Precious Metal AgCu-Eutectic-AB (As built (as printed))
Print state
UNS P07720
Reference condition for joint design: properties of the re-solidified eutectic in a brazed lap or butt joint.
Values for the AB condition
Other AgCu-Eutectic tempers and conditions
AgCu-Eutectic is listed in 6 conditions; see the grade overview at AgCu-Eutectic.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
F | Choose for ingot stock, braze shot/paste feedstock and cast contact blanks where mechanical properties are secondary. | 115 | 260 | 20 | 58 HB | 85 % IACS |
Vacuum grade | Specify for vacuum-tube, accelerator and UHV brazing where Zn/Cd/P outgassing and volatiles are prohibited. | 125 | 300 | 30 | 63 HB | 87 % IACS |
ODefault Annealed | Standard supply condition for braze wire, foil, rings and contact strip where maximum ductility and formability are needed. | 130 | 300 | 30 | 65 HB | 86 % IACS |
ABThis page As built (as printed) | Reference condition for joint design: properties of the re-solidified eutectic in a brazed lap or butt joint. | 150 | 275 | 18 | 60 HB | 85 % IACS |
Half hard | Use for stamped contact parts and springy strip needing higher hardness while retaining some bend ductility. | 330 | 420 | 10 | 105 HB | 84 % IACS |
Full hard | Pick for spring-temper contact blades, hard-drawn wire and applications needing maximum strength and wear life. | 480 | 550 | 3 | 138 HB | 83 % IACS |
What is AgCu-Eutectic-AB?
AgCu-Eutectic-AB is AgCu-Eutectic in the AB condition — reference condition for joint design: properties of the re-solidified eutectic in a brazed lap or butt joint. AgCu-Eutectic-AB has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 68% of precious metal grades. Elongation at break is 18% and the elastic modulus is 84 GPa (12.2 Msi). AgCu-Eutectic-AB has a density of 9.9 g/cm³ (0.358 lb/in³), lighter than 70% of precious metal grades. It melts at 779°C (1,434 °F). O is the default condition FabDigit quotes; AB is available on request or by drawing note.
Advantages
- Conducts heat well — 350 W/m·K (202.2 BTU/hr·ft·°F), better than 89% of precious metal grades
- High electrical conductivity — 85 % IACS, better than 88% of precious metal grades
Limitations
- Limited formability — 45/100, worse than 91% of precious metal grades
- Limited ductility — 18%, worse than 83% of precious metal grades
AgCu-Eutectic-AB properties
Typical room-temperature values for AgCu-Eutectic-AB; 19 are specific to this condition. Other listed values are AgCu-Eutectic reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
AgCu-Eutectic-AB has a density of 9.9 g/cm³ (0.358 lb/in³), lighter than 70% of precious metal grades. It melts at 779°C (1,434 °F).
Mechanical13
AgCu-Eutectic-AB has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 68% of precious metal grades. Elongation at break is 18% and the elastic modulus is 84 GPa (12.2 Msi).
Thermal6
AgCu-Eutectic-AB is rated for continuous service to 300°C (572 °F). It conducts heat at 350 W/m·K (202.2 BTU/hr·ft·°F), better than 89% of precious metal grades. Thermal expansion is 19 µm/m·K (10.6 µin/in·°F).
Electrical3
AgCu-Eutectic-AB conducts electricity at 85 % IACS, better than 88% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 66% of precious metal grades.
Sustainability4
Producing a kilogram of AgCu-Eutectic-AB takes about 1,130 MJ of energy and emits 80 kg of CO₂ — less than 68% of precious metal grades. Typical recycled content is 45%.
Manufacturability8
AgCu-Eutectic-AB's machinability is fair (50/100, better than 74% of precious metal grades); weldability fair (35/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AgCu-Eutectic-AB
Is AgCu-Eutectic easy to machine?
