Back Door Rust

Got a 1996 Series 1 Discovery.

Problem is the bottom of the back door seems to powdering like the aluminium is rotting away. More noticable on the inside edge but paint is wanting to peal on external face as well.


Is there any way to stop and cover this up? Anything I could treat it with or would it be easier to try and find a replacement door?


Any help would be appreciated.

Thanks

this is called oxidising. its like rust in steel but only happens on ali. if you do a google search it may come up with some sort of chemical to stop it, if so let me know cos my wheel arches are starting to go

last summer i did my wheel arches, i sprayed them with stone chip guard and got my local chipsaway man to paint them, still looking good