Precious Metal AgCu-Eutectic
UNS P07720
AgCu-Eutectic (UNS P07720) is the 72Ag-28Cu eutectic silver-copper alloy, used both as a contact brazing filler and as a lower-cost contact material where 86% IACS conductivity and moderate strength are acceptable.
Reference datasheet — AgCu-Eutectic 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 O condition
AgCu-Eutectic tempers and conditions
AgCu-Eutectic is supplied in 6 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
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 |
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?
AgCu-Eutectic (UNS P07720) is the 72Ag-28Cu eutectic silver-copper alloy, used both as a contact brazing filler and as a lower-cost contact material where 86% IACS conductivity and moderate strength are acceptable. Annealed material gives 300 MPa tensile, 130 MPa yield, 30% elongation and 65 HB, and it rolls to foil or draws to fine wire readily (formability score 85), with cast, O, H02 and H04 conditions on file. It tarnishes in sulfur-bearing atmospheres and softens with heat, so silver-cadmium-oxide or AgNi contacts are used for arcing duty and plated finishes for exposed contacts. AgCu-Eutectic 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). AgCu-Eutectic has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 72% of precious metal grades. Elongation at break is 30% and the elastic modulus is 85 GPa (12.3 Msi).
What is AgCu-Eutectic used for?
- contact brazing filler
- low-duty switch contacts
- electrical joints
Advantages
- Conducts heat well — 355 W/m·K (205.1 BTU/hr·ft·°F), better than 92% of precious metal grades
- High electrical conductivity — 86 % IACS, better than 90% of precious metal grades
AgCu-Eutectic properties
Typical room-temperature values for AgCu-Eutectic-O; bars are the position among precious metal grades.
Physical3
AgCu-Eutectic 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 has a yield strength of 130 MPa (18.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 72% of precious metal grades. Elongation at break is 30% and the elastic modulus is 85 GPa (12.3 Msi).
Thermal6
AgCu-Eutectic is rated for continuous service to 300°C (572 °F). It conducts heat at 355 W/m·K (205.1 BTU/hr·ft·°F), better than 92% of precious metal grades. Thermal expansion is 19 µm/m·K (10.6 µin/in·°F).
Electrical3
AgCu-Eutectic conducts electricity at 86 % IACS, better than 90% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (75/100), worse than 61% of precious metal grades.
Sustainability4
Producing a kilogram of AgCu-Eutectic 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's machinability is fair (50/100, better than 74% of precious metal grades); weldability fair (40/100); formability excellent (85/100).
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. AgCu-Eutectic is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AgCu-Eutectic
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.
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) |
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.
Equivalent designations
Standards and trade names that resolve to Precious Metal AgCu-Eutectic in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- P07720
- Also called
- BAg-8
How much does AgCu-Eutectic cost?
AgCu-Eutectic 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.
AgCu-Eutectic — frequently asked
What is AgCu-Eutectic used for?
AgCu-Eutectic 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?
AgCu-Eutectic has a typical yield strength of 130 MPa (18.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 72% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is AgCu-Eutectic 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 be welded?
With care — weldability is rated fair (40/100). 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?
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 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?
AgCu-Eutectic 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.
How much does AgCu-Eutectic cost?
AgCu-Eutectic 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 A5.8/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; 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.