Dr Tan Sui


Lecturer in Materials Engineering
BEng DPhil (Oxon) CSci FIMMM
+44 (0)1483 689670
15 AA 02

Biography

Areas of specialism

Multi-beam microscopy techniques (FIB-DIC, SEM, EDX, EBSD, STEM, Raman and TOF-SIMS); Multi-modal synchrotron X-ray techniques (SAXS/WAXS, Imaging and Spectroscopy)

University roles and responsibilities

  • FEPS representative for human tissue research
  • MES representative for social media

Affiliations and memberships

Member
EPSRC-WES membership - A Centenary Celebration: Women's Engineering Society Membership
Approved Assessor
Institute of Materials, Minerals & Mining (IOM3)
Member
EPSRC Peer Review Associate College
Member
International Association for Dental Research (IADR) Member
Committee Member
Advances in Functional Materials (AFM), Los Angeles, USA
Committee Member
International Conference on Mechanical and Aerospace Engineering (ICMAE)
Review Editor
Frontiers in Dental Medicine

Business, industry and community links

Diamond Light Source
Joint PhD studentship
Culham Centre for Fusion Energy
Doctoral College Studentship Award
Pilkington Technology Management
Joint EPSRC CDT in MiNMaT EngD Project

Research

Research interests

Research projects

Research collaborations

Supervision

Postgraduate research supervision

My teaching

My publications

Publications

Korsunsky A.M., Salvati E., Lunt A.G.J., Sui Tan, Mughal M.Z., Daniel R., Keckes J., Bemporad E., Sebastiani M. (2018) Nanoscale residual stress depth profiling by Focused Ion Beam milling and eigenstrain analysis, Materials & Design 145 pp. 55-64 Elsevier

Residual stresses play a crucial role in determining material properties and behaviour, in terms of structural integrity under monotonic and cyclic loading, and for functional performance, in terms of capacitance, conductivity, band gap, and other characteristics. The methods for experimental residual stress analysis at the macro- and micro-scales are well established, but residual stress evaluation at the nanoscale faces major challenges, e.g. the need for sample sectioning to prepare thin lamellae, by its very nature introducing major modifications to the quantity being evaluated.

Residual stress analysis by micro-ring core Focused Ion Beam milling directly at sample surface offers lateral resolution better than 1 ¼m, and encodes information about residual stress depth variation. We report a new method for residual stress depth profiling at the resolution better than 50 nm by the application of a mathematically straightforward and robust approach based on the concept of eigenstrain. The results are validated by direct comparison with measurements by nano-focus synchrotron X-ray diffraction.

