Compositional inhomogeneities in Nb-Ti and its alloys

Results are presented showing that commercially produced Nb-Ti and Nb-Ti-Ta can have extensive chemical inhomogeneities, of order 10 wt.%. These chemical inhomogeneities are associated with significant sub-structure irregularities and, in one case, with filament sausaging and poor Jcperformance. Homogenization of such alloys is discussed. Some recent ingots have been much more homogeneous than those first studied and it is concluded that purchase of chemically homogeneous materials is preferred for high Jccomposites.