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Yes, they are pot metal (zinc diecast, white metal, or whatever you chose to call it). Pot metal can be welded, but it's not easy to do, because of it's low melting point.
I'm sure if you want a pair just to have powder coated, you should be able to find some used ones to work with. Used ones are almost always pitted, but if you're powder coating them anyway, I'm sure you can get an acceptable surface with just some sanding and grinding.