Gold alloys Au alloys
Au82/Ni18 (gold 82, nickel 18, as listed)
Also known as AMS AMS4787
Gold is alloyed with nickel, palladium, silver, iron and antimony to change its strength, melting point and electrical behaviour.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Contact metal
15.5 microohm cm
Brazing
949 °C
Strength
616 MPa
Low-temperature sensing
16.966 microV/K
Recipe, share of the weight
- Au not statedGold
- Ni not statedNickel
- Pd not statedPalladium
- Fe not statedIron
- Sb not statedAntimony
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
Risk at a glance
- People None found. Gold is not hazardous; nickel is a sensitiser
- If it fails Moderate. Output scatter between thermocouple wires
- Corrosion Low. Supplier says Au-Ni resists oxidation and corrosion; no test data were read.
Quick facts: Au alloys
| Property | Value | Basis |
|---|---|---|
| Density | 15.8 to 16 g/cm³ | 2 sourced values across conditions |
| Tensile strength | 616 MPa | 1 sourced value |
| Young's modulus | 112 GPa | 1 sourced value |
| Thermal conductivity | 49 W/(m·K) | 1 sourced value |
| Thermal expansion (CTE) | 14 ppm/K | 1 sourced value |
| Melting point | 360 to 1,410 °C | 3 sourced values across conditions |
| Electrical resistivity | 1.5e-7 Ω·m | 1 sourced value |
What is the density of Gold alloys (Au alloys)?
Gold alloys (Au alloys) has a density of 15.8 to 16 g/cm³. The range covers 2 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the thermal conductivity of Gold alloys (Au alloys)?
Gold alloys (Au alloys) has a thermal conductivity of 49 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the coefficient of thermal expansion of Gold alloys (Au alloys)?
Gold alloys (Au alloys) has a coefficient of thermal expansion of 14 ppm/K. The source and test conditions are listed in the properties table on this page.
What is the melting point of Gold alloys (Au alloys)?
Gold alloys (Au alloys) has a melting point of 360 to 1,410 °C. The range covers 3 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the tensile strength of Gold alloys (Au alloys)?
Gold alloys (Au alloys) has a tensile strength of 616 MPa. The source and test conditions are listed in the properties table on this page.
What is Gold alloys (Au alloys) used for?
Uses recorded in the sources include High-reliability electrical contacts and microconnectors; Brazing filler for ceramics, steels and refractory metals in electronic packaging; Precision connector contacts and microelectronic bonding layers.
Why it exists
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.
Where it's used
Electronic contacts and microconnectors
Goodfellow describes Au82/Ni18 as used in high-reliability electrical contacts, and Au-Ni electrodeposited coatings are used in microconnectors and semiconductor devices.
Brazing in electronic packaging
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.
Precision connectors and aerospace parts
Goodfellow lists Au75/Pd25 foil for precision connector contacts, microelectronic bonding layers and corrosion-resistant aerospace components.
Cryogenic thermocouples
Sparks (NBS, 1972) measured Au-Fe against KP from 5 to 280 K and reported usable sensitivity below 4 K.
Recipe
Au82/Ni18 (gold 82, nickel 18, as listed); binary family Au-Ni, Au-Pd, Au-Ag, Au-Fe and Au-Sb
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.
| Ingredient | Share of the weight | What it does |
|---|---|---|
| Gold Au | not stated | Base metal. The supplier describes gold as resisting oxidation and carrying the electrical conduction in contacts. |
| Nickel Ni | not stated | Alloying partner. Au82/Ni18 melts at 955 degC (supplier). Supplier notes trace platinum and yttrium improve sulfurization resistance. |
| Palladium Pd | not stated | Hardness and wear resistance. The Au-Pd foil melts at 1410 degC. |
| Iron Fe | not stated | Gives the Au-Fe alloy its thermoelectric behaviour at very low temperature. |
| Antimony Sb | not stated | Forms the Au-Sb eutectic at 633 K. Other Au-Sb compositions were not read. |
Weight shares are as printed in the sources.
What it can do
Contact metal
15.5 microohm cm
measured
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.
