Nickel aluminide Ni3Al, NiAl

spore: profile
id: nickel-aluminide
spore_version: 0.2
family: nickel-alloys
name: Nickel aluminide
abbreviation: Ni3Al, NiAl
role: structural intermetallic
category: metals
type: nickel-superalloys
summary: |
  Nickel aluminides are ordered intermetallic compounds of nickel and aluminium. Ni3Al (gamma-prime, L1_2 structure) is the strengthening phase of nickel-based superalloys and is also used alone as a turbine blade and vane alloy, with a review quoting density 7.5 g/cm3 and a Young's modulus of 200 GPa for micro and nano forms. NiAl (beta, B2 structure) has excellent oxidation resistance, but NASA finds it less ductile than leaner-aluminium alloys, and its scale fails when aluminium falls below about 40 at percent. No space-environment or flight data were found for either compound.
best_for: High-temperature strength and oxidation resistance for turbine parts and hot-section coatings, where the material is run inside its stated temperature range
weakest_at: Lower ductility of stoichiometric NiAl (NASA), no sourced ductility value for Ni3Al, and no sourced melting point or flight record for either compound
identity:
  formula: 'Ni3Al (gamma-prime, L1_2 structure) and NiAl (beta, B2 structure): ordered intermetallic compounds of nickel and aluminium'
  source: wiki-nickel-aluminide
  where: 'Comparison table, Crystal structure (Strukturbericht) row: L12 for Ni3Al, B2 for NiAl (structure labels only; no numbers taken from this page)'
tags:
  environments: []
  stresses:
    - extreme-heat
    - thermal-cycling
  applications:
    - propulsion-and-tanks
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, Ni3Al (micro and nano forms)
    value: 7.5
    unit: g/cm3
    scope: material
    conditions:
      material: Ni3Al, micro and nano forms as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015) for micro and nano Ni3Al
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, density row
  - benchmark: elastic_modulus
    label: Young's modulus, Ni3Al (micro and nano forms)
    value: 200
    unit: GPa
    scope: material
    conditions:
      material: Ni3Al, micro and nano forms as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, Young's modulus row
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Ni3Al micro form
    value: 2300
    unit: MPa
    scope: material
    conditions:
      form: micro form of Ni3Al as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, tensile strength row, micro
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Ni3Al nano form
    value: 2900
    unit: MPa
    scope: material
    conditions:
      form: nano form of Ni3Al as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, tensile strength row, nano
  - benchmark: specific_stiffness
    label: Specific stiffness, Ni3Al (micro and nano forms)
    value: 26
    unit: GN/kg·m
    scope: material
    conditions:
      material: Ni3Al, micro and nano forms as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015); the review gives the same figure for both forms
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, specific stiffness row
  - benchmark: specific_strength
    label: Specific strength, Ni3Al micro form
    value: 0.31
    unit: MN/kg·m
    scope: material
    conditions:
      form: micro form of Ni3Al as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, specific strength row, micro
  - benchmark: specific_strength
    label: Specific strength, Ni3Al nano form
    value: 0.39
    unit: MN/kg·m
    scope: material
    conditions:
      form: nano form of Ni3Al as tabulated
      temperature: not stated
    method: Value printed in Table 2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Table 2, Section 3.2, specific strength row, nano
  - benchmark: stress_rupture_strength
    label: Stress-rupture strength, IC6 Ni3Al-based alloy
    value: 100
    unit: MPa
    scope: material
    conditions:
      alloy: IC6, a Ni3Al-based blade and vane alloy
      temperature: 1100 °C
      time: 100 h
    method: Value printed in Section 3.1.1 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Section 3.1.1, IC6 stress-rupture paragraph
  - benchmark: max_service_temp
    label: Service temperature, newer Ni3Al-based alloys
    value: 1373
    unit: K
    scope: material
    conditions:
      alloys: IC6CX, IC10 and VKNA, as named in the review
    method: Value printed in Section 3.1.1 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Section 3.1.1, service temperature for newer alloys (given in kelvin in the review)
  - benchmark: max_service_temp
    label: Operating range upper limit, IC6 blades and vanes
    value: 1100
    unit: °C
    scope: material
    conditions:
