Tight-binding quantum chemical molecular dynamics method has been applied in order to study the Σ3 (111), Σ5 (100) and random grain boundaries oxidation initiation mechanism of fcc Fe-Cr binary alloy in a boiling water reactor environment. The metal-water interaction at high temperatures causes diffusion of environmental species and segregation of metallic atoms. Water molecules favorably permeate through the random grain boundary (GB) to find the space generated by atomic rearrangement, although it is difficult to diffuse in the Σ3 (111) and Σ5 (100) grain boundaries. Moreover, applied strain creates extra spaces in the lattice that can facilitate the absorption of environmental species. The highly positively charged chromium and the negatively charged oxygen atoms or OH remain along the GB by forming bonds. The GB atoms selectively lose their valence electrons when dissociated atoms adsorb, indicating that the oxidation process is a possible mechanism of intergranular cracking initiation.
- Computer modeling and simulation
- Grain boundary oxidation
- Intergranular cracking initiation
ASJC Scopus subject areas
- Inorganic Chemistry
- Metals and Alloys
- Materials Chemistry