spore: profile
id: alloy-42
spore_version: 0.2
family: nickel-alloys
name: Alloy 42
abbreviation: FeNi42
role: controlled-expansion alloy for glass and ceramic seals
category: metals
type: nickel-superalloys
summary: |
  Alloy 42 is a binary nickel-iron alloy with 42 % nickel (UNS K94100, Werkstoff Nr. 1.3917), used where a low, nearly constant thermal expansion is needed up to about 300 °C. Special Metals gives a density of 8.11 g/cm3 and a mean linear expansion of 5.3 ppm/K from 20 to 300 °C, while NeoNickel prints 4.0 to 4.7 ppm/K from 30 to 300 °C. The two suppliers disagree, so both figures are kept. Annealed bar has a tensile strength of 490 MPa and a yield strength of 250 MPa at 20 °C in the Special Metals table.
best_for: Glass-to-metal and ceramic-to-metal seals, and lead frames for integrated circuits, where expansion must stay low up to 300 °C
weakest_at: 'Strength and corrosion data: no corrosion test was found, and the sources disagree on yield strength, tensile strength and elongation'
identity:
  formula: 'Fe-42Ni, nominal: a binary nickel-iron alloy with 41 % nickel minimum (42 % nominal) and iron as the balance; carbon 0.05 % maximum, manganese 0.8 % maximum, silicon 0.03 % maximum, chromium 0.25 % maximum, phosphorus and sulphur 0.025 % maximum, aluminium 0.1 % maximum (NeoNickel chemical analysis)'
  source: nilo-smc031
  where: 'Table 1 (Nominal compositions, NILO alloy 42: Ni 42.0, Fe 58.0) and the opening description (''a binary nickel-iron alloy containing 42% nickel''); maximum limits from the NeoNickel chemical analysis table'
  designations:
    - system: UNS
      code: K94100
      source: nilo-smc031
      where: Specifications and designations, NILO alloy 42 (UNS K94100, W.Nr. 1.3917)
    - system: EN
      code: '1.3917'
      source: nilo-smc031
      where: Specifications and designations, NILO alloy 42 (UNS K94100, W.Nr. 1.3917)
    - system: ASTM
      code: F30
      note: sheet, strip, rod, bar, tubing and wire
      source: nilo-smc031
      where: Specifications and designations, ASTM F 30 row
    - system: ASTM
      code: F29
      note: wire
      source: nilo-smc031
      where: Specifications and designations, ASTM F 29 (Wire) row
    - system: ASTM
      code: B753
      note: sheet and strip
      source: nilo-smc031
      where: Specifications and designations, ASTM B 753 (Sheet and strip) row
    - system: DIN
      code: '17745'
      source: nilo-smc031
      where: Specifications and designations, DIN 17745 (Composition) row
    - system: AFNOR
      code: NF A54-301
      note: composition
      source: nilo-smc031
      where: Specifications and designations, AFNOR NF A54-301 (Composition) row
    - system: ASTM
      code: F1684
      note: specification named by NeoNickel
      source: studer-alloy42
      where: Page title, 1.3917 - Alloy 42/FeNi42 / Ni42 / F1684 / K94100
    - system: Trade name
      code: Nilo 42
      source: aircraftmaterials-al42
      where: Specifications list, Tradename Nilo 42
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - electronics-and-chips
    - cryogenic-fuel
    - mechanisms
    - structures
properties:
  - benchmark: density
    label: Density, NILO alloy 42 (Special Metals)
    value: 8.11
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated in Table 2
      unit_in_source: 0.293 lb/in3
    method: Value printed in a Special Metals technical bulletin (publication SMC-031, Sept 2004)
    status: ground
    source: nilo-smc031
    where: Table 2 (Density), row NILO alloy 42
  - benchmark: density
    label: Density, Alloy 42 (NeoNickel)
    value: 8.12
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in a stockist product page (NeoNickel)
    status: ground
    note: Differs from the 8.11 g/cm3 printed by Special Metals; both are kept.
