This is a bit of a tricky question! It depends on how you're thinking about it:

* Aluminum cans and iron as separate items: This is a mixture, specifically a heterogeneous mixture. They are distinct substances that can be easily separated.

* The metal in an aluminum can and the iron in a piece of metal: These are pure substances, not mixtures. Aluminum and iron are elements, which are the simplest forms of matter and cannot be broken down into simpler substances.

Let me know if you have another question about mixtures or solutions!