Brazing
949 °C
measured
The 82Au-18Ni filler has a solidus-liquidus of 949 °C (1740 F). The Au-Pd foil has a melting point of 1410 °C.
Strength
616 MPa
measured
The rolled Au82/Ni18 foil reaches a tensile strength of 616 MPa with 13% elongation, reported by the supplier without a test standard.
Low-temperature sensing
16.966 microV/K
measured
The NBS pair of KP against Au-0.07 at% Fe gives 16.966 microV/K at 20 K.
How it compares
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.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | Au alloys | Au | Ag | Pt | Pd | Rh | Ru | Os | AuSn | Ag 92.5 Cu 7.5 | Ag alloys | Pd-Ag | Pd-Cu, Pd-Ni, Pd-Cr | Pt-Rh | Pt-Ir | Pt-W, Pt-Cu |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||||||||||||
| Melting point, Au82/Ni18 | 955 °C2 | 1065 °C | 961.9 °C | 1769 °C | 1555 °C | 1964 °C | 2334 °C | 3033 °C | 280 °C | 788 to 891 °C | 780 °C | no data | 1397 °C | 1840 to 1870 °C | 1790 to 1800 °C | 1865 to 1885 °C |
| Solidus-liquidus temperature, 82Au-18Ni brazing filler | 949 °C3 | 1065 °C | 961.9 °C | 1769 °C | 1555 °C | 1964 °C | 2334 °C | 3033 °C | 280 °C | 788 to 891 °C | 780 °C | no data | 1397 °C | 1840 to 1870 °C | 1790 to 1800 °C | 1865 to 1885 °C |
| Thermal conductivity, Au82/Ni18 foil | 49 W/(m K)5 | 320 W/(m K) | 429 W/(m K) | 74 W/(m·K) | 72 W/(m.K) | 150 W/(m·K) | 117 W/(m·K) | 87.6 W/(m·K) | 57 W/mK | no data | 371 W/m K | 61 W/(m.K) | no data | no data | no data | no data |
| Melting point, Au75/Pd25 foil | 1410 °C10 | 1065 °C | 961.9 °C | 1769 °C | 1555 °C | 1964 °C | 2334 °C | 3033 °C | 280 °C | 788 to 891 °C | 780 °C | no data | 1397 °C | 1840 to 1870 °C | 1790 to 1800 °C | 1865 to 1885 °C |
| Eutectic temperature, Au-Sb (24.8 wt% Sb) | 633 K12 | 1065 °C | 961.9 °C | 1769 °C | 1555 °C | 1964 °C | 2334 °C | 3033 °C | 280 °C | 788 to 891 °C | 780 °C | no data | 1397 °C | 1840 to 1870 °C | 1790 to 1800 °C | 1865 to 1885 °C |
| Physical and electrical | ||||||||||||||||
| Density, Au82/Ni18 foil | 15.8 g/cm³1 | 19.3 g/cm³ | 10.5 g/cm³ | 21.45 g/cm³ | 12.02 g/cm³ | 12.42 g/cm³ | 12.36 g/cm³ | 22.5 g/cm³ | 14.7 - | 10.4 g/cm³ | 10 Mg/m3 | 10.9 g/cm³ | 10.8 g/cm³ | 19.97 g/cm³ | 21.54 g/cm³ | 21.26 g/cm³ |
| Electrical resistivity, Au82/Ni18 foil | 15.5 µΩ·cm4 | 2.2×10^-8 ohm m | 1.63 µΩ·cm | 10.6 µΩ·cm | 10.8 uOhm.cm | 43.3 nΩ·m | 71 nΩ·m | 8.8 µΩ·cm | no data | 1.8 µOhmcm | 20.4 x10-9 ohm m | 15 uOhm.cm | no data | no data | no data | 62 to 68 µOhm cm |
| Density, Au75/Pd25 foil | 16 g/cm³11 | 19.3 g/cm³ | 10.5 g/cm³ | 21.45 g/cm³ | 12.02 g/cm³ | 12.42 g/cm³ | 12.36 g/cm³ | 22.5 g/cm³ | 14.7 - | 10.4 g/cm³ | 10 Mg/m3 | 10.9 g/cm³ | 10.8 g/cm³ | 19.97 g/cm³ | 21.54 g/cm³ | 21.26 g/cm³ |
| Other measurements | ||||||||||||||||
| Coefficient of thermal expansion, Au82/Ni18 | 14 ppm/K6 | 14.2 ppm/K | 19.1 ppm/K | 8.93 ppm/K | 11.8 ppm/K | 8.46 ppm/K | 6.78 ppm/K | 4.57 ppm/K | 16 ppm/°C | 19 x10-6 K-1 | 19.6 x10-6 per °C | no data | no data | no data | no data | no data |
| Modulus of elasticity, Au82/Ni18 foil | 112 GPa7 | 78 GPa | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data |
| Tensile strength, Au82/Ni18 foil | 616 MPa8 | no data | no data | 150 MPa | no data | no data | no data | no data | 275 MPa | 207 MPa | 372 MPa | 310 MPa | no data | 300 to 680 MPa | 340 MPa | 800 to 1100 MPa |
| Elongation at break, Au82/Ni18 foil | 13 %9 | no data | no data | 40 % | no data | no data | no data | no data | no data | no data | 19 % | 36 % | 3 % | 1.5 to 32 % | 32 % | 2 to 20 % |
| Seebeck coefficient, KP versus Au-0.07 at% Fe thermocouple at 20 K | 16.97 microV/K13 | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data | no data |
Why choose it, and why not
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 for
- 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.
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.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Other names and standards