      alloy: IC6 blades and vanes
      note: the review gives the range 1050 to 1100 °C; 1100 °C is the upper limit
    method: Value printed in Section 3.1.1 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Section 3.1.1, IC6 operating range
  - benchmark: max_service_temp
    label: Working temperature, Ni3Al thin foils
    value: 1300
    unit: °C
    scope: material
    conditions:
      form: thin foils used in MEMS and MECS parts
    method: Value printed in Section 3.2 of an open review (Jozwik, Polkowski and Bojar, 2015)
    status: ground
    source: jozwik2015
    where: Section 3.2, thin foils paragraph
  - benchmark: activation_energy_isothermal_oxidation
    label: Activation energy, isothermal oxidation, Ni-50.2 at percent Al with 0.04 at percent Zr
    value: 60.8
    unit: kcal/mole/deg
    scope: material
    conditions:
      alloy: beta-NiAl, Ni-50.2 at percent Al with 0.04 at percent Zr (report label p50.2+)
      temperature_range: 1100 to 1400 °C, isothermal
      note: the report prints the unit as kcal/mole/deg
    method: Arrhenius fit of parabolic growth rate constants, printed in Table 11 of the NASA Lewis report
    status: ground
    source: doychak1988
    where: Table 11, Activation Energies for Isothermal Oxidation, row p50.2+
  - benchmark: reaction_temperature
    label: Peritectoid formation of gamma-prime Ni3Al, Ni-Al-O system
    value: 1633
    unit: K
    scope: material
    conditions:
      system: Ni-Al-O with Al2O3 present
      reaction: gamma + beta (+ Al2O3) gives gamma-prime (+ Al2O3)
      note: the reaction composition is not given; the report prints 1633 +/- 1 K
    method: Invariant reaction temperature measured by NASA Glenn in the Ni-Al-O system
    status: ground
    source: copland2007
    where: Text, paragraph on the peritectoid reaction
  - benchmark: reaction_temperature
    label: Eutectic reaction, Ni-Al-O system
    value: 1640
    unit: K
    scope: material
    conditions:
      system: Ni-Al-O with Al2O3 present
      reaction: L (+ Al2O3) gives gamma + beta (+ Al2O3)
      note: the report prints 1640 +/- 1 K; this is a reaction temperature, not the melting point of either compound
    method: Invariant reaction temperature measured by NASA Glenn in the Ni-Al-O system
    status: ground
    source: copland2007
    where: Text, paragraph on the eutectic reaction
  - benchmark: liquid_composition
    label: Liquid composition at the eutectic, Ni-Al-O system
    value: 24.8
    unit: at percent Al
    scope: material
    conditions:
      system: Ni-Al-O, unknown oxygen content
      note: the report prints +/- 0.2 at percent Al
    method: Composition printed with the eutectic reaction in NASA Glenn's Ni-Al-O study
    status: ground
    source: copland2007
    where: Text, eutectic reaction paragraph
checked_values: 15
corrosion:
  - environment: Oxygen and carbon-bearing atmospheres up to 1100 °C
    headline: Ni3Al resists corrosion in these atmospheres up to 1100 °C, according to the review.
    effect: The review states that the corrosion resistance of Ni3Al holds up to 1100 °C in oxygen- and carbon-bearing atmospheres. It does not give mass-gain numbers or test durations for this claim.
    rating: low
    conditions:
      atmosphere: oxygen- and carbon-bearing atmospheres, not further specified in the text read
      temperature_limit: 1100 °C
    source: jozwik2015
    where: Section 2, corrosion resistance statement
  - environment: Isothermal and cyclic oxidation, 1000 to 1400 °C, beta-NiAl with Zr additions
    headline: Beta-NiAl forms a protective alumina scale, and Zr additions give the best oxidation performance in NASA tests.
    effect: NASA Lewis found that a stoichiometric NiAl alloy doped with Zr was superior to other alloy compositions in both cyclic and isothermal oxidation. The scale growth was controlled by grain-boundary diffusion, and Zr additions reduced the scale growth rates.
    rating: low
    conditions:
      material: beta-NiAl with Zr additions (the labelled alloys carry about 0.04 at percent Zr)
      temperature: 1000 to 1400 °C
      duration: up to 100 h isothermal, cyclic tests as stated in the report
    source: doychak1988
    where: Abstract, Isothermal Oxidation section, Summary of Results 4)
  - environment: Cyclic heating at 1200 °C, 1-hour cycles, aluminium below about 40 at percent
    headline: Low-aluminium NiAl loses its protective scale under cyclic heating at 1200 °C.
    effect: After 200 one-hour cycles at 1200 °C, alloys with less than about 40 at percent Al showed a sharp drop in weight change, which NASA linked to a less protective scale. The report concludes that the upper temperature limit for these alloys is below 1200 °C.
