Yes, it is. It is done all the time. Make no mistake about it. Aluminum on the atomic level (or a bit more if a cook is overzealous with utensils in the vessel) gets into the food cooked in uncoated...
Cast Aluminum is made by pouring heated molten aluminum into a mold. During this process, microscopic air pockets form in the metal. This means that the resulting cookware items will hold their heat...