spore: profile
id: gold-alloys
spore_version: 0.2
family: precious-metals
name: Gold alloys
abbreviation: Au alloys
role: electrical contact and microconnector metal, brazing filler, and jewellery alloy
category: metals
type: precious-metals
summary: |
  Gold is alloyed with nickel, palladium, silver, iron and antimony to change its strength, melting point and electrical behaviour. The best-documented grade in this file, Au82/Ni18, melts at 955 degC, has an electrical resistivity of 15.5 microohm cm and a tensile strength of 616 MPa as a rolled foil. A brazing filler of the same composition is specified at 949 degC solidus-liquidus. Au75/Pd25 foil melts at 1410 degC. An Au-Fe alloy with 0.07 at% iron is used as a thermocouple element down to very low temperatures (NBS, 1972).
best_for: Contacts, microconnectors and brazes that must resist oxidation and sulphur attack in a small volume (supplier statements for Au-Ni and Au-Pd)
weakest_at: Strength and hardness are set by the alloy and temper, and most alloys here have only supplier figures; Au-Ag and Au-Sb have almost no property data in this file
identity:
  formula: Au82/Ni18 (gold 82, nickel 18, as listed); binary family Au-Ni, Au-Pd, Au-Ag, Au-Fe and Au-Sb
  source: goodfellow-au82ni18
  where: Product page, composition line (Au 82/Ni 18); Au75/Pd25 composition from goodfellow-au75pd25; Au-Fe concentrations from sparks1972 (Au-0.02 at% Fe and Au-0.07 at% Fe)
  designations:
    - system: AMS
      code: AMS4787
      note: brazing filler metal, 82Au-18Ni, 1740 F solidus-liquidus; revision C
      source: ams4787c
      where: Title of the specification
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - electronics-and-chips
    - thermal-control
properties:
  - benchmark: density
    label: Density, Au82/Ni18 foil
    value: 15.8
    unit: g/cm3
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, film or sheet, as rolled
      temperature: not stated
    method: Physical property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Physical block, Density
  - benchmark: melting_point
    label: Melting point, Au82/Ni18
    value: 955
    unit: degC
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, as rolled
      note: single value printed, no range
    method: Thermal property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Thermal block, Melting point
  - benchmark: melting_point
    label: Solidus-liquidus temperature, 82Au-18Ni brazing filler
    value: 949
    unit: degC
    scope: material
    conditions:
      composition: 82Au-18Ni
      basis: specification title gives 1740 F (949 degC)
      revision: AMS4787 revision C, dated 4/1/1990
    method: Value printed in the title of the SAE specification
    status: ground
    note: The specification title gives 1740 F (949 degC). A later revision of the specification exists (per a search result, not read here), so check the current revision before quoting this value.
    source: ams4787c
    where: Title of AMS4787C; Scope
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Au82/Ni18 foil
    value: 15.5
    unit: microohm cm
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, as rolled
      temperature: not stated
    method: Electrical property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Electrical block, Electrical resistivity
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Au82/Ni18 foil
    value: 49
    unit: W/(m K)
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      temperature: 23 degC
    method: Thermal property printed on the supplier product page, value at 23 degC
    status: ground
    note: The supplier material-information page describes the alloy as having a thermal conductivity of approximately 150 W/(m K) without a table. The product page value of 49 at 23 degC is used here; the two supplier pages disagree.
