Palladium alloys (Pd-Cu, Pd-Ni, Pd-Cr) Pd-Cu, Pd-Ni, Pd-Cr

spore: profile
id: palladium-alloys
spore_version: 0.2
family: precious-metals
name: Palladium alloys (Pd-Cu, Pd-Ni, Pd-Cr)
abbreviation: Pd-Cu, Pd-Ni, Pd-Cr
role: hydrogen separation membrane (Pd-Cu), electroplated contact coating (Pd-Ni) and high-temperature strain gage alloy (Pd-Cr)
category: metals
type: precious-metals
summary: |
  This profile covers three palladium alloy families other than palladium-silver. Pd-Cu alloys are hydrogen-permeable membranes that the US DOE tested for hydrogen separation from gasifier gas, including H2S-bearing streams. The NETL poster says 60 wt% Pd-40 wt% Cu gave the highest permeance, but only at 350 degC in the bcc phase, and the DOE slides place the switch between the B2 and fcc structures near 500 degC. Pd-Ni at about 80 wt% Pd and 20 wt% Ni is sold as a bright, ductile electroplated coating for reel-to-reel plating. Pd-13 wt% Cr is a NASA strain gage alloy: its bulk resistance is stable in air at 1000 degC, but unprotected fine wire gages degrade above 600 degC from oxidation. The sources read here do not give density or resistivity for Pd-Cu or wrought Pd-Ni.
best_for: Hydrogen passage in sulfur-bearing gas, where a Pd-Cu membrane resists H2S better than pure palladium (DOE slides, with the composition caveat in the story)
weakest_at: Pd-Cr fine wire above 600 degC in air, where unprotected gages oxidise and lose electrical performance (NASA)
identity:
  formula: Palladium-copper solid solutions (Pd-Cu, tested at 80, 60, 53 and 40 wt% Pd), palladium-nickel electrodeposit (about 80 wt% Pd, 20 wt% Ni) and palladium-chromium solid solution (Pd-13 wt% Cr, 23 at% Cr)
  crystal_system: Pd-Cu is fcc above about 500 degC and B2 below it for 60 wt% Pd (DOE slides), and 53 wt% Pd shows a bcc to fcc transition (NETL poster); Pd-Cr and Pd-Ni structures are not stated in the sources read
  source: morreale2009
  where: Technical accomplishments, Task 2 PdCu System (B2 and fcc structures for 60Pd-Cu and 80Pd-Cu)
tags:
  environments: []
  stresses: []
  applications:
    - cryogenic-fuel
    - structures
    - electronics-and-chips
properties:
  - benchmark: crystal_structure_switch_temperature
    label: Temperature where the most permeable Pd-Cu composition changes between B2 and fcc structure
    value: 500
    unit: degC
    scope: material
    conditions:
      below_500_degC: 60 wt% Pd, 40 wt% Cu, B2 structure
      above_500_degC: 80 wt% Pd, 20 wt% Cu, fcc structure
      basis: approximate, printed with a tilde as about 500 degC
    method: 'Statement on a DOE 2009 hydrogen program review slide: 60Pd-Cu has the highest permeability below about 500 degC and 80Pd-Cu above it'
    status: ground
    source: morreale2009
    where: Technical accomplishments, Task 2 PdCu System, first bullet group
  - benchmark: highest_permeance_temperature
    label: Temperature at which 60Pd-40Cu gives its highest hydrogen permeance (bcc)
    value: 350
    unit: degC
    scope: material
    conditions:
      composition: 60 wt% Pd, 40 wt% Cu
      structure: bcc
      basis: wt% as printed on the NETL poster
    method: 'Conclusions bullet on the NETL poster: 60Pd-40Cu yielded the highest permeance but only at 350 degC (bcc)'
    status: ground
    note: The poster says the highest permeance is reached only at this temperature, so it is not a working temperature for the alloy.
