Pretty sure hammerers need a hammer. I don't think mauls count either.
The noble position "hammerer" can be made to use a crossbow. Its generally recommended, as even with a full quiver he'll still use the stock of his xbow. So long as said xbow isn't made of copper or some heavy artifact metal, it'll be fine. I typically just use bone crossbows... which I just assign to all my regular marksdorfs. I typically have to use wood for things like pearlash/pottery glaze/charcoal/bins/beds/shields/etc, but bone is far more abundant on all maps and generally less useful outside of exotic animal bones as trading materials.
To actually answer the OP's question... No. While aluminum is the lightest -metal-, it's still twice the weight of the heaviest wood (its roughly as heavy as your average stone, actually). If you don't have featherwood/candlenut/willow wood on your embark/can't import it (anywhere there is water there are willows just about), use bone or any generic wood instead. Bone and your average tree are about the same density, and that is a mere fraction of what aluminium is.
Also consider that it is an artifact weapon that boasts a 50% better hit rate and no material drawbacks (since crossbows only check quality of the xbow when firing-only bolts get a material check) Instead of bashing in the heads of drunks and whoever your nobles are pissed at this time, use them to shoot up forgotten beasts or at least station them out front to take pot-shots at those damned keas.