It strikes me (and no, it didn't hurt. . . much) that the disimilar metals could, in most cases, cause electrolisys problems. That's why hman recommended avoiding moisture. Recently, I had acquired some Aluminium "solder" or "welding rods". The actual metal I think is Zinc, but only counts as something less likely to corrode than Copper. The "solder" is about 1/16" per strand and is soft enough to flatten with pliers. If it were at hand, I would think it would make a better "filler" than Copper. Again thinking (not my strong point) that the Zinc would , with time, bond to the aluminium casting making a more reliable repair.
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