How thick material are you talking about, and how much length that needs beveling?

For not a lot of thickness and length, the flap wheel on an angle grinder as mentioned previously here will work just fine. Just don't rush it but trying to press down too hard. Take your time and let the abraisives do the work, you don't want to melt the aluminum. (That can fold in oxides under the surface, and generally do bad things when it comes time to weld.)

If you have more thickness and length, an aluminum-specific grinding disc works several times a lot faster; and is a lot more aggressive. You can push down pretty hard and the aluminum comes off pretty fast. They are not too common, (and the common kind will just load with aluminum) but the aluminum-specific ones are available via mail order for not too much. Let me know if you need a link, they are kind of specialized. I have posted links to them here before, if you want to do a search you can probably find it.

Of course if you have a super amount of thickness and length, probably even a grinding disc wouldn't be enough, you might want mitering bandsaw or a mitering carbide tooth circular, or something like that. It all depends what kind of beveling you are talking about.