Abstract
The addition of oversized solutes has the potential to reduce the effects of radiation-induced segregation (RIS) in austenitic alloys. Radiation induced segregation has been implicated as one of several factors in enhancing stress corrosion cracking (SCC) under irradiation, so oversized solute additions could promote SCC resistance. Zr or Hf were added to 316-type stainless steel at levels between 0.05 at% and 0.37 at%. Samples were irradiated with 3 MeV protons to 3 dpa at 400�C, and analyzed in HR-STEM with EDS to measure the grain boundary composition. Zr additions substantially reduced the amount of RIS while Hf was much less effective. Despite similar sizes, first-principles calculations using VASP demonstrate that solute-vacancy binding for Zr is 1.05 eV vs. 0.69 eV for Hf. This difference results in a greater effectiveness of Zr in reducing radiation induced segregation as determined by kinetic rate theory calculations, in agreement with measured results.
