Commodity Summaries 2026: Molybdenum'
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: Public domain (USGS)
  pubchem-ni:
    title: 'PubChem compound record: Nickel (CID 935), GHS classification'
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Nickel
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA and notifiers
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 32
  unreachable: 0
  caveats: 5
  note: 'Values were read by an AI assistant on 2026-10-26 from the datasheets, web pages and reports named in each entry. Caveats: the values are typical or nominal, not guaranteed; the composition is the molybdenum-bearing grade, not the original 80/20 Ni-Fe; three sources disagree on Curie temperature and thermal conductivity; the spacecraft use is a photomultiplier shielding study, not a flight record; the hazard codes are for nickel metal.'
story:
  risk_groups:
    - title: For people
      lead: The hazard classes in the sources are for nickel metal, which makes up about 80 % of the alloy. No separate classification of the alloy was found.
      level: 1
      verdict: Nickel classes
      points:
        - label: Nickel as a substance
          line: PubChem's GHS record for nickel lists H317 allergic skin reaction, H351 suspected cancer and H372 organ damage from repeated exposure, with signal word Danger.
        - label: Alloy as handled
          line: No health classification of the 80 Ni and 4.8 Mo alloy itself was found in the sources read.
    - title: If it fails
      lead: The failure routes in the sources are mechanical and thermal. None of them is a flight result for this grade.
      points:
        - label: Forming and shock
          line: Plastic deformation after the anneal degrades the magnetic properties, according to Matthey. The sources do not say how to recover them.
        - label: Poor anneal
          line: Oxidation or contamination during the hydrogen anneal degrades the part, so a protective atmosphere and clean, degreased parts are needed.
        - label: Mass
          line: At 8.7 g/cm3 the alloy is heavy, so a shield adds mass to the spacecraft or instrument.
    - title: Handling and storage
      points:
        - label: Clean before anneal
          line: Degrease the parts and keep the inert powder anhydrous before the anneal.
        - label: Anneal in dry hydrogen
          line: Matthey recommends pure dry hydrogen between 800 and 1150 °C. The Moly Permalloy page recommends annealing at 1900°F or higher for effective shielding.
  why: Permalloy 80 is used where a part must carry magnetic flux with very little loss, and shield a field. Matthey says its high permeability gives a low reluctance path for the flux, and its very low coercive force gives low hysteresis loss in AC circuits. Its molybdenum content raises the permeability, according to Matthey. Wikipedia credits Gustav Elmen at Bell Telephone Laboratories with the original nickel-iron permalloy (Wikipedia).
  uses:
    - where: Magnetic shields, cans and films
      line: VDM lists shielding films, shielding cans and spatial shielding arrangements as typical applications of Magnifer 7904.
    - where: Relays, stepper motors and magnetic sensors
      line: Matthey lists relays for ground fault circuit breakers, stepper motors for watches and magnetic sensors for current and position as main applications.
    - where: Photomultiplier shield in the DAMPE calorimeter
      line: A one-layer permalloy strip cylinder keeps the gain loss of a photomultiplier under a 3 G field to less than 1 percent, in a 2013 study for the DAMPE calorimeter.
  recipe:
    line: Permalloy 80, molybdenum-bearing grade, is a nickel-iron-molybdenum alloy of about 80 % Ni and 4.8 to 4.9 % Mo, with balance Fe and small Mn and Si (Moly Permalloy nominal composition; VDM typical). It is cold rolled into strip and sheet (Matthey), and its magnetic properties come from a high-temperature anneal in pure dry hydrogen at 800 to 1150 °C (Matthey).
