An interesting alloy indeed

I thought I would put this here more as a sort of public journal entry of sorts. Feel free to respond with thoughts and comments if you like :slight_smile:

I know that Germany has lowest legal gold karat to my knowledge, that is 8K gold or 0.333 fine. I was very curious about this alloy, and had 2-3 grams of 10K lying around which also happened to be a homemade recipe. I added all silver down to 8K and was left with an alloy of 33.3% gold, 28.7% copper and 38% silver. The colour was certainly yellow but somewhat more coppery than commercial 10K gold. Although I wonder if this is due to lack of zinc rather it’s lower purity. It’s working properties are what was interesting though. It wasn’t super hard per se, but it showed a lack of ductility requiring frequent annealing and also was quite springy. It melted at a very low temperature and in fact I couldn’t solder it. It fused terribly and sort of just melted into a little blob which I hammered flat. I am interested to see how it tarnishes. If anyone has worked with 8K gold I would enjoy hearing your experiences,


Hi Jonah,
Your 10KY gold composition appears to land near the slope of what is called a “eutectic trough or valley”, a bunch of gold alloys all having the lowest melting ranges in ternary Au-Ag-Cu system! I roughly calculated the melting range for your 10K gold to be 850C or 1592F. I don’t know the flow point of solder you were using, but if it were a hard solder, you might face issues of reflow of your 10K gold! It is practically another solder, LOL!


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How did your investigation into the 8k alloy continue?
I’m interested in the properties of any in the Au-Ag-Cu system.
In fact I think I’d prefer - if making 8k from 10k - to add just copper.
I imagine the ductility might be better.

Did you do any more experiments with 8k?