    rating: moderate
    conditions:
      test: 200 cycles, 1 h at 1200 °C, about 20 min cooling each cycle
      material: Zr-doped NiAl and two-phase NiAl with gamma-prime
    source: doychak1988
    where: Cyclic Oxidation section and Conclusions 2)
risks:
  hazards:
    - text: PubChem's ECHA summary for nickel metal (4778 company reports) lists H317 (99.9 percent), H372 (99.7 percent), H351 (72.9 percent), H350 (22.5 percent), H360F (18 percent), H341 (13.5 percent), H334 (10.3 percent) and H412 (47.2 percent), with signal word Danger. No compound-specific classification for Ni3Al or NiAl was found; the bulk-metal entry is used as the closest record.
      ghs:
        - H317
        - H372
        - H351
        - H350
        - H360F
        - H341
        - H334
        - H412
      source: pubchem-nickel
      where: GHS Classification, ECHA C and L Notifications Summary (codes above 10 percent)
    - text: The NIOSH IDLH for nickel metal and other compounds (as Ni) is 10 mg Ni/m3, based on animal acute inhalation data and described as conservative. NIOSH sets a REL of 0.015 mg/m3 TWA, and the OSHA PEL is 1 mg/m3 TWA for metal and insoluble compounds.
      ghs: []
      source: cdc-idlh-nickel
      where: Revised IDLH, OSHA PEL and NIOSH REL entries
  failure_risks:
    - mode: Limited ductility of stoichiometric NiAl
      trigger: Structural loading of stoichiometric beta-NiAl
      consequence: NASA says leaner-aluminium alloys may gain ductility relative to stoichiometric NiAl, which is why they are studied
      severity: moderate
      source: doychak1988
      where: Introduction
    - mode: Loss of protective alumina scale on low-aluminium NiAl
      trigger: Cyclic heating at 1200 °C in one-hour cycles, alloy below about 40 at percent Al
      consequence: After 200 cycles the weight change drops sharply, which NASA links to a less protective scale; the report says such alloys have exceeded their useful life under the test
      severity: high
      source: doychak1988
      where: Cyclic Oxidation section and Conclusions 2)
  side_effects:
    - text: NiAl forms a protective alumina scale easily (NASA). Loss of that scale in cyclic tests showed as a sharp drop in weight change at about 40 at percent Al.
      affects: Turbine parts and hot-section coatings
      source: doychak1988
      where: Introduction and Cyclic Oxidation section
  handling:
    - text: Keep nickel-aluminide dust out of the breathing zone. The NIOSH REL for nickel compounds is 0.015 mg/m3 TWA and the OSHA PEL is 1 mg/m3 TWA.
      source: cdc-idlh-nickel
    - text: Do not run low-aluminium NiAl (below about 40 at percent Al) in cyclic service at 1200 °C; NASA found its useful life under the test had ended.
      source: doychak1988
  mitigations:
    - text: Keep aluminium at or above about 40 at percent, the level NASA found necessary for protective alumina growth in 200-cycle tests at 1200 °C.
      source: doychak1988
      where: Cyclic Oxidation section and Conclusions 2)
    - text: 'Add zirconium: NASA reports that Zr additions reduce the scale growth rates of alloys in the beta-NiAl and two-phase fields.'
      source: doychak1988
      where: Summary of Results 4)
uses:
  - application: propulsion-and-tanks
    device: Turbine blades and vanes
    example: IC6, a Ni3Al-based blade and vane alloy, with an operating range of 1050 to 1100 °C as printed in the review; newer alloys IC6CX, IC10 and VKNA are given up to 1373 K.
    source: jozwik2015
    where: Section 3.1.1
  - application: electronics-and-chips
    device: Thin-foil MEMS and MECS parts and electronic substrates
    example: Ni3Al thin foils for MEMS and MECS parts, working up to 1300 °C; electronic substrates are given a requirement of at least 1000 °C in the review.
    source: jozwik2015
    where: Section 3.2 and Section 3.2.2
  - application: propulsion-and-tanks
    device: Single-crystal NiAl turbine blade (NASA reliability study)
    example: NASA Glenn's reliability analysis of single-crystal NiAl turbine blades. The report says the blades allow a reduction of density by as much as a third without significantly sacrificing strength.
