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I'm just getting-into melting-down cans to make aluminum-based slingshots, hammers and the like. In my ignorance I didn't realize that copper/brass were also things that I could process which has left me hoping to learn:

  • should I be looking to make an alloy or using 1 metal and, if 1, which would be optimal?

  • are there any "additional treatments", such as quickly cooling the hot metal-product into a block of ice, or perhaps having the casting box on a vibrating-panel to further 'settle' things? All I know to do for increased-strength is to make as-clean-as-possible a mix IE scoop as much slag/skim from the top of the molten metal as possible!

  • is there enough variance among aluminum (or non-alloy metal products) to make it worthwhile to source specific-types, IE maybe aluminum from a car-engine part will make a stronger/better ingot than one made from a heap of aluminum cans?

A hammer and a sling-shot are my 1st goals with this, so while I'm not the best at knowing 'strength-types' I don't think "tensile" strength will be as important as yield-strength or compressive-strength but not sure, if I've gotta choose between optimizing for the slingshot OR the hammer, the hammer is far more important (and I'm not interested in working with lead to do this!)

Thanks a ton for any insight on this am in the middle of diving-in, learning I could do this at-home was truly a christmas-present LOL :)

user23895
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Copper with aluminum is called aluminum bronze in the trade; no zinc. Up to about 10% aluminum and a couple % iron . That system will get to about 300 BHN / Rc 30; a respectable hammer - not ductile. Manganese bronze is copper with 30 % zinc and a few % Al , Mn, and iron , also a very strong system for copper alloys . Copper Development Association will have more info. On the otherhand , I can't imagine how you could make them in the "backyard". I used to work at a smelter that produced these and other alloys and even with full foundry and lab facilities the melter would keep his fingers crossed on the aluminum and manganese bronzes because it was not a simple matter of getting chemistry in the right ranges but also getting ratios correct such as Al/Fe, Al/Mn , and others. I suggest staying with copper + 9 % aluminum , no zinc, and see what happens. If you get in the ballpark , aluminum bronze has a narrow freezing range and requires a large riser to get a sound casting. I hate to say it but both aluminum and manganese bronzes have a "martensite" reaction and can be heat-treated but not nearly as much affect as steel heat treatment. For now just stay with melting.

blacksmith37
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I've been doing research recently for similar applications not the same but testing aluminum bronze and you might try silicon for better mixing and machining or phosphorus or both (less than 1%) or maybe magnesium for hardness and though it won't help with hardness if mixing is the problem a little lead if you're not totally against it

Rob Lee
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