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UKAEA-CCFE-PR(20)1052020
Dislocation climb is an important high temperature process of metals plasticity, responsible for phenomena such as creep, swelling, or hardening. Climb is defined by the ability of dislocations to leave their original glide plane by interaction with point defects. As such, dislocation climb is controlled by point defect diffusion/absorption/emis…
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UKAEA-CCFE-PR(20)792020
Point defects in body-centred cubic Fe, Cr and concentrated random magnetic Fe-Cr are investigated using density functional theory and theory of elasticity. The volume of a substitutional Cr atom in ferromagnetic bcc Fe is approximately 18% larger than the volume of a host Fe atom, whereas the volume of a substitutional Fe atom in antiferromagnetic…
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UKAEA-CCFE-PR(20)742020
The impacts of ions and neutrons in metals causes cascades of atomic collisions that expand and shrink, leaving microstructure defect debris, i.e. interstitial or vacancy clusters or loops of different sizes. In [A. De Backer, A. E. Sand, K. Nordlund, L. Lun´eville, D. Simeone, and S. L. Dudarev. EPL, 115(2):26001, 2016.], we described a method…
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UKAEA-CCFE-PR(20)722020
Self-ion bombardment of pure tungsten with ion energies of 2 MeV is used to mimic the defects created by neutrons in a fusion reactor. Electron microscopy is used to characterize the microstructure of samples. Thermal Desorption Spectrometry (TDS) is performed on deuterium implanted samples in order to estimate deuterium inventory as function of…
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UKAEA-CCFE-PR(20)1282019
It has been long hypothesized that the structure of a material bombarded by energetic particles might approach a certain asymptotic steady state in the limit of high exposure to irradiation. There is still no definitive verdict regarding the validity of this hypothesis or the conditions where it applies. To clarify this, we explore a highly simplif…
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2018
Atomic collision processes are fundamental to numerous advanced materials technologies such as electron microscopy, semiconductor processing and nuclear power generation. Extensive experimental and computer simulation studies over the past several decades provide the physical basis for understanding the atomic-scale processes occurring during prima…
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UKAEA-CCFE-PR(20)732018
The evolution of the defect microstructure in materials at high temperature is dominated by diffusion-mediated interactions between dislocations, vacancy clusters and surfaces. This gives rise to complex non-linear couplings between interstitial and vacancy-type dislocation loops, cavities and the field of diffusing vacancies that adiabatically …
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UKAEA-CCFE-PR(19)152020
Vacancy formation and migration control self-diffusion in pure crystalline materials, whereas irradiation produces high concentrations of vacancy and self-interstitial atom defects, exceeding by many orders of magnitude the thermal equilibrium concentrations. The defects themselves, and the extended dislocation microstructure formed under irradi…
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UKAEA-CCFE-PR(19)062020
For several decades, the striking contradiction between the Huang diffuse scattering experiments, resistivity recovery data, and predictions derived from density functional theory (DFT) remained one of the mysteries of defect physics in molybdenum. Since the nineteen seventies, observations of Huang X-ray diffuse scattering appeared to indicate …
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UKAEA-CCFE-PR(19)562019
Linear elasticity theory predicts a divergent strain field at the dislocation core, resulting from the continuum approximation breaking down at the atomic scale. We introduce a minimum model that includes elastic interactions and discrete lattice periodicity, and derive a set of equations that treat the core of an edge dislocation from a solely geo…
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