aluminium booms are designed to break, yep you heard it here first.
honestly, with the loads people put into booms, unless you are particularly light, or just sail perfectly flat water i don't think it's possible to have any aluminium boom that will last forever, unless you make it horrendously fat and heavy.
that said, most ally booms seem to last well enough in general use, thou there has been examples of some with some serious design flaws, such as the first few versions of the NP booms with the hydroformed front end, pretty sure a heap of them failed at the exact same spot after very little sailing. but that's why we have warranties

doesn't save you swimming, but anyway