    source: goodfellow-au82ni18
    where: Product page, Thermal block, Thermal conductivity, 49 at 23 degC
  - benchmark: cte
    label: Coefficient of thermal expansion, Au82/Ni18
    value: 14
    unit: ppm/K
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      temperature_range: 20 to 700 degC
    method: Printed by the supplier as x10-6 K-1, which is the same unit as ppm/K; no numeric conversion made
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Thermal block, Coefficient of thermal expansion
  - benchmark: youngs_modulus
    label: Modulus of elasticity, Au82/Ni18 foil
    value: 112
    unit: GPa
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, as rolled
    method: Mechanical property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Mechanical block, Modulus of elasticity
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Au82/Ni18 foil
    value: 616
    unit: MPa
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, as rolled
      test_standard: not stated
    method: Mechanical property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Mechanical block, Tensile strength
  - benchmark: elongation
    label: Elongation at break, Au82/Ni18 foil
    value: 13
    unit: '%'
    scope: material
    conditions:
      composition: Au 82 / Ni 18 as listed
      form: foil, as rolled
      test_standard: not stated
    method: Mechanical property printed on the supplier product page
    status: ground
    source: goodfellow-au82ni18
    where: Product page, Mechanical block, Elongation at break
  - benchmark: melting_point
    label: Melting point, Au75/Pd25 foil
    value: 1410
    unit: degC
    scope: material
    conditions:
      composition: Au 75 / Pd 25
      form: foil, 0.2 mm thick, as rolled
    method: Thermal property printed on the supplier product page
    status: ground
    source: goodfellow-au75pd25
    where: Product page, Thermal block, Melting point
  - benchmark: density
    label: Density, Au75/Pd25 foil
    value: 16
    unit: g/cm3
    scope: material
    conditions:
      composition: Au 75 / Pd 25
      form: foil, 0.2 mm thick, as rolled
    method: Physical property printed on the supplier product page, printed without decimals
    status: ground
    note: The page prints 16 with no decimals, so the value is likely rounded.
    source: goodfellow-au75pd25
    where: Product page, Physical block, Density
  - benchmark: melting_point
    label: Eutectic temperature, Au-Sb (24.8 wt% Sb)
    value: 633
    unit: K
    scope: material
    conditions:
      composition: Sb 24.8 wt%, gold remainder
      basis: gold binary eutectic alloy row in the table
    method: Table of gold binary eutectic alloys; the row prints 633 K and 680 F (633 K is 360 degC)
    status: ground
    note: The table lists the value only in kelvin. No Au-Sb density, resistivity or hardness was found in a page read in this run.
    source: engtoolbox-gold
    where: Table, row Sb - Antimony (Stibium), Melting point (K)
  - benchmark: seebeck_coefficient
    label: Seebeck coefficient, KP versus Au-0.07 at% Fe thermocouple at 20 K
    value: 16.966
    unit: microV/K
    scope: material
    conditions:
      pair: KP versus Au-0.07 at% Fe, pair output, not the alloy alone
      temperature: 20 K
      wire_diameters: 0.127 mm, 0.152 mm and 0.254 mm (Table 1)
    method: Value printed in a table of the NBS paper for one thermocouple pair
    status: ground
    note: Seebeck coefficient is not in spores/property-canon.yaml, so this uses a short snake_case name. The same paper gives a low-temperature maximum of 16.82 microV/K at 17.9 K for the same pair.
    source: sparks1972
    where: Table 5 (KP versus Au-0.07 at% Fe at 20 K); Table 3 for the low-temperature maximum
corrosion:
  - environment: Air and high-temperature oxidation (Au-Ni, supplier statements only)
    headline: Supplier says Au-Ni resists oxidation and corrosion; no test data were read.
    effect: The Goodfellow material page describes Au-Ni as having exceptional corrosion resistance and as resistant to oxidation, and says a trace of platinum and yttrium improves sulfurization resistance. It gives no test conditions, times or measured rates.
    rating: low
    conditions:
      basis: supplier statements without test data
      composition: Au82/Ni18 family
    source: goodfellow-aunimaterial
    where: Lead paragraph; Material Overview
  - environment: Sulfur-bearing atmospheres (Au-Ni)
    headline: Sulfurization resistance is claimed through trace platinum and yttrium additions; no rate was read.
    effect: The supplier page says Au-Ni alloys gain sulfurization resistance from trace additions of platinum and yttrium, which lengthen component life in harsh environments. The page gives no exposure data.
