Michigan State University, East Lansing
NSCL, East Lansing, Michigan
MSU, East Lansing, Michigan
Superconducting radio frequency (SRF) cavities are often formed from fine-grain niobium sheet produced by forging and rolling of ingots that contain very large grains. Texture heterogeneity is consistently observed in such sheets, and is related to heterogeneous deformation and recrystallization of the large grains in the ingot. Relationships between the deformed, recovered, and recrystallized microstructures are required to eventually produce a homogeneous recrystallization texture. Effects of dislocations and grain boundaries on recrystallization and recovery are examined in several kinds of samples: Differently oriented single crystal and bicrystal samples deformed by uniaxial tension and heat treated, and a bicrystal rolled to various reductions and then heat treated. Active slip systems, dislocation substructures, recovery, and recrystallization will be examined by orientation imaging microscopy at incremental stages of deformation, and compared with crystal plasticity model predictions, to determine the influence of dislocation substructure on the orientations of recrystallized grains.
