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Qing-Jie Li1 Ju Li2 Evan Ma1

1, Johns Hopkins University, Baltimore, Maryland, United States
2, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

Irradiation often generates excess point defects well beyond the equilibrium concentration in a crystal. Annihilation or annealing of these point defects plays an important role in keeping materials from accumulating damage. Here, using atomistic simulations, we demonstrate that screw dislocations in body-centered-cubic (BCC) metals often transport point defects along the line sense direction, efficiently annihilating point defects either at interfaces or with their opposite counterparts. This ‘displacive annihilation’ mechanism stems from the capability of screw dislocation to decompose point defects into cross-kinks, a reverse process to creating point defects via cross-kink pinch-off. We speculate that, under appropriate conditions, 'displacive annihilation' may overwhelm 'displacive accumulation' to heal the material, and we call this ‘displacive annealing’. Our findings shed new light on the defect-property relations in BCC metals subjected to irradiation.

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