A high-purity predominantly single crystalline zirconium was subjected to controlled focused ion beam (FIB) damage. Damage estimates were obtained from electron backscattered diffraction (EBSD) and nano-indentation measurements on exactly the same area/orientation. The damage kinetics, between different crystallographic orientations, differed by one order of magnitude and a clear hierarchy of orientation sensitive ion damage emerged. Use of a simple geometric approach, linear density of atoms and corresponding scattering cross-sections to impinging gallium ions, could differentiate between extreme damage kinetics; but failed when such differences were relatively minor. Numerically intensive molecular dynamics (MD) simulations, on the other hand, were more effective. However, MD simulations or direct EBSD observations failed to justify anisotropic irradiation hardening (AIH): 3-8 times more hardening for near basal. Though explanation for AIH is indirect, evidence and rationalization for orientation-sensitive radiation damage appears clear and statistically reproducible.
The anodic polarization behavior of Sanicro 28 austenitic stainless steels has been established in the cold worked (10 to 80% reduction in thickness) samples in 1N HCl, 1M H2SO4+ 1.5N HCl and 3N HCl solutions at room temperature. The current oscillations during the potentiodynamic scans appeared in 3N HCl implying formation of meta stable pits and this solution more severe than 1N HCl and 1M H2SO4+ 1.5N HCl. Two anodic peaks were observed in as-received and the cold worked samples in 3N HCl. In as-received state, the first anodic peak appeared at-3.95 mVSCEand the second anodic peak appeared at 116 mVSCE. It was established that selective dissolution started from 18mVSCE. The grains and grain boundaries were not attacked at the beginning of the first peak-168 mVSCEand started revealing at 18 and 216 mVSCEin the potentiodynamic polarization test. The fore-scatter detector (FSD) attached to FEI Quanta EBSD revealed the pitting morphology of the specimens. It is shown that pit dimensions, types, distribution, the shape of pits in all deformation conditions is hemispherical and number of pits did not depend on the microstructural features, irrespective of the plastic deformation and it may not be related to severity of plastic deformation.
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