The Cessna 120-140 Association Forum

I am working on restoring a 1946 Cessna 120 and the frame around the windows appears to be very corroded (probably from sitting out in a field for 20 years).
I am trying to figure out what this material is and if it's something I can fabricate a replacement for.
There appear to be two components, made of a couple parts:
1. L-channel aluminum around the entire frame
2. A square (maybe box tube?) inner frame in two parts that holds the window into the L-channel

Has anyone replaced these? I can't find any specs on these sub-components anywhere.

Try BAS or other salvage yard for a new window frame and retainers if the frame itself is corroded. That's the route I last took. De-rivet, clean, paint, trim new window, re-rivet; done.