    source: howard2003
    where: Conclusions bullet list
  - benchmark: test_temperature_range
    label: Temperature range of the NETL Pd-Cu permeability study
    value: 350
    value_high: 900
    bound: range
    unit: degC
    scope: material
    conditions:
      basis: project objective, printed as 623 to 1173 K (350 to 900 degC)
      compositions: 80-20, 60-40, 53-47 and 40-60 wt% Pd-Cu
    method: Project objective bullet on the NETL poster
    status: ground
    source: howard2003
    where: Project objective bullets
  - benchmark: hydrogen_partial_pressure_range
    label: Hydrogen partial pressure range of the NETL Pd-Cu permeability study
    value: 0.1
    value_high: 2.6
    bound: range
    unit: MPa
    scope: material
    conditions:
      basis: project objective, printed as 0.1 to 2.6 MPa (14 to 380 psi)
      compositions: 80-20, 60-40, 53-47 and 40-60 wt% Pd-Cu
    method: Project objective bullet on the NETL poster
    status: ground
    source: howard2003
    where: Project objective bullets
  - benchmark: density
    label: Density of an electrodeposited Pd-Ni coating, 80 wt% Pd and 20 wt% Ni
    value: 10.8
    unit: g/cm3
    scope: material
    conditions:
      composition: 80 wt.% Pd, 20 wt.% Ni
      form: electrodeposit from PALLUNA 468 electrolyte, not a wrought alloy
    method: Printed in the Coating characteristics table of the Umicore electrolyte datasheet
    status: ground
    note: A coating value, not a wrought alloy value. No density for a wrought Pd-Ni alloy was found.
    source: umicore-palluna-468
    where: Coating characteristics table, Density row
  - benchmark: vickers_hardness
    label: Vickers hardness of an electrodeposited Pd-Ni coating, 80 wt% Pd
    value: 580
    value_high: 620
    bound: range
    unit: HV
    scope: material
    conditions:
      composition: 80 wt.% Pd, 20 wt.% Ni
      form: electrodeposit
      test: HV 0.015 (Vickers), approximate values as printed
    method: Printed in the Coating characteristics table, Hardness of deposit row
    status: ground
    source: umicore-palluna-468
    where: Coating characteristics table, Hardness of deposit row
  - benchmark: elongation
    label: Elongation of an electrodeposited Pd-Ni coating, 80 wt% Pd
    value: 3
    unit: '%'
    scope: material
    conditions:
      composition: 80 wt.% Pd, 20 wt.% Ni
      form: electrodeposit, approximate
    method: Printed as Approx. 3 % in the Coating characteristics table
    status: ground
    note: The same table reports a 2 um crack-free result on a 10 mm mandrel bend test, which describes the same coating.
    source: umicore-palluna-468
    where: Coating characteristics table, Elongation row
  - benchmark: max_coating_thickness
    label: Maximum thickness of the Pd-Ni electroplated coating
    value: 10
    unit: um
    scope: material
    conditions:
      process: PALLUNA 468 electrolyte, reel-to-reel plating
      composition: 80 wt.% Pd, 20 wt.% Ni
    method: Printed as Max. coating thickness 10 um in the Coating characteristics table
    status: ground
    source: umicore-palluna-468
    where: Coating characteristics table, Max. coating thickness row
  - benchmark: melting_point
    label: Melting point of the Pd-13 wt% Cr solid solution
    value: 1397
    unit: degC
    scope: material
    conditions:
      composition: Pd-13 wt% Cr (23 at% Cr, as printed in NASA CR-205287)
      form: bulk alloy
    method: Stated in the introduction of NASA TM 1993 as a relatively high melting point of 1397 degC
    status: ground
    source: nasa-tm-1993
    where: Introduction, first paragraph
  - benchmark: max_service_temp
    label: Upper temperature for unprotected fine-wire Pd-Cr strain gages in air
    value: 600
    unit: degC
    scope: material
    conditions:
      composition: Pd-13 wt% Cr
      form: unprotected free wire strain gage
      atmosphere: air
    method: 'NASA CR-205287 summary: unprotected free wire gages perform well only to 600 degC, and at higher temperatures severe oxidation degrades their electrical performance'
    status: ground
    note: A fine-wire gage limit. The bulk alloy is stable to a higher temperature (see resistance_stable_temperature_in_air).
    source: nasa-cr-205287
    where: Summary, first paragraph
  - benchmark: resistance_stable_temperature_in_air
    label: Temperature to which bulk Pd-Cr electrical resistance stays stable in air
    value: 1000
    unit: degC
    scope: material
    conditions:
      composition: Pd-13 wt% Cr
      form: bulk alloy
      atmosphere: air
    method: 'NASA CR-205287 summary: stable electrical resistance in air at 1000 degC, with a linear resistance-temperature curve to 1000 degC'
    status: ground
    note: Bulk alloy only. Fine wire and thin film oxidise sooner (see the 600 degC fine-wire limit).
    source: nasa-cr-205287
    where: Summary, first paragraph
corrosion:
  - environment: H2S introduced into hydrogen streams over Pd-Cu membranes
    headline: Pd-Cu responds differently to H2S by composition and temperature, and no test conditions are printed
    effect: The DOE slides group the alloys by H2S behaviour. 53 and 60 wt% Pd-Cu lose permeance at once through catalytic poisoning, with no significant surface scale. Pure Pd and 80 wt% Pd-Cu decay gradually with significant surface scale. Above about 450 degC, 80, 60 and 53 wt% Pd-Cu showed no change when H2S was introduced, and no surface scale. The slides print no H2S concentration, duration or pressure for these results.