    rating: unknown
    conditions:
      basis: supplier claim for alloys with trace additions; plain Au82/Ni18 not tested here
    source: goodfellow-aunimaterial
    where: Material Overview, sulfurization sentence
  - environment: Corrosive and high-vacuum aerospace environments (Au-Pd, supplier statements only)
    headline: Supplier describes the Au-Pd foil as combining gold's corrosion resistance with palladium's hardness.
    effect: Goodfellow says the Au75/Pd25 foil merges the corrosion resistance and conductivity of gold with the hardness and wear resistance of palladium, and it lists corrosion-resistant aerospace components as an application. No corrosion test is quoted.
    rating: low
    conditions:
      basis: supplier product description without test data
      composition: Au 75 / Pd 25
    source: goodfellow-au75pd25
    where: Product description; Applications
  - environment: Au-Fe thermocouple use at cryogenic temperatures
    headline: No corrosion test was read; the NBS paper reports the alloys as metallurgically stable.
    effect: Sparks (NBS, 1972) calls the Au-Fe alloys metallurgically stable and says heat treatment matters for their thermopower. Corrosion and oxidation were not studied in the paper.
    rating: unknown
    conditions:
      basis: statement on metallurgical stability; no corrosion test
      temperature_range: 5 to 280 K in the paper
    source: sparks1972
    where: Introduction and Results
  - environment: Not read (Au-Ag and Au-Sb)
    headline: No corrosion data for these two alloy systems were read in this run.
    effect: The Wikipedia electrum article gives the composition range and the natural occurrence of Au-Ag, but it does not discuss corrosion. Au-Sb corrosion was not found.
    rating: unknown
    conditions:
      basis: composition and occurrence only
    source: wiki-electrum
    where: Lead paragraph; Natural occurrence
risks:
  hazards:
    - text: Nickel, the second metal in Au-Ni and in white gold, is a skin sensitiser. PubChem lists the H317 allergic-skin-reaction statement in 99.9% of company reports and the H351 suspected-cancer statement in 72.9%.
      ghs:
        - H317
        - H351
      source: pubchem-nickel
      where: Safety and Hazards, GHS Classification (CID 935)
    - text: Pure gold does not meet GHS hazard criteria in 99.2% (502 of 506) of company reports on PubChem. No GHS classification was read for the Au-Pd, Au-Ag, Au-Fe or Au-Sb alloys.
      ghs: []
      source: pubchem-gold-ghs
      where: GHS Classification (CID 23985)
  failure_risks:
    - mode: Output scatter between thermocouple wires
      trigger: Au-Fe wire from different melts, or wire in a different annealing state
      consequence: Sparks found wire-to-wire output differences of 2 to 4 percent typically and up to about 9 percent at 4 to 20 K. Heat treatment of Au-0.07 at% Fe was critical, and annealing raised the thermopower.
      severity: moderate
      source: sparks1972
      where: Results, wire-to-wire comparison; Discussion of heat treatment
  side_effects:
    - text: Nickel in white gold and Au-Ni can cause an allergic skin reaction when worn for long periods. Wikipedia notes that many countries do not use nickel in white gold.
      affects: Skin of wearers sensitive to nickel
      source: wiki-white-gold
      where: Composition and nickel allergy sections
  handling:
    - text: Sparks annealed one Au-Fe specimen at 350 degC for 20 minutes in air before testing. Annealing raised the thermopower, so the heat treatment must be recorded with each wire.
      source: sparks1972
      where: Specimen preparation; Results
    - text: The Goodfellow foil is supplied as rolled, with a thickness of 0.2 mm for Au75/Pd25. Shape it as foil, because the supplier gives no hot-working data.
      source: goodfellow-au75pd25
      where: Product page, Form and Temper
  mitigations:
    - text: Sparks states that the reference data can be adjusted with spot calibration on particular wires, which handles the wire-to-wire scatter.
