Regarding what it would look like, cu's characteristic K radiation is =1.5418Å As I recall copper tends to have a high diffraction ratio..
It's density is considerably off that of iron (Steel ~7.85 gm/cm^3 copper ~8.94 gm/cm^3).
http://www.engineeringtoolbox.com/metal-alloys-densities-d_50.htmlI would suspect an
inclusion if one were possible would contain a diffraction halo around it similar to what thin (.05" or less) titanium welds sometimes have. There would be only a slight difference in density given that by comparison,
tungsten is ~19.6 gm/cm^3 which shows up strong on a graph. It would be a shadow at best on the film unless there were a large volume of it.
Thats my WAG on it.