    rating: moderate
    conditions:
      temperature: about 450 degC and above for the no-change result
      basis: qualitative groupings on the DOE slides
    source: morreale2009
    where: Technical accomplishments, Task 2 PdCu System, H2S bullet group
  - environment: Air at 600 degC and above, unprotected Pd-13 wt% Cr fine wire or ribbon
    headline: Fine Pd-Cr wire oxidises above 600 degC and loses electrical performance
    effect: NASA CR-205287 says unprotected free wire gages perform well only to 600 degC. At higher temperatures severe oxidation degrades their electrical performance. The same NASA summary says the oxidation mechanism is not fully understood, and a chromium oxide layer forms beneath a palladium-rich surface layer.
    rating: severe
    conditions:
      form: unprotected free wire or ribbon
      composition: Pd-13 wt% Cr
    source: nasa-cr-205287
    where: Summary, first paragraph
  - environment: Air, bulk Pd-13 wt% Cr alloy
    headline: A self-protective chromium oxide film gives bulk Pd-Cr good oxidation resistance
    effect: NASA TM 1993 says the formation of an adherent, self-protective chromium oxide film provides the bulk alloy with good oxidation resistance. It also says the alloy adheres strongly to alumina, which isolates the sensor from its substrate. No exposure time is given in the introduction.
    rating: low
    conditions:
      form: bulk alloy
      composition: Pd-13 wt% Cr
    source: nasa-tm-1993
    where: Introduction, paragraph 1
  - environment: Tarnishing and corrosion of the electroplated Pd-Ni coating
    headline: The Pd-Ni coating is described as resistant to tarnishing and corrosion
    effect: Umicore describes the ductile white Pd-Ni layers from PALLUNA 468 as showing good resistance to tarnishing and corrosion. The datasheet prints no exposure test, duration or standard.
    rating: low
    conditions:
      form: electrodeposited coating, 80 wt% Pd
      basis: manufacturer statement, not a test result
    source: umicore-palluna-468
    where: Introduction paragraph on layer properties
risks:
  hazards:
    - text: 'PubChem palladium record (CID 23938): 59.3% (365 of 616) of company reports say palladium does not meet GHS hazard criteria; 31.5% classify it as a flammable solid (H228, Danger).'
      ghs:
        - H228
      source: pubchem-pd
      where: Safety and Hazards, GHS Classification (aggregated block)
    - text: 'PubChem nickel record (CID 935), aggregated over 4778 reports: H317 99.9%, H372 99.7%, H351 72.9%, H350 22.5%, H412 47.2%, H341 13.5%, H360F 18% and H334 10.3%. Five reports say nickel does not meet GHS criteria.'
      ghs:
        - H317
        - H372
        - H351
        - H350
        - H412
        - H341
        - H360F
        - H334
      source: pubchem-ni
      where: Safety and Hazards, GHS Classification (aggregated block)
    - text: 'PubChem copper record (CID 23978): 52.5% (1818 of 3463) of reports do not meet GHS criteria. Reported codes are H400 43.1%, H411 22.5%, H302 21.7% and H410 18.8%.'
      ghs:
        - H400
        - H411
        - H302
        - H410
      source: pubchem-cu
      where: Safety and Hazards, GHS Classification (aggregated block)
    - text: 'PubChem chromium record (CID 23976): 50% (1202 of 2404) of reports do not meet GHS criteria. Reported codes are H317 20.7%, H334 20.3% and H319 19.1%.'
      ghs:
        - H317
        - H334
        - H319
      source: pubchem-cr
      where: Safety and Hazards, GHS Classification (aggregated block)
    - text: PubChem reports palladium as pyrophoric under a hydrogen atmosphere and to some extent in air. Palladium on carbon frequently ignites on first contact with methanol.
      ghs: []
      source: pubchem-pd
      where: Safety and Hazards, reactivity text for palladium
  failure_risks:
    - mode: Permeance loss from H2S in the gas stream
      trigger: H2S exposure of 53 and 60 wt% Pd-Cu membranes (test temperature not printed on the slide)
      consequence: The DOE slides report an immediate decrease in performance from catalytic poisoning, with no significant surface scale. The slides print no H2S concentration or duration for this result.
