The structure dependence of oxidation behavior of high-angle grain boundaries of alloy 600 in simulated pressurized water reactor primary water

The intergranular degradation of seven different types of high-angle grain boundaries (HAGBs) were investigated on Alloy 600 after exposure to simulated pressurized water reactor primary water. All boundaries are susceptible to preferential intergranular oxidation (PIO) except for ideal coherent twin boundary. Diffusion induced grain boundary migration (DIGM) normally occurs and its depth is positively correlated with the PIO extent. Interestingly, the PIO susceptibility is independent on the grain boundary misorientation angle or & sigma; value, but related to the grain boundary atom packing density (GBAPD). Grain boundaries with higher GBAPD values show higher PIO resistance as the element diffusion is slower.

Automated summary

The intergranular degradation of Alloy 600 was studied in simulated pressurized water reactor primary water for seven different types of high-angle grain boundaries. All boundaries exhibited susceptibility to preferential intergranular oxidation (PIO), except for the ideal coherent twin boundary. Diffusion induced grain boundary migration (DIGM) typically occurred, and its depth was positively correlated with the extent of PIO. Interestingly, the PIO susceptibility was independent of the grain boundary misorientation angle or σ value, but related to the grain boundary atom packing density (GBAPD), where higher GBAPD values correlated with higher PIO resistance due to slower element diffusion.