Zhang H, Sui T, Salvati E, Daisenberger D, Lunt A, Fong K, Song X, Korsunsky A (2018) Digital Image Correlation of 2D X-ray Powder Diffraction Data for Lattice Strain Evaluation, Materials 11 (3) MDPI
High energy 2D X-ray powder diffraction experiments are widely used for lattice strain measurement. The 2D to 1D conversion of diffraction patterns is a necessary step used to prepare the data for full pattern refinement, but is inefficient when only peak centre position information is required for lattice strain evaluation. The multi-step conversion process is likely to lead to increased errors associated with the ?caking? (radial binning) or fitting procedures. A new method is proposed here that relies on direct Digital Image Correlation analysis of 2D X-ray powder diffraction patterns (XRD-DIC, for short). As an example of using XRD-DIC, residual strain values along the central line in a Mg AZ31B alloy bar after 3-point bending are calculated by using both XRD-DIC and the conventional ?caking? with fitting procedures. Comparison of the results for strain values in different azimuthal angles demonstrates excellent agreement between the two methods. The principal strains and directions are calculated using multiple direction strain data, leading to full in-plane strain evaluation. It is therefore concluded that XRD-DIC provides a reliable and robust method for strain evaluation from 2D powder diffraction data. The XRD-DIC approach simplifies the analysis process by skipping 2D to 1D conversion, and opens new possibilities for robust 2D powder diffraction data analysis for full in-plane strain evaluation.
Ying S, Ma L, Sui T, Papadaki C, Salvati E, Brandt L, Zhang H, Korsunsky A (2018) Nanoscale Origins of the Size Effect in the
Compression Response of Single Crystal Ni-Base
Superalloy Micro-Pillars,
Materials 11 (4) 561 MDPI
Nickel superalloys play a pivotal role in enabling power-generation devices on land, sea,
and in the air. They derive their strength from coherent cuboidal precipitates of the ordered ³? phase
that is different from the ³ matrix in composition, structure and properties. In order to reveal the
correlation between elemental distribution, dislocation glide and the plastic deformation of microand
nano-sized volumes of a nickel superalloy, a combined in situ nanoindentation compression
study was carried out with a scanning electron microscope (SEM) on micro- and nano-pillars
fabricated by focused ion beam (FIB) milling of Ni-base superalloy CMSX4. The observed mechanical
response (hardening followed by softening) was correlated with the progression of crystal slip that
was revealed using FIB nano-tomography and energy-dispersive spectroscopy (EDS) elemental
mapping. A hypothesis was put forward that the dependence of material strength on the size of
the sample (micropillar diameter) is correlated with the characteristic dimension of the structural
units (³? precipitates). By proposing two new dislocation-based models, the results were found to be
described well by a new parameter-free Hall?Petch equation.
Sui Tan, Salvati Enrico, Harper Robert A, Zhang Hongjia, Shelton Richard M, Landini Gabriel, Korsunsky Alexander M (2018) In situ monitoring and analysis of enamel demineralisation using synchrotron X-ray scattering, Acta Biomaterialia 77 pp. 333-341 Elsevier
Dental caries is one of the most common chronic diseases that affect human teeth. It often initiates in enamel, undermining its mechanical function and structural integrity. Little is known about the enamel demineralisation process caused by dental caries in terms of the microstructural changes and crystallography of the inorganic mineral phase. To improve the understanding of the carious lesion formation process and to help identify efficient treatments, the evolution of the microstructure at the nano-scale in an artificially induced enamel erosion region was probed using advanced synchrotron small-angle and wide-angle X-ray scattering (SAXS and WAXS). This is the first in vitro and time-resolved investigation of enamel demineralisation using synchrotron X-ray techniques which allows in situ quantification of the microstructure evolution over time in a simulated carious lesion. The analysis revealed that alongside the reduction of mineral volume, a heterogeneous evolution of hydroxyapatite (HAp) crystallites (in terms of size, preferred orientation and degree of alignment) could be observed. It was also found that the rate and direction of dissolution depends on the crystallographic orientation. Based on these findings, a novel conceptual view of the process is put forward that describes the key structural parameters in establishing high fidelity ultrastructure-based numerical models for the simulation of the enamel demineralisation process.
Kageyama K., Adziman F., Alabort E., Sui Tan, Korsunsky A. M., Reed R. C. (2018) In Situ Diagnostics of Damage Accumulation in Ni-Based Superalloys Using High-Temperature Computed Tomography, Metallurgical and Materials Transactions A 49 (9) pp. 4274-4289 Springer Verlag
