149 results on '"Anthony E. Hughes"'
Search Results
2. Combined influence of Ce(III) and iodide ions for corrosion protection of AA 2024-T3 in acidic to neutral chloride-rich environments: Electrochemical and surface characterization studies
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Mohammed A. El-Hashemy, Anthony E. Hughes, Thomas Gengenbach, A. Matthew Glenn, and Ivan S. Cole
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Geochemistry and Petrology ,General Chemistry - Published
- 2023
3. Quantitative 3D Characterization for Kinetics of Corrosion Initiation and Propagation in Additively Manufactured Austenitic Stainless Steel (Adv. Sci. 36/2022)
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Jianli Li, Anthony E. Hughes, Y. S. Yang, Majid Laleh, Haipeng Wang, Xufang Zhang, Jie Ma, Wei Xu, and Mike Y. Tan
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General Chemical Engineering ,General Engineering ,General Physics and Astronomy ,Medicine (miscellaneous) ,General Materials Science ,Biochemistry, Genetics and Molecular Biology (miscellaneous) - Published
- 2022
4. Grain boundary character distribution in an additively manufactured austenitic stainless steel
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Sophie Primig, Nima Haghdadi, Majid Laleh, Anthony E. Hughes, Mike Y. Tan, and Gregory S. Rohrer
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010302 applied physics ,education.field_of_study ,Materials science ,Mechanical Engineering ,Population ,Metals and Alloys ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Microstructure ,01 natural sciences ,Stress (mechanics) ,Character (mathematics) ,Mechanics of Materials ,0103 physical sciences ,Thermal ,engineering ,General Materials Science ,Grain boundary ,Texture (crystalline) ,Austenitic stainless steel ,Composite material ,0210 nano-technology ,education - Abstract
The grain boundary character distribution (GBCD) in an austenitic stainless steel produced by additive manufacturing (AM) in both as-built and annealed conditions was studied. Relatively fine grains and a non-fibre texture was achieved by AM, and as-built structure showed a high population of Σ3 boundaries. A five-parameter GBCD analysis revealed that the microstructure is mostly dominated by highly incoherent Σ3 boundaries. The grain boundary network also consisted of random high angle, coherent Σ3s terminating on (111) planes with a pure twist character, and tilt Σ9 boundaries. The findings show prospects for the possibility of engineering the grain boundary network of materials in-situ, via the stress and heat induced by the thermal cycles during AM.
- Published
- 2021
5. Heat treatment for metal additive manufacturing
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Majid Laleh, Esmaeil Sadeghi, Reynier I. Revilla, Qi Chao, Nima Haghdadi, Anthony E. Hughes, Wei Xu, Iris De Graeve, Ma Qian, Ian Gibson, Mike Y. Tan, Materials and Chemistry, and Electrochemical and Surface Engineering
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General Materials Science - Abstract
Metal additive manufacturing (AM) refers to any process of making 3D metal parts layer-upon layer via the interaction between a heating source and feeding material from a digital design model. The rapid heating and cooling attributes inherent to such an AM process result in het erogeneous microstructures and the accumulation of internal stresses. Post-processing heat treatment is often needed to modify the microstructure and/or alleviate residual stresses to achieve properties comparable or superior to those of the conventionally manufactured (CM) counterparts. However, the optimal heat treatment conditions remain to be defined for the ma jority of AM alloys and are becoming another topical issue of AM research due to its industrial importance. Existing heat treatment standards for CM metals and alloys are not specifically designed for AM parts and may differ in many cases depending on the initial microstructures and desired properties for specific applications. The purpose of this paper is to critically review current knowledge and discuss the influence of post-AM heat treatment on microstructure, me chanical properties, and corrosion behavior of the major categories of AM metals including steel, Ni-based superalloys, Al alloys, Ti alloys, and high entropy alloys. This review clarifies significant differences between heat treating AM metals and their CM counterparts. The major sources of differences include microstructural heterogeneity, internal defects, and residual stresses. Under standing the influence of such differences will benefit industry by achieving AM metals with consistent and superior balanced performance compared to as-built AM and CM metals.
- Published
- 2023
6. Advances in the development of rare earth metal and carboxylate compounds as corrosion inhibitors for steel
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Yu Peng, Brw Hinton, Anthony Somers, Alison L. Chong, Anthony E. Hughes, Douglas R. MacFarlane, Peter C. Junk, Glen B. Deacon, James I. Mardel, and Maria Forsyth
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Materials science ,020209 energy ,General Chemical Engineering ,Rare earth ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Corrosion ,Dielectric spectroscopy ,Metal ,Cerium ,chemistry.chemical_compound ,chemistry ,visual_art ,0202 electrical engineering, electronic engineering, information engineering ,visual_art.visual_art_medium ,General Materials Science ,Carboxylate ,0210 nano-technology - Abstract
Research into non-toxic rare earth metal organic compounds providing an alternative to chromates as corrosion inhibitors was pioneered by research at Monash University almost 20 years ago. Further ...