      severity: moderate
      source: morreale2009
      where: Technical accomplishments, Task 2 PdCu System, H2S bullet group
    - mode: Phase change in Pd-Cu membranes at the bcc to fcc transition
      trigger: Operation of 53 and 60 wt% Pd-Cu through the transition near 500 degC
      consequence: The NETL poster reports a distinct drop in permeance for 53Pd-47Cu and 60Pd-40Cu at the bcc to fcc transition. The 80Pd-20Cu and 40Pd-60Cu alloys showed no discontinuity over 350 to 900 degC.
      severity: moderate
      source: howard2003
      where: Conclusions bullet list
    - mode: Oxidation failure of unprotected Pd-Cr fine wire gages
      trigger: Operation above 600 degC in air without a protective coating
      consequence: NASA reports that severe oxidation degrades the electrical performance of unprotected free wire gages at higher temperatures. Oxidation is most serious in fine wire, so the sensor signal can drift or fail.
      severity: high
      source: nasa-cr-205287
      where: Summary, first paragraph
  side_effects: []
  handling:
    - text: Treat palladium catalyst powders, including palladium on carbon, as pyrophoric. Keep them away from methanol and hydrogen together (PubChem palladium record).
      source: pubchem-pd
      where: Safety and Hazards, reactivity text
    - text: Nickel is a sensitiser and a suspected carcinogen in several PubChem notifications. Control nickel and chromium dust and fume at the workplace, and check the supplier's safety data sheet for the powder or fume you handle.
      source: pubchem-ni
      where: Safety and Hazards, GHS Classification (H334, H350, H351)
  mitigations:
    - text: The NETL poster says composite Pd-Cu membranes need a passivation layer for high-temperature use.
      source: howard2003
      where: Conclusions bullet list
    - text: Above about 450 degC, the DOE slides show no change in Pd-Cu performance when H2S is introduced, with no surface scale, for 80, 60 and 53 wt% Pd.
      source: morreale2009
      where: Technical accomplishments, Task 2 PdCu System, H2S bullet group
uses:
  - application: cryogenic-fuel
    device: Pd-Cu composite membrane for hydrogen separation from gasifier gas
    example: The NETL and Parsons project tested Pd-Cu membranes from 350 to 900 degC and 0.1 to 2.6 MPa H2 partial pressure, aimed at gasification-related hydrogen separation. The poster says a 60Pd-40Cu membrane gave the highest permeance, but only at 350 degC. This is ground research, not a flight application.
    source: howard2003
    where: Project objective bullets and Conclusions
  - application: structures
    device: High-temperature strain gage of Pd-13 wt% Cr wire or ribbon
    example: NASA describes Pd-13 wt% Cr as a promising high-temperature strain gage alloy with a linear resistance-temperature curve to 1000 degC. Unprotected fine wire gages perform well only to 600 degC, which is why the gage needs protection above that temperature.
    source: nasa-cr-205287
    where: Summary, first paragraph
  - application: electronics-and-chips
    device: Electroplated Pd-Ni coating on reel-to-reel plated parts
    example: Umicore's PALLUNA 468 electrolyte deposits coatings of at least 80 wt% Pd and 20 wt% Ni at up to 10 um. The datasheet cites abrasion resistance, a high number of mating cycles and good solderability. These are manufacturer claims, not test results printed in the datasheet.
    source: umicore-palluna-468
    where: Advantages and Applications table; Coating characteristics table
supply:
  - subject: Palladium (through the platinum-group metals)
    abundance: World palladium mine production was 217,000 kg in 2024 and an estimated 190,000 kg in 2025 (USGS world totals, rounded).
    producers:
      - country: Russia
        share_percent: 41
        year: 2024
      - country: South Africa
        share_percent: 38.1
        year: 2024
      - country: Canada
        share_percent: 7.8
        year: 2024
      - country: Zimbabwe
        share_percent: 7
        year: 2024
      - country: United States
        share_percent: 4.7
        year: 2024
    critical_lists: []
    recycling: About 140,000 kg of palladium and platinum were recovered from scrap in 2025, including about 50,000 kg of palladium from US automobile catalytic converters.
    substitutes:
      - 'USGS: palladium has replaced platinum in most gasoline-engine catalytic converters, and about 25% of palladium can routinely be substituted for platinum in diesel converters.'
    source: usgs-mcs2026-pgm
    where: Salient Statistics; World Mine Production and Reserves table (2024 column, which sums to the 217,000 kg world total); Recycling; Substitutes. Producer shares are calculated by Space Mushroom as each country's 2024 kg divided by 217,000 kg, so they are approximate.
  - subject: Nickel
    abundance: World nickel mine production was an estimated 3,900,000 t of nickel content in 2025 and 3,710,000 t in 2024 (USGS world totals, rounded).
