Precious Metal BVAu-7 AS-BRAZED
Heat-treated state
UNS P00507
Reference condition for joint design allowables; note AuCu3 ordering on slow cooling raises hardness and lowers ductility.
Values for the AS-BRAZED condition
What is BVAu-7 AS-BRAZED?
BVAu-7 AS-BRAZED is BVAu-7 heat treated to AS-BRAZED — reference condition for joint design allowables; note AuCu3 ordering on slow cooling raises hardness and lowers ductility. BVAu-7 AS-BRAZED has a yield strength of 200 MPa (29 ksi) and a tensile strength of 420 MPa (60.9 ksi) — stronger than 51% of precious metal grades. Elongation at break is 8% and the elastic modulus is 95 GPa (13.8 Msi). BVAu-7 AS-BRAZED has a density of 12.2 g/cm³ (0.441 lb/in³), heavier than 69% of precious metal grades. It melts at 970°C (1,778 °F).
Limitations
- Limited ductility — 8%, worse than 92% of precious metal grades
BVAu-7 AS-BRAZED properties
Typical room-temperature values for BVAu-7 AS-BRAZED; 5 are specific to this condition. Other listed values are BVAu-7 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
BVAu-7 AS-BRAZED has a density of 12.2 g/cm³ (0.441 lb/in³), heavier than 69% of precious metal grades. It melts at 970°C (1,778 °F).
Mechanical9
BVAu-7 AS-BRAZED has a yield strength of 200 MPa (29 ksi) and a tensile strength of 420 MPa (60.9 ksi) — stronger than 51% of precious metal grades. Elongation at break is 8% and the elastic modulus is 95 GPa (13.8 Msi).
Thermal6
BVAu-7 AS-BRAZED is rated for continuous service to 425°C (797 °F). It conducts heat at 65 W/m·K (37.6 BTU/hr·ft·°F), worse than 67% of precious metal grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
BVAu-7 AS-BRAZED conducts electricity at 25 % IACS, better than 64% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (76/100), worse than 59% of precious metal grades.
Sustainability4
Producing a kilogram of BVAu-7 AS-BRAZED takes about 130,000 MJ of energy and emits 9,000 kg of CO₂ — more than 70% of precious metal grades. Typical recycled content is 55%.
Manufacturability6
BVAu-7 AS-BRAZED's machinability is fair (35/100, worse than 73% of precious metal grades); weldability poor (30/100); formability very good (80/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BVAu-7 AS-BRAZED
Is BVAu-7 easy to machine?
Rarely machined; the alloy is soft and gummy — use sharp, polished-flute carbide tools, light feeds and collect all swarf for precious-metal recovery.
Can BVAu-7 be welded?
Not a structural weld consumable; join by vacuum or dry-hydrogen furnace brazing at about 1000–1050 °C with tight 25–75 µm gaps and no flux.
Can BVAu-7 be formed, bent or molded?
Readily cold drawn to fine wire and rolled to foil with interstage anneals at 600–700 °C in protective atmosphere; slow cooling promotes AuCu3 ordering and hardening.
What surface finishes work on BVAu-7?
As-brazed fillets are bright and need no post-clean; can be lightly polished or ultrasonically cleaned, and plating is unnecessary since the alloy does not scale.
BVAu-7 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 |
|---|---|---|
| Auvacuum-grade purity, refined bullion feedstock | 49.5 – 50.5 | 50 |
| Znhigh-vapour-pressure element, restricted for vacuum service | ≤ 0 | |
| Cdhigh-vapour-pressure element, restricted | ≤ 0 | |
| Prestricted to avoid brittle phosphides | ≤ 0 | |
| Pbvolatile impurity limit | ≤ 0 | |
| Cresidual from processing | ≤ 0.01 | |
| Other elements, totalsum of unspecified residuals per vacuum-grade practice | ≤ 0.15 | |
| Cuoxygen-free / vacuum-refined copper | balance |
BVAu-7 AS-BRAZED — frequently asked
What is BVAu-7 AS-BRAZED used for?
BVAu-7 AS-BRAZED is typically used for vacuum electronic device brazing, aerospace vacuum-tight joints, precision instrument assemblies and hermetic feedthroughs. In short: lowest-cost vacuum Au braze; half-gold Au-Cu filler; tight-clearance vacuum joints.
What is the yield strength of BVAu-7 AS-BRAZED?
BVAu-7 AS-BRAZED has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 420 MPa (60.9 ksi) — stronger than 51% of precious metal grades.
Is BVAu-7 AS-BRAZED easy to machine?
Not especially — machinability is rated fair (35/100, worse than 73% of precious metal grades). Rarely machined; the alloy is soft and gummy — use sharp, polished-flute carbide tools, light feeds and collect all swarf for precious-metal recovery.
Can BVAu-7 AS-BRAZED be welded?
Not readily — weldability is rated poor (30/100). Not a structural weld consumable; join by vacuum or dry-hydrogen furnace brazing at about 1000–1050 °C with tight 25–75 µm gaps and no flux.
What surface finishes work on BVAu-7 AS-BRAZED?
As-brazed fillets are bright and need no post-clean; can be lightly polished or ultrasonically cleaned, and plating is unnecessary since the alloy does not scale.
Can BVAu-7 AS-BRAZED be formed, bent or molded?
Readily cold drawn to fine wire and rolled to foil with interstage anneals at 600–700 °C in protective atmosphere; slow cooling promotes AuCu3 ordering and hardening.
What is the maximum service temperature of BVAu-7 AS-BRAZED?
BVAu-7 AS-BRAZED is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- AWS A5.8M/A5.8 Specification for Filler Metals for Brazing and Braze Welding — American Welding Society (2019)
- Brazing Handbook, 5th Edition — American Welding Society (2007)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- ASM Handbook Vol.2 — Properties of Nonferrous Alloys (precious metals) — ASM International (1990)
- Gold-copper vacuum brazing filler metals (wire, foil, preforms) — Morgan Advanced Materials / Wesgo Metals (2022)
- GB/T 18762 (precious metal brazing filler metals) — SAC (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.