Well! There seems to be some disagreement among the answers here.
To clarify, the “aluminum foil” I’m talking about here is kind of oven liner that can be purchased at such places as hardware stores, home improvement stores, Target, Bed, Bath & Beyond, etc. that is intended for use on the oven floor, perhaps to catch drippings, spillings, cake batter overflows, and what not. In my case, I have an electric oven, and the foil liner can be placed between the bottom heating element and the oven floor. For convenience, I leave it in there all the time. My concern was that I might forget to remove it before running the self-cleaning cycle.
I’m assuming the liner is aluminum, since it seems very similar to aluminum foil, only thicker. But as someone pointed out, aluminum is extremely reactive, so this would not be pure aluminum, but aluminum oxide and/or some sort of alloy. Though the melting point of aluminum is 1220 degrees F and the oven only reaches 875 F during the self-cleaning cycle, I can’t rely on this fact, since I don’t have pure aluminum. Plus, I’ve read somewhere that aluminum will ignite or burn before it melts.
@AmWiser and @john65pennington are two folks who seem to have had actual experiences with this, and they differ. Anyone else?