      source: sparks1972
      where: Discussion of calibration
uses:
  - application: electronics-and-chips
    device: High-reliability electrical contacts and microconnectors
    example: Goodfellow says Au82/Ni18 is extensively used in high-reliability electrical contacts and brazing alloys, and that Au-Ni electrodeposited coatings are used in microconnectors and semiconductor devices.
    source: goodfellow-aunimaterial
    where: Applications and Advantages
  - application: electronics-and-chips
    device: Brazing filler for ceramics, steels and refractory metals in electronic packaging
    example: The AMS4787 specification covers an 82Au-18Ni brazing filler in wire, rod, sheet, strip, foil, pig, powder, shot and chips. Goodfellow says the same alloy joins ceramics, steels and refractory metals in electronic packaging.
    source: ams4787c
    where: Scope; Goodfellow Applications and Advantages (goodfellow-aunimaterial)
  - application: electronics-and-chips
    device: Precision connector contacts and microelectronic bonding layers
    example: Goodfellow lists precision connector contacts, bonding layers in microelectronics and corrosion-resistant aerospace components as uses of the Au75/Pd25 foil.
    source: goodfellow-au75pd25
    where: Applications
  - application: thermal-control
    device: Cryogenic thermocouple element (Au-Fe against KP or chromel)
    example: NBS calls Au-Fe alloys the most promising thermoelement for very low temperatures. The paper measures the pair from 5 to 280 K and reports usable sensitivity below 4 K.
    source: sparks1972
    where: Introduction; Results (temperature range)
supply:
  - subject: Gold (base metal of every alloy in this file)
    abundance: 'Consumption in 2025: jewelry 40%, electrical and electronics 7% (USGS, share of global consumption)'
    producers:
      - country: China
        share_percent: 11.5
        year: 2025
      - country: Russia
        share_percent: 9.4
        year: 2025
      - country: Australia
        share_percent: 8.5
        year: 2025
      - country: Canada
        share_percent: 6.1
        year: 2025
      - country: United States
        share_percent: 4.8
        year: 2025
    critical_lists:
      - list: Not checked in this run
        listed: false
    recycling: 'USGS: about 90 tons of scrap were recycled in 2025, equal to about 60% of reported consumption.'
    substitutes:
      - 'USGS: palladium, platinum and silver may substitute for gold; base metals clad with gold alloys economise on gold in electrical and electronic products.'
    source: usgs-gold
    where: World Mine Production table, 2025e (world total 3300 t; shares calculated by Space Mushroom); Consumption; Recycling; Substitutes
  - 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: New Caledonia
        share_percent: 3.6
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: Not checked in this run
        listed: false
    recycling: 'USGS: nickel recovered from scrap was about 60% of apparent consumption in 2025, mostly as stainless-steel scrap.'
    substitutes:
      - 'USGS: low-nickel, duplex and ultrahigh-chromium stainless steels substitute for austenitic grades in some uses.'
    source: usgs-nickel
    where: World Mine Production table, 2025e (world total 3900000 t; shares calculated by Space Mushroom); Recycling; Substitutes
  - subject: Silver
    producers:
      - country: China
        share_percent: 13.1
        year: 2025
      - country: Bolivia
        share_percent: 5.8
        year: 2025
      - country: Chile
        share_percent: 5.4
        year: 2025
      - country: United States
        share_percent: 4.2
        year: 2025
    critical_lists:
      - list: USGS 2025 Final List of Critical Minerals (silver added in 2025)
        listed: true
    recycling: 'USGS: about 1000 tons of silver was recovered from scrap in 2025, about 11% of apparent consumption.'
    substitutes:
      - 'USGS: digital imaging, reduced-silver film and non-silver batteries substitute for silver in some uses; aluminum and rhodium may replace silver in others.'
