"Bob Engelhardt" wrote in message
. ..
erik litchy wrote:
... the aluminum is caustic when its molten and can eat through iron.

Well, it might, but so slowly as to be irrelevant. I have melted aluminum
in sawed off propane torch cans (20 ga?) without any noticeable thinning
of the steel.

Bob

It's a noticeable problem in aluminum diecasting, where the aluminum
impinges on the steel with some pressure and cuts right through the oxide to
the parent metal. Other than that, the process of dissolving iron in
aluminum is pretty slow, although, as others have said, it quickly becomes
enough to degrade the aluminum if you melt it in an iron or steel crucible.
One useful solution is Dave Gingery's method of using crucibles made from
"iron" pipe: he coated the inside with a thin wash of refractory clay and
allowed it to dry before using the crucible to melt aluminum.

Aluminum will dissolve in iron, and vice versa, even at temperatures far
below the melting point of iron. The two metals can exist in a very wide
range of solutions.

--
Ed Huntress