The design, operation, and performance of a laboratory-scale X-ray computed tomography arrangement that is capable of elevated-temperature deformation studies of superalloys to 800 °C and possibly beyond are reported. The system is optimized for acquisition of three-dimensional (3D) backprojection images recorded sequentially during tensile deformation at strain rates between 10?4 and 10?2 s?1, captured in situ. It is used to characterize the evolution of damage?for example, void formation and microcracking?in Nimonic 80A and Inconel 718 superalloys, which are studied as exemplar polycrystalline alloys with lesser and greater ductility, respectively. the results indicate that such damage can be resolved to within 30 to 50 ¼m. Collection of temporally and spatially resolved data for the damage evolution during deformation is proven. Hence, the processes leading to creep fracture initiation and final rupture can be quantified in a novel way.
Sui Tan, Dluhoa JiYí, Li Tao, Zeng Kaiyang, Cernescu Adrian, Landini Gabriel, Korsunsky Alexander (2018) Structure-Function Correlative Microscopy of Peritubular and Intertubular Dentine, Materials 11 (9) MDPI
Peritubular dentine (PTD) and intertubular dentine (ITD) were investigated by 3D correlative Focused Ion Beam (FIB)-Scanning Electron Microscopy (SEM)-Energy Dispersive Spectroscopy (EDS) tomography, tapping mode Atomic Force Microscopy (AFM) and scattering-type Scanning Near-Field Optical Microscopy (s-SNOM) mapping. The brighter appearance of PTD in 3D SEM-Backscattered-Electron (BSE) imaging mode and the corresponding higher grey value indicate a greater mineral concentration in PTD (~160) compared to ITD (~152). However, the 3D FIB-SEM-EDS reconstruction and high resolution, quantitative 2D map of the Ca/P ratio (~1.8) fail to distinguish between PTD and ITD. This has been further confirmed using nanoscale 2D AFM map, which clearly visualised biopolymers and hydroxyapatite (HAp) crystallites with larger mean crystallite size in ITD (32 ± 8 nm) than that in PTD (22 ± 3 nm). Correlative microscopy reveals that the principal difference between PTD and ITD arises primarily from the nanoscale packing density of the crystallites bonded together by thin biopolymer, with moderate contribution from the chemical composition difference. The structural difference results in the mechanical properties variation that is described by the parabolic stiffness-volume fraction correlation function introduced here. The obtained results benefit a microstructure-based mechano-chemical model to simulate the chemical etching process that can occur in human dental caries and some of its treatments.
Sui Tan, Salvati Enrico, Zhang Hongjia, Nyaza Kirill, Senatov Fedor S., Salimon Alexei I., Korsunsky Alexander M. (2018) Probing the complex thermo-mechanical properties of a 3D-printed polylactide-hydroxyapatite composite using in situ synchrotron X-ray scattering, Journal of Advanced Research Elsevier
Polylactide (PLA)-hydroxyapatite (HAp) composite components have attracted extensive attentions for a variety of biomedical applications. This study seeks to explore how the biocompatible PLA matrix and the bioactive HAp fillers respond to thermo-mechanical environment of a PLA-HAp composite manufactured by 3D printing using Fused Filament Fabrication (FFF). The insight is obtained by in situ synchrotron small- and wide- angle X-ray scattering (SAXS/WAXS) techniques. The thermo-mechanical cyclic loading tests (0-20MPa, 22-56°C) revealed strain softening (Mullins effect) of PLA-HAp composite at both room and elevated temperatures (50°C) due to the increased chain mobility. Above this temperature the deformation behaviour of the soft PLA lamella changes drastically. The thermal test (0-110°C) identified multiple crystallisation mechanisms of the PLA amorphous matrix, including reversible stress-induced large crystal formation at room temperature, reversible coupled stress-temperature-induced PLA crystal formation appearing at around 60°C, as well as irreversible heating-induced crystallisation above 92°C. The shape memory test (0-3.75MPa, 0-70°C) of the PLA-HAp composite demonstrates a fixing ratio (strain upon unloading/strain before unloading) of 65% and rather a
Wang Haibin, Sun Yinghao, Tan Yunzhi, Sui Tan, Sun Guanhua (2019) Deformation characteristics and stability evolution behavior of Woshaxi landslide during the initial impoundment period of the Three Gorges reservoir, Environmental Earth Sciences 78 (20) 592 Springer-Verlag
