I'm having trouble seeing how the AL would be chemically comprimised, and I couldn't see it.
the holes and lumps are your first clue.
If it had bonded with something else, in a way such that it would have been weaker, wouldn't the wire brush have been some indication of that? (As in it would have removed a bit of the softer metal?)
That metal may be long gone by now. Leaving nothing for your wire brush to remove.
As far as a changing in the structure of the alloy, I know heat can do that but how could a chem do that to the inside of a metal?
It probably wouldn't. But it clearly has affected the outside of this frame. Was it 5%, 10%, 35%? Can't tell. How much can be destroyed before you are risking failure? Don't know.
Perhaps I am underestimating the permeability of metals at standard temps, but wouldn't the chem stop after it reacted with the surface? I have always been taught that the oxide layers on top of a metal actually protect it from future corrosion (In fact don't they do a black oxide layer on some steels....). Also, IF the chem that made the aluminum for a soft white crusty, why wouldn't all of the reacted AL have formed a chloride/who knows what that would be white and soft? Why would it have just changed the structure, and not just formed a white crusty?
http://www.youtube.com/watch?v=52olS...eature=related
I don't see any white crusties do you?