    source: palko1995
    where: Abstract
  - application: propulsion-and-tanks
    device: NiAl bond coat under a thermal barrier coating on Ren N5 turbine blades
    example: A NiAl-AlN-CoCrAlY bond coat studied by NASA Glenn. The baseline TBC on Ren N5 lasted 188 plus or minus 19 cycles, and the new coat specimens stayed intact after 1000 cycles.
    source: nasa2003-bondcoat
    where: Test results paragraphs
supply:
  - subject: Nickel
    abundance: Global nickel resources are estimated to exceed 350 million tons, with 54 percent in laterites and 35 percent in magmatic sulfide deposits (USGS)
    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: New Caledonia
        share_percent: 3.6
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
      - country: China
        share_percent: 3.1
        year: 2025
      - country: Brazil
        share_percent: 1.8
        year: 2025
    critical_lists:
      - list: USGS 2025 final list of critical minerals
        listed: true
    recycling: Most secondary nickel came from the nickel content of stainless-steel scrap, and most recycled nickel went into new alloys (USGS).
    substitutes: []
    source: usgs-mcs2026-nickel
    where: Salient Statistics, World Mine Production and Reserves (2025e), Recycling; shares calculated here from the printed 2025e world total of 3900000 t
  - subject: Aluminum
    abundance: Global bauxite resources are estimated at 55 billion to 75 billion tons, sufficient for world demand for aluminum well into the future (USGS)
    producers:
      - country: China
        share_percent: 60.8
        year: 2025
      - country: India
        share_percent: 5.7
        year: 2025
      - country: Russia
        share_percent: 5.3
        year: 2025
      - country: Canada
        share_percent: 4.5
        year: 2025
      - country: United Arab Emirates
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: USGS 2025 final list of critical minerals
        listed: true
    recycling: In 2025 the US recovered about 3.6 million tons of aluminum from purchased scrap, and old scrap was about 28 percent of apparent consumption (USGS).
    substitutes: []
    source: usgs-mcs2026-aluminum
    where: World Smelter Production and Capacity table (2025e), Recycling; shares calculated here from the printed 2025e world total of 74000 thousand tons
documents:
  - title: Mineral Commodity Summaries 2026, Nickel (USGS)
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: Mineral Commodity Summaries 2026, Aluminum (USGS)
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
  - title: 'Applications of Ni3Al Based Intermetallic Alloys: Current Stage and Potential Perspectives (Materials 8, 2537)'
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5455558/
    year: 2015
  - title: The Oxidation of Ni-Rich Ni-Al Intermetallics, NASA TM 101455
    type: report
    url: https://ntrs.nasa.gov/api/citations/19890005862/downloads/19890005862.pdf
    year: 1988
  - title: Reliability Analysis of Single Crystal NiAl Turbine Blades, NASA TM-111138
    type: report
    url: https://ntrs.nasa.gov/citations/19960007500
    year: 1995
gaps:
  - 'Melting point of Ni3Al and NiAl: no measured value found in a source read in this run. The two Ni-Al-O reaction temperatures are recorded as properties but are not melting points.'
  - 'Yield strength against temperature for Ni3Al: the review shows it only in a figure and gives only the range 600 to 900 °C for the anomalous increase. No numbers were copied from the figure.'
  - 'Elongation, ductility and hardness of Ni3Al: no value found. The review was read for Table 2 and Sections 2, 3.1 and 3.2 only; its last 50000 characters were not read.'
  - 'Density, Young''s modulus and melting point of NiAl: the NASA sources read here give no numbers, so only qualitative statements are used.'
  - 'Oxidation mass-gain values for Ni3Al: none in the review text; NASA weight-change values are in figures only.'
  - 'Corrosion in sulfur, chloride, aqueous or molten-salt environments: no source read.'
  - 'Atomic oxygen, outgassing, radiation, thermal vacuum and flight data for Ni3Al or NiAl: none found.'
  - 'Ageing and long-term microstructure stability of Ni3Al and NiAl: not sourced.'
  - 'CAS number, compound-specific SDS and PubChem record for Ni3Al or NiAl: not found. Hazards use the nickel metal record.'
  - 'Aluminium powder flammability and dust-explosion data: not sourced.'
  - 'European Commission critical raw materials list status for nickel and aluminium: not checked in this run.'
  - 'Non-canonical property names used: specific_stiffness, specific_strength, stress_rupture_strength, activation_energy_isothermal_oxidation, reaction_temperature, liquid_composition. Not in property-canon.yaml.'