The study area, Woshaxi landslide, is 400 m long and 700 m wide, with an average thickness of approximately 15 m and a volume of 4.2 × 106 m3. The Woshaxi landslide, which is located on the Qinggan River, a tributary of the Yangtze River in the Three Gorges reservoir area, is just 1.5 km from the Qianjiangping landslide. The Qianjiangping landslide following the Three Gorges reservoir impoundment was caused by the combined effects of rainfall and reservoir water-level fluctuation. In this study, the Woshaxi landslide?s deformation characteristics and mechanism are investigated based on deformation monitoring data and a geological survey during the initial impoundment period of the Three Gorges reservoir. Furthermore, based on the characteristics of the combined effects of reservoir water level fluctuation and rainfall in the Three Gorges reservoir area, the stability evolution behavior of the Woshaxi landslide during the initial impoundment period of the Three Gorges reservoir is investigated.
The distinct molecular architecture and thermomechanical properties of polyurethane block copolymers make them suitable for applications ranging from textile fibers to temperature sensors. In the present study, differential scanning calorimetry (DSC) analysis and macroscopic stress relaxation measurements are used to identify the key internal processes occurring in the temperature ranges between ?10 °C and 0 °C and between 60 °C and 70 °C. The underlying physical phenomena are elucidated by the small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) study of synchrotron beams, allowing the exploration of the structure-property relationships as a function of temperature. In situ multiscale deformation analysis under uniaxial cyclic thermomechanical loading reveals a significant anomaly in the strain evolution at the nanoscale (assessed via SAXS) in the range between ?10 °C and 0 °C owing to the ?melting? of the soft matrix. Furthermore, WAXS measurement of crystal strain within the hard regions reveals significant compressive residual strains arising from unloading at
Sun Guanhua, Lin Shan, Zheng Hong, Tan Yunzhi, Sui Tan (2020) The virtual element method strength reduction technique for the stability analysis of stony soil slopes, Computers and Geotechnics 119 103349 Elsevier
Based on the incremental method of elastic-plastic mechanics and bilinear projection operators, by combining the strength reduction method with the Æ-v inequality, this paper proposes a virtual element method strength reduction technique for slope stability analysis. The deformations of a homogeneous slope and heterogeneous slope are solved under different strength reduction factors, and the mesh dependency problem of the method is discussed. Numerical examples verify the correctness and effectiveness of the proposed method. The results demonstrate that due to the differences in the physical and mechanical properties of soil and rocks, stress becomes concentrated in the contact zone between soil and rocks, and thus, the plastic zone surrounds the rocks. Therefore, it is difficult to form regular connections in a plastic zone, such as a soil slope. This method can be used to analyse the stability of a stony soil slope and to study the effects of particle size, rock content, rock density, and rock spatial distribution on the mechanical behaviour of stony soil slopes.
Hu Jinan, Sui Tan (2020) Insights into the reinforcement role of peritubular dentine subjected to acid dissolution, Journal of the Mechanical Behavior of Biomedical Materials 103 103614 Elsevier
Human dentine is a mineralised dental tissue that consists of dentinal tubules surrounded by two distinct dentinal phases: peritubular dentine (PTD) and intertubular dentine (ITD). Dental caries, which manifests itself as a consequence of demineralisation, is one of the most common chronic diseases that affect the function of human teeth. Due to the difference in the packing density of crystallites, PTD and ITD exhibit different reaction rates to acid dissolution. The present study evaluates how the effective Young?s modulus degrades and how the effective stress redistributes in demineralised human dentine as a result of incremental acid dissolution process. An analytical two-layer composite model is proposed and used for the effective Young?s modulus calculation. 3D numerical representative volume elements (RVEs) with different variations in PTD fraction and dentinal tubule density are established to evaluate effective stress redistribution and examine the critical factors that can affect the mechanical performance. The models are then applied on an actual dentine bulk sample. The results reveal how PTD serves as a protection to ITD thus highlight the important role that PTD plays for the structural integrity of dentine. The obtained insights are crucial for advancing the understanding of a variety of natural and therapeutic effects from the mechanical perspective, e.g. the mechanical performance assessment of human dentine subject to complex dynamic processes of de- and re-mineralisation that can occur in human dental caries and dental treatments. It will ultimately inspire the biomimetic design towards strengthening the dentine and dentine-like materials.

Additional publications