Multiscale analysis of dislocation loops and voids in tungsten

Pui-Wai Ma, D. R. Mason, and S. L. Dudarev
Phys. Rev. Materials 4, 103609 – Published 22 October 2020

Abstract

We performed ab initio density functional theory simulations of 12111 interstitial dislocation loops, closed and open vacancy loops, 100 interstitial loops, and voids in tungsten, using simulation cells involving from 2000 to 2700 atoms. The size of the loops transcends the microscopic scale and reaches the mesoscopic scale where asymptotic elasticity treatment applies. Comparing the formation energies of dislocation vacancy loops and voids, we conclude that a void remains the most energetically favorable vacancy defect over the entire range of sizes investigated here. A closed 12111 vacancy loop is more stable than an open loop if the number of vacancies in the loop is greater than 45, corresponding to the diameter of a loop of approximately 1.8 nm. We have also computed elastic dipole tensors and relaxation volumes of loops and voids, representing the source terms in continuum models for radiation induced stresses and strains in the material. A detailed analysis of metastable configurations of closed and open vacancy loops performed using molecular statics simulations shows that vacancy loop configurations are not unique, and significant fluctuations of defect structures may occur in the course of microstructural evolution under irradiation.

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  • Received 25 August 2020
  • Accepted 3 September 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.103609

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Pui-Wai Ma*, D. R. Mason, and S. L. Dudarev

  • UK Atomic Energy Authority, Culham Science Centre, Oxfordshire OX14 3DB, United Kingdom

  • *leo.ma@ukaea.uk

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Issue

Vol. 4, Iss. 10 — October 2020

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