Stability of small vacancy clusters in tungsten by molecular dynamics

J Fikar and R Schaublin, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 464, 56-59 (2020).

DOI: 10.1016/j.nimb.2019.11.044

The vacancies produced in collision cascades of irradiated metals form voids and vacancy clusters. The stability of vacancy clusters and voids is usually studied by kinetic Monte-Carlo methods. We investigated the stability of these vacancy defects at high temperatures using molecular dynamics and recent embedded-atom method potential. We confirm that the vacancy cluster dissociation is thermally activated. We have obtained dissociation energies and characteristic temperatures, both increasing with the number of vacancies and tending to saturate at 3.5 eV and 1200 K, respectively, for large vacancy clusters. Our results qualitatively agree with Monte-Carlo results, but predict somewhat smaller values for both the dissociation energy and characteristic temperature.

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