    source: neonickel-alloy42
    where: Key Properties, row Density
  - benchmark: melting_point
    label: Melting range, Alloy 42 (NeoNickel)
    value: 1425
    value_high: 1435
    bound: range
    unit: °C
    scope: material
    conditions:
      basis: melting range as printed
      unit_in_source: 1425°C - 1435°C
    method: Range printed in a stockist product page (NeoNickel)
    status: ground
    source: neonickel-alloy42
    where: Key Properties, row Melting Range
  - benchmark: melting_point
    label: Melting point, NILO alloy 42 (Special Metals)
    value: 1435
    unit: °C
    scope: material
    conditions:
      unit_in_source: 2615 °F
    method: Value printed in a Special Metals technical bulletin, Table 3
    status: ground
    note: Special Metals gives a single figure at the top of the NeoNickel range.
    source: nilo-smc031
    where: Table 3 (Melting and Inflection Points), row NILO alloy 42
  - benchmark: melting_point
    label: Melting point, Alloy 42 (High Temp Metals)
    value: 1427
    unit: °C
    scope: material
    conditions:
      unit_in_source: 2600 °F
    method: Value printed in a supplier technical data sheet
    status: ground
    source: hightemp-alloy42
    where: Physical Properties table, row Melting Point, °C column
  - benchmark: curie_temperature
    label: Curie temperature, Alloy 42 (NeoNickel)
    value: 380
    unit: °C
    scope: material
    conditions:
      basis: as printed on the product page; no test method given
    method: Value printed in a stockist product page (NeoNickel)
    status: ground
    note: High Temp Metals prints the same 380 °C (715 °F).
    source: neonickel-alloy42
    where: Key Properties, row Curie Temperature
  - benchmark: thermal_conductivity
    label: Thermal conductivity, NILO alloy 42 (Special Metals)
    value: 10.5
    unit: W/m°C
    scope: material
    conditions:
      temperature: 20 °C (68 °F)
      unit_in_source: W/m°C; 72.8 Btu in/ft2h °F
    method: Value printed in a Special Metals technical bulletin, Table 4
    status: ground
    source: nilo-smc031
    where: Table 4 (Thermal Conductivity at 20 °C), row NILO alloy 42
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Alloy 42 (NeoNickel)
    value: 10.7
    unit: W/m-K
    scope: material
    conditions:
      temperature: 20/100 °C, as printed
    method: Value printed in a stockist product page (NeoNickel)
    status: ground
    note: Special Metals gives 10.5 W/m°C at 20 °C; High Temp Metals prints 10.7 W/m-K at 20/100 °C too.
    source: neonickel-alloy42
    where: Key Properties, row Thermal Conductivity at 20/100°C
  - benchmark: cte
    label: Mean linear expansion, 20 to 300 °C, typical (Special Metals)
    value: 5.3
    unit: ppm/K
    scope: material
    conditions:
      temperature_range: 20 to 300 °C (68 to 572 °F)
      basis: typical mean linear coefficient for NILO alloy 42 as printed
      unit_in_source: 10-6/°C
    method: Typical value printed in a Special Metals technical bulletin, Table 8 (not a guaranteed minimum or maximum)
    status: ground
    note: Differs from the 4.0 to 4.7 ppm/K printed by NeoNickel and High Temp Metals for 30 to 300 °C; both are kept and the sources are not reconciled.
