Well I've gone to Bunnings a couple of times to build a motor. There are Galvanised Steel (zinc coating I believe), copper, aluminium should be there. However if you want to perform this in an experience format, and I think you should, use metallic material of identical or close shape and size so you should look at the nails there instead or use metallic sheets of similar size.
Galvanised Steel is in the form of a pipe so that might not be useful if you want identical materials.
Best bet is to use different type of nails made of different metals such as copper, iron and stainless steel (use more if you can)
Idk much about marine environment of the Antarctic, but I think you can research that. Consider: temperature, ion concentration, oxygen, pH and those type of factors.