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 80
        share_note: nominal, 80.0 % in the Moly Permalloy nominal composition
        role: Main element of the alloy, nominal 80 %
        source: hpmetals-moly-permalloy
        where: Nominal Composition table, Nickel 80.0%
      - name: Molybdenum
        symbol: Mo
        share_percent: 4.8
        share_note: nominal, 4.8 % in the Moly Permalloy nominal composition
        role: Alloying element; Matthey says molybdenum increases the magnetic permeability
        source: hpmetals-moly-permalloy
        where: Nominal Composition table, Molybdenum 4.8%
      - name: Manganese
        symbol: Mn
        share_percent: 0.5
        share_note: nominal, 0.50 %
        role: Minor element, nominal
        source: hpmetals-moly-permalloy
        where: Nominal Composition table, Manganese 0.50%
      - name: Silicon
        symbol: Si
        share_percent: 0.35
        share_note: nominal, 0.35 %
        role: Minor element, nominal
        source: hpmetals-moly-permalloy
        where: Nominal Composition table, Silicon 0.35%
      - name: Iron
        symbol: Fe
        share_note: balance
        role: Balance of the alloy
        source: hpmetals-moly-permalloy
        where: Nominal Composition table, Iron Balance
  can_do:
    - label: Shield a field
      value: 470000 DC permeability
      benchmark: permeability_dc
      line: Matthey gives a DC permeability of 470,000 at 5 mOe for 1.00 mm strip annealed in dry hydrogen, and VDM gives 320,000 to 480,000 maximum permeability on tape-wound cores at 50 Hz.
    - label: Saturate at low field
      value: 0.8 T
      benchmark: saturation_induction
      line: The saturation induction is 0.8 T in the VDM and Matthey datasheets, so the alloy saturates at low fields.
    - label: Weight
      value: 8.7 g/cm3
      benchmark: density
      line: The relative density is 8.7 g/cm3 in the VDM datasheet, and the Moly Permalloy page prints 0.315 lbs./cu.in.
    - label: Strength when soft annealed
      value: 500 to 700 N/mm2 tensile
      benchmark: ultimate_tensile_strength
      line: Matthey gives 500 to 700 N/mm2 tensile and 200 to 450 N/mm2 yield for soft annealed R500 strip. After the final anneal, VDM gives 450 N/mm2 tensile and 170 N/mm2 yield.
  compare: 'This molybdenum-bearing Permalloy 80 is in the ASTM A753 Alloy 4 class, the same class given for mu-metal in its own profile. The two grades from the datasheets read here, Moly Permalloy and Magnifer 7904, print 4.8 % and 4.9 % molybdenum with about 80 % nickel, and their magnetic and density figures sit in the same range as the Matthey Permimphy sheet. Permalloy is the older name: Wikipedia credits Gustav Elmen at Bell Telephone Laboratories with the original nickel-iron alloy. The three sources read here print Curie temperatures of 410, 420 and 455 °C, and thermal conductivities of 19, 32 and 34.6 W/m K, so a design needs the datasheet of the actual supplier. The unmodified 80/20 nickel-iron permalloy has no molybdenum and is a different alloy, not covered by these values.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: DC permeability
      benchmark: permeability_dc
    - label: Thermal expansion
      benchmark: cte
  handling:
    - Anneal in pure dry hydrogen between 800 and 1150 °C, after degreasing the parts and using an anhydrous inert powder to keep them apart.
    - Avoid shock and plastic deformation after the anneal, because the magnetic properties degrade.
    - The only hazard codes found are for nickel metal (PubChem); treat the alloy with the same care until a supplier classification is found.
  good_for:
    - Shielding sensitive electronics from static and slowly varying fields, with a DC permeability of about 470,000 (Matthey).
    - Relay, stepper-motor and magnetic-sensor parts, as the datasheets list.
    - Magnetic shields for photomultipliers in a calorimeter, as the DAMPE study shows (a ground test study, not flight data).
  watch_out:
    - 'Soft and weak: 170 N/mm2 yield after the final anneal (VDM).'
    - 'Heavy: 8.7 g/cm3, so a shield adds mass.'
    - Plastic deformation or shock after the anneal degrades the magnetic properties.
    - No corrosion rate or flight record was found; the only statement is a manufacturer's claim that no coating is needed.
    - The hazard codes are for nickel metal, not for the alloy.
  verdict: The molybdenum-bearing Permalloy 80 is a soft nickel-iron-molybdenum alloy with very high permeability, about 80 % Ni and 4.8 to 4.9 % Mo. It is the same class as mu-metal, and it is used to shield sensitive electronics and to make relay and sensor parts. It is heavy and weak, and its permeability depends on a careful dry hydrogen anneal and on keeping the part free of deformation. No flight record was found in this run.