Cascade Collision near the Grain Boundary of Fe-Cr Alloy by MD Simulation

Abstract

Using molecular dynamics method to study the cascade collision for the case of PKA(Primary Knock-on Atom) atoms at different distance from the grain boundary(GB) of iron chromium alloy. It is found that the PKA atoms at the GB will produce a large size cluster (size from 11 to 409 ) consisting of interstitial and vacancies, and many small clusters (number from 5 to 50). The size and number of the cluster depend heavily on PKA energy, while depend weakly on temperature. The PKA atom at distance of 1nm from the GB, sometimes produces large size defect clusters both inside and outside the GB region. When the PKA atom is at 1nm, 2nm and even 3nm, 4nm from the GB, the GB will effectively absorb the interstitial atoms. It is found that the atomic ratio of Cr-interstitial to total interstitial produced at the GB region is much less than one at outside of GB region.

Properties of radiation-induced point defects in austenitic steels: a molecular dynamics study

“…A lower PKA energy was used because we aimed to study point defects in the collision cascade. MD simulations at low PKA energies (1-5 keV [47] or 0.5-15 keV [48]) have also been reported by several researchers. For all simulations, the temperature was set to 300 K and three-dimensional periodic boundary conditions were used.…”

“…So, 10 cascades in the <135> direction were performed in this paper. It was worth noting that electron-phonon coupling and electron-stopping effects were not included in the simulations, as has been the case in some of the literature [47,48,50]. At these PKA energies and for the focus on point defects in this paper, it is not important.…”