Hi, is it possible, with nx, to save an assembly as a single part?
You can do 'File > Export > Part' and use the available options so that all geometry will be exported in a single part with options to remove/retain the feature parameters.
Export Part dialog box
For an assemblie you can use EXPORT -- PARASOLID, than open an new empty part and import the parasolid file. You get the same geometrie without an assemblie structure and without features.