    source: nilo-smc031
    where: Table 8 (Typical Thermal Expansion of NILO alloy 42), row 20-300
  - benchmark: cte
    label: Mean linear expansion, 30 to 300 °C (NeoNickel)
    value: 4
    value_high: 4.7
    bound: range
    unit: ppm/K
    scope: material
    conditions:
      temperature_range: 30 to 300 °C
      unit_in_source: 10-6/°C
    method: Range printed on a stockist product page (NeoNickel); High Temp Metals prints the same range
    status: ground
    source: neonickel-alloy42
    where: Key Properties, Coefficient of Thermal Expansion, row 30 to 300°C
  - benchmark: cte
    label: Mean linear expansion, 30 to 450 °C (NeoNickel)
    value: 6.7
    value_high: 7.4
    bound: range
    unit: ppm/K
    scope: material
    conditions:
      temperature_range: 30 to 450 °C
      unit_in_source: 10-6/°C
    method: Range printed on a stockist product page (NeoNickel)
    status: ground
    source: neonickel-alloy42
    where: Key Properties, Coefficient of Thermal Expansion, row 30 to 450°C
  - benchmark: elastic_modulus
    label: Elastic modulus, NILO alloy 42 (Special Metals)
    value: 150
    unit: GPa
    scope: material
    conditions:
      temperature: not stated in Table 16
      unit_in_source: 21.8 x 10^3 ksi
    method: Value printed in a Special Metals technical bulletin, Table 16
    status: ground
    source: nilo-smc031
    where: Table 16 (Elastic Modulus Data), row NILO alloy 42
  - benchmark: elastic_modulus
    label: Elastic modulus at 20 °C, Alloy 42 (NeoNickel)
    value: 148
    unit: GPa
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in a stockist product page (NeoNickel)
    status: ground
    source: neonickel-alloy42
    where: Key Properties, row Modulus of Elasticity at 20°C
  - benchmark: yield_strength
    label: Yield strength (0.2% offset), annealed bar at 20 °C (Special Metals)
    value: 250
    unit: MPa
    scope: material
    conditions:
      temper: annealed, hot-rolled bar
      temperature: 20 °C (68 °F)
      test: 0.2% offset
      unit_in_source: 36.0 ksi
    method: Value printed in a Special Metals technical bulletin, Table 12
    status: ground
    source: nilo-smc031
    where: Table 12 (Typical Mechanical Properties of NILO alloy 42), 20 °C row
  - benchmark: yield_strength
    label: Yield strength (0.2% offset), annealed at room temperature (Aircraft Materials)
    value: 250
    unit: MPa
    scope: material
    conditions:
      temper: annealed
      test: 0.2% offset
      unit_in_source: 36,000 psi
    method: Value printed in a supplier technical data sheet (Typical Mechanical Properties table)
    status: ground
    source: aircraftmaterials-al42
    where: Typical Mechanical Properties table, row Alloy 42 (Nilo 42), annealed
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed bar at 20 °C (Special Metals)
    value: 490
    unit: MPa
    scope: material
    conditions:
      temper: annealed, hot-rolled bar
      temperature: 20 °C (68 °F)
      unit_in_source: 71.0 ksi
    method: Value printed in a Special Metals technical bulletin, Table 12
    status: ground
    note: The same 490 MPa is printed by Aircraft Materials for annealed material; High Temp Metals prints 517 MPa.
    source: nilo-smc031
    where: Table 12 (Typical Mechanical Properties of NILO alloy 42), 20 °C row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, annealed material (High Temp Metals)
    value: 517
    unit: MPa
    scope: material
    conditions:
      temper: annealed, material as tested by the supplier
      unit_in_source: 75 ksi
    method: Typical value printed in a supplier technical data sheet
    status: ground
    note: Differs from the 490 MPa printed by Special Metals and Aircraft Materials; both are kept.
    source: hightemp-alloy42
    where: Typical Mechanical Properties table, annealed row
  - benchmark: elongation
    label: Elongation on 50 mm (2 in), annealed bar at 20 °C (Special Metals)
    value: 43
    unit: '%'
    scope: material
    conditions:
      temper: annealed, hot-rolled bar
      temperature: 20 °C (68 °F)
      gauge: 50 mm (2 inch)
    method: Value printed in a Special Metals technical bulletin, Table 12
    status: ground
    source: nilo-smc031
    where: Table 12 (Typical Mechanical Properties of NILO alloy 42), 20 °C row, elongation column
  - benchmark: elongation
    label: Elongation in 2 in, annealed (High Temp Metals)
    value: 30
    unit: '%'
    scope: material
    conditions:
      temper: annealed
      gauge: 2 in
    method: Typical value printed in a supplier technical data sheet
    status: ground
    note: Differs from the 43 % printed by Special Metals; both are kept.
    source: hightemp-alloy42
    where: Typical Mechanical Properties table, annealed row, % Elongation in 2 in column
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C, NILO alloy 42 (Special Metals)
    value: 61
    unit: microhm-cm
    scope: material
    conditions:
      temperature: 20 °C (68 °F)
      unit_in_source: 61 microhm cm (367 ohm circ mil/ft)
    method: Value printed in a Special Metals technical bulletin, Table 6
    status: ground
    source: nilo-smc031
    where: Table 6 (Electrical Resistivity), row 20 °C, NILO alloy 42 column
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Alloy 42 (High Temp Metals)
    value: 66
    unit: microhm-cm
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: 400 ohm-cir mil/ft
    method: Value printed in a supplier technical data sheet
    status: ground
    note: Differs from the 61 microhm-cm at 20 °C printed by Special Metals; both are kept.
