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Silver Alloys

Silver is the best electrical and thermal conductor of any metal — 106 % IACS, 429 W/m·K — and the most reflective in visible light. Fine silver (Silver 999) is 10.5 g/cm³, melts at 962 °C and is soft at about 25 HV; sterling (Silver 925, 7.5 % copper) hardens to 70 HV annealed and 140 HV cold-worked and is the working alloy for anything handled. The series also holds the silver-based brazing fillers (BAg-1 to BAg-37, the largest group of fillers in industrial use), the silver-metal-oxide and silver-tungsten contact materials of switchgear, and the germanium-modified Argentium 935.

Popular silver grades

Compare in the explorer
GradeYield, MPaTensile, MPaDensity, g/cm³MachinabilityWeldabilityBest for
Silver 9995514010.49FairGoodHighest-conductivity contacts, plating, mirrors
Silver 9257528010.36GoodGoodSterling jewelry, tableware, machined parts
Argentium 9358026010.3GoodExcellentTarnish-resistant, firescale-free sterling
BAg-72904159.5GoodPoorCadmium-free general-purpose brazing filler
BAg-816038010GoodPoorEutectic Ag-Cu filler for vacuum and electronics
90Ag-10SnO21302409.95FairPoorAnti-welding contactor and breaker contacts
AgW5028042013.7PoorNot recommendedHigh-current arcing contacts

All 86 silver grades

Choose silver for

Relay, switch, contactor and circuit-breaker contacts; bus-bar, RF and waveguide plating; the brazing of copper, steel, stainless, carbide and nickel alloys with a filler that flows at 600–800 °C; mirrors and reflectors; battery and solar-cell conductors; and sterling jewelry, tableware and decorative parts that are cast, spun or machined.

Look elsewhere when

The contact must stay clean at signal-level voltage in sulfur-bearing air — silver tarnishes, so Gold 24K plating or a Pd60Ag40 alloy is used; the conductor is large, where C11000 copper carries 95 % of the current at a small fraction of the cost; the brazing temperature must stay below 450 °C (a tin-silver solder) or above 900 °C (a copper or BAu-4 gold filler); or the jewelry must be white and never need polishing (Pt950, Pd950).

Yield strength against electrical conductivity, Silver alloys among every precious metal grade

No materials in view have both of these properties.

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Silver by application

Switchgear contacts
90Ag-10SnO2 and 88Ag-12SnO2 for contactors and breakers that must not weld shut; AgNi10 and Silver 999 for relays under a few amps; AgW50, AgWC60 and AgC3 for heavy arcing and anti-weld duty in breakers.
Brazed joints
BAg-7 for most steel, stainless and copper work; BAg-5 for copper and brass where lower silver is acceptable; BAg-8 and BVAg-8 for vacuum and electronic assemblies; BAg-24 for stainless; Ticusil (Ag-Cu-Ti) and Incusil-10 (Ag-Cu-In-Ti) for active brazing of ceramics to metal.
Conductors and plating
Silver 999 plating on bus bar, RF connectors and waveguides; IC-Ag99.99 for interconnect and sputter-target purity; AgCu-Eutectic for high-strength conductor wire.
Jewelry and tableware
Silver 925 as the standard, Argentium 935 for a brighter finish that resists tarnish and firescale, Britannia Silver (958) for softer, purer pieces, Coin Silver 900 and 800 Silver on continental and antique work.

Working with silver

Machining
Soft and gummy: sharp polished tools, high speed, light cuts and a light oil. Silver 925 and Argentium 935 turn and mill acceptably; Silver 999 smears and is better formed than cut. Every chip is recovered and the job is reconciled by weight.
Forming and heat treatment
Fine silver and sterling deep-draw, spin and raise like copper; anneal sterling at 600–650 °C and quench. Copper in sterling forms firescale (a subsurface copper-oxide stain) when heated in air; Argentium 935 does not, and it can be hardened to about 110 HV by holding at 300 °C after annealing.
Joining
Sterling is hard-soldered with graded silver fillers (hard, medium, easy) so successive joints do not remelt the earlier ones; Argentium 935 can be fusion-welded and laser-welded without filler. Industrial silver brazing uses the BAg fillers with flux in air or fluxless in furnace and vacuum.
Finishing
Polish to mirror; anti-tarnish passivation, lacquer or rhodium plating for jewelry and a thin gold flash for contacts that must stay clean. Fine silver tarnishes slowly, sterling faster, Argentium 935 slowest of the three.

Other precious metal series

Silver Alloys — frequently asked

What is silver?

Silver is the best electrical and thermal conductor of any metal — 106 % IACS, 429 W/m·K — and the most reflective in visible light. Fine silver (Silver 999) is 10.5 g/cm³, melts at 962 °C and is soft at about 25 HV; sterling (Silver 925, 7.5 % copper) hardens to 70 HV annealed and 140 HV cold-worked and is the working alloy for anything handled. The series also holds the silver-based brazing fillers (BAg-1 to BAg-37, the largest group of fillers in industrial use), the silver-metal-oxide and silver-tungsten contact materials of switchgear, and the germanium-modified Argentium 935.

Which grade of silver should I use?

Silver 999 for contacts, bus-bar and waveguide plating, mirrors and anything where conductivity is the point and the part is not handled. Silver 925 for jewelry, tableware, hollowware and machined decorative parts; Argentium 935 when firescale and tarnish are the problem — it is fusion-weldable and can be precipitation-hardened. BAg-7 (56Ag-22Cu-17Zn-5Sn, 618–652 °C) is the cadmium-free general-purpose brazing filler for steel, stainless, copper and nickel; BAg-8 (72Ag-28Cu eutectic, 780 °C) for vacuum and electronic joints with no zinc; BAg-24 for stainless where nickel improves wetting; BAg-1 and BAg-3 are the older cadmium-bearing fillers still on legacy drawings. For contacts, 90Ag-10SnO2 and 88Ag-12SnO2 are the cadmium-free anti-welding materials for contactors and breakers, AgNi10 for low-current relays, and AgW50 and AgWC60 for high-current arcing contacts.

Which grade of silver is the strongest?

B631 Class C has the highest yield strength in the series at 420 MPa; Ag145 follows at 340 MPa. Values are for each grade's default condition.

Which grade of silver is easiest to machine?

AgC3 (machinability good, 62/100), then 950 Silver (Minerve) (60/100).

Which silver brazing filler should I use?

BAg-7 for general work: cadmium-free, flows at 618–652 °C, wets steel, stainless, copper, brass and nickel alloys and gives a colour-matched joint on stainless. BAg-5 where a lower-silver, higher-temperature filler is acceptable on copper and brass. BAg-8 (the 72Ag-28Cu eutectic, 780 °C) for vacuum, electronic and furnace-brazed joints because it has no zinc to vaporize. Replace BAg-1 and BAg-3 on old drawings with BAg-7 or BAg-24 unless a procedure qualification forbids it — cadmium fume is the reason they were retired.

Sterling or Argentium?

Silver 925 is the standard sterling: 92.5 % silver, 7.5 % copper, the alloy every hallmark and every supplier knows. Argentium 935 swaps some of the copper for germanium, which stops firescale during soldering and annealing, slows tarnish noticeably, allows fusion welding without filler and can be precipitation-hardened. It costs a little more per gram and is made in fewer forms, so it is chosen for pieces where finishing time or tarnish complaints matter more than the alloy price.