    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
      - country: New Caledonia
        share_percent: 3.6
        year: 2025
    critical_lists: []
    recycling: 'USGS: in 2025, nickel recovered from scrap accounted for approximately 60% of apparent consumption.'
    substitutes:
      - 'USGS: low-nickel, duplex and ultrahigh-chromium stainless steels have been substituted for austenitic grades, and titanium alloys can substitute for nickel-base alloys in corrosive environments.'
    source: usgs-mcs2026-nickel
    where: Salient Statistics; World Mine Production and Reserves table (2025e column); Recycling; Substitutes. Shares are calculated by Space Mushroom as each country's 2025e tonnes divided by the 3,900,000 t world total. The critical-mineral lists are not named in the text read, so the list is empty.
  - subject: Copper
    abundance: World copper mine production was an estimated 23,000 thousand t of copper content in 2025 and 23,000 thousand t in 2024 (USGS world totals, rounded).
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: Old (post-consumer) scrap, converted to refined metal, alloys and other forms, provided an estimated 160,000 tons of copper in 2025, and about 760,000 tons was recovered from new scrap.
    substitutes:
      - 'USGS: aluminum substitutes for copper in automobile radiators, cooling and refrigeration tube, electrical equipment and power cable.'
    source: usgs-mcs2026-copper
    where: Salient Statistics; World Mine and Refinery Production and Reserves table (mine production, 2025e column); Recycling; Substitutes; the critical list change is in the Commodity text. Shares are calculated by Space Mushroom as each country's 2025e thousand t divided by the 23,000 thousand t world total.
  - subject: Chromium
    abundance: World chromium mine production (chromium content) was an estimated 51,000 thousand t in 2025 and 49,600 thousand t in 2024 (USGS world totals, rounded).
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
      - country: Turkey
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
      - country: India
        share_percent: 5.9
        year: 2025
      - country: Zimbabwe
        share_percent: 3.9
        year: 2025
    critical_lists: []
    recycling: 'USGS: in 2025, recycled chromium contained in reported stainless-steel scrap receipts accounted for 21% of apparent consumption.'
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel, the leading end use, or in superalloys. Chromium-containing scrap can substitute for ferrochromium in some metallurgical uses.'
    source: usgs-mcs2026-chromium
    where: Salient Statistics; World Mine Production table (2025e column, thousand t of chromium content); Recycling; Substitutes. Shares are calculated by Space Mushroom as each country's 2025e thousand t divided by the 51,000 thousand t world total.
documents:
  - title: Development of Robust Metal Membranes for Hydrogen Separation (Morreale, DOE 2009 Hydrogen Program Review, slides)
    type: report
    url: https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/review09/pd_45_morreale.pdf
    year: 2009
  - title: The Hydrogen Permeability of Palladium-Copper Alloy Composite Membranes Over a Wide Range of Temperatures and Pressures (DOE NETL poster)
    type: report
    url: https://netl.doe.gov/File%20Library/Events/2003/materials/Howard_poster.pdf
    year: 2003
  - title: 'NASA TM 1993: Auger Electron Spectroscopy Study of Oxidation of a PdCr Alloy Used for High-Temperature Sensors'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19930014229/downloads/19930014229.pdf
    year: 1993
  - title: 'NASA CR-205287 (1997): Contact Sensor Attachment to Titanium Metal Composites, summary of PdCr strain gage oxidation'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19970027546/downloads/19970027546.pdf
    year: 1997
  - title: 'NASA TM 106725: Oxidation of Palladium-Chromium Alloys for High Temperature Applications'
    type: report
    url: https://ntrs.nasa.gov/api/citations/20060005568/downloads/20060005568.pdf
    year: 1994
  - title: 'Umicore PALLUNA 468 palladium-nickel electrolyte: technical specification sheet (version 16 April 2019)'
    type: datasheet
    url: https://umicore.com/en/api/fw/file/e6b7f5c432665144ea3a28bbf43c0a10a3fd7d50
    year: 2019
  - title: 'USGS Mineral Commodity Summaries 2026: Platinum-Group Metals'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: 'PubChem compound record: Palladium (CID 23938), GHS classification and reactivity'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23938/JSON
    year: 2026
  - title: 'PubChem compound record: Nickel (CID 935), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON
    year: 2026
  - title: 'PubChem compound record: Copper (CID 23978), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23978/JSON
    year: 2026
  - title: 'PubChem compound record: Chromium (CID 23976), GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    year: 2026
gaps:
  - No density, melting point or electrical resistivity for Pd-Cu alloys was found in any page or PDF read in this run. The DOE and NETL sources give permeability and phase behaviour only. The 2020 PMC review and the 2017 Conde review (only a bibliographic record was reachable) printed no Pd-Cu numbers in the text read.
