Screw dislocation kink dynamics model in BCC iron based on first-principles and molecular dynamics calculations

Itakura, Mitsuhiro  ; Kaburaki, Hideo; Yamaguchi, Masatake   

Nuclear materials undergo hardening owing to the neutron irradiation. This phenomena is caused by the pinning effect of lattice defects which prevents the motion of dislocation line. The precise modeling of dislocation motion requires atomistic modeling based on a large-scale first-principles calculations. We have carried out a large scale first-principles calculations to evaluate the Peierls potential and line tension coefficient to develop a model for the nucleation and migration of kinks in screw dislocation in BCC iron, and used molecular dynamics calculations to estimate the dynamic parameters such as effective mass and viscosity coefficient. The most important result of numerical simulation is that this model can reproduce the jerky motion of screw dislocations observed in low-temperature in-situ observation experiments. The developed model opens a way for the multiscale modeling for the study of irradiation hardening in nuclear materials.