Atomistic investigation on initiation of stress corrosion cracking of polycrystalline Ni60Cr30Fe10 alloys under high-temperature water by reactive molecular dynamics simulation

Abstract

Targeting atomistic initiation of stress corrosion cracking (SCC) of Alloy 690, reactive molecular dynamics simulations of SCC of polycrystalline Ni60Cr30Fe10 alloys under water with dissolved oxygen at 900 K were performed employing newly developed reactive force field (ReaxFF) of Ni-Cr-Fe-H-O system. Observed atomistic mechanochemical mechanism involve dissolution-precipitation and diffusion-oxidation behaviors for corrosion, and cleavage-slipping-twinning behaviors for cracking initiation with its driving forces including loacl shear stress/strain and oxidation-enhanced atomistic stress. Roles of cold work, tensile strain and grain boundary (GB) structures in impacting these mechanochemical behaviors were explored based on calculated surface and GB energy, GB diffusivity and atomistic stress/strain.