    source: hightemp-alloy42
    where: Physical Properties table, row Electrical resistivity
  - benchmark: specific_heat
    label: Specific heat, Alloy 42 (High Temp Metals)
    value: 0.5
    unit: kJ/kg-K
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: 0.12 Btu/lb-°F
    method: Value printed in a supplier technical data sheet
    status: ground
    source: hightemp-alloy42
    where: Physical Properties table, row Specific heat
  - benchmark: density
    label: Density, 1.3917 Alloy 42 (METALCOR)
    value: 8.15
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in a METALCOR datasheet, Physical Properties 20°C table
    status: ground
    note: Third density figure for this alloy; Special Metals gives 8.11 g/cm3 and NeoNickel 8.12 g/cm3. All three are kept.
    source: metalcor-alloy42
    where: Physical Properties 20°C table, row Density
  - benchmark: thermal_conductivity
    label: Thermal conductivity, 1.3917 Alloy 42 (METALCOR)
    value: 12.5
    unit: W/m K
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in a METALCOR datasheet, Physical Properties 20°C table
    status: ground
    note: Higher than the 10.5 W/m°C (Special Metals) and 10.7 W/m-K (NeoNickel) figures. All three are kept and not reconciled.
    source: metalcor-alloy42
    where: Physical Properties 20°C table, row Thermal conductivity
  - benchmark: yield_strength
    label: Yield strength Rp (0.2% proof), lower limit at 20 °C (METALCOR)
    value: 300
    bound: lower
    unit: N/mm2
    scope: material
    conditions:
      temperature: 20 °C
      test: 0.2% proof (Rp) as printed
      basis: lower limit printed with the sign ≥
    method: Lower limit printed in a METALCOR datasheet, Mechanical Properties 20°C table
    status: ground
    note: A lower limit, not a typical value, so it is not directly comparable with the 250 MPa typical yield from Special Metals. Both are kept.
    source: metalcor-alloy42
    where: Mechanical Properties 20°C table, row 0.2% yield strength Rp
  - benchmark: ultimate_tensile_strength
    label: Tensile strength Rm, lower limit at 20 °C (METALCOR)
    value: 500
    bound: lower
    unit: N/mm2
    scope: material
    conditions:
      temperature: 20 °C
      basis: lower limit printed with the sign ≥
    method: Lower limit printed in a METALCOR datasheet, Mechanical Properties 20°C table
    status: ground
    note: A lower limit, not a typical value. Special Metals prints 490 MPa typical and High Temp Metals 517 MPa; all are kept.
    source: metalcor-alloy42
    where: Mechanical Properties 20°C table, row Tensile strength Rm
  - benchmark: elastic_modulus
    label: Modulus of elasticity, 1.3917 Alloy 42 (METALCOR)
    value: 145
    unit: kN/mm2
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in a METALCOR datasheet, Mechanical Properties 20°C table
    status: ground
    note: Lower than the 148 GPa (NeoNickel) and 150 GPa (Special Metals) figures. All three are kept.
    source: metalcor-alloy42
    where: Mechanical Properties 20°C table, row Modulus of elasticity
corrosion:
  - environment: Air under standard service conditions
    headline: The supplier describes Alloy 42 as strongly resistant to oxidation and corrosion, with no test data given.
    effect: Studer describes the alloy as having strong resistance to oxidation and corrosion under standard service conditions. The page names no environment, exposure time, test standard or corrosion rate.
    rating: low
    conditions:
      basis: qualitative supplier statement; standard service conditions not defined
      test: none stated
    method: Qualitative statement read from the supplier product page
    source: studer-alloy42
    where: Description text, 1.3917 Alloy 42 page
  - environment: Annealing atmosphere at 850 to 1000 °C
    headline: Alloy 42 is annealed at 850 to 1000 °C in a protective atmosphere, and the bulletin gives no oxidation rate.
    effect: Special Metals says that NILO alloys 42 and 48 can be annealed at 850 to 1000 °C in a protective atmosphere. The bulletin does not give an oxide thickness, a scaling rate or the type of protective gas.