- Published
- 2020
7. Rare earth elements recovery from secondary sources
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Shuronjit K. Sarker, Shanjida Sultana, Nawshad Haque, Anthony E. Hughes, Warren Bruckard, and Biplob K. Pramanik
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- 2022
8. Self-healing coatings
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Anthony E. Hughes, Priscilla Johnston, and Tristan J. Simons
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- 2022
9. Contributors
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Oludayo Ajisafe, Fang Chen, Xiaming Feng, Martin D. Hager, Christopher J. Hansen, Akira Harada, Xu He, Anthony E. Hughes, Gefu Ji, Manu John, Priscilla Johnston, Bodiuzzaman Jony, Xiao Kuang, Ang Li, Guoqiang Li, Weihang Li, Lu Lu, Harper Meng, Sameer B. Mulani, Jones Nji, Motofumi Osaki, Junsu Park, H. Jerry Qi, Min Zhi Rong, Samit Roy, G.M. Shashi, Amir Shojaei, Tristan J. Simons, Xiaohao Sun, Yoshinori Takashima, Jinrong Wu, Kai Yu, Liang Yue, Stefan Zechel, Ming Qiu Zhang, Linjun Zhang, Pengfei Zhang, Dong Yu Zhu, and Yong Zhu
- Published
- 2022
10. Leaching Behavior and Corrosion Inhibition of a Rare Earth Carboxylate Incorporated Epoxy Coating System
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Yu Peng, James I. Mardel, Anthony Somers, Bruce Hinton, Peter C. Junk, Maria Forsyth, Anthony E. Hughes, and Glen B. Deacon
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inorganic chemicals ,Materials science ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,engineering.material ,010402 general chemistry ,complex mixtures ,01 natural sciences ,Chloride ,Corrosion ,Metal ,chemistry.chemical_compound ,Coating ,medicine ,General Materials Science ,Carboxylate ,technology, industry, and agriculture ,Epoxy ,equipment and supplies ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Chemical engineering ,visual_art ,engineering ,visual_art.visual_art_medium ,Leaching (metallurgy) ,0210 nano-technology ,medicine.drug - Abstract
While paint coatings act as important barriers to corrosion, defects can lead to localized, rapid metal loss. The addition of corrosion inhibitors that are capable of leaching from a coating to protect the metal surface at a defect can prevent this type of corrosion. This work investigates the release and corrosion protection capabilities of two rare earth (RE) carboxylate inhibitors from an epoxy coating as an initial step to understanding their leaching behavior and interaction with the coating system. Leaching experiments were performed via inductively coupled plasma mass spectroscopy (ICP-MS) analyses of the solutions in which free-standing coatings loaded with varying concentrations of inhibitor compounds had been immersed. Inhibitor release from the epoxy coating was observed to be dependent on initial inhibitor concentration, inhibitor chemistry, and solution pH conditions. The coating systems with greater initial inhibitor loadings showed higher leaching rates, particularly in acidic environments. Following immersion, the absence of characteristic inhibitor peaks in the FTIR spectra of the coatings also confirmed leaching had taken place. Cross-sectional views of the coatings after exposure to the pH 1 environment presented a chloride infusion zone at the coating/solution interface where the inhibitor had leached out. The RE active inhibition provided by the leached RE carboxylate inhibitors was verified by exposure of a coating defect to a chloride contaminated environment.
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- 2019
11. Unexpected erosion-corrosion behaviour of 316L stainless steel produced by selective laser melting
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Majid Laleh, Wei Xu, Mike Yongjun Tan, Ian Gibson, and Anthony E. Hughes
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Materials science ,020209 energy ,General Chemical Engineering ,Erosion corrosion ,Metallurgy ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Corrosion ,0202 electrical engineering, electronic engineering, information engineering ,Pitting corrosion ,Relative density ,General Materials Science ,Jet impingement ,Selective laser melting ,0210 nano-technology - Abstract
The erosion-corrosion behaviour of a near fully dense 316L stainless steel (316L SS), with relative density higher than 99.5%, produced by selective laser melting (SLM) has been evaluated, for the first time, in a jet impingement system. Although the SLM-produced 316L SS possessed superior pitting corrosion resistance and higher hardness, unexpectedly, it has shown lower erosion-corrosion resistance than its conventionally produced commercial counterpart. This behaviour has been related to weaker repassivation ability of the SLM-produced 316L SS mainly due to the presence of the SLM process-induced pores within the specimen.
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- 2019
12. A study of rare-earth 3-(4-methylbenzoyl)-propanoate compounds as corrosion inhibitors for AS1020 mild steel in NaCl solutions
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Maria Forsyth, Anthony E. Hughes, James I. Mardel, Yu Peng, Anthony Somers, Peter C. Junk, Bruce Hinton, and Glen B. Deacon
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Nacl solutions ,General Chemical Engineering ,Rare earth ,Substrate surface ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Surface film ,0104 chemical sciences ,Corrosion ,Metal ,chemistry ,visual_art ,visual_art.visual_art_medium ,Lanthanum ,General Materials Science ,0210 nano-technology ,Nuclear chemistry - Abstract
In this work two novel rare-earth (RE) 3-(4-methylbenzoyl)-propanoate (mbp) complexes (RE(mbp)3; RE = La, Y) have been investigated and compared with the well-researched inhibitor, lanthanum 4-hydroxycinnamate (La(4-OHcin)3), for AS1020 mild steel in 0.01 M NaCl solutions. The electrochemical results reveal a high corrosion inhibition performance of Y(mbp)3 which is attributed to the build-up of a protective surface film with a high level of corrosion resistance particularly after 24 h. Surface analyses indicate that the metal surface is protected during the immersion in Y(mbp)3-inhibited solutions and the presence of Y is confirmed on the substrate surface.