  - 'Recycling of Ni3Al or NiAl parts specifically: not sourced; the supply entries cover the base metals only.'
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 15
  note: Written by an AI assistant on 2026-10-26 from pages fetched in this run. Values are as printed in the cited sources; the melting point of Ni3Al and NiAl is not sourced.
sources:
  jozwik2015:
    title: 'Applications of Ni3Al Based Intermetallic Alloys: Current Stage and Potential Perspectives'
    id: doi:10.3390/ma8052537 (Materials 8, 2537-2568, PMC5455558)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5455558/
    year: 2015
    kind: paper
    license: MDPI open access (licence not read in this run)
  doychak1988:
    title: The Oxidation of Ni-Rich Ni-Al Intermetallics (NASA Technical Memorandum 101455)
    id: NASA TM 101455; NTRS 19890005862
    url: https://ntrs.nasa.gov/api/citations/19890005862/downloads/19890005862.pdf
    year: 1988
    kind: report
    license: public domain (NASA)
  palko1995:
    title: Reliability Analysis of Single Crystal NiAl Turbine Blades
    id: NASA TM-111138; NTRS 19960007500
    url: https://ntrs.nasa.gov/citations/19960007500
    year: 1995
    kind: report
    license: public domain (NASA)
  nasa2003-bondcoat:
    title: High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application
    id: NTRS 20050214552 (Research and Technology 2002)
    url: https://ntrs.nasa.gov/citations/20050214552
    year: 2003
    kind: report
    license: public domain (NASA)
  copland2007:
    title: Solidification Behavior of gamma-prime-Ni3Al Containing Alloys in the Ni-Al-O System
    id: NTRS 20070021778 (CALPHAD XXXVI, 2007)
    url: https://ntrs.nasa.gov/citations/20070021778
    year: 2007
    kind: paper
    license: public domain (NASA)
  pubchem-nickel:
    title: PubChem compound record, Nickel (CID 935; CAS 7440-02-0)
    id: CID 935; CAS 7440-02-0
    url: https://pubchem.ncbi.nlm.nih.gov/compound/935
    year: 2026
    kind: database
    license: public domain (NCBI)
  cdc-idlh-nickel:
    title: NIOSH IDLH entry, Nickel metal and other compounds (as Ni)
    id: CAS 7440-02-0
    url: https://www.cdc.gov/niosh/idlh/7440020.html
    year: 2026
    kind: database
    license: public domain (CDC)
  usgs-mcs2026-nickel:
    title: Mineral Commodity Summaries 2026, Nickel
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-aluminum:
    title: Mineral Commodity Summaries 2026, Aluminum
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, 60 minerals)
    id: USGS final 2025 list, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  wiki-nickel-aluminide:
    title: Nickel aluminide (Wikipedia)
    id: Wikipedia article, comparison table (structure labels only)
    url: https://en.wikipedia.org/wiki/Nickel_aluminide
    year: 2026
    kind: web
    license: CC BY-SA 4.0
story:
  recipe:
    line: Ni3Al is an ordered compound with three nickel atoms for each aluminium atom, and NiAl has one of each. The gamma-prime Ni3Al phase is the strengthening precipitate in nickel-based superalloys.
    parts:
      - name: Nickel
        symbol: Ni
        share: 75 percent of the formula in Ni3Al, 50 percent in NiAl
        role: The base metal, which forms the ordered lattice with aluminium and gives the compounds their high-temperature strength.
      - name: Aluminium
        symbol: Al
        share: 25 percent of the formula in Ni3Al, 50 percent in NiAl
        role: Forms the protective alumina scale on the surface in oxidizing service; lowering it below about 40 at percent weakens that scale in NASA's tests.
  risk_groups:
    - title: For people
      level: 2
      verdict: Nickel sensitiser and possible carcinogen
      lead: No hazard record for Ni3Al or NiAl was found, so the nickel metal classification is used. Nickel metal is a skin sensitiser and is classed as a possible carcinogen.
      points:
        - label: Skin
          line: The ECHA summary lists H317 (May cause an allergic skin reaction) for 99.9 percent of company reports.
        - label: Dust
          line: NIOSH gives an IDLH of 10 mg Ni/m3 and a REL of 0.015 mg/m3 TWA for nickel metal and compounds.
        - label: Cancer
          line: The ECHA summary lists H351 (Suspected of causing cancer) for 72.9 percent of reports.
