Precious Metal BVAu-4: Properties, Machinability & Uses

BVAu-4 tempers and conditions

BVAu-4 is supplied in one standard condition, AS-BRAZED. AS-BRAZED is the default FabDigit quotes; the values on this page are for it.

AS-BRAZED

Supply forms, finishes and certifications

Ways BVAu-4 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
FOIL	Rolled foil / shim preform	Supply form
POWDER-PASTE	Atomised powder / brazing paste	Supply form

What is BVAu-4?

A vacuum-service grade of the 82%Au-18%Ni composition with reduced volatile-element content, chosen for brazing high-temperature vacuum and aerospace turbine components where outgassing must be minimized. BVAu-4 has a density of 15.9 g/cm³ (0.574 lb/in³), heavier than 81% of precious metal grades. It melts at 950°C (1,742 °F). BVAu-4 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 87% of precious metal grades. Elongation at break is 10% and the elastic modulus is 115 GPa (16.7 Msi).

What is BVAu-4 used for?

High-vacuum furnace assemblies
Aerospace turbine component brazing
Traveling-wave tube components
Nickel superalloy vacuum joints

Advantages

High service temperature — 800°C (1,472 °F), better than 90% of precious metal grades
High strength — 260 MPa (37.7 ksi), better than 87% of precious metal grades
Stiff — 115 GPa (16.7 Msi), better than 77% of precious metal grades

Limitations

Poor heat conductor — 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 96% of precious metal grades
Low electrical conductivity — 6 % IACS, worse than 92% of precious metal grades
Limited ductility — 10%, worse than 89% of precious metal grades
Heavy — 15.9 g/cm³ (0.574 lb/in³), worse than 81% of precious metal grades
High embodied carbon — 13,000 kg CO₂/kg, worse than 81% of precious metal grades

BVAu-4 properties

Typical room-temperature values for BVAu-4-AS-BRAZED; bars are the position among precious metal grades.

Physical3

BVAu-4 has a density of 15.9 g/cm³ (0.574 lb/in³), heavier than 81% of precious metal grades. It melts at 950°C (1,742 °F).

Density15.9 g/cm³0.57 lb/in³

Melting Point (Solidus)950°C1,742 °F

Liquidus Temperature950°C1,742 °F

Mechanical9

BVAu-4 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 87% of precious metal grades. Elongation at break is 10% and the elastic modulus is 115 GPa (16.7 Msi).

Elastic (Young's) Modulus115 GPa16.7 Msi

Shear Modulus42 GPa6.1 Msi

Bulk Modulus155 GPa22.5 Msi

Poisson's Ratio0.36

Tensile Strength (Ultimate)400 MPa58 ksi

Yield Strength (0.2% offset)260 MPa37.7 ksi

Elongation at Break10%

Shear Strength210 MPa30.5 ksi

Hardness, Vickers130 HV

Thermal6

BVAu-4 is rated for continuous service to 800°C (1,472 °F). It conducts heat at 25 W/m·K (14.4 BTU/hr·ft·°F), worse than 96% of precious metal grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).

Thermal Conductivity25 W/m·K14.4 BTU/hr·ft·°F

Specific Heat Capacity185 J/kg·K0.04 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)15.5 µm/m·K8.6 µin/in·°F

Latent Heat of Fusion105 J/g45.1 BTU/lb

Max Service Temperature (continuous)800°C1,472 °F

Min Service Temperature-269°C-452 °F

Electrical3

BVAu-4 conducts electricity at 6 % IACS, worse than 92% of precious metal grades.

Electrical Conductivity6 % IACS

Electrical Resistivity3×10⁻⁷ Ω·m11.8 µΩ·in

Magnetic Responsenon-magnetic

Chemical & Environmental3

Corrosion resistance is excellent (90/100), better than 69% of precious metal grades.

Galvanic Potential (seawater, vs SCE)0.25 V

Corrosion ResistanceExcellent90/100

Chemical Resistance SummaryHighly resistant to oxidation, sulphidation and most acids; attacked by aqua regia and by hot halogen/cyanide media that dissolve gold; nickel-rich phase can be etched by strong oxidising acids.

Sustainability4

Producing a kilogram of BVAu-4 takes about 200,000 MJ of energy and emits 13,000 kg of CO₂ — more than 85% of precious metal grades. Typical recycled content is 50%.

Embodied Energy (primary production)200,000 MJ/kg8.6×10⁷ BTU/lb

Embodied Carbon (primary production)13,000 kg CO₂/kg

Embodied Water200,000 L/kg23,965 gal/lb

Typical Recycled Content50%

Manufacturability7

BVAu-4's machinability is fair (35/100, worse than 73% of precious metal grades); weldability fair (40/100); formability very good (75/100).

MachinabilityFair35/100

WeldabilityFair40/100

Formability (cold)Very good75/100

CastabilityVery good80/100

Brazeability / SolderabilityExcellent98/100

PolishabilityExcellent85/100

Anodizing Responsen/a — precious metal, not anodizable

Common Calculations5

Specific Strength (UTS / density)calculated25 kN·m/kg

Specific Stiffness (E / density)calculated7.2 MN·m/kg

Modulus of Resiliencecalculated294 kJ/m³

Thermal Diffusivitycalculated8.5 mm²/s

Thermal Shock Resistance Indexcalculated6

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-4 is highlighted; hover a dot for its name, or open the interactive family chart.

Working with BVAu-4

Is BVAu-4 easy to machine?

Rarely machined; the alloy is gummy and precious — use sharp carbide, light cuts and capture all swarf for refining.

Can BVAu-4 be welded?

Not a structural weld metal; joined by melting in vacuum or dry H2 at 950–1010 °C with 0.025–0.075 mm joint clearance.

Can BVAu-4 be formed, bent or molded?

Very ductile — cold drawn to fine wire and rolled to 25 µm foil with interstage anneals at 700–800 °C.

BVAu-4 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 per AWS A5.8 BAu-4/BVAu-4	81.5 – 82.5	82
Cdvacuum-grade volatile limit	≤ 0
Znvacuum-grade volatile limit	≤ 0
Pvacuum-grade limit	≤ 0
Other (total)total of all other elements	≤ 0.15
Nibalance nickel	≥ 17 (balance)

What surface finishes work on BVAu-4?

Fillets need no coating; degrease with solvent only, avoid halogenated residues, and do not plate over the joint in vacuum service.

Equivalent designations

Standards and trade names that resolve to Precious Metal BVAu-4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.

UNS: P00827
Also called: AWS BVAu-4BAu-4

Other Gold alloys grades

Closest precious metal grades by properties

Compare BVAu-4 with…

Benchmark BVAu-4 against the top 3 neighbours

How much does BVAu-4 cost?

BVAu-4 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-4 — frequently asked

What is BVAu-4 used for?

BVAu-4 is typically used for high-vacuum furnace assemblies, aerospace turbine component brazing, traveling-wave tube components and nickel superalloy vacuum joints. In short: low-outgassing gold-nickel filler; 800 °C joint service; highest cost braze family.

What is the yield strength of BVAu-4?

BVAu-4 has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 87% of precious metal grades.

Is BVAu-4 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 — use sharp carbide, light cuts and capture all swarf for refining.

Can BVAu-4 be welded?

With care — weldability is rated fair (40/100). Not a structural weld metal; joined by melting in vacuum or dry H2 at 950–1010 °C with 0.025–0.075 mm joint clearance.