    source: usgs-silver
    where: Introduction (critical-minerals list); World Mine Production table, 2025e (world total 26000 t; shares calculated by Space Mushroom); Recycling; Substitutes
  - subject: Antimony
    producers:
      - country: China
        share_percent: 36.4
        year: 2025
      - country: Bolivia
        share_percent: 4.5
        year: 2025
      - country: Burma
        share_percent: 4.1
        year: 2025
      - country: Australia
        share_percent: 1.2
        year: 2025
    critical_lists:
      - list: Not checked in this run
        listed: false
    recycling: 'USGS: most secondary antimony is recovered at secondary lead smelters as antimonial lead.'
    substitutes:
      - 'USGS: chromium, tin, titanium, zinc and zirconium compounds substitute for antimony chemicals in enamels, paint and pigments.'
    source: usgs-antimony
    where: World Mine Production table, 2025e (world total 110000 t; shares calculated by Space Mushroom, listed countries only); Recycling; Substitutes
media: []
documents:
  - title: Goodfellow Au82-Ni18 foil product page (gold-nickel foil, as rolled)
    type: datasheet
    url: https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group
    year: 2026
  - title: 'Goodfellow: Gold-Nickel alloy material information'
    type: datasheet
    url: https://www.goodfellow.com/usa/resources/gold-nickel-alloy-material-information/
    year: 2026
  - title: Goodfellow Au75/Pd25 gold-palladium alloy foil product page
    type: datasheet
    url: https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group
    year: 2026
  - title: AMS4787C brazing filler metal, high temperature 82Au-18Ni (SAE)
    type: standard
    url: https://saemobilus.sae.org/content/AMS4787C
    year: 1990
  - title: 'Low Temperature Thermocouples: KP, normal silver and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe (NBS, open access)'
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6706574
    year: 1972
  - title: 'USGS Mineral Commodity Summaries 2026: Gold'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gold.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: Silver'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Antimony'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf
    year: 2026
  - title: PubChem compound record Nickel (CID 935), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Nickel
    year: 2026
  - title: PubChem compound record Gold (CID 23985), GHS classification
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23985
    year: 2026
gaps:
  - 'Au-Ni contact grade hardness and conductivity (for example AuNi5): the Heraeus product pages returned 404 in this run, so no value was read.'
  - 'Au-Ag: no numeric property (density, melting range, resistivity, hardness) was read in a source this run. Wikipedia gives only the 20 to 80% gold range and the natural occurrence.'
  - 'Au-Sb: only the eutectic row (24.8 wt% Sb, 633 K) was read. No density, resistivity, hardness or corrosion data. Antimony GHS classification was not retrieved (PubChem antimony REST request failed).'
  - 'Au-Fe: only dilute compositions (Au-0.02 at% Fe and Au-0.07 at% Fe) were read; no commercial wire specification or density, melting point or tensile value was read.'
  - 'Palladium supply: the USGS Platinum-Group Metals chapter could not be retrieved (the PDF URL returned an HTML page), so no palladium producer shares are given.'
  - 'EU nickel release limits (REACH Annex XVII entry 27, EN 1811): the numeric limits were not read. The TUV page returned 403 and the EUR-Lex page was empty. Nickel release limits are therefore not quoted.'
  - 'Au-Ni or Au-Pd corrosion test data (salt spray, humidity, sulfur exposure): none found; the corrosion entries rest on supplier statements only.'
  - 'Jewellery grades (karat composition tables for gold alloys): only the Wikipedia white gold composition statements were read; no grade table was checked against a manufacturer page.'
  - 'Crystal structure and space group of the alloys: not read in this run.'
  - 'Au-Ag and Au-Pd wire or foil in a space application: no flight, vacuum or radiation result was found for these alloys.'
  - 'Au82/Ni18 thermal conductivity conflict: product page 49 W/(m K) at 23 degC against about 150 W/(m K) on the material-information page (no table).'
  - AMS4787 revision C (1990) was read; a later revision (H) exists per a search result that was not opened, so the current value may differ.