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- 2018
13. Role of microstructure in corrosion initiation of a highly-deformed AA2024 wire
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A. Matthew Glenn, Anthony E. Hughes, Reza Parvizi, Mike Y. Tan, Maria Forsyth, and Pavel Cizek
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Materials science ,Scattering ,020209 energy ,General Chemical Engineering ,Intermetallic ,02 engineering and technology ,General Chemistry ,Plasticity ,021001 nanoscience & nanotechnology ,Microstructure ,Grain size ,Corrosion ,0202 electrical engineering, electronic engineering, information engineering ,Annulus (firestop) ,General Materials Science ,Grain boundary ,Composite material ,0210 nano-technology - Abstract
Stable pits with H2 evolution preferentially occurred in an annular region surrounding the centre of AA2024 wire. The grain size and intermetallic particles (α-phase, Al7Cu2Fe, Al2CuMg, Mg2Si, Al2Cu) distributions were the same for both regions. However, the annulus had mixed orientations, high angle grain boundaries and microshear bands while the centre was dominated by [111] orientations and low angle grain boundaries with the latter being responsible for its passive nature.
- Published
- 2018
14. Enhancing the repassivation ability and localised corrosion resistance of an additively manufactured duplex stainless steel by post-processing heat treatment
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Majid Laleh, Nima Haghdadi, Anthony E. Hughes, Sophie Primig, and Mike Y.J. Tan
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General Chemical Engineering ,General Materials Science ,General Chemistry - Published
- 2022
15. ECS PRimE 2020 paper Mike Tan
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Anthony E. Hughes, Majid Laleh, Mike Yongjun Tan, Facundo Varela, Ying Huo, and Reza Parvizi
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Surface (mathematics) ,ECSarXiv|Engineering|Materials Science and Engineering ,Materials science ,ECSarXiv|Engineering|Materials Science and Engineering|Corrosion ,Scale (ratio) ,bepress|Engineering ,Metallurgy ,ECSarXiv|Engineering ,bepress|Engineering|Materials Science and Engineering ,Electrochemistry ,Corrosion - Abstract
Localized corrosion is usually resulted from nonuniform electrochemical and chemical processes occurring on metal surfaces at different spatial and temporal scales, frequently influenced by large scale environmental complexities such as stray currents and nano- or micro-scale heterogeneous metallurgical structures/defects such as porosities in materials. In order to predict the corrosion of large infrastructure such as buried pipelines and to develop alloys with superior corrosion resistance, it is necessary to probe and understand multi-scale electrochemical and chemical processes. Unfortunately conventional electrochemical and surface analytical techniques have difficulties in doing so due to the lack of either spatial or temporal resolution. This paper provides an overview of recent approaches to facilitating the probing of spatial and temporal scale localized corrosion processes by means of the combined used of advanced electrochemical and surface analytical techniques. Cases that the authors have firsthand experiences are briefly described to illustrate these applications.
- Published
- 2020
16. Observations on the Early Stages of Corrosion on AA2099-T83
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Nick Wilson, A. Matthew Glenn, Colin M. MacRae, Xiaorong Zhou, Anthony E. Hughes, and Aaron Torpy
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Materials science ,Scanning electron microscope ,020209 energy ,Alloy ,Analytical chemistry ,Intermetallic ,02 engineering and technology ,Electron microprobe ,engineering.material ,021001 nanoscience & nanotechnology ,Corrosion ,0202 electrical engineering, electronic engineering, information engineering ,engineering ,Galvanic cell ,Grain boundary ,0210 nano-technology ,Instrumentation ,Electron backscatter diffraction - Abstract
An Al–Cu–Li aerospace alloy has been investigated to determine the order in which corrosion at different types of sites occurs in AA2099-T83. Specifically, the sequence of galvanic attack on intermetallic (IM) particles and other sites of AA2099-T83 was determined as a function of time, in 0.1 M NaCl, through the use of scanning electron microscopy and electron backscatter diffraction characterization techniques. The earliest attack occurred at isolated grains and grain boundaries and on Li-containing dispersoids. Similarly, some constituent IM particles showed evidence of trenching in the surrounding alloy matrix. These IM particles included Al7Cu2Fe and another group of unidentified particles which displayed complete trenching within the first 10 min of exposure. Al13(Fe, Mn)4 were next most active followed by Al37Fe12Cu2 with Al6(Fe,Mn) and large TiB2 particles being the least active.
