There are some people that say the use a GMAW process with aluminum wire and a dabber wire feeder and run it 30-40 cycles per a min and tune the welding current to match. The problem is aluminum melts at a lower temp so you have to control the temp of the work piece.
When i went to school they showed use a way to bond them with a oxy/fuel torch and silver solder. Its basically brassing, and doesn't turn out all that strong.
