Precious Metal AuNi
AuNi is gold hardened with a few percent nickel, which raises hardness and wear resistance over pure gold while retaining the tarnish and corrosion immunity required for dry-circuit contacts.
Reference datasheet — AuNi is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the H04 condition
AuNi tempers and conditions
AuNi is supplied in 6 conditions, soft to hard. H04 is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As cast | Intermediate form from the refinery before rolling/drawing; not used in service. | 150 | 350 | 20 | 105 HB | 12.5 % IACS |
Annealed | Pick for deep drawing, riveting, bonding wire and any part that must be formed before service. | 180 | 400 | 30 | 125 HV | 14 % IACS |
Quarter hard | Light temper for stampings that still need moderate bending but a bit more stiffness than soft. | 380 | 500 | 15 | 147 HB | 13.5 % IACS |
Half hard | Balanced temper for connector contacts formed with generous bend radii. | 480 | 590 | 8 | 171 HB | 13.2 % IACS |
H04Default Full hard | Standard stocked condition for contact wire, pins and slip-ring brushes needing wear resistance. | 620 | 700 | 3 | 215 HV | 13 % IACS |
Spring hard | Highest strength temper for fine contact springs and probe wires; almost no formability left. | 760 | 820 | 1.5 | 21 HRC | 12.8 % IACS |
Supply forms, finishes and certifications
Ways AuNi is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PLATE | Electrodeposited hard gold | Supply form |
CLAD | Inlay / clad contact strip on Cu-alloy carrier | Coating |
What is AuNi?
AuNi is gold hardened with a few percent nickel, which raises hardness and wear resistance over pure gold while retaining the tarnish and corrosion immunity required for dry-circuit contacts. It is used for very low-current signal contacts and is available as annealed and cold-worked wire and strip (O through H08), clad stock, electroplated overlays and cast material. Strength is high at 620 MPa yield and 700 MPa tensile with service to 400 °C, but elongation is only 3 % in the default condition and conductivity is 13 % IACS, so it is unsuitable for power switching. Cost normally restricts it to thin overlays and small rivets, with electroplated hard gold the cheaper route. AuNi has a density of 18.3 g/cm³ (0.661 lb/in³), heavier than 89% of precious metal grades. It melts at 955°C (1,751 °F). AuNi has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 98% of precious metal grades. Elongation at break is 3% and the elastic modulus is 95 GPa (13.8 Msi).
What is AuNi used for?
- reed switch contacts
- connector plating overlays
- low-level signal relay contacts
- precision instrument connectors
Advantages
- High strength — 620 MPa (89.9 ksi), better than 98% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
- Good corrosion resistance — 96/100, better than 85% of precious metal grades
- Readily welded — 75/100, better than 78% of precious metal grades
Limitations
- High embodied carbon — 24,000 kg CO₂/kg, worse than 98% of precious metal grades
- Limited ductility — 3%, worse than 95% of precious metal grades
- Heavy — 18.3 g/cm³ (0.661 lb/in³), worse than 89% of precious metal grades
- Limited formability — 55/100, worse than 89% of precious metal grades
AuNi properties
Typical room-temperature values for AuNi-H04; bars are the position among precious metal grades.
Physical3
AuNi has a density of 18.3 g/cm³ (0.661 lb/in³), heavier than 89% of precious metal grades. It melts at 955°C (1,751 °F).
Mechanical10
AuNi has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 98% of precious metal grades. Elongation at break is 3% and the elastic modulus is 95 GPa (13.8 Msi).
Thermal6
AuNi is rated for continuous service to 400°C (752 °F). It conducts heat at 58 W/m·K (33.5 BTU/hr·ft·°F), worse than 74% of precious metal grades. Thermal expansion is 14.2 µm/m·K (7.89 µin/in·°F).
Electrical3
AuNi conducts electricity at 13 % IACS, worse than 72% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (96/100), better than 85% of precious metal grades.
Sustainability4
Producing a kilogram of AuNi takes about 240,000 MJ of energy and emits 24,000 kg of CO₂ — more than 91% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
AuNi's machinability is fair (45/100, better than 59% of precious metal grades); weldability very good (75/100); formability good (55/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the precious metal family
Yield strength against density for every precious metal grade FabDigit runs. AuNi is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AuNi
Is AuNi easy to machine?
Gummy and expensive — use sharp, polished-flute carbide or diamond tools, high speed, light feed, oil mist, and capture every chip for refining.
Can AuNi be welded?
Resistance, percussion and laser welding of contact rivets/wires to Cu-alloy carriers is routine; avoid fusion welding to steels which forms brittle intermetallics.
Can AuNi be formed, bent or molded?
Anneal at 600–750 °C in inert or reducing atmosphere, then cold roll/draw with >70 % reduction possible between anneals; hard tempers must be formed with generous radii (≥2t).
AuNi chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Nisolid-solution hardener; raises hardness and wear life | 4.5 – 5.5 | 5 |
| Cuimpurity limit | ≤ 0.05 | |
| Feimpurity limit | ≤ 0.03 | |
| Agimpurity limit | ≤ 0.05 | |
| Other, totaltotal residuals | ≤ 0.1 | |
| Aubalance, ≥94.9 % typical (Au 950 fineness) | balance |
What surface finishes work on AuNi?
Not anodizable; finish by burnishing, diamond turning or fine polishing — or apply as an electrodeposited hard-gold layer over 1–2 µm Ni underplate to block copper diffusion.
How much does AuNi cost?
AuNi is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
AuNi — frequently asked
What is AuNi used for?
AuNi is typically used for reed switch contacts, connector plating overlays, low-level signal relay contacts and precision instrument connectors. In short: hardest tarnish-free contact gold; dry-circuit signal reliability; thin-overlay cost control.
What is the yield strength of AuNi?
AuNi has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 700 MPa (102 ksi) — stronger than 98% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is AuNi easy to machine?
Reasonably — machinability is rated fair (45/100, better than 59% of precious metal grades). Gummy and expensive — use sharp, polished-flute carbide or diamond tools, high speed, light feed, oil mist, and capture every chip for refining.
Can AuNi be welded?
Yes — weldability is rated very good (75/100). Resistance, percussion and laser welding of contact rivets/wires to Cu-alloy carriers is routine; avoid fusion welding to steels which forms brittle intermetallics.
What surface finishes work on AuNi?
Not anodizable; finish by burnishing, diamond turning or fine polishing — or apply as an electrodeposited hard-gold layer over 1–2 µm Ni underplate to block copper diffusion.
Can AuNi be formed, bent or molded?
Anneal at 600–750 °C in inert or reducing atmosphere, then cold roll/draw with >70 % reduction possible between anneals; hard tempers must be formed with generous radii (≥2t).
What is the maximum service temperature of AuNi?
AuNi is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AuNi-H04 and AuNi Cast?
H04 is the default condition — standard stocked condition for contact wire, pins and slip-ring brushes needing wear resistance. Cast: intermediate form from the refinery before rolling/drawing; not used in service. Yield strength is 620 MPa in H04 versus 150 MPa in Cast.
How much does AuNi cost?
AuNi is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM B541 — Standard Specification for Gold Electrical Contact Alloy — ASTM International (2018)
- ASTM B488 — Electrodeposited Coatings of Gold for Engineering Uses — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Precious Metals) — ASM International (1990)
- ASM Alloy Phase Diagrams — Au-Ni system — ASM International (2016)
- Precious-metal electrical contact alloy wire and strip data (Deringer-Ney / Materion / Heraeus style datasheets) — various producers (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.