Vivian Tong
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Vivian Tong has a total of 12 co-authors. Here are the top co-authors by number of shared publications:
Helen Jones
National Physical Laboratory Hampton Road TW11 0LW Teddington Middlesex UK
2 shared publicationsKen Mingard
National Physical Laboratory Hampton Road TW11 0LW Teddington Middlesex UK
2 shared publications- Ken P. Mingard
National Physical Laboratory, Hampton Road, Teddington, Middlesex TW11 0LW, UK
2 shared publications - Brian Cantor
Department of Materials, University of Oxford, Oxford, UK
1 shared publication - Chamini Lakshi Mendis
Helmholtz-Zentrum Geesthacht
1 shared publication - Feng Wang
Brunel Centre for Advanced Solidification Technology (BCAST), Brunel University London, London UB8 3PH, UK
1 shared publication
Latest Publications
- Open Access
Microstructure and Mechanical Properties of Ultrafine Quaternary Al-Cu-Si-Mg Eutectic Alloy
The microstructure evolution and mechanical properties of quaternary Al-Cu-Si-Mg eutectic alloy prepared via arc melting and suction casting were studied. This alloy exhibits a single endothermic DSC peak with a melting temperature of 509 °C upon heating, suggesting a eutectic reaction. The cast alloy microstructure consisted of four phases, α-Al, Al2Cu (), Si and Al4Cu2Mg8Si7 (Q), in the eutectic cells and also in the nano-scale anomalous eutectic in the intercellular regions. The eutectic cells show different morphologies in different parts of the sample. Well-defined orientation relationships between the α-Al, Al2Cu, and Q phases were found in the eutectic cell centres, while decoupled growth of Q phase occurred at the cell boundaries. The bimodal microstructure exhibits excellent compressive mechanical properties, including a yield strength of 835 ± 35 MPa, a fracture strength of ~1 GPa and a compressive fracture strain of 4.7 ± 1.1%. The high strength is attributed to a combination of a refined eutectic structure and strengthening from multiple hard phases.Open AccessMicrostructure and Mechanical Properties of Ultrafine Quaternary Al-Cu-Si-Mg Eutectic Alloy
The microstructure evolution and mechanical properties of quaternary Al-Cu-Si-Mg eutectic alloy prepared via arc melting and suction casting were studied. This alloy exhibits a single endothermic DSC peak with a melting temperature of 509 °C upon heating, suggesting a eutectic reaction. The cast alloy microstructure consisted of four phases, α-Al, Al2Cu (), Si and Al4Cu2Mg8Si7 (Q), in the eutectic cells and also in the nano-scale anomalous eutectic in the intercellular regions. The eutectic cells show different morphologies in different parts of the sample. Well-defined orientation relationships between the α-Al, Al2Cu, and Q phases were found in the eutectic cell centres, while decoupled growth of Q phase occurred at the cell boundaries. The bimodal microstructure exhibits excellent compressive mechanical properties, including a yield strength of 835 ± 35 MPa, a fracture strength of ~1 GPa and a compressive fracture strain of 4.7 ± 1.1%. The high strength is attributed to a combination of a refined eutectic structure and strengthening from multiple hard phases. - Open Access
Micropillar compression of single crystal tungsten carbide, Part 2: Lattice rotation axis to identify deformation slip mechanisms
The plastic deformation mechanisms of tungsten carbide at room and elevated temperatures influence the wear and fracture properties of WC-Co hardmetal composite materials. The relationship between residual defect structures, including glissile and sessile dislocations and stacking faults, and the slip deformation activity, which produce slip traces, is not clear. Part 1 of this study showed that {10-10} was the primary slip plane at all measured temperatures and orientations, but secondary slip on the basal plane was activated at 600 {\deg}C, which suggests that dislocations can cross-slip onto the basal plane at 600 {\deg}C. In the present work, Part 2, lattice rotation axis analysis of deformed WC micropillar mid-sections was used to discriminate prismatic slip from multiple prismatic slip in WC, which enabled the dislocation types contributing to plastic slip to be distinguished, independently of TEM residual defect analysis. Prismatic-oriented micropillars deformed primarily by multiple prismatic slip at room temperature, but by prismatic slip at 600 {\deg}C. Deformation in the near-basal oriented pillar at 600 {\deg}C can be modelled as prismatic slip along constrained by the indenter face and pillar base. Secondary basal slip, which was observed near the top of the pillar, was activated to maintain deformation compatibility with the indenter face. The lattice rotations, buckled pillar shape, mechanical data, and slip traces observed in the pillar are all consistent with this model.
