Experimental Mechanics of Advanced Materials Group

We are an experimental characterization group with unique capabilities to understand the damage and fracture of advanced materials under extreme conditions over multiple length-scales.

It is essential to gain a mechanistic understanding of failure in materials, to make an informed choice on how material properties can be improved to survive harsh environments such as irradiation, extreme high/low temperatures, and hydrogen exposure. This characterisation is key for industrial applications such as nuclear fission/fusion reactors and aerospace fuel systems, at present and in the future.

EMAM's main research themes are:
• TRISO fuel particles/compacts;
• Graphite/Carbon;
• Alloys in Extreme Environments;
• Semiconductors;
• Ceramic Matrix Composites.

Novel and cutting-edge techniques have been developed and used to study these materials over multiple length scales. These include frequency-domain thermoreflectance (FDTR), electron channelling contrast imaging (ECCI), neutron diffraction beamline experiments, Raman spectroscopy, and cryogenic mechanical testing. We correlate nano- and micro-structure due to materials processing with macro-scale damage and fracture from in-service conditions. EMAM uses rigorous scientific approaches to gain a mechanistic understanding of failure modes in materials exposed to extreme environments, underpinning their subsequent industrial applications.

EMAM has formed strong collaborative ties with key national and international players in the nuclear fission, nuclear fusion and aerospace fields, such as EDF, UKAEA, UK NNL and Rolls-Royce plc, and are keen to continue collaborations with current and new industrial partners.

We have active ongoing projects in the following areas with open DPhil and Postdoctoral opportunities. In addition, we are interested in hosting undergraduate summer placements within the group. Please contact us if you interested in learning more.

Funding sources: EPSRC, STFC, BEIS and various UK and US industrial funding.

Main Research Themes

TRISO fuel particles/compacts

Thermal and mechanical characterisation of TRISO fuels

This programme investigates a range of Tristructural Isotropic nuclear fuel particles (TRISO), both free-standing or embedded in SiC or graphite matrix, in terms of their local properties, residual stresses and high temperature mechanical properties changing with processing parameters.

Carbon/graphite

Damage and fracture in nuclear graphite composites over multiple length-scale

This topic studies a large range of polycrystalline graphite materials, from highly oriented pyrolytic graphite to fine/medium/coarse grained graphite composite, unirradiated or irradiated with ions, neutrons or protons, to understand their multiple length-scale structure, physical properties before and after irradiation, at ambient and up to 1100°C.

Alloys in Extreme Environments

Hydrogen embrittlement, cryogenic temperatures, fatigue, etc.

This topic studies alloys for aerospace and hydrogen pipelines, from nickel-based alloys to stainless steels, across cryogenic to room temperatures, and the impact of hydrogen on mechanical properties. Techniques such as neutron diffraction, X-ray diffraction, and EBSD are employed to elucidate their mechanical behaviour.

Semiconductors

Micromechanical testing and measuring defects and strains in power electronic materials

Interfacial strength of heterogeneously integrated ceramic films

A range of micro-mechanical testing methods have been developed to evaluate the interfacial toughness of thin ceramic films (e.g., GaN) integrated on stiff substrates, including SiC, Si and single/polycrystalline diamond, with the aim of enabling the development of novel semiconductor materials for high-power radio frequency (RF) devices.

Strain & defect in power electronic materials

The INTERVENE project is investigating the strains and defects in power electronic materials, in collaboration with REWIRE-IKC, the University of Bristol, and the University of Warwick.

Ceramic Matrix Composites

Mechanistic Understanding of the Damage and Fracture in Ceramic-Matrix Composites under Extreme Conditions

Working with many industries and processing groups, this area studies a range of aerospace and nuclear fission/fusion ceramic matrix composites (CMCs) in extreme environments. in terms of their local mechanical and thermal properties, residual stresses, deformation and fracture including crack initiation and propagation from ambient to temperatures higher than 1000°C with in situ imaging and diffraction methods.

The CMCs of interest to EMAM are SiC/SiC and Oxide/Oxide composites.