Searching for bwxt and/or sglb, company names, company officers names.
I saw a few things out there about AM and BWXT. Haven't see any with the BWXT and SGLB together I did see something with BWXT and Oak Ridge National Laboratory
Just take bits of unique information from the articles. Start with google or your choice of search engine and follow the trail shouldn't take more that a hour or so.
If they were to have a strategic partnership, it would be announced. They may work in the background, but unlikely. Most, if not all of Sigmas, partnerships have been announced.