A. S. Pohjonen F. Djurabekova K. Nordlund A. Kuronen S. P. Fitzgerald
We examine a possible mechanism for the formation of protrusions on a metallic surface held in a sufficiently high electric field in the presence of a near-surface void. By means of molecular dynamics simulations we show that the high tensile stress exerted on a Cu f110g surface with a near-surface void can promote the nucleation of dislocations on…
PublishedM. Cecconello M. Turnyanskiy S. Conroy G. Ericsson E. Ronchi S. Sangaroon R. Akers I. Fitzgerald A. Cullen M. Weiszflog
A prototype neutron camera has been developed and installed at MAST as part of a feasibility study for a multichord neutron camera system with the aim to measure the spatial and time resolved 2.45 MeV neutron emissivity profile. Liquid scintillators coupled to a fast digitizer are used for neutron/ gamma ray digital pulse shape discrimination. The …
PublishedSteven P. Fitzgerald
Frank-Read sources are among the most important mechanisms of dislocation multiplication, and their operation signals the onset of yield in crystals. We show that the critical stress required to initiate dislocation production falls dramatically at high elastic anisotropy, irrespective of the mean shear modulus. We hence predict the yield stress of…
PublishedS P Fitzgerald S Aubry
A dislocation segment in a crystal experiences a “self force,” by virtue of the orientation-dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers…
PublishedSteven P. Fitzgerald
Prismatic dislocation loops are the primary manifestation of radiation damage in crystals, and contribute to the phenomenon of radiation embrittlement. This undesirable effect, most serious for materials used in high-dose environments such as next-generation fission and future fusion reactors, results from the strong interaction between gliding dis…
PublishedS. P. Fitzgerald D. Nguyen-Manh
We present the first derivation of the analytic expression for the Peierls-Nabarro potential for crowdion migration using the double sine-Gordon model. The analysis is guided by the group-specific trend in the shapes of the periodic lattice potentials calculated for the body-centered-cubic transition metals in groups 5B and 6B of the periodic table…
PublishedS. P. Fitzgerald D. Nguyen-Manh
In this paper we model (111) self-interstitial defects, or crowdions, using an extended version of the analytical Frenkel-Kontorova model. We use a more general potential than the traditional sinusoidal one, and find that it can better describe the lattice potentials experienced by crowdions in the body-centred-cubic transition metals, as calculate…
Published