    rating: unknown
    conditions:
      temperature_range: 850 to 1000 °C (1560 to 1830 °F)
      atmosphere: protective atmosphere, type not named
    method: Heat-treatment instruction printed in a Special Metals technical bulletin
    source: nilo-smc031
    where: Heat Treatment, section NILO alloys 42 and 48
risks:
  hazards:
    - text: PubChem's GHS summary for nickel (CID 935) lists H317, 'May cause an allergic skin reaction', H351, 'Suspected of causing cancer', and H412, 'Harmful to aquatic life with long lasting effects'. Alloy 42 is 41 % nickel minimum, so these are the hazard data we hold for it.
      ghs:
        - H317
        - H351
        - H412
      source: pubchem-nickel
      where: Safety and Hazards, GHS Classification summary lines (CID 935, Nickel)
  failure_risks:
    - mode: Dimensional drift from cold work
      trigger: Use in a cold-worked or unannealed condition where maximum dimensional stability is needed
      consequence: Special Metals says the annealed condition should be used where maximum dimensional stability is required. The bulletin gives no drift figure.
      severity: moderate
      source: nilo-smc031
      where: Heat Treatment, section NILO alloys 42 and 48
    - mode: Sulphur pick-up during hot working
      trigger: Prolonged soaking in the furnace atmosphere before or during forging
      consequence: High Temp Metals advises avoiding prolonged soaking to prevent sulphur absorption from the furnace atmosphere. The page gives no sulphur content or embrittlement data.
      severity: low
      source: hightemp-alloy42
      where: Workability, Forging
  side_effects: []
  handling:
    - text: Machine in the annealed condition with high speed steel or tungsten carbide tipped tools, using straight cutting oil or soluble oil (Special Metals).
      source: nilo-smc031
      where: Machining section
    - text: For welding alloy 42 tooling for aerospace composites, Special Metals introduced NILO Filler Metals CF42. MIG spray and submerged arc welding are not recommended for the NILO series (Special Metals).
      source: nilo-smc031
      where: Fabrication section
    - text: High Temp Metals gives a forging temperature of 2150/2200 °F (1177/1204 °C) and advises avoiding prolonged soaking to prevent sulphur absorption from the furnace atmosphere.
      source: hightemp-alloy42
      where: Workability, Forging
  mitigations:
    - text: Anneal at 850 to 1000 °C in a protective atmosphere, the range Special Metals gives for NILO alloys 42 and 48, and use the annealed condition where dimensions must stay fixed.
      source: nilo-smc031
      where: Heat Treatment, section NILO alloys 42 and 48
uses:
  - application: electronics-and-chips
    device: Semiconductor lead frames in integrated circuits
    example: Aircraft Materials says Alloy 42 (Nilo 42) is used for semiconductor lead frames in integrated circuits.
    source: aircraftmaterials-al42
    where: Introduction paragraph
  - application: electronics-and-chips
    device: Glass-to-metal seals in electronic tubes and lamps
    example: High Temp Metals says Alloy 42 has been used for the glass-to-metal seals in electronic tubes, automotive and industrial lamps, transformer and capacitor bushings.
    source: hightemp-alloy42
    where: Applications
  - application: structures
    device: Tooling for aerospace composites
    example: Special Metals says NILO alloy 42 is used for tooling for aerospace composites and for thermostat rods.
    source: nilo-smc031
    where: Introduction (page 1, description of NILO alloy 42)
  - application: cryogenic-fuel
    device: Cryogenic components and liquid-gas storage tanks
    example: NeoNickel lists cryogenic components among the applications of Alloy 42, and says it shows low thermal expansion from cryogenic temperatures up to 300 °C.
    source: neonickel-alloy42
    where: Characteristics and Applications of Alloy 42
  - application: mechanisms
    device: Thermostatic bimetal strip
    example: Special Metals says NILO alloy 42 is used in thermostatic bi-metal strip, as the low-expansion component.
    source: nilo-smc031
    where: Introduction (page 1, description of NILO alloy 42)
  - application: cryogenic-fuel
    device: Tanks for liquid natural gas
    example: METALCOR lists tanks for liquid natural gas, with measuring and thermostatic instruments, among the applications of 1.3917 Alloy 42.
