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Aluminum Copper Alloy Experiment

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Will_D:
As the melting points are widely different the only way to get Cu and Al to alloy is by disolution.

The molten aluminium will alloy with the copper at the surface of the copper and create a eutectic. Given time and agitation the copper will sloooowly disolve into the aluminium.

The way to speed things up would be to increase the surface area a LOT so cut the copper wire into short (say = to the diameter) lengths and then see how quickly they disolve also stirring the pot will help.

PS: This is only my theory!

mattinker:
It's not only your theory! That's how it works. I used fine stranded wire when dissolving Cu into Al to make ZA12. 1%Cu, 11% Al 88% Zn by weight. 10%Cu will dissolve easily into Al.

Regards, Matthew.

vtsteam:
re. ZA-12:

Matt what were your feelings/results of the ZA-12 that you made? Did you make any castings with it?

The ZA-2 and ZA-3 I tried were purchased virgin alloy ingots. ZA-12 is not available easily here, and I have some pure zinc coming shortly to try different shop mized ZA numbers. But would be curious re. your results w/ZA-12.

re. al/cu:

I don't have fine copper wire, but didn't have any problem melting the copper tubing I used, folded into a couple of pellets (first photo at start of thread).

Perhaps as Ironman says it was the pre-heating that helped. I'll give here the exact procedure I followed in case it makes any difference:

First tried melting the copper, and I think it was 20+ minutes from placing cold crucible and pellets in the furnace. The crucible and pellet were glowing orange when I added a few small pieces of the 6061 to start a heel. I noticed that it immediately wetted the copper when melted (like solder). I gradually added more pieces of 6061 (low silicon Al) as it melted, then finally stuck the piston (high silicon Al) on top. It took awhile to heat up and melt -- probably 5 minutes. When I stirred it all there was no evidence of the copper pellets left, and I poured.

I wonder if preheating the copper pellets with a torch would allow them to be added after the aluminum, and still combine easily. That would save a lot of time and fuel and allow heavier section copper to be added (if they are a problem unheated). Even a mapp gas portable torch should bring a small pellet of copper up to red heat.

I also wonder if the cleanliness of the copper is a factor in getting the aluminum to wet it out initially -- like solder. Mine was clean copper tubing, and folding it with hammer also exposed bright areas.

mattinker:
I was very pleased with the ZA12 I made, it casts well in sand and machines beautifully! It has good bearing qualities. I am very lucky as here in France A lot of roofs are covered with pure zinc sheet so good quality pure stuff is available, and having done roofing work, I've been saving off cuts (drops) and scrap from dismantled roofs for years. My stash is probably worth quit a lot as scrap alone! ZA12 is supposed to have similar bearing and vibration dampening characteristics to cast Iron.

Regards, Matthew

ironman:
I did do a lot of stirring to get the copper to dissolve quicker but made no difference. My thoughts were that to heat the copper up would create an oxide coating and make it difficult to dissolve copper in aluminium. It could be that I will have wait longer for the copper to dissolve. As I pour mostly iron I have not gotten back to this experiment but will give it a try in the near future.

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