The intergranular oxidation behavior of low-angle grain boundary of alloy 600 in simulated pressurized water reactor primary water

The preferential intergranular oxidation (PIO) behavior of low-angle grain boundaries (LAGBs) with misorientation angle 0 ranging from 5.7 to 14.0 degrees on alloy 600 were investigated after exposure to simulated pressurized water reactor primary water. Interestingly, all LAGBs are susceptible to PIO. When 0 < 8.8 degrees, diffusion-induced grain boundary migration (DIGM) does not occur as Cr is immobile and the PIO depth varies slightly among those LAGBs. As 0 increases above 8.8 degrees, Cr starts to diffuse outwards and DIGM occurs. The depths of PIO and DIGM are positively correlated in this case. Also, the PIO depth is not related to the change of 0, but instead poses an inverse relationship with the atom packing density of GB planes. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigated the preferential intergranular oxidation (PIO) behavior of low-angle grain boundaries (LAGBs) in alloy 600 exposed to simulated pressurized water reactor primary water. The results showed that all LAGBs were susceptible to PIO. Below a misorientation angle of 8.8 degrees, diffusion-induced grain boundary migration (DIGM) did not occur, resulting in slightly varied PIO depths among LAGBs. However, as the misorientation angle increased above 8.8 degrees, chromium (Cr) began to diffuse outward and DIGM took place, leading to a positive correlation between PIO and DIGM depths. Additionally, the PIO depth was not related to the misorientation angle, but instead exhibited an inverse relationship with the atom packing density of grain boundary planes.