The Shop > Metal Stuff
Aluminum Copper Alloy Experiment
WeldingRod:
--- Quote from: Biggles on May 19, 2017, 09:27:21 PM ---If you really want a hard alloy try Beryllium with Copper. It’s used to cover expensive golf clubs and can be used for armour piercing bullets!
--- End quote ---
Please don't play with Beryllium; it's toxic. The machining award from it is too. We use Beryllium Copper for downhill tools, and it requires special handling in the machine shop.
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WeldingRod:
--- Quote from: NormanV on October 30, 2017, 04:02:14 PM ---I have just cast another alloy, 90% copper 10% aluminium. I tried a file on it and it just skidded with barely a mark. It is certainly hard, will I be able to machine it? I'll find out tomorrow.
What I found interesting is the colour, with all that copper I expected it to be bronze coloured but it is silver with just a blush to it.
The copper that I used was old plumbing pipes with a few brass glands on it, so the actual composition if a bit vague.
One problem that I encountered was the low heat output of my propane torch. When I melt aluminium it normally takes approx. one hour to melt my 3kg ingots. I had thought that this was due to the size of the ingot, I have read of people having molten aluminium in 15-20 minutes.
Today I melted the aluminium first and then added the copper, from start to finish was over 4 hours! After two hours I almost gave up but by that time I had invested so much gas into the project I thought that I would see it through. I don't think that I will be trying to melt any iron with this torch.
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My experience was that my random aluminum bronze was brass colored, quite hard, and super brittle. I shattered some parts just getting them out of the sand.
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RotarySMP:
The rivets referred to above are -DD rivets. The need to be heat solution heat treated, and come of of the heat treatment in the unstable "W" state, where they are soft, but will naturally age harden. You keep them in a chilly bin with liquid nitrogen to retard that process, long enough to insert and rivet a whole batch in a shift. They are very nice to rivet with, as they are nice and soft. They are normally only used by the manufacturers. For repairs, -AD rivets are used, which have a stable heat treat, and are a fair bit harder to drive.
With resect to aluminium bronze, this patent https://www.google.com/patents/US3378413 has an interesting line:
With the conventional copper-aluminum-iron alloy, lower annealing temperatures in the' range of 800 to 1050 F. cannot be used because the martensitic structure transforms to eutectoid which results in a more brittle alloy having reduced strength and loss of ductility.
The present invention is based on the discovery that by adding nickel, or nickel and manganese, to an aluminum bronze alloy containing from 10 to 12% aluminum, the tendency of the martensitic structure to transform to the eutectoid is substantially suppressed. The suppression or elimination of the tendency to form the eutectoid enables the alloy to be stress relieved and permits secondary alpha precipitation at a temperature in the range of 800 to 1050 F. to thereby produce an alloy having high tensile strength and high yield strength with good ductility. The aluminum bronze alloy treated in accordance with the invention compares favorably with the more expensive cast and heat treated beryllium copper alloys.
So basically Cupper/Aluminium/Iron alloy, is probably pretty useless, as you confirmed.
Mark
vtsteam:
Photos restored after Photobucket broke the links.
Interesting re-reading this thread. Just wanted to point out that I began it by trying to compound a specific silicon and copper bearing aluminum alloy, rather than an aluminum bronze -- which is a copper alloy with some aluminum in it . Quite a different purpose and metal alloy.
The aluminum alloy I chose to try to make was EN AC-45000. Which is 6% silicon and only 4% copper. I think that was a success and it certainly machined fine. I will have to check it again now for hardness after aging a further 3 years. I did make a part for the lathe project with it -- a base extension.
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