    source: metalcor-alloy42
    where: Application row
supply:
  - subject: Nickel
    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
      - country: Canada
        share_percent: 3.6
        year: 2025
    critical_lists: []
    recycling: 'USGS: nickel recovered from scrap accounted for approximately 60% of apparent consumption in 2025.'
    substitutes:
      - 'USGS: titanium alloys can substitute for nickel or nickel-base alloys in corrosive environments.'
    source: usgs-mcs2026-nickel
    where: World Mine Production and Reserves table, mine production 2025e (world total 3,900,000 t, nickel content; shares calculated by Space Mushroom from the printed country values 2,600,000, 270,000, 200,000 and 140,000 t, method approximate); Recycling; Substitutes. Critical-list status not read in this run.
media: []
documents:
  - title: 'Special Metals: The NILO and NILOMAG Nickel-Iron Alloys (publication SMC-031, Sept 2004)'
    type: datasheet
    url: https://www.specialmetals.com/documents/technical-bulletins/nilo-alloys.pdf
    year: 2004
  - title: 'NeoNickel: Alloy 42 product page (UNS K94100)'
    type: datasheet
    url: https://www.neonickel.com/alloys/all-alloys/alloy-42
    year: 2026
  - title: 'Aircraft Materials: Nickel Iron Alloy 42 / Nilo 42 (ASTM F30) technical data sheet'
    type: datasheet
    url: https://aircraftmaterials.com/data/nickel/al42.html
    year: 2013
  - title: 'High Temp Metals: Alloy 42 technical data'
    type: datasheet
    url: https://hightempmetals.com/techdata/hitempInvar42data.php
    year: 2015
  - title: 'Studer: 1.3917 Alloy 42/FeNi42 / Ni42 / F1684 / K94100 (product page)'
    type: datasheet
    url: https://www.studersa.com/en/materials/13917-alloy-42-feni42-ni42-f1684-k94100;138
    year: 2026
  - title: 'PubChem: Nickel (CID 935), GHS classification summary'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
  - title: USGS Mineral Commodity Summaries 2026, Nickel
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: 'METALCOR: Alloy 42 (1.3917), K94100 datasheet'
    type: datasheet
    url: http://www.metalcor.de/en/datenblatt/80/
gaps:
  - No flight, vacuum, radiation or thermal-vacuum result for Alloy 42 was found. The two NASA reports searched (NTRS 19740012950 and 19680006647) name Kovar but not Alloy 42.
  - No corrosion test (salt spray, humid air, immersion, or oxidation rate) was found. The only corrosion statement is a qualitative supplier phrase, and no published paper on Alloy 42 oxidation was found.
  - No safety data sheet for Alloy 42 itself was read. The hazard data are PubChem's record for elemental nickel.
  - Density, melting point, thermal conductivity, elongation and resistivity differ between sources; every figure is kept with its source. The METALCOR datasheet adds a third density (8.15 g/cm3) and conductivity (12.5 W/m K), and its strength values are lower limits. Special Metals and NeoNickel disagree on the expansion figures at 20 to 300 °C (5.3 against 4.0 to 4.7 ppm/K).
  - DIN 17744 is printed by NeoNickel but DIN 17745 by Special Metals and Aircraft Materials. Only DIN 17745 is listed.
  - Hardness (Special Metals Table 15, annealed 76 Rockwell B maximum) is not recorded because its benchmark name is not in the canonical list.
  - Nickel's status on the USGS 2025 critical minerals list and the EU critical raw materials list was not read in this run, so critical_lists is empty.
  - Iron supply was not read. Only nickel supply is given.
  - Welding filler and weld-metal property data beyond the CF42 filler name were not found.
