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Aluminum Copper Alloy Experiment

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Since David (Meldonmech) in his QCTP build thread and Andrew mentioned alloying copper with aluminum to increaase hardness, I did a few lookups online (and in a book I have) and found an alloy that looked interesting using 6% silicon and 4% copper, so decided to try it with scrap onhand.

I used a 14 oz piston for silicon content (likely about 12%) and 14 oz 6061 extrusions, which would bring the silicon level to about the 6% needed, and 1.2 oz of copper tubing for the 4% copper. I flattened it and rolled it together to reduce oxidation. Here are the ingredients:

I wasn't sure if the aluminum would dissolve the copper directly, or whether the copper should be molten first, so I tried melting the copper to start with. After about 25 minutes and the copper glowing bright orange, it still wasn't molten, and being impatient, I started dropping some of the aluminum in. When a good heel was going I added more and eventually the piston, and had a brimfull crucible as a result.

The copper did dissolve in the aluminum, so I probaby could have saved much time and fuel had I just put them all together to begin with.
I'm new to this forum and this will be my first post.
Re the comment you make about aluminium and copper reminded me of a demonstration of eutectic alloying that our metalwork master showed the class back in the 60s.
He heated a strip of copper to a dull red then applied a thin piece of aluminium wire to the surface.It melted onto it and he then proceed to poke a hole through the strip thereby demonstrating how alloying changes the melting point.

I've enjoyed catching up on a lot of the posts since Doubleboost recommended the site and am learning a great deal. I'm keen to make a small furnace myself as the last casting that I did was 50 years ago!


Interesting Steve  :thumbup:  how dose your new alloy machine ? 


I found out about the copper by mistake droped a piece of copper pipe in the furness , by the time I bent a pice of wire the fish it out half it had melted , so I added all my offcutts the resulting poure turned very nicely on the lathe into pullys .


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