- Published
- 2020
17. Investigation of the Internal Structure of a Modern Seafloor Hydrothermal Chimney With a Combination of EBSD, EPMA, and XRD
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Raymond A Binns, Aaron Torpy, Si-Yu Hu, Nick Wilson, Colin M. MacRae, Joanna Parr, Matthew Glenn, Stephen Barnes, Anthony E. Hughes, and Nathan A. S. Webster
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Materials science ,010504 meteorology & atmospheric sciences ,Chalcopyrite ,Mineralogy ,Crystal growth ,Electron microprobe ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Hydrothermal circulation ,Sphalerite ,visual_art ,engineering ,visual_art.visual_art_medium ,Pyrite ,Instrumentation ,0105 earth and related environmental sciences ,Wurtzite crystal structure ,Electron backscatter diffraction - Abstract
Samples from the sphalerite-dominated zone of a seafloor massive sulfide chimney, the Satanic Mills Chimney of the PACMANUS hydrothermal field, have been investigated to determine the internal macrostructure and microstructure of this zone, the phases present, and the distribution of metals. A combination of electron probe microanalysis, electron backscattered diffraction, and x-ray diffraction has been used. At the macroscale, this zone of the chimney wall is heavily porous and is comprised primarily of sphalerite, enclosing minor chalcopyrite, pyrite, and wurtzite. A Pb–As sulfosalt layer of possible microbial origins is present at the outer edge of the sphalerite matrix, next to a pore. The sphalerite has grown in globules on the order of 300 μm in diameter. At the microscale, the sphalerite features a colloform texture and a duplex-type grain structure consisting of either fine-grain regions in the center surrounded by coarse-grained regions or radiating coarse grains only. Pb- and As-rich bands have been detected in the colloform sphalerite, and growth twins have been observed in both the sphalerite and chalcopyrite crystals. A qualitative description of the growth of a typical globule is given, including nucleation, crystal growth, and solute redistribution.
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- 2020
18. An Examination of the Composition and Microstructure of Coarse Intermetallic Particles in AA2099-T8, Including Li Detection
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Aaron Torpy, George Thompson, Anthony E. Hughes, A.M. Glenn, Colin M. MacRae, Nick Wilson, Mark A. Gibson, Xiaorong Zhou, James S Laird, and Nick Birbilis
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010302 applied physics ,Materials science ,Misorientation ,Alloy ,Analytical chemistry ,Intermetallic ,02 engineering and technology ,Electron microprobe ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,0103 physical sciences ,engineering ,Grain boundary ,Soft X-ray emission spectroscopy ,0210 nano-technology ,Instrumentation ,Electron backscatter diffraction - Abstract
Electron and proton microprobes, along with electron backscatter diffraction (EBSD) analysis were used to study the microstructure of the contemporary Al–Cu–Li alloy AA2099-T8. In electron probe microanalysis, wavelength and energy dispersive X-ray spectrometry were used in parallel with soft X-ray emission spectroscopy (SXES) to characterize the microstructure of AA2099-T8. The electron microprobe was able to identify five unique compositions for constituent intermetallic (IM) particles containing combinations of Al, Cu, Fe, Mn, and Zn. A sixth IM type was found to be rich in Ti and B (suggesting TiB2), and a seventh IM type contained Si. EBSD patterns for the five constituent IM particles containing Al, Cu, Fe, Mn, and Zn indicated that they were isomorphous with four phases in the 2xxx series aluminium alloys including Al6(Fe, Mn), Al13(Fe, Mn)4 (two slightly different compositions), Al37Cu2Fe12 and Al7Cu2Fe. SXES revealed that Li was present in some constituent IM particles. Al SXES mapping revealed an Al-enriched (i.e., Cu, Li-depleted) zone in the grain boundary network. From the EBSD analysis, the kernel average misorientation map showed higher levels of localized misorientation in this region, suggesting greater deformation or stored energy. Proton-induced X-ray emission revealed banding of the TiB2 IM particles and Cu inter-band enrichment.
- Published
- 2018
19. Corrosion behaviour of AA 1370 strands for wires: Identification of the critical metallurgical parameters
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Bernard Viguier, Christine Blanc, Claudie Josse, Anthony E. Hughes, Joël Alexis, Rosanne Gravina, Adrien Laurino, Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT), Centre de microcaractérisation Raimond Castaing (Centre Castaing), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), LEONI WIRING SYSTEMS FRANCE (FRANCE), Laboratoire Génie de Production (LGP), Ecole Nationale d'Ingénieurs de Tarbes (ENIT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université de Toulouse (UT), Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Centre de microcaractérisation Raimond Castaing (CMCR), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Ecole Nationale d'Ingénieurs de Tarbes, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - INPT (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Commonwealth Scientific and Industrial Research Organisation - CSIRO (AUSTRALIA), Centre de microcaractérisation Raimond Castaing (Toulouse, France), and Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
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Diffraction ,Materials science ,Misorientation ,Scanning electron microscope ,Matériaux ,020209 energy ,General Chemical Engineering ,02 engineering and technology ,Electron ,[SPI.MAT]Engineering Sciences [physics]/Materials ,Corrosion ,C. Interfaces ,0202 electrical engineering, electronic engineering, information engineering ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,General Materials Science ,Génie des procédés ,B. TEM ,Metallurgy ,A. Aluminium ,B. Polarisation ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Grain size ,Transmission electron microscopy ,A. Alloy ,0210 nano-technology - Abstract
International audience; The corrosion behaviour of AA 1370 in different metallurgical states was studied in chloride-containing sulphatesolutions. The microstructures of a rod, a deformed strand and an annealed strand constitutive of wires wereexamined using scanning electron microscopy, transmission electron microscopy and electron backscattereddiffraction. Results offered evidence for the ultra-fine grain size, high density of interfaces and high level ofmisorientation of the interfaces as relevant explanations for the low corrosion resistance of the deformed strandcompared to the rod and the annealed strand.
