My father (an aerospace/semiconductor engineer) used to tell me about a way that bars of half aluminum, half copper were made. I think pressed together under high current in an inert atmosphere. Conductors for joining power station circuits that were dissimilar metals, IIRC.
Just the other day I was going through his stuff and I found a couple of these. One polished, the othe rough finished. Really interesting objects. Can anyone expand on the welding process and maybe on the parts' application? My memory is really fuzzy since I was pretty young at the time.