Aluminum cracks as well. Sure you can fix it but probably will crack somewhere else at some point in the future, obviously depends where the crack is too. But yes eventually you can but who knows how long it will last before another crack shows up maybe in the surrounding area. If you need to buy some time until u get money for another one, then fix can be done... your call after all..

The issue with aluminum is that the joints (or were the weld is) get stronger than the tubing and thats why needs to be heat threaded so the whole frame gets structurally even. Thats the reason good aluminum frames are expensive, for example the cheapo stuff sure is not even heat treated

good luck.