Dong (Lilly) Liu BEng PhD

Prof. Dong (Lilly) Liu joined the University of Oxford in January 2024, as Associate Professor in Engineering Science and Tutorial Fellow in Trinity College. Prior to this, she was an Associate Professor at the University of Bristol where she was Lead of the Materials and Device Theme in the School of Physics, and Head of the Experimental Mechanics of Advanced Materials group (EMAM). She joined the University of Bristol as Lecturer in July 2018 from Oxford University (2015-2018) where she held an 1851 Exhibition Royal Commission Fellowship (Brunel) and an EPSRC Postdoctoral Research Fellowship. She was also awarded a Junior Research Fellowship (2016-2018) in Mansfield College whilst at the University of Oxford.

Prof. Liu serves on several international technical committees, including the ASTM C28.07 Committee (Ceramic Matrix Composites), Composite Materials Handbook Standards (CMH-17) Ceramic Matrix Testing Working Group and the IOM3 Ceramic Science Committee. She is also a member of the Leadership Team at IOM3 Ceramics Group. At TMS (The Minerals, Metals & Materials Society, USA), she was appointed the Program Committee Representative to the SMD Council (Structural Materials Division), as well as to the Program Committee as the SMD Representative for 2024-2027. She was appointed to the TMS Education Committee for 2024-2027 and TMS Nuclear Materials Committee MiNES Liaison (Materials in Nuclear Energy Systems, USA) for 2023-2026. Prof. Liu is currently a member of the EPSRC’s Research Infrastructure Strategic Advisory Team (SAT), and she serves on review panels of various research councils/funding bodies/international facilities in the UK, USA, Canada, Spain and Italy.

New research projects are available in Prof. Liu’s group on nuclear graphite, TRISO, ceramics, barrier coatings and high entropy alloy areas. Please contact Prof. Liu about research opportunities. Three recent examples of DPhil projects openly advertised for Oct 2024 entry are listed below:

1. Research Studentship in ‘Damage Tolerance of Ni-Based Alloys at Cryogenic Temperatures’

3.5-year DPhil studentship

Supervisors: Prof Dong (Lilly) Liu and Prof Felix Hofmann

As part of the drive for Net Zero emissions by 2050 aerospace OEMs are in the early stages of development of hydrogen fuelled gas turbine engines. Rolls-Royce has launched a programme to run a full-scale liquid hydrogen fuelled engine ground test. When using liquid hydrogen as a fuel, much of the fuel system will be operating at cryogenic temperature. Hence a good understanding of how aerospace alloys will behave at cryogenic temperatures is essential to inform component integrity assessment. A key input into this is understanding of damage tolerance/fracture toughness at cryogenic temperatures. This sets the horizon of this DPhil project.

Specifically, in this project, you will be using a range of advanced experimental techniques to characterize the deformation and fracture of Ni-based alloys over a range of cryogenic temperatures down to 20K. There will also be the opportunity to study other materials of interest during the project. In situ experiments with neutron/X-ray diffraction/imaging will be carried out at Rutherford Appleton Laboratory, and lab-based analysis using Electron Backscatter Diffraction (EBSD), focused ion beam milling and micro-mechanical testing will be carried out to further understand the mechanisms controlling the deformation and fracture behaviour of these materials.

In the later years of the project, there will be the opportunity to collaborate with Profs. Hofmann and Tarleton’s groups to investigate the process of embrittlement in these materials from hydrogen. During the project, the student is expected to attend regular progress meetings with the industrial supervision team (Louise Gale and Neil Glover, Rolls Royce plc).

In summary, this jointed DPhil project between Oxford and Rolls Royce is considered a very important effort to further establish UK cryogenic testing capability and to foster next generation young researchers in this field.

2. Research Studentship in Deformation and fracture of TRISO fuel particles

3.5-year DPhil studentship

Supervisors: Prof Dong (Lilly) Liu and Prof Emilio Martinez-Paneda

The proposed PhD project will focus on an Advanced Reactor fuel form called TRi-structural ISOtropic (TRISO) fuel. Each TRISO particle has a spherical uranium-based kernel (although this project only studies particles with surrogate kernels of Alumina or Zirconia) that is surrounded by four coating layers made of pyrolytic carbon and silicon carbide (SiC). These coatings work together to prevent the release of radioactive fission products from the kernel.

This PhD project will be performed under the direct supervision of Prof. Dong (Lilly) Liu and Prof. Emilio Martinez-Paneda of Oxford University and co-supervised by Canadian Nuclear Laboratories. In this project, you will have the opportunity to be trained and become a proficient user of a range of advanced experimental techniques. For instance, you will learn how to use in-situ X-ray Computed Tomography (XCT), a non-destructive imaging technique, to perform crushing experiments of TRISO particles over a range of temperatures, thereby achieving a better understanding of the deformation behaviour of the particle fuel, crack initiation/propagation and failure mechanisms in relation to test temperature.