Open AccessMicropillar compression of single crystal tungsten carbide, Part 2: Lattice rotation axis to identify deformation slip mechanisms
The plastic deformation mechanisms of tungsten carbide at room and elevated temperatures influence the wear and fracture properties of WC-Co hardmetal composite materials. The relationship between residual defect structures, including glissile and sessile dislocations and stacking faults, and the slip deformation activity, which produce slip traces, is not clear. Part 1 of this study showed that {10-10} was the primary slip plane at all measured temperatures and orientations, but secondary slip on the basal plane was activated at 600 {\deg}C, which suggests that dislocations can cross-slip onto the basal plane at 600 {\deg}C. In the present work, Part 2, lattice rotation axis analysis of deformed WC micropillar mid-sections was used to discriminate prismatic slip from multiple prismatic slip in WC, which enabled the dislocation types contributing to plastic slip to be distinguished, independently of TEM residual defect analysis. Prismatic-oriented micropillars deformed primarily by multiple prismatic slip at room temperature, but by prismatic slip at 600 {\deg}C. Deformation in the near-basal oriented pillar at 600 {\deg}C can be modelled as prismatic slip along constrained by the indenter face and pillar base. Secondary basal slip, which was observed near the top of the pillar, was activated to maintain deformation compatibility with the indenter face. The lattice rotations, buckled pillar shape, mechanical data, and slip traces observed in the pillar are all consistent with this model.
- Open Access
Micropillar compression of single crystal tungsten carbide, Part 1: temperature and orientation dependence of deformation behaviour
Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject to high operation temperature and pressures, where the mechanical performance of the tungsten carbide phase affects the wear and lifetime of the material. In this study, the mechanical behaviour of the isolated tungsten carbide (WC) phase was investigated using single crystal micropillar compression. Micropillars in two crystal orientations, 1-5 ${\mu}$m in diameter, were fabricated using focused ion beam (FIB) machining and subsequently compressed between room temperature and 600 {\deg}C. The activated plastic deformation mechanisms were strongly anisotropic and weakly temperature dependent. The flow stresses of basal-oriented pillars were about three times higher than the prismatic pillars, and pillars of both orientations soften slightly with increasing temperature. The basal pillars tended to deform by either unstable cracking or unstable yield, whereas the prismatic pillars deformed by slip-mediated cracking. However, the active deformation mechanisms were also sensitive to pillar size and shape. Slip trace analysis of the deformed pillars showed that {10-10} prismatic planes were the dominant slip plane in WC. Basal slip was also activated as a secondary slip system at high temperatures.
Open AccessMicropillar compression of single crystal tungsten carbide, Part 1: temperature and orientation dependence of deformation behaviour
Tungsten carbide cobalt hardmetals are commonly used as cutting tools subject to high operation temperature and pressures, where the mechanical performance of the tungsten carbide phase affects the wear and lifetime of the material. In this study, the mechanical behaviour of the isolated tungsten carbide (WC) phase was investigated using single crystal micropillar compression. Micropillars in two crystal orientations, 1-5 ${\mu}$m in diameter, were fabricated using focused ion beam (FIB) machining and subsequently compressed between room temperature and 600 {\deg}C. The activated plastic deformation mechanisms were strongly anisotropic and weakly temperature dependent. The flow stresses of basal-oriented pillars were about three times higher than the prismatic pillars, and pillars of both orientations soften slightly with increasing temperature. The basal pillars tended to deform by either unstable cracking or unstable yield, whereas the prismatic pillars deformed by slip-mediated cracking. However, the active deformation mechanisms were also sensitive to pillar size and shape. Slip trace analysis of the deformed pillars showed that {10-10} prismatic planes were the dominant slip plane in WC. Basal slip was also activated as a secondary slip system at high temperatures.