    - title: If the part is heated and cycled
      level: 1
      verdict: Low-aluminium NiAl loses its scale at 1200 C
      lead: These results come from laboratory cyclic tests, not from flight or field service.
      points:
        - label: Scale
          line: After 200 one-hour cycles at 1200 °C, NiAl with less than about 40 at percent Al lost protection, according to NASA Lewis.
        - label: Low temperature
          line: NASA says leaner-aluminium NiAl alloys may gain ductility relative to stoichiometric NiAl, which is why they are studied.
    - title: Handling and storage
      level: 1
      verdict: Dust controlled by nickel exposure limits
      points:
        - label: Exposure
          line: Keep dust below the NIOSH REL of 0.015 mg/m3 and the OSHA PEL of 1 mg/m3 for nickel compounds.
  why: Nickel aluminides are intermetallic compounds of nickel and aluminium that keep their strength at high temperature because their atoms order into a fixed lattice. Ni3Al is the gamma-prime phase that strengthens nickel superalloys, and a review of Ni3Al alloys describes a strength that rises with temperature between about 600 and 900 °C. NiAl is valued for its protective alumina scale, and NASA finds stoichiometric NiAl less ductile than leaner alloys.
  uses:
    - where: Turbine blades and vanes
      line: The review describes Ni3Al-based blade and vane alloys, including IC6 with an operating range of 1050 to 1100 °C, and newer alloys up to 1373 K. The review presents these as Ni3Al-based alloys.
    - where: Thin-foil MEMS parts
      line: The review describes Ni3Al thin foils for MEMS and MECS parts working up to 1300 °C, and electronic substrates that need at least 1000 °C.
    - where: NiAl bond coats for turbine blades
      line: A NASA Glenn study of a NiAl-AlN-CoCrAlY bond coat on Ren N5 blades reported a baseline thermal barrier coating life of 188 plus or minus 19 cycles, and a coat whose specimens stayed intact after 1000 cycles.
  can_do:
    - label: Density
      benchmark: density
      value: 7.5 g/cm3
      line: A review gives Ni3Al a density of 7.5 g/cm3 for micro and nano forms. No density for NiAl was found in the sources read.
    - label: Stiffness
      benchmark: elastic_modulus
      value: 200 GPa
      line: Young's modulus of 200 GPa is printed for Ni3Al in the same review. The review gives no value for NiAl's stiffness.
    - label: Service temperature
      benchmark: max_service_temp
      value: Up to 1373 K
      line: Newer Ni3Al-based blade and vane alloys are given a service temperature of up to 1373 K, which is about 1100 °C. The review gives this limit as printed; no creep or life data were read for it.
    - label: Oxidation
      benchmark: activation_energy_isothermal_oxidation
      value: 60.8 kcal/mole/deg
      line: NASA Lewis measured an isothermal oxidation activation energy of 60.8 kcal/mole/deg for beta-NiAl with 0.04 at percent Zr, in the 1100 to 1400 °C range. Zr doping reduces scale growth, but the value is for NiAl, not Ni3Al.
  compare: Ni3Al is the gamma-prime phase that strengthens nickel superalloys, and the review presents it as a blade and vane alloy in its own right. NiAl is valued in the NASA studies mainly for its oxidation resistance, and NASA finds it less ductile than leaner-aluminium alloys. The table compares them on properties the sources give.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Service temperature
      benchmark: max_service_temp
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
  handling:
    - Keep dust below the NIOSH REL of 0.015 mg/m3 for nickel compounds and the OSHA PEL of 1 mg/m3.
    - Do not run NiAl with less than about 40 at percent Al in cyclic service at 1200 °C.
    - Use zirconium doping to slow scale growth, as NASA Lewis found.
  good_for:
    - Turbine blades and vanes that run near 1100 °C. The review gives a 1050 to 1100 °C operating range for IC6.
    - Oxidation-resistant hot-section coatings. The NiAl-AlN-CoCrAlY bond coat studied by NASA Glenn stayed intact on test specimens after 1000 cycles.
  watch_out:
    - Lower ductility for stoichiometric NiAl (NASA), and no sourced ductility value for Ni3Al.
    - Low-aluminium NiAl loses its scale under cyclic heating at 1200 °C.
    - No melting point, flight record or space-environment data were found for either compound.
  verdict: Nickel aluminides are strong, oxidation-resistant intermetallics for hot parts. The Ni3Al figures here are the strongest sourced ones, and NiAl needs enough aluminium to keep its scale. There is no space record and no sourced melting point.