UKAEA Papers

Showing 71 - 80 of 80 UKAEA Paper Results
2018
UKAEA-CCFE-PR(18)6

Velocity-space tomography provides a way of diagnosing fast ions in a fusion plasma by combining measurements from multiple instruments. We use a toroidally viewing and a vertically viewing fast-ion D-alpha (FIDA) diagnostic installed on the spherical tokamak MAST (before the upgrade) to perform velocity-space tomography of the fast-ion distributio…

Preprint Published
2018
UKAEA-CCFE-PR(18)9

Elastic follow-up is a mechanical boundary condition lying between constant load and constant strain control. It exists in many engineering components operating at high temperature and can result in dramatically different creep stress relaxation and strain accumulation rates in a localized region of a component. We have performed creep tests under …

Preprint Published
2018
UKAEA-CCFE-PR(18)16

The processing code SPECTRA-PKA produces energy spectra of primary atomic recoil events (or primary knock-on atoms, PKAs) for any material composition exposed to an irradiation spectrum. Such evaluations are vital inputs for simulations aimed at understanding the evolution of damage in irradiated material, which is generated in cascade displacement…

Preprint Published
2018
UKAEA-CCFE-PR(18)17

Stronger and more resistant alloys are required in order to increase the performance and efficiency 11 of jet engines and gas turbines. This will eventually require planar faults engineering, or a complete 12 understanding of the effects of composition and temperature on the various planar faults that 13 arise as a result of shearing of the γ prec…

Preprint Published
2018
UKAEA-CCFE-PR(18)2

Precipitation-hardened Cu-Cr-Zr will be used in heat-sink components in the Iter tokomak. After irradiation it will not be possible to test the mechanical properties of Cu-Cr-Zr using conventional, large-scale, techniques and methods requiring reduced sample sizes will have to be used. Spherical nano-indentation is one such method. In this work, Cu…

Preprint Published
2018
UKAEA-CCFE-PR(18)25

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 fol…

Preprint Published
2018
UKAEA-CCFE-PR(18)5

As shown experimentally, the interplay between screw and edge dislocations in uranium dioxide (UO2) determines the low-temperature plasticity in this material. For the latter, neither the mobility of screw dislocations nor the mechanisms of their glide had been assessed — up until now. It is particularly interesting to evaluate the mobility of 1/…

Preprint Published
2018
UKAEA-CCFE-PR(18)38

Conventional linear elasticity theory predicts the strain fields of a dislocation core to diverge, whereas it is known from atomistic simulations that strains at dislocation cores remain finite. We present an analytical solution to a generalised, variational Peierls-Nabarro model of edge dislocation displacement fields that features a finite core w…

Preprint Published
2018
UKAEA-CCFE-PR(18)50

There are many sources of random and systematic error in composition quantification by atom probe, however, often only statistical error is reported. Identification of ions and overlaps or interferences of peaks in the mass spectrum are one major source of uncertainty much larger than counting error. These overlaps can be solved using maximum likel…

Preprint Published
2018
UKAEA-CCFE-PR(18)7

The line tension model of obstacle hardening is modified to account for the thermally activated, kink-limited glide of 1=2h111i screw dislocations, allowing application to the plastic flow of bcc metals. Using atomistically-informed dislocation mobility laws, Frenkel-Kontorova simulations and a simplified dislocation obstacle model, we identify a …

Preprint Published