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heat transfer coefficient and three constants k, b, c, representing the thermal conductivity as a function of radius λ = k + b×r + c×r 2 ) are altered and used as inputs in finite element software (FlexPDE). The parameters are changed until the least square difference between the numerical and experimental thermograms reaches a minimum. Deformation Modelling of Hard-facing Alloys Researcher: Bartosz Barzdajin Supervisors: David Stewart Prof Fionn Dunne and Tony Paxton Sponsors: Rolls-Royce The goal of this project is to develop hierarchical theoretical framework that will further the understanding of phenomena behind galling and wear resistance of hard facing materials, particularly duplex stainless steel RR2450 and establish a link between some key characteristics like chemical composition and microstructure with the performance in this scope. We hope that this research will result in guidelines for chemists and process engineers who are working on improving existing alloys and development of new ones. Galling and wear is associated with local elastic and plastic deformations that define stress states that may result in formation of cracks and material separation as a consequence of the crack growth. We expect that the biggest impact on galling resistance will be due to microstructure i.e. phase fractions, texture and morphology. To study the influence of this type of characteristics, the most suitable method is crystal plasticity finite element (CPFE) method that will be used to perform systematic studies on galling resistance as a function of phase fractions in duplex systems. Our CPFE models will use a physically based slip and hardening rule, allowing it to be informed by quantum mechanical methods, such as density functional theory (DFT) or tight-binding (TB), through evaluation of key CPFE parameters extending its predictive value by taking influence of chemistry into account. Simulation of Materials for Nuclear Fusion Reactors Researcher: Matthew Jackson Supervisors: Prof Robin Grimes and Dr Sergei Dudarev Sponsors: Culham Centre for Fusion Energy Beryllium and its compounds such as Be 12 Ti and Be 12 V are under investigation for use as a first wall material and neutron multiplier for tritium breeding in nuclear fusion reactors: applications in which they will be subjected to extreme temperatures and radiation. Density functional theory and empirical potentials in conjunction with molecular dynamics have been used to investigate the processes occurring during radiation damage in these materials on an atomic level, calculating key parameters such as the threshold displacement energy and defect formation enthalpies that can be fed into models to predict the long term behaviour of these materials. Understanding Crystallographic Texture Evolution in Two-Phase (hcp/bcc) Alloys Researcher: Simon Wyatt Supervisor: Dr Ben Britton Sponsors: Rolls-Royce Metals are widely used for load-bearing applications in complex environments. Their properties are dependent on the underlying behaviour of the material microstructure, which is naturally anisotropic due to the discreet and crystallographic nature of slip and anisotropic elastic properties. This project focuses on developing efficient methods of modelling the evolution of crystallographic texture in two-phase alloys 37 http://www.imperial.ac.uk/nuclear-engineering
using efficient crystal plasticity based upon the fast Fourier transform. Working with Rolls- Royce plc, materials will be characterised using HR-EBSD to determine textures which will further stimulate the computational work. [0001] PD 0 [0001] PD 50 Discrete Dislocation Dynamics coupled with Discrete Solute Diffusion to Model the Effect of Hydrogen in Steel Researcher: William White Supervisor: Dr Ben Britton Sponsors: EPSRC CDT and Rolls-Royce Plastic deformation in metals is due to the motion of mobile dislocations subject to shear stresses in excess of a critical value. At particular strain rates and temperatures mobile solutes form atmospheres at the base of dislocations pinning dislocation motion. This results in an inverse strain response, jerky plastic flow and decreased ductility. In the worst case, ductility is reduced significantly and brittle fracture may occur. We attempt to understand the interaction and effects of mobile dislocations and solutes in metals using discrete dislocation dynamics coupled with an appropriate discrete solute diffusion model. In the first instance our model will be developed to describe carbon solutes in saturated iron. A generalized model will be developed so as to give insight to the deleterious effects of hydrogen in industrial steels. [1010] PD 0 [1010] PD 50 Primary Knock-On Atom Energy (eV) 40 60 80 100 120 Matthew Jackson: [0001] and [1010] pole figures showing the directional dependence of the simulated threshold displacement energy in Be. Atomic-scale Simulation of Mixed Oxide and Conventional Nuclear Fuel Researcher: Conor Galvin Supervisor: Prof Robin Grimes Sponsors: Los Alamos National Laboratory and CASL Mixed actinide oxides have been used as nuclear fuel material, furthermore conventional UO2 fuel effectively becomes a mixed oxide during reactor operation due to transmutation and decay. Moreover, there is growing interest in ThO 2 mixed oxide fuel due to the beneficial Centre for Nuclear Engineering <strong>Annual</strong> <strong>Report</strong> 2014-2016 38
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Page 91 and 92: Sam delivered his third and final l
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the UK representative on the Manhat
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