- Published
- 2018
20. Platinum Group Metals: A Review of Resources, Production and Usage with a Focus on Catalysts
- Author
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Stephen Northey, Nawshad Haque, Sarbjit Giddey, and Anthony E. Hughes
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Waste management ,platinum group metal (PGM) ,business.industry ,Science ,Oil refinery ,Automotive industry ,recycling ,Management, Monitoring, Policy and Law ,Platinum group ,catalysts ,Catalysis ,Ammonia production ,life cycle assessment ,0502 Environmental Science and Management, 0907 Environmental Engineering ,autocatalysis ,Environmental science ,Production (economics) ,mineral resources ,business ,Life-cycle assessment ,Nature and Landscape Conservation ,Hydrogen production - Abstract
The major applications of PGMs are as catalysts in automotive industry, petroleum refining, environmental (gas remediation), industrial chemical production (e.g., ammonia production, fine chemicals), electronics, and medical fields. As the next generation energy technologies for hydrogen production, such as electrolysers and fuel cells for stationary and transport applications, become mature, the demand for PGMs is expected to further increase. Reserves and annual production of Ru, Rh, Pd, Ir, and Pt have been determined and reported. Based on currently available resources, there is around 200 years lifetime based on current demand for all PGMs, apart from Pd, which may be closer to 100 years. Annual primary production of 190 t/a for Pt and 217 t/a for Pd, in combination with recycling of 65.4 t/a for Pt and 97.2 t/a for Pd, satisfies current demand. By far, the largest demand for PGMs is for all forms of catalysis, with the largest demand in auto catalysis. In fact, the biggest driver of demand and price for Pt, Pd, and Rh, in particular, is auto emission regulation, which has driven auto-catalyst design. Recovery of PGMs through recycling is generally good, but some catalytic processes, particularly auto-catalysis, result in significant dissipation. In the US, about 70% of the recycling stream from the end-of-life vehicles is a significant source of global secondary PGMs recovered from spent auto-catalyst. The significant use of PGMs in the large global auto industry is likely to continue, but the long-term transition towards electric vehicles will alter demand profiles.
- Published
- 2021
21. An Al-Cu Multielectrode Model for Studying Corrosion Inhibition with Praseodymium Mercaptoacetate at Intermetallic Particles in AA2024
- Author
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Ivan S. Cole, Yongjun Tan, Maria Forsyth, Rainier Catubig, Anthony E. Hughes, and Bruce Hinton
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Materials science ,Renewable Energy, Sustainability and the Environment ,Condensed Matter Physics ,Electrochemistry ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Anode ,Corrosion ,Cathodic protection ,Galvanic corrosion ,Corrosion inhibitor ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Materials Chemistry ,Pitting corrosion ,Galvanic cell - Abstract
Dealloying of S-phase particles on AA2024-T3 leave behind highly cathodic Cu-rich particles, creating a galvanic corrosion environment. Clustering of these particles intensify localised dissolution of adjacent matrix leading to pitting. Evaluation of such galvanic activities is critical to develop effective corrosion inhibitors. Unfortunately conventional electrochemical methods are unable to probe this type of anodic attack because in principle they only evaluate general corrosion and cannot measure galvanic corrosion currents flowing between particles and adjacent matrix. This work uses a multielectrode composed of four copper and forty-four aluminium electrodes to model galvanic activities occurring over a cluster of dealloyed S-phase particles to better understand localised attack and at clustered sites. The model Al-Cu multielectrode was shown to be an effective tool to investigate local interactions between Cu electrodes and Al electrodes which undergo significant anodic current densities, simulating the anodic attack on the aluminium matrix of AA2024-T3. Additionally this tool can more strictly differentiate between inhibitors for localised corrosion control. An environmentally friendly rare earth corrosion inhibitor, praseodymium mercaptoacetate (Pr(MAcet)3), has been evaluated by this technique and has been found to rapidly reduce anodic current densities at a faster rate than PrCl3 when concentrations were sufficiently high (>10-3 M).
- Published
- 2021
22. Probing corrosion initiation at interfacial nanostructures of AA2024-T3
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Maria Forsyth, Reza Parvizi, Pavel Cizek, Anthony E. Hughes, Mike Y. Tan, A.M. Glenn, and Ross K. W. Marceau
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6111 aluminium alloy ,Materials science ,020209 energy ,General Chemical Engineering ,Metallurgy ,Alloy ,Oxide ,Intermetallic ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,Corrosion ,chemistry.chemical_compound ,chemistry ,Aluminium ,0202 electrical engineering, electronic engineering, information engineering ,engineering ,General Materials Science ,Dislocation ,Composite material ,0210 nano-technology - Abstract
High-strength aluminium alloys such as AA2024-T3 are often developed by the introduction of plastic deformation to a precipitate containing microstructure. These alloys contain complex, near-surface nanostructures whose effects on localised corrosion processes have not been well understood due primarily to the difficulty of characterising these heterogeneous compositions and structures. In this work, we observed entangled oxide networks co-located with dislocation structures piled up at corroded intermetallic particles of an AA2024-T3 alloy. It was revealed that dislocation arrays act as pathways for corrosive species and promote structural degradation at interfacial regions, providing a new insight into corrosion initiation at the nano-scale.
