The effects of electron-phonon coupling on defect production by displacement cascades in α-iron

Molecular dynamics (MD) simulations have been used to investigate the effects of electron-phonon coupling on defect production and clustering produced in the primary cascade state of neutron radiation damage in alpha-Fe. A simplified physical model of electron-phonon coupling has been incorporated with the hybrid continuum/MD code developed by Gao et al to allow heat transfer from phonons to electrons, and applied to study defect generation as a function of the strength of electron-phonon coupling for cascade energy of 2, 5 and 10 keV. The number of point defects produced in the primary damage state increases with increasing strength of electron-phonon coupling. Most of the additional defects form in the cascade core, but the fraction of interstitials in clusters remains almost constant. These effects arise from reduced mobility of atoms in the shorter thermal spike. The quenched-in clustering of vacancies plays a role in the increase of the vacancy clustering fraction with increasing strength of electron-phonon coupling. This mechanism is predicted to inhibit the formation of dislocation vacancy loops and the strong coupling, therefore, reduces the probability of loop formation.