AFM evaluation of grain boundary corrosion behavior on ion irradiated stainless steel

Nemoto, Yoshiyuki  ; Miwa, Yukio; Tsukada, Takashi ; Tsuji, Hirokazu

It is essential to evaluate corrosion behavior at grain boundary of irradiated materials for mechanistic understanding of Irradiation assisted stress corrosion cracking (IASCC). However there is no suitable technique to evaluate grain boundary corrosion behavior of irradiated materials. The aim of this work is to develop the measurement method for the grain boundary corrosion behavior of irradiated materials using atomic force microscope (AFM). Ni ion was irradiated to solution annealed Fe-18Cr-12Ni alloy at about 573K. The peak damage level was estimated as 1 dpa. To study relationship of grain boundary character and corrosion behavior, orientation imaging microscope (OIM) observation was conducted. After potentiostatic corrosion procedure, the surface of the specimens were examined with AFM and OIM. Some of grain boundaries were corroded, and these were random coincidence grain boundaries. The depth of the corroded region at grain boundaries was successfully evaluated with AFM in nanometer scale.