Use "ncheck" to find a filename given an inode.
You will need to supply the inode and the filesystem that it came from.
If the file has been deleted - meaning ALL instances of it - then this command will not work as it uses filesystem directory entires to make the connection between a filename and the inode.
When you rm a file, you are actually un-linking it. This means that you are removing the directory entry and releasing the inode. So if you still have the file open, and it has been deleted (rm'ed) then it does not have a name (anymore).
Of course it is possible to have multiple (hard) links to a file - and therefore it would be possible to find a filename although it would not be the same as the deleted name. (name = full path to file).
The ncheck command (as well as other AIX info) can be found here:
AIX QuickStart