Precious Metal BVAu-5: Properties, Machinability & Uses

BVAu-5 tempers and conditions

BVAu-5 is supplied in one standard condition, AS-BRAZED.

AS-BRAZED

Supply forms, finishes and certifications

Ways BVAu-5 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.

Option	What it is	Type
1/2H-WIRE	Wire, half-hard	Supply form
FOIL	Foil / strip and stamped preforms	Supply form
Wire-AnnDefault	Wire / rod, annealed	Supply form
PASTE	Paste	Printing process
POWDER	Atomised powder	Printing process

What is BVAu-5?

BVAu-5 is the vacuum grade of the BAu-5 gold–silver–copper filler (about 30% Au, UNS P00307), with outgassing elements controlled for ultra-high-vacuum and hermetic sealing applications. It is chosen for vacuum tube sealing, sapphire-to-metal joints and microwave devices, and is supplied as annealed and half-hard wire, foil, powder, paste and as-brazed stock. Properties are about 340 MPa tensile, 150 MPa yield and 28% elongation, with a formability score of 88. It brazes at roughly 900–960 °C, the Ag- and Cu-rich phases tarnish in sulphur-bearing environments, and BVAu-6 is the higher-gold, higher-temperature alternative. BVAu-5 has a density of 11.3 g/cm³ (0.408 lb/in³), heavier than 59% of precious metal grades. It melts at 845°C (1,553 °F). BVAu-5 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 68% of precious metal grades. Elongation at break is 28% and the elastic modulus is 95 GPa (13.8 Msi).

What is BVAu-5 used for?

vacuum tube sealing
sapphire/metal hermetic joints
aerospace instrument brazing
microwave device assembly

Advantages

Polishes to a fine finish — 95/100, better than 86% of precious metal grades
High service temperature — 500°C (932 °F), better than 79% of precious metal grades

BVAu-5 properties

Typical room-temperature values; bars are the position among precious metal grades.

Physical3

BVAu-5 has a density of 11.3 g/cm³ (0.408 lb/in³), heavier than 59% of precious metal grades. It melts at 845°C (1,553 °F).

Density11.3 g/cm³0.41 lb/in³

Melting Point (Solidus)845°C1,553 °F

Liquidus Temperature890°C1,634 °F

Mechanical10

BVAu-5 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 68% of precious metal grades. Elongation at break is 28% and the elastic modulus is 95 GPa (13.8 Msi).

Elastic (Young's) Modulus95 GPa13.8 Msi

Shear Modulus36 GPa5.2 Msi

Bulk Modulus125 GPa18.1 Msi

Poisson's Ratio0.36

Tensile Strength (Ultimate)340 MPa49.3 ksi

Yield Strength (0.2% offset)150 MPa21.8 ksi

Elongation at Break28%

Shear Strength215 MPa31.2 ksi

Hardness, Brinell95 HB

Hardness, Vickers100 HV

Thermal6

BVAu-5 is rated for continuous service to 500°C (932 °F). It conducts heat at 75 W/m·K (43.3 BTU/hr·ft·°F), worse than 57% of precious metal grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).

Thermal Conductivity75 W/m·K43.3 BTU/hr·ft·°F

Specific Heat Capacity255 J/kg·K0.06 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)16.5 µm/m·K9.2 µin/in·°F

Latent Heat of Fusion130 J/g55.9 BTU/lb

Max Service Temperature (continuous)500°C932 °F

Min Service Temperature-269°C-452 °F

Electrical3

BVAu-5 conducts electricity at 19 % IACS, worse than 51% of precious metal grades.

Electrical Conductivity19 % IACS

Electrical Resistivity9×10⁻⁸ Ω·m3.54 µΩ·in

Magnetic Responsenon-magnetic

Chemical & Environmental3

Corrosion resistance is very good (78/100), worse than 56% of precious metal grades.

