The effects of grain-boundary misorientation upon radiation-induced segregation in proton-irradiated AISI304 stainless steel was investigated. Four test conditions were used. These were: as-received with enriched Cr at the grain boundary, as-received + 1dpa proton irradiated at 450C, thermally sensitized, and thermally sensitized + 1dpa proton irradiated at 450C. As compared with the no pre-enrichment condition, a delayed Cr depletion was found at grain boundaries in the as-received + 1dpa specimens. After irradiation, the Cr concentration profile across the grain boundaries became narrower and deeper in the thermally sensitized + 1dpa specimens. The degree of grain boundary segregation was higher at random boundaries than at special boundaries. In the case of thermally sensitized + 1dpa specimens, segregation cusps were observed at grain boundaries with Σ = 3, 9 or 15. The Cr segregation levels at special boundaries increased with Σ, for values of up to 15. A simple rate-equation model, with modified boundary conditions that were related to the grain-boundary diffusion of defects and the densities of grain-boundary dislocations, was developed in order to describe radiation-induced segregation at boundaries with various Σ and Δθ values. The calculations showed that a radiation-induced segregation model with modified boundary conditions could clearly predict the trends seen in experiments; where the Cr depletion levels at special boundaries increased with Σ. The calculations also showed that the widths of the segregation cusps decreased with increasing Σ.

Effects of Grain Boundary Misorientation on Radiation-Induced Solute Segregation in Proton Irradiated 304 Stainless Steels. J.J.Kai, F.R.Chen, T.S.Duh: Materials Transactions, 2004, 45[1], 40-50