Yeah, some combinations are not good. Aluminum and steel for instance. Mix a little well water (relatively high iron content) in there and you have a corrosion salad.
Brass fittings and Ethanol are not good bed fellows either.
Quick WiKi definition:
Galvanic corrosion (also called
bimetallic corrosion or
dissimilar metal corrosion) is an
electrochemical process in which one
metal corrodes preferentially when it is in electrical contact with another, different metal, when both in the presence of an
electrolyte. A similar galvanic reaction is exploited in
single-use battery cells to generate a useful electrical voltage to power portable devices. This phenomenon is named after Italian physician
Luigi Galvani (1737–1798).