Observation of Transient and Asymptotic Driven Structural States of Tungsten Exposed to Radiation
DR Mason and S Das and PM Derlet and SL Dudarev and AJ London and HB Yu and NW Phillips and D Yang and K Mizohata and RQ Xu and F Hofmann, PHYSICAL REVIEW LETTERS, 125, 225503 (2020).
Combining spatially resolved x-ray Laue diffraction with atomic-scale simulations, we observe how ion-irradiated tungsten undergoes a series of nonlinear structural transformations with increasing radiation exposure. Nanoscale defect-induced deformations accumulating above 0.02 displacements per atom (dpa) lead to highly fluctuating strains at similar to 0.1 dpa, collapsing into a driven quasisteady structural state above similar to 1 dpa. The driven asymptotic state is characterized by finely dispersed vacancy defects coexisting with an extended dislocation network and exhibits positive volumetric swelling, due to the creation of new crystallographic planes through self- interstitial coalescence, but negative lattice strain.
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