Precious Metal BVAu-3
UNS P00357
BVAu-3 is the vacuum grade of BAu-3, a nominally 35Au-62Cu-3Ni gold brazing filler (UNS P00357) refined to keep low-vapor-pressure impurities down for high-vacuum work.
Reference datasheet — BVAu-3 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 AB condition
BVAu-3 tempers and conditions
BVAu-3 is supplied in one standard condition, AB. AB is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways BVAu-3 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
ANN-WIRE | Annealed wire / rod | Supply form |
CR-STRIP | Cold-rolled strip / foil and stamped preforms | Supply form |
POWDER | Atomized powder / paste | Printing process |
What is BVAu-3?
BVAu-3 is the vacuum grade of BAu-3, a nominally 35Au-62Cu-3Ni gold brazing filler (UNS P00357) refined to keep low-vapor-pressure impurities down for high-vacuum work. It is specified for electron-tube seals, vacuum feedthroughs and other hermetic brazes where outgassing must be minimal, and is available as as-brazed stock, annealed wire, cold-rolled strip and powder. As-brazed properties are about 415 MPa tensile, 210 MPa yield, 25% elongation, 9% IACS conductivity and service to roughly 500 °C. The 1030–1090 °C braze cycle and gold content are the main constraints; BVAu-6 serves higher temperatures. BVAu-3 has a density of 11.1 g/cm³ (0.401 lb/in³), heavier than 58% of precious metal grades. It melts at 975°C (1,787 °F). BVAu-3 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 61% of precious metal grades. Elongation at break is 25% and the elastic modulus is 105 GPa (15.2 Msi).
What is BVAu-3 used for?
- electron tube seals
- vacuum feedthroughs
- hermetic electronic packages
- high-reliability instrument brazing
Advantages
- High service temperature — 500°C (932 °F), better than 79% of precious metal grades
Limitations
- Low electrical conductivity — 9 % IACS, worse than 84% of precious metal grades
- Poor heat conductor — 45 W/m·K (26 BTU/hr·ft·°F), worse than 82% of precious metal grades
- Limited formability — 70/100, worse than 78% of precious metal grades
- Needs corrosion protection — 65/100, worse than 77% of precious metal grades
BVAu-3 properties
Typical room-temperature values for BVAu-3-AB; bars are the position among precious metal grades.
Physical3
BVAu-3 has a density of 11.1 g/cm³ (0.401 lb/in³), heavier than 58% of precious metal grades. It melts at 975°C (1,787 °F).
Mechanical8
BVAu-3 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 61% of precious metal grades. Elongation at break is 25% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
BVAu-3 is rated for continuous service to 500°C (932 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), worse than 82% of precious metal grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
BVAu-3 conducts electricity at 9 % IACS, worse than 84% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is good (65/100), worse than 77% of precious metal grades.
Sustainability3
Producing a kilogram of BVAu-3 takes about 88,000 MJ of energy and emits 7,000 kg of CO₂ — more than 65% of precious metal grades. Typical recycled content is 60%.
Manufacturability6
BVAu-3's machinability is fair (35/100, worse than 73% of precious metal grades); weldability poor (30/100); formability very good (70/100).
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. BVAu-3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BVAu-3
Is BVAu-3 easy to machine?
Rarely machined — the alloy is gummy and precious; buy to size as wire, foil or stamped preform and recover all swarf for refining.
Can BVAu-3 be welded?
Not a structural weld alloy; join by vacuum or dry-hydrogen furnace brazing at 1030–1090 °C with tight 0.02–0.08 mm joint clearance and no flux.
Can BVAu-3 be formed, bent or molded?
Very ductile FCC solid solution: draws to fine wire and rolls to <0.05 mm foil, with interstage anneals around 700–800 °C in protective atmosphere.
BVAu-3 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 |
|---|---|---|
| AuAWS A5.8 BAu-3 / BVAu-3 | 34.5 – 35.5 | 35 |
| Ni | 2.5 – 3.5 | 3 |
| Cdvacuum-grade volatile-impurity limit | ≤ 0 | |
| Znvacuum-grade volatile-impurity limit | ≤ 0 | |
| Pvacuum-grade limit | ≤ 0 | |
| other, totaltotal impurities per AWS A5.8 | ≤ 0.15 | |
| Cu | balance |
What surface finishes work on BVAu-3?
Braze fillets are self-bright after vacuum cycles; avoid abrasive blasting of joints and keep parts clean of Cd/Zn plating that would contaminate the vacuum charge.
Equivalent designations
Standards and trade names that resolve to Precious Metal BVAu-3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- P00357
How much does BVAu-3 cost?
BVAu-3 is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
BVAu-3 — frequently asked
What is BVAu-3 used for?
BVAu-3 is typically used for electron tube seals, vacuum feedthroughs, hermetic electronic packages and high-reliability instrument brazing. In short: nickel-bearing gold braze; electron-tube vacuum grade; low-outgassing hermetic filler.
What is the yield strength of BVAu-3?
BVAu-3 has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 415 MPa (60.2 ksi) — stronger than 61% of precious metal grades.
Is BVAu-3 easy to machine?
Not especially — machinability is rated fair (35/100, worse than 73% of precious metal grades). Rarely machined — the alloy is gummy and precious; buy to size as wire, foil or stamped preform and recover all swarf for refining.
Can BVAu-3 be welded?
Not readily — weldability is rated poor (30/100). Not a structural weld alloy; join by vacuum or dry-hydrogen furnace brazing at 1030–1090 °C with tight 0.02–0.08 mm joint clearance and no flux.
What surface finishes work on BVAu-3?
Braze fillets are self-bright after vacuum cycles; avoid abrasive blasting of joints and keep parts clean of Cd/Zn plating that would contaminate the vacuum charge.
Can BVAu-3 be formed, bent or molded?
Very ductile FCC solid solution: draws to fine wire and rolls to <0.05 mm foil, with interstage anneals around 700–800 °C in protective atmosphere.
What is the maximum service temperature of BVAu-3?
BVAu-3 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does BVAu-3 cost?
BVAu-3 is a high-cost precious metal ($$$$), 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
- AWS A5.8M/A5.8 Specification for Filler Metals for Brazing and Braze Welding — AWS (2019)
- Brazing Handbook, 5th ed. — AWS (2007)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- Gold-copper-nickel vacuum braze alloy datasheets (precious-metal braze producers) — various (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.