Annual Report

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