Calling metallurgists, jewelers and others…Silver alloy question.

RWB

Can anyone tell me what an alloy of 95% silver and 5% nickel (no copper) would look like? Color, surface, malleability, etc.

I have the following basic info: Nickel by itself makes silver very hard and brittle, such alloys being difficult to work. But by adding some copper the alloys can be cast, rolled and fused, and the articles manufactured from them are harder than those from silver and copper alloys….Alloys of silver, copper, nickel and zinc…have been used in Switzerland for the preparation of small coins. The coins…soon loose their original beautiful whit color and acquire a disagreeable yellowish shade resembling …poor brass.

cladking

I don't really know but I'll bump your thread.

Silver is a very strong coloring agent and will even turn gold silver
colored with only a little being added.

Ny guess is that your alloy would appear to be almost indistinguis-
hible from silver by color and weight. It would probably have sim-
ilar properties to silver as well except that it couldn't be made into
thin sheets because it would break apart.

ttt

Coxe

I haven't looked at this stuff in a long time. Alloys are tricky business because what will alloy and its properties comes down to the detailed electronic structure at the atomic and interatomic lattice levels. I would venture to guess than the reason Ag-Ni alloys aren't out there in common use is because structurally useful properties are unobtainable in the binary mixture. Therefore, Cu, Sn, Co and other condidates are used as doping agents.

As for the color, that is purely the consquence of the reflected light form the surface of the lattice. If memory serves me, it is a combination of lattice momentum conservation using the particle wave vectors and the photonic momentum (proportional to its frequency) and reradiation of photonic energy be the outer valence electrons. Skipping all of the complexity, the fact is that both Ag and Ni as simple FCC crystals reflect the full visible spectrum and, thus, appear white naturally. I would expect a binary alloy of the two to behave similarly, but there is no guarantee of that. Note this is not a matter of the crystal structure as Au and Cu are also FCC crystals. In fact, additionally, the lattice constant for Cu is nearly the same as for Ni and Au's is very close tot he same as Ag. It comes down to atomic electronic structure.

I believe we have another physicist on here who is in solid state physics and would be more accurate in a response than me. My familiarity is back to grad school classes and university symposia. I am getting increasingly interested in it all though, moreso than when I originally studied it. Also, we have someone who does coinhis own tokens too. Maybe he has experimented with various alloys?

CaptHenway

<< <i>Can anyone tell me what an alloy of 95% silver and 5% nickel (no copper) would look like? Color, surface, malleability, etc.

I have the following basic info: Nickel by itself makes silver very hard and brittle, such alloys being difficult to work. But by adding some copper the alloys can be cast, rolled and fused, and the articles manufactured from them are harder than those from silver and copper alloys….Alloys of silver, copper, nickel and zinc…have been used in Switzerland for the preparation of small coins. The coins…soon loose their original beautiful whit color and acquire a disagreeable yellowish shade resembling …poor brass. >>



That Swiss alloy sounds like the quad alloy the Australians used from 1946 to 1964(?). They would pickle the planchets in a mild acid to leach the base metals out of the surfaces before striking, so that the coins when new had a wonderful silvery color. However, as the coins wore down the exposed quad alloy turned an ugly dirty yellow, while the protected areas still retained the silvery appearance.

TD

coinman420

nickel is harder and would make the coin tougher. i think when newly struck it would look much like pre-1965 circ silver but as it wore it would look different than circ silver.

cladking

<< <i>their original beautiful whit color and acquire a disagreeable yellowish shade resembling …poor brass. >>



That Swiss alloy sounds like the quad alloy the Australians used from 1946 to 1964(?). They would pickle the planchets in a mild acid to leach the base metals out of the surfaces before striking, so that the coins when new had a wonderful silvery color. However, as the coins wore down the exposed quad alloy turned an ugly dirty yellow, while the protected areas still retained the silvery appearance.
>>




Weren't the Swiss coins only 835 fine though?

ProofArtworkonCircs

This is a bit OT, but 95% gold, 5 % Aluminum will age to a nice purple color.

Nysoto

As an "other" I would speculate that a 5% nickle/95% silver alloy would be harder, both in an annealed state and a cold worked state, would have a higher melting temperature than coin or sterling silver with different annealing requirements, would be more resistant to tarnish, and probably white in color. The alloy D50F is 15% nickel/85% silver, is much harder than sterling. Nickel is used to make stainless steel corrosion resistant. We use millions of pounds of Invar where I work, which is 36% nickel and has the lowest level of thermal expansion of all metals.

Argentium sterling, or a close alloy, could be a good metal for coins. It is more ductile, and does not tarnish because of a small amount of germanium added. If I get back into silversmithing, I would choose Argentium sterling.

edit - its D50F, not DF50

RWB

Thanks to everyone so far - I'm trying to identify use of this alloy in some experimental/pattern coins, but have scant good data to start with.