Asymmetrical response of edge pyramidal dislocations in HCP zirconium under tension and compression: A molecular dynamics study

The structure and motion of <c + a> edge dislocations on the pyramidal I {10 (1) over bar1} plane in alpha-Zr was characterized by atomistic simulations. The dislocations dissociate into 1/6 [02 (2) over bar3] and 1/6 [(4) over bar 043] partial dislocations with dissimilar core structures. In order to capture the slip behavior of the system, shear stress was applied, in tandem with tension or compression normal stress. The simulations indicate that the critically resolved shear stress (CRSS) increases under compression and decreases under tension. They also indicate that CRSS associated with a single dislocation depends on the direction of shear, as this alters the nature of the leading partial dislocation during slip. Finally, the molecular dynamics indicates that compression leads to cross-slip of the partial dislocations.