Aluminum can be Tig welded. There is also a "brazing" system that uses special aluminum rods with a propane torch. Some people have mastered the skill of aluminum brazing , and some, like myself could only burn holes! Tig welding involves a tungsten welding tip that creates an arc, and then you feed a flux coated rod into the joint. Good tig welders are artists too. Do an internet search on both processes, and you should be able to find loads of information. Ask in your local clubs, or hobby shops who repairs broken mufflers, or engine crankcases. Good luck, Greg