Interaction between collision cascades and nanocrack in hcp zirconium by molecular dynamics simulations

In this work, molecular dynamics simulations are performed to investigate the interaction between the collision cascades and nanocrack in hcp zirconium. When the thermal spike overlaps with the nanocrack, the collision cascades will induce the healing of the nanocrack. Higher PKA energy leads to higher degree of crack healing at the same separation distance between PKA and nanocrack. The PKA velocity direction changes the fraction of atoms entering the crack by influencing the shape and distribution of the thermal spike. Furthermore, both Zr #3 and #2 potentials show that the degree of crack healing drops as the distance between the nanocrack and PKA decreases. In particular, collision cascades induce the transformation of nanocrack in the basal plane into prismatic vacancy loop is captured due to the interaction between thermal spike with nanocrack. Lastly, the preexisting nanocrack may induce cascade splitting of hcp Zr. This work provides a mechanistic understanding of the interaction between the nanocrack and irradiation damages in Zr and other hcp metals.