The same grade under other systems, as datasheets and standards print them. Each code was checked against the page it comes from.
| System | Codes |
|---|---|
| AMS | AMS4787 |
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density, Au82/Ni18 foil | Physical property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, film or sheet, as rolledtemperature not stated | — |
| 2 | Melting point, Au82/Ni18 | Thermal property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, as rollednote single value printed, no range | — |
| 3 | Solidus-liquidus temperature, 82Au-18Ni brazing filler | Value printed in the title of the SAE specification | composition 82Au-18Nibasis specification title gives 1740 F (949 °C)revision AMS4787 revision C, dated 4/1/1990 | 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. |
| 4 | Electrical resistivity, Au82/Ni18 foil | Electrical property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, as rolledtemperature not stated | — |
| 5 | Thermal conductivity, Au82/Ni18 foil | Thermal property printed on the supplier product page, value at 23 degC | composition Au 82 / Ni 18 as listedtemperature 23 °C | 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. |
| 6 | Coefficient of thermal expansion, Au82/Ni18 | Printed by the supplier as x10-6 K-1, which is the same unit as ppm/K; no numeric conversion made | composition Au 82 / Ni 18 as listedtemperature range 20 to 700 °C | — |
| 7 | Modulus of elasticity, Au82/Ni18 foil | Mechanical property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, as rolled | — |
| 8 | Tensile strength, Au82/Ni18 foil | Mechanical property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, as rolledtest standard not stated | — |
| 9 | Elongation at break, Au82/Ni18 foil | Mechanical property printed on the supplier product page | composition Au 82 / Ni 18 as listedform foil, as rolledtest standard not stated | — |
| 10 | Melting point, Au75/Pd25 foil | Thermal property printed on the supplier product page | composition Au 75 / Pd 25form foil, 0.2 mm thick, as rolled | — |
| 11 | Density, Au75/Pd25 foil | Physical property printed on the supplier product page, printed without decimals | composition Au 75 / Pd 25form foil, 0.2 mm thick, as rolled | The page prints 16 with no decimals, so the value is likely rounded. |
| 12 | Eutectic temperature, Au-Sb (24.8 wt% Sb) | Table of gold binary eutectic alloys; the row prints 633 K and 680 F (633 K is 360 degC) | composition Sb 24.8 wt%, gold remainderbasis gold binary eutectic alloy row in the table | The table lists the value only in kelvin. No Au-Sb density, resistivity or hardness was found in a page read in this run. |
| 13 | Seebeck coefficient, KP versus Au-0.07 at% Fe thermocouple at 20 K | Value printed in a table of the NBS paper for one thermocouple pair | pair KP versus Au-0.07 at% Fe, pair output, not the alloy alonetemperature 20 Kwire diameters 0.127 mm, 0.152 mm and 0.254 mm (Table 1) | 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. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air and high-temperature oxidation (Au-Ni, supplier statements only) | low | Supplier says Au-Ni resists oxidation and corrosion; no test data were read.1 |
| Sulfur-bearing atmospheres (Au-Ni) | not rated | Sulfurization resistance is claimed through trace platinum and yttrium additions; no rate was read.2 |
| Corrosive and high-vacuum aerospace environments (Au-Pd, supplier statements only) | low | Supplier describes the Au-Pd foil as combining gold's corrosion resistance with palladium's hardness.3 |
| Au-Fe thermocouple use at cryogenic temperatures | not rated | No corrosion test was read; the NBS paper reports the alloys as metallurgically stable.4 |
| Not read (Au-Ag and Au-Sb) | not rated | No corrosion data for these two alloy systems were read in this run.5 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air and high-temperature oxidation (Au-Ni, supplier statements only) | 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. | basis supplier statements without test datacomposition Au82/Ni18 family |