- Published
- 2017
23. A closer look at constituent induced localised corrosion in Al-Cu-Mg alloys
- Author
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Allan James Morton, Nick Birbilis, Anthony E. Hughes, Johannes M. C. Mol, M.A. Glenn, S.K. Kairy, Yaiza Gonzalez-Garcia, Jian Feng Nie, Yuman Zhu, Herman Terryn, Faculty of Sciences and Bioengineering Sciences, Materials and Chemistry, Electrochemical and Surface Engineering, and Materials and Surface Science & Engineering
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Materials science ,Intermetallics ,AA2024 ,020209 energy ,General Chemical Engineering ,pitting corrosion ,Intermetallic ,chemistry.chemical_element ,02 engineering and technology ,Corrosion ,Crystal ,Aluminium ,0202 electrical engineering, electronic engineering, information engineering ,Pitting corrosion ,General Materials Science ,stem ,Mg alloys ,Metallurgy ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Localised corrosion ,chemistry ,TEM ,0210 nano-technology - Abstract
The role of constituent intermetallic particles in the pitting corrosion of aluminium (Al) alloys is well recognised. A definitive quantification of the role of unique constituent particles has contributed towards an enhanced understanding of Al-alloy corrosion, however the complexity of Al-alloy microstructures warrants further attention. In the present work we identify a unique intermetallic type in contemporary versions of AA2024-T3, which has a two-phase structure, defined by two distinct crystal types, and distinct compositions. Detailed characterisation is used to unambiguously define this constituent, along with its role in localised corrosion.
- Published
- 2016
24. New approach to probing localised corrosion processes over wide length and time scales using integrated multi-scale electrode arrays
- Author
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Mike Y.J. Tan, Reza Parvizi, and Anthony E. Hughes
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Materials science ,Scale (ratio) ,business.industry ,020209 energy ,General Chemical Engineering ,Combined use ,Alloy ,02 engineering and technology ,General Chemistry ,engineering.material ,021001 nanoscience & nanotechnology ,Corrosion ,Localised corrosion ,visual_art ,Electrode ,0202 electrical engineering, electronic engineering, information engineering ,Aluminium alloy ,visual_art.visual_art_medium ,engineering ,Electrode array ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
Electrochemically integrated multi-electrode arrays are variously designed for probing complex localised corrosion initiation and propagation processes occurring over different spatial and temporal scales. Electrode arrays made of 100 μm and 1 mm diameter aluminium alloy AA2024-T3 wires were used to illustrate the probing of submillimetre and millimetre scale localised corrosion processes over heterogeneous metal surfaces, while a patterned electrode array was employed to probe co-operative corrosion occurring across different metallurgical and microstructural features. The combined use of variously designed and patterned electrode arrays and surface analytical techniques is shown to provide unique insights into different stages of localised corrosion on heterogeneous alloy surfaces.
- Published
- 2021
25. A critical insight into lack-of-fusion pore structures in additively manufactured stainless steel
- Author
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Majid Laleh, Sam Yang, Anthony E. Hughes, A. Matt Glenn, Jianli Li, Mike Y. Tan, Wei Xu, and Jiangting Wang
- Subjects
0209 industrial biotechnology ,Void (astronomy) ,Materials science ,Biomedical Engineering ,Oxide ,Computed tomography ,02 engineering and technology ,Industrial and Manufacturing Engineering ,law.invention ,Metal ,chemistry.chemical_compound ,020901 industrial engineering & automation ,law ,medicine ,General Materials Science ,Composite material ,Porosity ,Engineering (miscellaneous) ,Fusion ,medicine.diagnostic_test ,021001 nanoscience & nanotechnology ,Nanocrystalline material ,chemistry ,visual_art ,visual_art.visual_art_medium ,Electron microscope ,0210 nano-technology - Abstract
Despite the obvious advantages of additive manufacturing (AM) in producing metallic parts, defect formation remains a challenge that deleteriously impacts some critical materials properties of AM parts. Here, through electron microscopy and X-ray computed tomography (X-ray CT), new insights are revealed about lack-of-fusion (LOF) pores; the most common defect reported for AM. We show that LOF pores are not simply a void but a complex structure comprising oxide films decorating pore walls and grain refined regions with dislocation structures surrounding the pore. The formation of a thin nanocrystalline metallic layer on the pore wall is also observed. Spatter particles are the source of most LOF structures at high densities typical of recommended processing conditions and can only be eliminated by careful selection of processing parameters. Data constrained modelling, which uses the materials’ properties, was used for generating 3D representations of the complex structure surrounding LOF pores from X-ray CT datasets.
- Published
- 2021
26. Two and three-dimensional characterisation of localised corrosion affected by lack-of-fusion pores in 316L stainless steel produced by selective laser melting
- Author
-
Mike Y. Tan, Wei Xu, Sam Yang, Anthony E. Hughes, Majid Laleh, Jianli Li, and Ian Gibson
- Subjects
Fusion ,Materials science ,020209 energy ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Microstructure ,Chloride ,Corrosion ,Localised corrosion ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Ferric ,General Materials Science ,Selective laser melting ,Composite material ,0210 nano-technology ,Porosity ,medicine.drug - Abstract
Localised corrosion of 316 L stainless steel (316 L SS) produced by selective laser melting (SLM) was investigated by two and three-dimensional techniques. It was revealed that porosity, which inevitably exists in the SLM-produced parts, is a critical factor determining the susceptibility to localised corrosion. Specimens containing lack-of-fusion (LOF) pores were found to be extremely susceptible to localised corrosion, as indicated by their lower breakdown potentials measured in polarisation tests. Computed tomography (CT) analysis, capable of linking the microstructure and corrosion propagation paths in three dimensions, showed the development of localised corrosion at the sites of LOF pores upon exposure to ferric chloride solution.