  - The AWS BAu-4 designation was not checked against an AWS page and is left out of designations.
  - Seebeck coefficient is not in property-canon.yaml; the benchmark name seebeck_coefficient is a short snake_case name used here.
  - Pure gold reference values were not re-read for this file; see gold.yaml for those.
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 13
  unreachable: 2
  caveats: 4
  note: Written by an AI assistant on 2026-10-26. Au82/Ni18 values, Au75/Pd25 values, the AMS4787 solidus-liquidus, the Au-Sb eutectic row, the Au-Fe Seebeck values and the USGS shares were read from pages fetched in this run. Heraeus contact-grade pages returned 404 and the PGM chapter was not retrieved, so those are gaps. The Au82/Ni18 thermal conductivity disagrees between two supplier pages.
sources:
  goodfellow-au82ni18:
    title: 'Goodfellow: Gold-Nickel alloy foil (Au82-Ni18) product page'
    id: Goodfellow product page, Au 82 / Ni 18, foil as rolled
    url: https://www.goodfellow.com/usa/gold-nickel-alloy-foil-au82-ni18-group
    year: 2026
    kind: datasheet
    license: supplier product page, linked not reproduced
  goodfellow-aunimaterial:
    title: 'Goodfellow: Gold-Nickel alloy material information (Au82/Ni18)'
    id: Goodfellow resources page, gold-nickel material information
    url: https://www.goodfellow.com/usa/resources/gold-nickel-alloy-material-information/
    year: 2026
    kind: web
    license: supplier web page, linked not reproduced
  goodfellow-au75pd25:
    title: 'Goodfellow: Gold-Palladium alloy foil (Au75/Pd25) product page'
    id: Goodfellow product page, Au 75 / Pd 25, 0.2 mm foil
    url: https://www.goodfellow.com/usa/gold-palladium-alloy-foil-au75-pd25-group
    year: 2026
    kind: datasheet
    license: supplier product page, linked not reproduced
  ams4787c:
    title: 'AMS4787C: Brazing filler metal, high temperature 82Au-18Ni, 1740 F (949 C) solidus-liquidus temperature'
    id: SAE AMS4787 revision C, dated 4/1/1990
    url: https://saemobilus.sae.org/content/AMS4787C
    year: 1990
    kind: standard
    license: SAE International, title and scope read, text not reproduced
  sparks1972:
    title: 'Low Temperature Thermocouples: KP, normal silver and copper versus Au-0.02 at% Fe and Au-0.07 at% Fe'
    id: Sparks, L. L., J. Res. Natl. Bur. Stand. A 76A(3), 263-283, doi 10.6028/jres.076A.029
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC6706574
    year: 1972
    kind: paper
    license: public domain (NBS)
  engtoolbox-gold:
    title: 'Engineering ToolBox: Gold binary eutectic alloys and melting points'
    id: Engineering ToolBox, gold alloys melting points table (cited 2008 on page)
    url: https://www.engineeringtoolbox.com/gold-alloys-melting-points-d_1434.html
    year: 2008
    kind: web
    license: web page, linked not reproduced
  usgs-gold:
    title: 'Mineral Commodity Summaries 2026: Gold'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gold.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-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-silver:
    title: 'Mineral Commodity Summaries 2026: Silver'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-antimony:
    title: 'Mineral Commodity Summaries 2026: Antimony'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  pubchem-nickel:
    title: PubChem compound record, Nickel (CID 935), GHS classification
    id: CID 935
    url: https://pubchem.ncbi.nlm.nih.gov/compound/Nickel
    year: 2026
    kind: database
    license: public domain (NCBI)
  pubchem-gold-ghs:
    title: PubChem compound record, Gold (CID 23985), GHS classification
    id: CID 23985
    url: https://pubchem.ncbi.nlm.nih.gov/compound/23985
    year: 2026
    kind: database
    license: public domain (NCBI)
  wiki-white-gold:
    title: 'Wikipedia: White gold'
    id: en.wikipedia.org, White gold article
    url: https://en.wikipedia.org/wiki/White_gold
    year: 2026
    kind: web
    license: CC BY-SA 4.0
  wiki-electrum:
    title: 'Wikipedia: Electrum'
    id: en.wikipedia.org, Electrum article
    url: https://en.wikipedia.org/wiki/Electrum
    year: 2026
    kind: web
    license: CC BY-SA 4.0
story:
  recipe:
    line: Au82/Ni18 is gold and nickel in an 82 to 18 ratio, sold by the supplier as foil and spooled wire. Au75/Pd25 is gold and palladium in a 75 to 25 ratio. The Au-Fe thermocouple alloys contain 0.02 and 0.07 at% iron, and the Au-Sb eutectic is 24.8% antimony by weight.