Machines gummy like fine silver — use sharp, high-rake carbide or HSS tools, high speed, light feed and soluble-oil flood to avoid built-up edge.
Can AgCu-Eutectic be welded?
Normally applied as the filler rather than welded; torch, induction, furnace or vacuum braze at 780–870 °C with white/AWS Type 3 flux (flux-free in dry H2 or vacuum) and 0.05–0.13 mm joint clearance.
Can AgCu-Eutectic be formed, bent or molded?
Very ductile when annealed — rolls to thin foil and draws to fine wire with interanneals at 600–650 °C; work hardens quickly, so plan 40–50 % reductions between anneals.
What surface finishes work on AgCu-Eutectic?
Not anodizable; polishes to a bright mirror, and is commonly hard-silver, gold or nickel plated or lacquered to suppress H2S tarnish on contacts.
AgCu-Eutectic 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 |
|---|---|---|
| AgAWS A5.8 BAg-8 / UNS P07720 | 71 – 73 | 72 |
| Cdcadmium-free grade | ≤ 0.01 | — |
| Pimpurity limit | ≤ 0.01 | — |
| Znimpurity; further restricted in vacuum grade | ≤ 0.05 | — |
| Pbimpurity limit | ≤ 0.03 | — |
| Other (total)total of all other elements per AWS A5.8 | ≤ 0.15 | — |
| Cu | ≥ 27 (balance) | — |
AgCu-Eutectic-AB — frequently asked
What is AgCu-Eutectic-AB used for?
AgCu-Eutectic-AB is typically used for contact brazing filler, low-duty switch contacts and electrical joints. In short: standard silver braze eutectic; most formable contact alloy; tarnishes in sulfur atmospheres.
What is the yield strength of AgCu-Eutectic-AB?
AgCu-Eutectic-AB has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 275 MPa (39.9 ksi) — weaker than 68% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is AgCu-Eutectic-AB easy to machine?
Reasonably — machinability is rated fair (50/100, better than 74% of precious metal grades). Machines gummy like fine silver — use sharp, high-rake carbide or HSS tools, high speed, light feed and soluble-oil flood to avoid built-up edge.
Can AgCu-Eutectic-AB be welded?
With care — weldability is rated fair (35/100). Normally applied as the filler rather than welded; torch, induction, furnace or vacuum braze at 780–870 °C with white/AWS Type 3 flux (flux-free in dry H2 or vacuum) and 0.05–0.13 mm joint clearance.
What surface finishes work on AgCu-Eutectic-AB?
Not anodizable; polishes to a bright mirror, and is commonly hard-silver, gold or nickel plated or lacquered to suppress H2S tarnish on contacts.
Can AgCu-Eutectic-AB be formed, bent or molded?
Very ductile when annealed — rolls to thin foil and draws to fine wire with interanneals at 600–650 °C; work hardens quickly, so plan 40–50 % reductions between anneals.
What is the maximum service temperature of AgCu-Eutectic-AB?
AgCu-Eutectic-AB is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AgCu-Eutectic-O and AgCu-Eutectic-H04?
O is the default condition — standard supply condition for braze wire, foil, rings and contact strip where maximum ductility and formability are needed. H04: pick for spring-temper contact blades, hard-drawn wire and applications needing maximum strength and wear life. Yield strength is 130 MPa in O versus 480 MPa in H04.
Sources
- AWS A5.8/A5.8M — Specification for Filler Metals for Brazing and Braze Welding (BAg-8) — AWS (2019)
- GB/T 10046 — SAC (2018)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (silver and silver alloys) — ASM International (1990)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (brazed joint strengths) — ASM International (1993)
- ASM Handbook Vol.3 — Alloy Phase Diagrams (Ag-Cu system) — ASM International (1992)
- Silver brazing alloy datasheets (BAg-8 / 72Ag-28Cu, standard and vacuum grade) — Lucas-Milhaupt / Umicore / Materion (2023)
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.