I rode an aluminum frame Cannondale T1000 around Australia. The bike frame broke near Shark Bay about ~280km from nearest bike store in Geraldton. I rode those 280km with the rear chainstay attached together with duct tape. It held. I didn't try very hard to find someone to weld aluminum and at that time there wasn't a Cannondale frame in my size available when we phoned anywhere in Australia. I flew back to the US to pick up a replacement bike since it wasn't that much more expensive than having the replacement packed and shipped and because I knew I could rely on getting it there.

With that said, and experience I had... I'd still tour on aluminum in some outback regions including outback Australia or other remote areas since likely I'd want something more than a simple weld anyways. I might also try an alternate strategy such as when I cross Russia and had a spare bike stashed with friends elsewhere in the country. Worst came to worst, I could get to the bike with a week of train travel...