    parts:
      - name: Gold
        symbol: Au
        share: 82 wt% (Au-Ni) or 75 wt% (Au-Pd); remainder of each alloy
        role: Base metal. The supplier describes gold as resisting oxidation and carrying the electrical conduction in contacts.
      - name: Nickel
        symbol: Ni
        share: 18 wt% in Au82/Ni18
        role: Alloying partner. Au82/Ni18 melts at 955 degC (supplier). Supplier notes trace platinum and yttrium improve sulfurization resistance.
      - name: Palladium
        symbol: Pd
        share: 25 wt% in Au75/Pd25
        role: Hardness and wear resistance. The Au-Pd foil melts at 1410 degC.
      - name: Iron
        symbol: Fe
        share: 0.07 at% (Au-0.07 at% Fe); 0.02 at% in the other specimen
        role: Gives the Au-Fe alloy its thermoelectric behaviour at very low temperature.
      - name: Antimony
        symbol: Sb
        share: 24.8 wt% at the eutectic
        role: Forms the Au-Sb eutectic at 633 K. Other Au-Sb compositions were not read.
  risk_groups:
    - title: For people
      level: 0
      verdict: Gold is not hazardous; nickel is a sensitiser
      lead: Gold on its own is classed as not hazardous in most company reports, but nickel in an alloy can cause skin allergy.
      points:
        - label: Nickel
          line: PubChem lists the allergic-skin-reaction statement for nickel in 99.9% of company reports. Nickel is in Au-Ni and in most white gold.
        - label: Gold
          line: Pure gold does not meet GHS hazard criteria in 99.2% (502 of 506) of company reports on PubChem.
        - label: Other alloys
          line: No GHS classification was read for the Au-Pd, Au-Ag, Au-Fe or Au-Sb alloys.
    - title: Heating and brazing
      level: 1
      verdict: Brazing near 949 °C; fumes not assessed
      lead: Au-Ni brazing filler melts at about 949 °C. Fume and flux hazards were not read in this run.
      points:
        - label: Solidus-liquidus
          line: The AMS specification gives 949 °C (1740 F) for the 82Au-18Ni filler metal.
        - label: Joint
          line: The brazing range is set by the alloy, so keep the joint below the melting point of the parts being joined.
    - title: Handling
      points:
        - label: Heat treatment
          line: Annealing changes the thermopower of Au-Fe wire, so each wire needs its heat treatment recorded.
        - label: Foil
          line: The Au75/Pd25 foil is 0.2 mm thick and supplied as rolled.
  why: Gold is alloyed with a second metal to change its strength, hardness or melting point. Au-Ni brazing filler is specified at 949 °C (1740 F) and is used to join ceramics, steels and refractory metals in electronic packaging. Au-Pd foil is described by the supplier as combining gold's corrosion resistance with palladium's hardness, for connectors. Au-Fe is used for thermocouples at very low temperature, where the NBS paper found its thermopower the best available. Au-Ag and Au-Sb are included as family members, but this file has little property data for them.
  uses:
    - where: Electronic contacts and microconnectors
      line: Goodfellow describes Au82/Ni18 as used in high-reliability electrical contacts, and Au-Ni electrodeposited coatings are used in microconnectors and semiconductor devices.
