A Phenomenological micromechanical model of FCC metals under radiation induced crystal defects

Aoyagi, Yoshiteru; Tsuru, Tomohito   ; Kaji, Yoshiyuki  

In this study, we construct a new crystal plasticity model considering densities of crystal defects induced by irradiation. Evolution equation of densities of imperfect dislocation loop is proposed by considering disappearance of imperfect dislocation loops originated in dislocation movement. Moreover, in order to predict increase of CRSS due to irradiation and decrease of work-hardening ratio, information of densities of imperfect dislocation loop and stacking fault tetrahedron are introduced into a hardening modulus of crystal. Value of controlling parameters operating effect of crystal defects on flow stress are decided by a MD simulation. We conduct a crystal plasticity simulation for simple tension of polycrystal using the presented model. The macroscopic stress-strain responses such as increase of yield stress and decrease of work-hardening ratio due to irradiation are numerically predicted. We investigate comprehensively the effect of behaviors of crystal defects on the mechanical property of irradiated materials and the generation of dislocation substructures depending on mechanical conditions.