- Published
- 2020
27. Unanticipated drastic decline in pitting corrosion resistance of additively manufactured 316L stainless steel after high-temperature post-processing
- Author
-
Pavel Cizek, Wei Xu, Mike Yongjun Tan, Majid Laleh, and Anthony E. Hughes
- Subjects
Materials science ,020209 energy ,General Chemical Engineering ,Metallurgy ,0202 electrical engineering, electronic engineering, information engineering ,Pitting corrosion ,General Materials Science ,02 engineering and technology ,General Chemistry ,Selective laser melting ,021001 nanoscience & nanotechnology ,0210 nano-technology ,Corrosion - Abstract
The pitting corrosion resistance of 316L stainless steel (316L SS) additively manufactured by selective laser melting (SLM) has been reported to be substantially higher than its commercial counterpart due to the elimination of MnS inclusions. Here we report that the pitting corrosion resistance of the SLM-produced 316L SS declines drastically after thermal post-processing above 1000 °C. This unanticipated drastic decline in pitting resistance is explained based on the formation of deleterious MnS inclusions in the SLM-produced 316L SS after high-temperature thermal post-processing. This finding may have wide implications for determining suitable post-processing and industry application conditions for SLM-produced 316L SS.
- Published
- 2020
28. On the unusual intergranular corrosion resistance of 316L stainless steel additively manufactured by selective laser melting
- Author
-
Ian Gibson, Wei Xu, Majid Laleh, Mike Yongjun Tan, Nima Haghdadi, Anthony E. Hughes, Ke Wang, Pavel Cizek, and Design Engineering
- Subjects
Materials science ,Additive manufacturing ,Precipitation (chemistry) ,020209 energy ,General Chemical Engineering ,Metallurgy ,Grain boundary ,Precipitation ,02 engineering and technology ,General Chemistry ,Intergranular corrosion ,021001 nanoscience & nanotechnology ,Electrochemistry ,22/4 OA procedure ,Corrosion ,316L stainless steel ,Microscopy ,0202 electrical engineering, electronic engineering, information engineering ,General Materials Science ,Selective laser melting ,0210 nano-technology - Abstract
The intergranular corrosion (IGC) resistance of 316L stainless steel (316L SS) produced by selective laser melting (SLM) was investigated using microscopy analysis and electrochemical measurements. The IGC resistance of SLM-produced 316L SS, determined using a double-loop electrochemical potentiokinetic reactivation test, was found to be substantially higher than that of conventional 316L SS. This unusual behaviour was explained by the fact that no Cr-rich precipitates were detected for SLM-produced specimens after long-term sensitisation heat-treatment and those SLM-produced specimens exhibited a high frequency of twin boundaries and low-angle grain boundaries along with fine grains, leading to the avoidance of localised Cr depletion.
- Published
- 2019
29. Contributors
- Author
-
Matthew Dargusch, Raymond J. Donahue, Thomas Dorin, Mark Easton, Zhongyun Fan, Daniel Freiberg, Anthony E. Hughes, Justin Lamb, Timothy Langan, Sri Lathabai, Hu-Tian Li, Roger N. Lumley, Ross K.W. Marceau, Jaime Lazaro Nebreda, Reza Parvizi, Jayesh Patel, Alex Poznak, Mahendra Ramajayam, Hossain M.M.A. Rashed, Paul Sanders, Geoffry Scamans, David StJohn, Ian Stone, Mike Y. Tan, Alireza Vahid, Yun Wang, Gui Wang, David Weiss, and Xinliang Yang
- Published
- 2018
30. Recent Insights Into Corrosion Initiation at the Nanoscale
- Author
-
Reza Parvizi, Anthony E. Hughes, and Mike Yongjun Tan
- Subjects
Materials science ,Nanostructure ,020209 energy ,Alloy ,Intermetallic ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,engineering.material ,021001 nanoscience & nanotechnology ,Microstructure ,Corrosion ,chemistry ,Aluminium ,Nano ,0202 electrical engineering, electronic engineering, information engineering ,engineering ,Deformation (engineering) ,0210 nano-technology - Abstract
Localized corrosion compromises the durability of high-strength aluminium alloys and challenges the value of these high-performance materials. Currently, the role of structures (especially nanostructures) that lead to localized corrosion initiation is not well understood due primarily to the difficulty of characterizing chemistry and structure at the atomic scales. Development of new alloys will add to the complexity arising from the emergence of heterogeneous structure/chemistry of new types of coarse intermetallic particles at the nanoscale. These complex structures might include inclusions containing residual deformation or small amounts of less considered elements, such as Mg or Li in particles consisting of Al, Cu, Fe, Mn, and Si elements. Besides, from nano- to even microscales, high-density structural features induced during deformation processes are prone sites of preferential attack. These aspects are interesting topics of ongoing research in alloy development and new applications should spur further investigations of their atomic-scale corrosion initiation.