sources:
  nilo-smc031:
    title: The NILO and NILOMAG Nickel-Iron Alloys (Special Metals Corporation, publication SMC-031)
    id: Special Metals SMC-031, copyright 2004 (Sept 04)
    url: https://www.specialmetals.com/documents/technical-bulletins/nilo-alloys.pdf
    year: 2004
    kind: datasheet
    license: manufacturer document, linked not reproduced
  neonickel-alloy42:
    title: Alloy 42, NeoNickel product page (Key Properties, Chemical analysis, Characteristics)
    id: NeoNickel, Alloy 42 page; UNS K94100
    url: https://www.neonickel.com/alloys/all-alloys/alloy-42
    year: 2026
    kind: web
    license: stockist web page, cited not reproduced
  aircraftmaterials-al42:
    title: Nickel Iron Alloy 42 / Nilo 42 (ASTM F30), Technical Data Sheet (Aircraft Materials)
    id: Aircraft Materials, UNS K94100
    url: https://aircraftmaterials.com/data/nickel/al42.html
    year: 2013
    kind: datasheet
    license: supplier document, cited not reproduced
  hightemp-alloy42:
    title: Alloy 42 Technical Data (High Temp Metals)
    id: High Temp Metals, Alloy 42 technical data page
    url: https://hightempmetals.com/techdata/hitempInvar42data.php
    year: 2015
    kind: datasheet
    license: supplier document, cited not reproduced
  studer-alloy42:
    title: 1.3917 - Alloy 42/FeNi42 / Ni42 / F1684 / K94100 (Studer SA, product page)
    id: Studer, Werkstoffe 1.3917
    url: https://www.studersa.com/en/materials/13917-alloy-42-feni42-ni42-f1684-k94100;138
    year: 2026
    kind: web
    license: stockist web page, cited not reproduced
  pubchem-nickel:
    title: PubChem compound record, Nickel (CID 935), GHS classification
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
    kind: database
    license: public domain (NCBI)
  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)
  metalcor-alloy42:
    title: Alloy 42 (1.3917), K94100 datasheet (METALCOR)
    id: METALCOR datasheet 80, Alloy 42
    url: http://www.metalcor.de/en/datenblatt/80/
    kind: datasheet
    license: supplier document, cited not reproduced
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 0
  caveats: 3
  note: Read by an AI assistant on 2026-11-01. Values were read from fetched pages (Special Metals PDF, NeoNickel, Aircraft Materials, High Temp Metals, Studer). Where sources disagree, both values are kept and noted.
story:
  recipe:
    line: Alloy 42 is a binary nickel-iron alloy. It is about 42 % nickel with iron as the balance, plus small maximum limits on carbon, manganese, silicon, chromium, phosphorus, sulphur and aluminium (Special Metals; NeoNickel).
    parts:
      - name: Nickel
        symbol: Ni
        share_percent: 41
        role: 41 % minimum in the chemical limits; the nominal 42 % gives the alloy its name (NeoNickel; Special Metals Table 1).
      - name: Iron
        symbol: Fe
        role: The balance of the composition in every limit table read.
      - name: Carbon
        symbol: C
        share_high: 0.05
        role: Maximum 0.05 % (Aircraft Materials; High Temp Metals).
      - name: Manganese
        symbol: Mn
        share_high: 0.8
        role: Maximum 0.8 % (NeoNickel).
      - name: Silicon
        symbol: Si
        share_high: 0.03
        role: Maximum 0.03 % (NeoNickel).
      - name: Chromium
        symbol: Cr
        share_high: 0.25
        role: Maximum 0.25 % (NeoNickel).
      - name: Phosphorus
        symbol: P
        share_high: 0.025
        role: Maximum 0.025 % (NeoNickel).
      - name: Sulphur
        symbol: S
        share_high: 0.025
        role: Maximum 0.025 % (NeoNickel).
      - name: Aluminium
        symbol: Al
        share_high: 0.1
        role: Maximum 0.1 % (NeoNickel).
  risk_groups:
    - title: For people
      level: 0
      verdict: 'Nickel content: skin sensitiser, suspected carcinogen'
      lead: No safety data sheet for Alloy 42 itself was read. The hazard data we hold are PubChem's record for nickel, and Alloy 42 is 41 % nickel minimum.
      points:
        - label: The nickel record
          line: PubChem's nickel summary lists skin sensitisation, suspected cancer and harm to aquatic life. These are hazards of the element, not a test of the alloy.
        - label: Dust and fume
          line: Machining, grinding and welding make metal dust and fume. Handle the material as a nickel-containing alloy and avoid breathing the dust.
    - title: If the alloy is heated
      verdict: Hot working needs a controlled furnace atmosphere
      lead: These instructions come from the suppliers' heat-treatment and forging advice, not from incident reports.
      points:
        - label: Annealing
          line: Special Metals gives an annealing range of 850 to 1000 °C in a protective atmosphere for NILO alloys 42 and 48.
