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

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 alpha-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 alpha-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 theta = 90 degrees. 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 theta = 90 degrees. A sharp rise and fall were observed for the number of SIAs and vacancies at theta = 90 degrees 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.