I've got a couple of old General Electric alarm clocks (probably from the 1960s or 1970s).

The pins on the molded-on plugs are made out of aluminium. I've been using them for the better part of two or three years without a problem.

But I'm wondering if there could be some sort of interaction between the aluminium of the blades and the brass used for the contacts inside the receptacle? The blades are a bit "tarnished" but there have been no signs of overheating.

I know that copper and aluminium don't get along...so I was wondering if that's also the case with copper-based alloys like brass.

I wonder also how the crimp between the aluminium pin and the copper wire hasn't gone bad in all these years!