    - where: Brazing in electronic packaging
      line: The 82Au-18Ni brazing filler is specified by SAE AMS4787 for wire, rod, sheet, strip, foil, pig, powder, shot and chips. Goodfellow says it joins ceramics, steels and refractory metals in electronic packaging.
    - where: Precision connectors and aerospace parts
      line: Goodfellow lists Au75/Pd25 foil for precision connector contacts, microelectronic bonding layers and corrosion-resistant aerospace components.
    - where: Cryogenic thermocouples
      line: Sparks (NBS, 1972) measured Au-Fe against KP from 5 to 280 K and reported usable sensitivity below 4 K.
  can_do:
    - label: Contact metal
      benchmark: electrical_resistivity
      value: 15.5 microohm cm
      line: Au82/Ni18 foil has an electrical resistivity of 15.5 microohm cm as printed by the supplier. This is a single supplier figure and is not compared here with other contact materials.
    - label: Brazing
      benchmark: melting_point
      value: 949 °C
      line: The 82Au-18Ni filler has a solidus-liquidus of 949 °C (1740 F). The Au-Pd foil has a melting point of 1410 °C.
    - label: Strength
      benchmark: ultimate_tensile_strength
      value: 616 MPa
      line: The rolled Au82/Ni18 foil reaches a tensile strength of 616 MPa with 13% elongation, reported by the supplier without a test standard.
    - label: Low-temperature sensing
      benchmark: seebeck_coefficient
      value: 16.966 microV/K
      line: The NBS pair of KP against Au-0.07 at% Fe gives 16.966 microV/K at 20 K.
  compare: The gold alloys in this file span a wide range of melting points. The Au-Ni brazing filler has a solidus-liquidus of 949 °C and the Au82/Ni18 foil melts at 955 °C, the Au-Sb eutectic is at 633 K, and the Au75/Pd25 foil melts at 1410 °C. The Au-Pd foil is slightly denser (16 g/cm3) than the Au82/Ni18 foil (15.8 g/cm3). The table compares the melting point, density and resistivity of these alloys using the supplier and specification figures.
  compare_rows:
    - label: Melting point, Au-Ni foil
      benchmark: melting_point
    - label: Density, Au-Pd foil
      benchmark: density
    - label: Electrical resistivity, Au-Ni foil
      benchmark: electrical_resistivity
  handling:
    - Au-Ni and Au-Pd foil are supplied as rolled (Goodfellow temper). The supplier gives no hot-working data.
    - Keep nickel-containing alloys away from skin that is sensitive to nickel. PubChem lists nickel as a skin sensitiser.
    - Record the heat treatment of Au-Fe wire, because annealing changes its thermopower.
    - The Au-Ni brazing filler is specified with a solidus-liquidus of 949 °C (AMS4787).
  good_for:
    - Oxidation-resistant contacts and microconnectors (Goodfellow, Au-Ni and Au-Pd).
    - Brazing ceramics and refractory metals in packages at about 949 °C (AMS4787 Au-Ni filler).
    - Thermocouples at very low temperature, where NBS found Au-Fe the most promising thermoelement (5 to 280 K).
  watch_out:
    - Most alloys here have only supplier figures. The Au-Ag and Au-Sb entries have almost no property data.
    - Nickel in Au-Ni and white gold can cause skin allergy.
    - Wire-to-wire scatter in Au-Fe thermocouples reached about 9% at 4 to 20 K in the NBS comparison.
  verdict: Gold alloys are chosen for oxidation-resistant contacts, brazes and thermocouples. The Au-Ni, Au-Pd and Au-Fe entries have usable data, while Au-Ag and Au-Sb are thin, and the nickel allergy risk should be handled in design.