Atomistic investigation of the effects of symmetric tilt grain boundary structures on irradiation response of the α-Fe containing carbon in solution.

• Molecular dynamics simulations were used to investigate the effect of the presence of carbon atoms in low-carbon α-Fe containing a symmetric tilt grain boundary (STGB) on the number of interstitials and vacancies produced by displacement cascades. • The cohesive energy of Fe atoms and C atoms in the α-Fe matrix was estimated to be E Fe = - 4.01292 C + - 2.9728 e - 6 and E C = - 15.34462 C + - 9.16691 e - 5. • GB energies of the structures for 17 110 STGBs as a function of the GB angle for 27 different at.%C ranging from 0.0058% to 0.1569% was calculated and a deep cusp at GB misorientation of θ = 90 ° was observed. • The results of the thermal spike stage and the consequent recombination stage showed that the PKA energy and the presence of GB in Fe-C have no effect on the time at which point defects reach to their maximum values at the thermal spike stage. • The results showed that the number of defects in the presence of GB drops in comparison to the number of defects produced in the case of Fe-C without GB planes. • The results showed that carbon, either dispersed form or C-rich region in α-Fe, has no meaningful effect on the number of residual point defects. In this paper, molecular dynamics simulations were used to investigate the effect of the presence of carbon atoms, either in dispersed form or C-rich region, in low-carbon α-Fe containing symmetric tilt grain boundary (STGB) with a boundary plane rotated about the 110 misorientation axis on the number of SIAs and vacancies produced by PKA energies of 3, 5, 7 and 9 keV at 300 K. Results were compared with the SIAs and vacancies produced in pure α-Fe. It was also shown that the presence of GBs in this Fe-C alloy has no effect on the time at which point defects reach to their maximum values at the thermal spike stage. On the other hand, the GBs decrease the number of point defects in comparison to Fe-C without GB planes. It was also concluded that the carbon, either in dispersed form or C-rich region, has no meaningful effect on the number of survived point defects. Furthermore, the number of SIAs is less than the number of vacancies, except at θ = 90 °. This result was attributed to GB energy because by calculating GB energies as a function of the GB angles for 27 different at.%C ranging from 0.0058% to 0.1569%, a deep cusp was obtained at θ = 90 °. A sharp rise and fall were observed for the number of SIAs and vacancies at θ = 90 ° misorientation, respectively. The sharp rising becomes smooth for the number of SIAs with increasing E PKA and the sharp falling becomes deeper for the number of vacancies with increasing E PKA. [ABSTRACT FROM AUTHOR]