        - label: Forging
          line: High Temp Metals advises a forging temperature of 2150/2200 °F and avoiding prolonged soaking, which can pick up sulphur from the furnace atmosphere.
    - title: Handling and fabrication
      verdict: Machine annealed; weld with the matching filler
      lead: The fabrication advice below comes from the Special Metals bulletin and the High Temp Metals data sheet.
      points:
        - label: Machining
          line: Machine in the annealed condition with high speed steel or tungsten carbide tipped tools.
        - label: Welding
          line: For tooling welds, Special Metals introduced NILO Filler Metals CF42. MIG spray and submerged arc welding are not recommended for the NILO series.
  why: Alloy 42 is a nickel-iron alloy with about 42 % nickel. Its thermal expansion is low and nearly constant from room temperature to about 300 °C, which is why it is used where it must seal to glass or ceramic, or hold a dimension while the temperature changes. The sources name lead frames in integrated circuits, glass-to-metal seals in electronic tubes and lamps, and tooling that shapes aerospace composites as its uses.
  uses:
    - where: Electronic packages
      line: Aircraft Materials says Alloy 42 is used for semiconductor lead frames in integrated circuits. High Temp Metals says it has been used for glass-to-metal seals in electronic tubes and lamps.
    - where: Composite tooling
      line: Special Metals says NILO alloy 42 is used for tooling for aerospace composites, and NeoNickel lists composite tooling among its applications.
    - where: Cryogenic and bimetal parts
      line: NeoNickel lists cryogenic components and liquid-gas storage tanks. Special Metals lists its use in thermostatic bi-metal strip as the low-expansion component.
  can_do:
    - label: Low expansion
      value: 4.0 to 4.7 ppm/K
      benchmark: cte
      line: Holds a low, nearly constant expansion from cryogenic temperatures up to about 300 °C (NeoNickel), and NeoNickel prints a mean of 4.0 to 4.7 ppm/K from 30 to 300 °C.
    - label: Strength when annealed
      value: 490 MPa tensile, 250 MPa yield
      benchmark: ultimate_tensile_strength
      line: Annealed bar has a tensile strength of 490 MPa and a yield strength of 250 MPa at 20 °C (Special Metals Table 12).
    - label: Stiffness
      value: 150 GPa
      benchmark: elastic_modulus
      line: Elastic modulus of 150 GPa (Special Metals Table 16), against 148 GPa at 20 °C on the NeoNickel page.
  compare: Alloy 42 has a density of 8.11 g/cm3 in Special Metals' table and 8.12 g/cm3 in NeoNickel's, so the two sources differ only slightly. On expansion, Special Metals' typical table gives a mean linear coefficient of 5.3 ppm/K from 20 to 300 °C, while NeoNickel gives 4.0 to 4.7 ppm/K from 30 to 300 °C. The sources disagree on this figure, so the conditions of each value matter more than the single number. The table compares the three properties most often used to choose the alloy.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Thermal expansion
      benchmark: cte
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Machine in the annealed condition, with high speed steel or tungsten carbide tipped tools.
    - Use NILO Filler Metals CF42 for tooling welds, and avoid MIG spray and submerged arc welding.
    - Anneal at 850 to 1000 °C in a protective atmosphere.
    - Avoid prolonged soaking in the furnace to prevent sulphur pick-up.
  good_for:
    - 'Low expansion to about 300 °C: 4.0 to 4.7 ppm/K from 30 to 300 °C (NeoNickel), for glass and ceramic seals.'
    - Lead frames and bimetal parts, where the alloy is named in both the Aircraft Materials and Special Metals sources.
  watch_out:
    - The sources disagree on expansion (5.3 against 4.0 to 4.7 ppm/K), on tensile strength (490 against 517 MPa) and on elongation (43 against 30 %).
    - No corrosion test data were found, and the only corrosion statement is a qualitative supplier phrase.
    - Alloy 42 is a nickel alloy, so its hazard data come from the nickel record.
  verdict: Alloy 42 is a low-expansion nickel-iron alloy for glass seals, lead frames and composite tooling, with consistent density and modulus data. The expansion figures and strength values differ by source, and no flight or corrosion test data were found.