Galvanic Potential (seawater, vs SCE)0.15 V

Corrosion ResistanceVery good78/100

Chemical Resistance SummaryExcellent in humid air, neutral salt and most acids; not attacked by nitric acid as fast as silver brazes but the Ag/Cu phases can tarnish in H2S/SO2 and are attacked by aqua regia, cyanide and strong oxidising chloride media.

Sustainability4

Producing a kilogram of BVAu-5 takes about 76,000 MJ of energy and emits 5,300 kg of CO₂ — more than 64% of precious metal grades. Typical recycled content is 60%.

Embodied Energy (primary production)76,000 MJ/kg3.27×10⁷ BTU/lb

Embodied Carbon (primary production)5,300 kg CO₂/kg

Embodied Water60,000 L/kg7,190 gal/lb

Typical Recycled Content60%

Manufacturability7

BVAu-5's machinability is fair (45/100, better than 59% of precious metal grades); weldability fair (40/100); formability excellent (88/100).

MachinabilityFair45/100

WeldabilityFair40/100

Formability (cold)Excellent88/100

CastabilityVery good80/100

Brazeability / SolderabilityExcellent97/100

PolishabilityExcellent95/100

Anodizing Responsen/a — not an anodisable alloy; joints are left as-brazed or gold/nickel plated

Common Calculations5

Specific Strength (UTS / density)calculated30 kN·m/kg

Specific Stiffness (E / density)calculated8.4 MN·m/kg

Modulus of Resiliencecalculated118 kJ/m³

Thermal Diffusivitycalculated26 mm²/s

Thermal Shock Resistance Indexcalculated16

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-5 is highlighted; hover a dot for its name, or open the interactive family chart.

Working with BVAu-5

Is BVAu-5 easy to machine?

Rarely machined — gummy, smearing noble alloy; use sharp carbide/HSS tools, high rake and light cuts, and capture all chips for refining.

Can BVAu-5 be welded?

Not a structural weld metal; joints are made by furnace brazing at ~900–960 °C in high vacuum or dry hydrogen with no flux.

Can BVAu-5 be formed, bent or molded?

Very ductile: cold rolls to thin foil and draws to fine wire with interanneals at 550–650 °C in a clean reducing atmosphere.

BVAu-5 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
Augold content of the ~30 % Au Au-Ag-Cu filler	29.5 – 30.5	30
Ag	32 – 34	33
Cdvacuum-grade restriction on volatile/outgassing elements	≤ 0
Znvacuum-grade restriction	≤ 0
Pvacuum-grade restriction	≤ 0
Pbvacuum-grade restriction	≤ 0
Other elements, totaltotal residuals	≤ 0.15
Cubalance, nominally ~37 %	balance

What surface finishes work on BVAu-5?

Leave as-brazed for vacuum service; degrease with residue-free solvents only, and avoid sulphur-bearing polishing compounds that tarnish the Ag/Cu phases.

Equivalent designations

Standards and trade names that resolve to Precious Metal BVAu-5 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.

UNS: P00307

Other Gold alloys grades

Closest precious metal grades by properties

Compare BVAu-5 with…

Benchmark BVAu-5 against the top 3 neighbours

How much does BVAu-5 cost?

BVAu-5 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-5 — frequently asked

What is BVAu-5 used for?

BVAu-5 is typically used for vacuum tube sealing, sapphire/metal hermetic joints, aerospace instrument brazing and microwave device assembly. In short: most ductile BVAu grade; lower-temperature gold braze; UHV hermetic sealing filler.

What is the yield strength of BVAu-5?

BVAu-5 has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 340 MPa (49.3 ksi) — weaker than 68% of precious metal grades.

Is BVAu-5 easy to machine?

Reasonably — machinability is rated fair (45/100, better than 59% of precious metal grades). Rarely machined — gummy, smearing noble alloy; use sharp carbide/HSS tools, high rake and light cuts, and capture all chips for refining.

Can BVAu-5 be welded?

With care — weldability is rated fair (40/100). Not a structural weld metal; joints are made by furnace brazing at ~900–960 °C in high vacuum or dry hydrogen with no flux.