title: Fast, vacancy-free climb of prismatic dislocation loops in bcc metals.
abstract: Vacancy-mediated climb models cannot account for the fast, direct coalescence of dislocation loops seen experimentally. An alternative mechanism, self climb, allows prismatic dislocation loops to move away from their glide surface via pipe diffusion around the loop perimeter, independent of any vacancy atmosphere. Despite the known importance of self climb, theoretical models require a typically unknown activation energy, hindering implementation in materials modeling. Here, extensive molecular statics calculations of pipe diffusion processes around irregular prismatic loops are used to map the energy landscape for self climb in iron and tungsten, finding a simple, material independent energy model after normalizing by the vacancy migration barrier. Kinetic Monte Carlo simulations yield a self climb activation energy of 2 (2.5) times the vacancy migration barrier for 1/2〈111〉 (〈100〉) dislocation loops. Dislocation dynamics simulations allowing self climb and glide show quantitative agreement with transmission electron microscopy observations of climbing prismatic loops in iron and tungsten, confirming that this novel form of vacancy-free climb is many orders of magnitude faster than what is predicted by traditional climb models. Self climb significantly influences the coarsening rate of defect networks, with important implications for post-irradiation annealing.
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Swinburne
authors.affiliation: Department of Materials Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Arakawa
authors.affiliation: Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Mori
authors.affiliation: Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Yasuda
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Isshiki
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Kouji
authors.initials: K
authors.lastname: Mimura
authors.affiliation: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-2-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Masahito
authors.initials: M
authors.lastname: Uchikoshi
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB, UK.
authors.forename: Sergei L
authors.initials: SL
authors.lastname: Dudarev