  - No density, resistivity or mechanical values for a wrought Pd-Ni alloy (80/20 or any other composition) were found. The only Pd-Ni physical values are for the electrodeposited coating from Umicore.
  - Pd-Cr thin-film resistor data (sheet resistance, temperature coefficient of resistance, film thickness) were not found. The Pd-Cr sources read are bulk alloy and fine-wire strain gage reports, so the thin-film use in the brief is not sourced.
  - No designations (UNS, EN, ASTM, DIN, JIS) for Pd-Cu, Pd-Ni or Pd-Cr grades were printed in the sources read, so identity.designations is left out. PALLUNA 468 is an electrolyte trade name, not a grade designation. ASTM B867 for electroplated Pd-Ni was found only in a search snippet and was not opened.
  - Permeance values in the NETL poster and DOE slides are shown only as plots, and no axis values were read, so no permeance number is entered.
  - The H2S test concentration, duration and pressure are not printed on the DOE slides, so only the performance groupings are used.
  - No acid, salt-spray or sulfide corrosion test for Pd-Ni or Pd-Cr was found.
  - No space-environment data (vacuum outgassing, radiation, thermal cycling, atomic oxygen) for these alloys was found. The NASA sources are ground tests.
  - Critical-mineral lists for nickel and chromium were not named in the USGS text read, and the palladium summary names none, so those lists are empty. Copper is on the USGS 2025 list as printed in the 2026 copper summary. EU list status was not checked for these metals.
  - Vickers hardness, crystal structure switch temperature, test temperature range and hydrogen partial pressure range are not canonical names in spores/property-canon.yaml, so short snake_case names are used.
  - Production and refining routes for the Pd-Cu, Pd-Ni and Pd-Cr alloys were not sourced. No prices are given.
sources:
  morreale2009:
    title: Development of Robust Metal Membranes for Hydrogen Separation (DOE 2009 Hydrogen Program Review, slides)
    id: pd_45_morreale, DOE NETL, May 22 2009
    url: https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/review09/pd_45_morreale.pdf
    year: 2009
    kind: report
    license: US government presentation; linked not reproduced
  howard2003:
    title: The Hydrogen Permeability of Palladium-Copper Alloy Composite Membranes Over a Wide Range of Temperatures and Pressures (NETL poster)
    id: DOE NETL poster, Events/2003 file path
    url: https://netl.doe.gov/File%20Library/Events/2003/materials/Howard_poster.pdf
    year: 2003
    kind: report
    license: US government poster; linked not reproduced
  nasa-tm-1993:
    title: Auger Electron Spectroscopy Study of Oxidation of a PdCr Alloy Used for High-Temperature Sensors (NASA TM)
    id: NTRS 19930014229, March 1993
    url: https://ntrs.nasa.gov/api/citations/19930014229/downloads/19930014229.pdf
    year: 1993
    kind: report
    license: public domain (NASA)
  nasa-cr-205287:
    title: Contact Sensor Attachment to Titanium Metal Composites (NASA CR-205287, final report, PdCr oxidation summary)
    id: NASA CR-205287, NTRS 19970027546
    url: https://ntrs.nasa.gov/api/citations/19970027546/downloads/19970027546.pdf
    year: 1997
    kind: report
    license: public domain (NASA)
  nasa-tm-106725:
    title: Oxidation of Palladium-Chromium Alloys for High Temperature Applications (NASA TM 106725)
    id: NASA TM 106725, NTRS 20060005568, October 1994
    url: https://ntrs.nasa.gov/api/citations/20060005568/downloads/20060005568.pdf
    year: 1994
    kind: report
    license: public domain (NASA)
  umicore-palluna-468:
    title: PALLUNA 468 Palladium-Nickel Electrolyte, technical specification (Umicore)
    id: Version 16 April 2019
    url: https://umicore.com/en/api/fw/file/e6b7f5c432665144ea3a28bbf43c0a10a3fd7d50
    year: 2019
    kind: datasheet
    license: manufacturer document; linked not reproduced
  usgs-mcs2026-pgm:
    title: 'Mineral Commodity Summaries 2026: Platinum-Group Metals'
    id: USGS MCS 2026, data to 2025
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-platinum-group.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-nickel:
    title: 'Mineral Commodity Summaries 2026: Nickel'
    id: USGS MCS 2026, data to 2025
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-copper:
    title: 'Mineral Commodity Summaries 2026: Copper'
    id: USGS MCS 2026, data to 2025
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-chromium:
    title: 'Mineral Commodity Summaries 2026: Chromium'
    id: USGS MCS 2026, data to 2025
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-pd:
    title: PubChem compound record, Palladium (CID 23938)
    id: CID 23938
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23938/JSON
    year: 2026
    kind: database
    license: public domain (NCBI)
  pubchem-ni:
    title: PubChem compound record, Nickel (CID 935)
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/935/JSON
    year: 2026
    kind: database
    license: public domain (NCBI)
  pubchem-cu:
    title: PubChem compound record, Copper (CID 23978)
    id: CID 23978
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23978/JSON
    year: 2026
    kind: database
    license: public domain (NCBI)
  pubchem-cr:
    title: PubChem compound record, Chromium (CID 23976)
    id: CID 23976
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23976/JSON
    year: 2026
    kind: database
    license: public domain (NCBI)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 11
  unreachable: 2
  caveats: 6
  note: 'Written by an AI assistant on 2026-10-26. Values were read in PDF text from the DOE 2009 slides, the NETL poster, NASA TM 1993, NASA CR-205287 and TM 106725, USGS MCS 2026 (PGM, nickel, copper, chromium), and in PubChem JSON for palladium, nickel, copper and chromium. The Umicore datasheet was read as PDF text. Pd-Cu density and resistivity were not found. The Conde 2017 review and the PMC 2020 review were checked, and neither printed Pd-Cu numbers in the text read. Two sources were not reachable as full text: the Conde review and the ASTM B867 standard.'
