The laser powder bed fusion process creates structures with architectural complexity through the use of thin layers, fine powder and small laser spot size. Builds are often custom and different scanning strategies, part geometries, number of builds per plate, layer size, laser parameters and material properties all contribute to complex, unique thermal conditions and solidification behavior from part to part. In alloys, crystallographic structure is dependent upon composition, which is dependent upon cooling rate. Uranium-6 wt. pct. niobium forms various metastable phases as a function of Nb concentration. Understanding the degree of segregation which occurs during processing is critical to the development of post-processing solutionizing heat treatments. Toward this end, we perform laser welding of as-cast U-6Nb, employ conductive and convective heat transfer models to calculate cooling rate across these welds, build microstructure (cell spacing/secondary arm spacing)-cooling rate relationship, and identify the degree of segregation in multiple welds.