First-principles study on the mobility of screw dislocations in bcc iron

Itakura, Mitsuhiro  ; Kaburaki, Hideo; Yamaguchi, Masatake   

Irradiation hardening of nuclear materials are caused by lattice defects which hinder the motion of dislocations and thus suppress plastic deformations. To understand the irradiation hardening, the precise knowledge about the dislocation motion inside the material is indispensable. In bcc metals the mobility of dislocations is determined by the atomic structure of the dislocation and thus quantum mechanical calculation is required to estimate the mobility of dislocations. We have devised a new method to calculate the dislocation properties combining linear elasticity theory and quantum mechanical calculations, and also developed a new method to control the two-dimensional motion of dislocation in the simulation. These new methods allowed us to identify the reason why wrong dislocation motion is observed in the current molecular dynamics simulations, and to present a guideline to improve these simulations. This work opened a way for the quantitative simulations of irradiation hardening.