Shear strain alters the structure and migration mechanism of self- interstitial atoms in copper

B Zhang and C Wheatley and P Chen and X Qian and MJ Demkowicz, PHYSICAL REVIEW MATERIALS, 6, 053605 (2022).

DOI: 10.1103/PhysRevMaterials.6.053605

We use atomistic modeling to show that externally applied shear strain causes the lowest energy self-interstitial atom (SIA) structure in copper (Cu) to change from a (100)-type dumbbell to a (110)-type dumbbell. Concurrently, SIA migration switches from the three- dimensional (3D) random walk characteristic of (100)-type dumbbells to a 1D mechanism analogous to that of crowdion SIAs. Furthermore, the relative energies of these two dumbbell structures as a function of strain are well predicted using elastic dipole tensors computed at zero strain, indicating that examination of these tensors may be used to assess the likelihood of strain-induced SIA structure transitions in other materials. Changes in lowest energy SIA structures and associated migration mechanisms stand to impact predictions of SIA behavior in irradiated solids.

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