Warning

My information below may all be terrible advice, and experts may tell you not to listen to a word of it. It worked for me though. Except for this next paragraph

Your Dewalt saw isn't really meant for cutting metal, not with carbide metal-cutting blades. It spins too fast, and is more likely to burn up an expensive blade (at minimum, it may be dangerous too). You really should have something that's meant for metal, or at least for also cutting metal like the Evolution brand saws.

/Warning

When I first wanted to cut some metal pieces on a budget, neater than a grinder, I picked up a cheap 8-1/4" blade and a cheap 8-1/4" miter saw, figuring I'd use them until one or the other died. I made a test cut on a piece of 3/16" 2x3 angle iron, and it made a nice clean cut through it. I would expect aluminum to cut a lot easier.

Given that information, there are 12" metal cutting blades available, though something like this looks pretty damn similar, for a fraction of the price, and might just work for a bit for you.

Here's a metal blade (12", 80T) for only $150 on eBay. http://www.ebay.com/itm/OSHLUN-SBF-140080-Steel-Cutting-Saw-Blade-14-x-80T/221245462330 Guess the same but in 60T is only $56 on Amazon: http://www.amazon.com/Oshlun-SBF-120100-12-Inch-1-Inch-Ferrous/dp/B0012YKRXS