story:
  recipe:
    line: These are palladium-rich binary alloys. Pd-Cu is a solid solution of copper in palladium, with the structure changing between fcc and B2 or bcc with composition and temperature. Pd-Ni is an electroplated coating of about 80 wt% palladium and 20 wt% nickel. Pd-Cr is a solid solution of 13 wt% chromium in palladium, equal to 23 at% chromium. The sources read do not describe the melting or casting route for the wrought alloys.
    parts:
      - name: Palladium
        symbol: Pd
        share: 40 to 80 wt% in the Pd-Cu compositions tested (NETL); 80 wt% in the Pd-Ni coating (Umicore); 87 wt% in the Pd-13 wt% Cr alloy (NASA)
        role: The matrix metal. Hydrogen passes through palladium, and the alloying element sets the crystal structure and permeance.
      - name: Copper
        symbol: Cu
        share: 20 to 60 wt% in the Pd-Cu compositions tested (NETL)
        role: Changes the crystal structure and sets the permeance and the sulfur response of the membrane. The 60 wt% Pd-Cu alloy forms a B2 phase below about 500 degC.
      - name: Nickel
        symbol: Ni
        share: 20 wt% in the Pd-Ni coating (Umicore)
        role: Co-deposits with palladium to form the alloy coating. The datasheet describes the layers as white, bright and ductile.
      - name: Chromium
        symbol: Cr
        share: 13 wt% in the Pd-Cr alloy (NASA)
        role: Forms a self-protective chromium oxide film, which gives bulk Pd-Cr its oxidation resistance. The film is not protective for fine wire above 600 degC.
  risk_groups:
    - title: For people
      level: 1
      verdict: Dust and catalyst powders need care
      lead: Solid alloy in use is a low concern. Palladium catalyst powders are pyrophoric, and nickel and chromium carry sensitiser codes in PubChem.
      points:
        - label: Palladium powder
          line: PubChem says palladium is pyrophoric under a hydrogen atmosphere and to some extent in air, and palladium on carbon frequently ignites on contact with methanol.
        - label: Nickel
          line: The PubChem nickel record shows H317 (allergic skin reaction) in 99.9% of 4778 reports and H372 (organ damage on repeated exposure) in 99.7%.
        - label: Chromium and copper
          line: About half the reports say chromium and copper do not meet GHS criteria. Those that do report sensitisation (chromium H317 and H334) and aquatic toxicity (copper H400 and H410).
    - title: If it fails
      lead: The documented failures are H2S poisoning and bcc to fcc permeance loss in Pd-Cu, and oxidation of fine Pd-Cr wire.
      points:
        - label: Pd-Cu and H2S
          line: The DOE slides show 53 and 60 wt% Pd-Cu losing permeance at once through poisoning, while Pd and 80 wt% Pd-Cu decay gradually with surface scale.
        - label: Phase change
          line: The NETL poster reports a distinct permeance drop for 53Pd-47Cu and 60Pd-40Cu at the bcc to fcc transition.
        - label: Pd-Cr fine wire
          line: NASA reports that unprotected fine wire gages perform well only to 600 degC and that severe oxidation degrades them above that temperature.
    - title: Handling and storage
      points:
        - label: Catalyst powders
          line: Keep palladium on carbon and palladium black away from methanol and hydrogen together.