| 2 | Sulfur-bearing atmospheres (Au-Ni) | 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. | basis supplier claim for alloys with trace additions; plain Au82/Ni18 not tested here |
| 3 | Corrosive and high-vacuum aerospace environments (Au-Pd, supplier statements only) | 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. | basis supplier product description without test datacomposition Au 75 / Pd 25 |
| 4 | Au-Fe thermocouple use at cryogenic temperatures | 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. | basis statement on metallurgical stability; no corrosion testtemperature range 5 to 280 K in the paper |
| 5 | Not read (Au-Ag and Au-Sb) | 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. | basis composition and occurrence only |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
Gold on its own is classed as not hazardous in most company reports, but nickel in an alloy can cause skin allergy.
- Nickel
- 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.
- Gold
- Pure gold does not meet GHS hazard criteria in 99.2% (502 of 506) of company reports on PubChem.
- Other alloys
- No GHS classification was read for the Au-Pd, Au-Ag, Au-Fe or Au-Sb alloys.
Heating and brazing
Au-Ni brazing filler melts at about 949 °C. Fume and flux hazards were not read in this run.
- Solidus-liquidus
- The AMS specification gives 949 °C (1740 F) for the 82Au-18Ni filler metal.
- Joint
- The brazing range is set by the alloy, so keep the joint below the melting point of the parts being joined.
Handling
- Heat treatment
- Annealing changes the thermopower of Au-Fe wire, so each wire needs its heat treatment recorded.
- Foil
- The Au75/Pd25 foil is 0.2 mm thick and supplied as rolled.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Output scatter between thermocouple wiresmoderate severity | Au-Fe wire from different melts, or wire in a different annealing stateSparks 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. |
Side effects on surrounding parts
| Affects | Effect |
|---|---|
| Skin of wearers sensitive to nickel | 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. |
Handling and storage
- 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.
- 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.
Mitigations
- Sparks states that the reference data can be adjusted with spot calibration on particular wires, which handles the wire-to-wire scatter.
Supply and geography
How common the raw materials are and where they come from.
Gold (base metal of every alloy in this file)
Consumption in 2025: jewelry 40%, electrical and electronics 7% (USGS, share of global consumption)
- Top producers (2025)
- China 11.5%, Russia 9.4%, Australia 8.5%, Canada 6.1%, United States 4.8%
- Critical mineral lists
- Not checked in this run: not listed
- 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.
Nickel
- Top producers (2025)
- Indonesia 66.7%, Philippines 6.9%, Russia 5.1%, New Caledonia 3.6%, Canada 3.6%
- Critical mineral lists
- Not checked in this run: not listed
- 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.
Silver
- Top producers (2025)
- China 13.1%, Bolivia 5.8%, Chile 5.4%, United States 4.2%
- Critical mineral lists
- US: listed
- 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.
Antimony
- Top producers (2025)
- China 36.4%, Bolivia 4.5%, Burma 4.1%, Australia 1.2%
- Critical mineral lists
- Not checked in this run: not listed
- 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.
Documents
Datasheets, safety data sheets, papers and standards you can open.
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
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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.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.