Finite element (FE) modelling using FE tools such as Abaqus, (or) Ansys, (or) COMSOL is optional to validate the experimental findings. High-temperature micromechanical experiments will also be conducted to determine the local properties, and potentially the creep behaviours, of the SiC layer as well as of the TRISO layer interfaces using in-situ and ex-situ micromechanical testing techniques. It is also possible that you will be contributing to international round-robin/bench marking exercises that aim to standardise the sub-sized specimen testing program. In addition, you will have the opportunity to present your work at international conferences/workshops.

Finally, as a part of your graduate experience, you will have the opportunity to spend some time as a visiting or exchange researcher at the collaborating organisation Canadian Nuclear Laboratories (CNL) at Chalk River, Ontario, where you would get exposure to applied R&D environment related to advanced reactors and contribute to ongoing activities aligned with your research.

3. Research Studentship in ‘Thermo-mechanical behaviour of TRISO coatings’

3.5-year DPhil studentship

Supervisors: Prof Dong (Lilly) Liu and Prof Clive Siviour

Since its invention in the United Kingdom as part of the Dragon reactor project in 1960s, Tristructural isotropic (TRISO) coated nuclear fuel particles are playing an increasingly important role in the nuclear energy production. TRISO is designed to have remarkable fission product retention capabilities and excellent high-temperature integrity, hence it is considered potentially ‘the safest fuel’. They are to be used in the high temperature gas-cooled reactors (HTGRs), specifically the Gen IV advanced reactor technology selected by the UK as the centrepiece of its Advanced Modular Reactor Research, Development & Demonstration Programme.

This DPhil project is co-funded by Ultra Safe Nuclear Corporation (USNC) UK who plays a key role in developing the design of a high temperature micro modular reactor, a type of AMR suited to UK industrial demands including hydrogen and sustainable aviation fuel production. The primary focus of this PhD project is on the fundamental study of the local and inter-layer properties of the TRISO coatings. The student will design and conduct micro-mechanical tests to obtain the interfacial strength including tensile and shear strengths at the coating interfaces in various types of TRISO particles. The local properties of each individual layer will also be generated using micro-mechanical testing as modelling input. Residual stresses, generated due to manufacturing processes, will be characterized by focussed ion beam-digital image correlation method combined with diffraction (either lab-based diffractometer or synchrotron X-ray diffraction).

During the project, thermal conductivity equipment will be made available to the student to generate line-scans and maps of the local thermal conductivity of each layer and across the interfaces. The data produced in this project will be used to support thermo-mechanical modelling of TRISO coatings.

Prof. Liu’s research interests lie in the area of multiple-scale nano-/microstructural and mechanical characterization of advanced engineering materials in extreme conditions, including ion/neutron/proton irradiation, elevated temperatures and cryogenic environments with applications across nuclear fission, fusion, aerospace, power electronics & RF devices, hydrogen storage, space and concentrated solar power. The primary materials of interest include carbon/graphite composites, TRISO fuels, ceramic-matrix composites, GaN-on-diamond, Ga2O3, high entropy alloys and environmental/thermal barrier coatings.

Prof. Liu’s group has a rich experience in a range of experimental techniques such as in-situ high-temperature X-ray/neutron tomography/diffraction with mechanical loading, FIB-SEM tomography, FIB-SEM digital image correlation, in-situ / ex-situ micromechanical testing, Raman spectroscopy and time/frequency-domain thermoreflectance. The ultimate goal is to understand the fundamental mechanisms controlling materials thermal/mechanical behaviours and irradiation degradation processes in conditions relevant to service.

Prof. Liu has published a co-authored textbook Ritchie & Liu, Introduction to Fracture Mechanics, 2021, Elsevier, several book chapters and >60 journal/conference papers. She has delivered >35 keynote/invited talks at premier international conferences and >30 colloquiums talks/seminars at universities and research institutes worldwide. Prof. Liu has organised / co-organised more than 25 international symposia/conferences inside and outside the UK including USA, EU and Canada.

As a PI, Prof. Liu has secured more than £3 million funding from multiple sources such as EPSRC, STFC, BEIS (DSIT/DESNZ), US DoE, EURATOM, the Royal Commission for the Exhibition of 1851, as well as multiple industrial organisations include National Nuclear Laboratory, Ultra Safe Nuclear Corporation, UK Atomic Energy Authority, EDF Energy, Westinghouse Electric Company, FermiLab, Canadian Nuclear Laboratories and so on.