        - label: Plating chemistry
          line: The Pd-Ni electrolyte is weakly ammoniacal, operates at about 45 degC and uses a platinum-titanium anode (datasheet). Handle it under the supplier's safety data sheet.
  why: Palladium alloys are used where palladium's hydrogen permeability, chemical stability or electrical contact behaviour matters more than cost. Pure palladium lets hydrogen pass but is brittle when cycled, so alloying changes both structure and permeance. Pd-Cu can be a more sulfur-tolerant membrane than pure palladium, according to the DOE slides, though the composition and temperature window matter. Pd-Ni gives a bright, ductile electroplated coating at about 80 wt% palladium, and Pd-13 wt% Cr has been used as a strain gage alloy that is stable in air to 1000 degC in bulk form, with a 600 degC limit for fine wire.
  uses:
    - where: Hydrogen separation from gasifier gas
      line: The NETL and Parsons project studied Pd-Cu membranes at 350 to 900 degC to support hydrogen separation from gasifier gas. The poster reports that 60Pd-40Cu gave the highest permeance, but only at 350 degC.
    - where: High-temperature strain gages
      line: NASA describes a Pd-13 wt% Cr alloy as a promising high-temperature strain gage material, with a linear resistance-temperature curve to 1000 degC. Unprotected fine wire gages perform well only to 600 degC.
    - where: Reel-to-reel electroplated coatings
      line: Umicore's PALLUNA 468 electrolyte deposits an 80 wt% Pd and 20 wt% Ni coating at up to 10 um for reel-to-reel plating. The datasheet cites abrasion resistance and a high number of mating cycles.
  can_do:
    - label: Hydrogen permeance
      value: Highest at 350 degC for 60Pd-40Cu
      line: In the NETL poster, 60Pd-40Cu gave the highest permeance but only at 350 degC in the bcc phase. Above about 500 degC, the DOE slides say 80Pd-Cu is the most permeable composition.
    - label: Strain gage range
      value: Stable to 1000 degC in bulk
      line: Bulk Pd-13 wt% Cr keeps stable electrical resistance in air at 1000 degC, with a linear resistance-temperature curve. Fine wire is limited to 600 degC unless protected.
    - label: Coating thickness
      value: Up to 10 um
      line: The Umicore datasheet gives a maximum coating thickness of 10 um for the Pd-Ni electrolyte, with a Vickers hardness of 580 to 620 HV and about 3 percent elongation in the deposit.
  compare: The three families serve different jobs and have different data. Pd-Cu is a membrane alloy with no density or resistivity found in the sources read. The Pd-Ni data are for an electroplated coating, not a wrought alloy, so they are not directly comparable with bulk values. Pd-13 wt% Cr has the only bulk melting point (1397 degC) and the only service temperature data here. The palladium-silver profile covers the 75/25 membrane alloy and the PdAg70 contact grade, which are separate compositions.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Upper service temperature
      benchmark: max_service_temp
  handling:
    - Treat palladium catalyst powders, including palladium on carbon, as pyrophoric. Keep them away from methanol and hydrogen together.
    - Control nickel and chromium dust and fume. Both carry sensitiser codes in PubChem.
    - Keep Pd-Cr fine wire below 600 degC in air unless it is protected.
    - Use a passivation layer on Pd-Cu composite membranes used at high temperature, as the NETL poster advises.
    - Store and handle the Pd-Ni electrolyte under the supplier's safety data sheet.
  good_for:
    - Hydrogen passage through thin, sulfur-bearing gas. Pd-Cu membranes are reported to resist H2S better than pure palladium, with the composition caveat.
    - Bright, ductile, abrasion-resistant plated coatings. Umicore cites a high number of mating cycles.
    - Bulk strain gage service up to 1000 degC in air. Pd-13 wt% Cr is stable in bulk form.
  watch_out:
    - Pd-Cu membranes lose permeance at the bcc to fcc transition, near 500 degC, and 53 and 60 wt% Pd-Cu lose performance at once to H2S.
    - Unprotected Pd-Cr fine wire oxidises above 600 degC in air and loses electrical performance.
    - The Pd-Ni data are for a coating, and the Pd-Cu density and resistivity were not found. Do not use coating values as wrought alloy values.
    - Palladium supply is concentrated. Russia (41 percent) and South Africa (38 percent) together mined most of the 2024 world total in the USGS table.
  verdict: 'Palladium alloys suit specific jobs: Pd-Cu for sulfur-bearing hydrogen separation within its composition and temperature window, Pd-Ni for coatings, and Pd-Cr for bulk strain gages up to 1000 degC. The sources here do not yet give the density or resistivity needed for a full Pd-Cu or Pd-Ni design.'