Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

Pyrometallurgy: Roasting, Smelting, Refining & Electrowinning

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How to Harden Tin/Bismuth Alloy? (4 replies)

johnywhy
4 years ago
johnywhy 4 years ago

This question concerns the making of alloys for casting.

I need a low-toxicity, low-melting point metal, to cast hardware parts.
The parts must not crack under torque or impact, and should remain hard up to 100 deg C.

My plan is to make a Tin/Bismuth alloy, since low-toxicity, low-melting point.
I've heard a tiny amount of silver can make this alloy less brittle.

Any suggestions? Could be a different alloy, or a hardening process.

thx!

johnywhy
4 years ago
johnywhy 4 years ago

I mean, parts should remain hard after casting. 

johnywhy
4 years ago
johnywhy 4 years ago

I'm not committed to tin, bismuth, or silver. But need to keep things relatively low-toxic and low-temp. (home, indoor fab). Need to minimize shrinkage/expansion of cast part. 

J
Julgo
1 week ago
Julgo 1 week ago

Hi,

I also want to make a a Tin/Bismuth alloy for small figurines (toys), & 'd like to have your feedback.

How did you finally make your alloy ? Is it enough to melt the both piece of metal in a pot or do we need to shake/mix the mixture ?

a 50-50% mix is ok ?

J
Jorge
4 days ago
Jorge 4 days ago
1 like by David

It is important to mention that bismuth has a special property of expanding during cooling. Therefore, is added to reduce the contraction of the alloy tin-bismuth. Also, the addition of bismuth is made considering a more crystalline grain to the tin-bismuth alloy. I would suggest to try 60 percent tin and 40 percent bismuth. This alloy is usually bright. In this case, the addition of tin regulated by observing a sample drop falling upon an iron plate forms a bright surface like a mirror.

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