- Published
- 2018
31. Fast Hyperspectral Soft X-Ray Mapping
- Author
-
Anthony E. Hughes, Aaron Torpy, Nick Wilson, and Colin M. MacRae
- Subjects
Soft x ray ,Materials science ,Hyperspectral imaging ,Instrumentation ,Remote sensing - Published
- 2019
32. Defect density associated with constituent particles in AA2024-T3 and its role in corrosion
- Author
-
A.M. Glenn, Anthony E. Hughes, Nick Birbilis, Gert Nolze, and Aaron Torpy
- Subjects
Materials science ,020209 energy ,Metallurgy ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,02 engineering and technology ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Corrosion ,Electron backscatter diffraction - Published
- 2015
33. Nuclear Microprobe Analysis for Determination of Element Enrichment Following Magnesium Dissolution
- Author
-
Nick Birbilis, John R. Scully, Jamie S. Laird, X. Xia, Anthony E. Hughes, and T. W. Cain
- Subjects
Microprobe ,Auger electron spectroscopy ,Materials science ,Magnesium ,Analytical chemistry ,chemistry.chemical_element ,Corrosion ,Fuel Technology ,chemistry ,X-ray photoelectron spectroscopy ,Transition metal ,Impurity ,Materials Chemistry ,Electrochemistry ,Dissolution - Abstract
With significant increases in the production and utility of magnesium (Mg) in the past decade, Mg-alloys remain an attractive material for weight reduction in several industries, 1 in addition to substantial exploration as electrode materials in primary and secondary batteries. 2‐3 In such cases, the unambiguous determination of factors that play a role in corrosion/electrochemistry of Mg are of critical importance. The influence of impurities on the corrosion of Mg has been well documented since the early 20 th century, 4 with tolerance limits for a number of elements in Mg proposed. 5 In particular, the influence of deliberate alloying additions of low levels of transition metals (iron, manganeseandzirconium)oncorrosionofMghavebeendocumented by systematic studies. 6 Furthermore, the comparison of the electrochemistry of pure Mg specimens with low (at commercial levels of ∼40 ppmw) and ultra low levels (≤ 1 ppmw) of Fe were also recently presented. 7 Such studies add to the evidence that impurity elements, nominally of low solubility, 8‐10 influence the corrosion electrochemistry of Mg. In spite of this, at least two key aspects with respect to the in-service performance of Mg remain under researched. The first of these includes the detection and analysis of impurity elements on the Mg surface, and the study of possible enrichment of impurity elements on Mg during dissolution; both aspects are worthy of elaboration. Regarding the analysis of impurity elements on Mg surfaces, this is a particularly challenging task for the common methods nominally used in corrosion related works. Nominally, impurity concentrations are in the parts per million range. For example, commercial purity Mg will nominally contain < 100 ppmw Fe, which is below < 0.01% on the basis of weight %, and even lower on the basis of atom %. The analysis of such low levels of Fe with accuracy is not readily possible by methods such as X-ray photoelectron spectroscopy or Auger electron spectroscopy, which require concentrations approaching 1% (which is ∼100 times larger than the typical Fe impurity content) for accurate detection. Similarly, the signal to noise ratio, and large interaction volume, from energy dispersive X-ray spectroscopy are also prohibitive. In fact, even imaging of, and evidence of, impurity Fe (which is known to be present from ICP analysis of chemically dissolved metals) using Field Emission Gun-Scanning Electron Microscopy (FEG-SEM) is elusive. Site-specific Transmission Elec
- Published
- 2015
34. The influence of rare earth mercaptoacetate on the initiation of corrosion on AA2024-T3 Part II: The influence of intermetallic compositions within heavily attacked sites
- Author
-
A.M. Glenn, F.F. Chen, Ivan S. Cole, Nick Wilson, Colin M. MacRae, Bruce Hinton, Rainier Catubig, Anthony E. Hughes, and Maria Forsyth
- Subjects
Materials science ,Praseodymium ,General Chemical Engineering ,Metallurgy ,Alloy ,Rare earth ,Intermetallic ,chemistry.chemical_element ,General Chemistry ,Electron microprobe ,engineering.material ,Corrosion ,Cerium ,chemistry ,Aluminium ,engineering ,General Materials Science - Abstract
Localised corrosion is typical on AA2024-T3 due to intermetallic particles embedded in the alloy. The effect of intermetallic compositions on corrosion are not yet fully understood. EPMA data on AA2024-T3 surfaces before and after a 16. min immersion, analyses the influence of intermetallic clustering on the severity attack at local sites. While sites with a high number of domains and a large S-phase surface area typically lead to severe attack, maximising these features did not always lead to severe corrosion attack. Cerium or praseodymium mercaptoacetate inhibited corrosion ring formation. The common trends observed from such attack sites was also discussed.
- Published
- 2015
35. The influence of rare earth mercaptoacetate on the initiation of corrosion on AA2024-T3 Part I: Average statistics of each intermetallic composition
- Author
-
A.M. Glenn, Anthony E. Hughes, Ivan S. Cole, F.F. Chen, Bruce Hinton, Colin M. MacRae, Maria Forsyth, Nick Wilson, and Rainier Catubig
- Subjects
Materials science ,Praseodymium ,General Chemical Engineering ,Metallurgy ,Alloy ,Inorganic chemistry ,Intermetallic ,chemistry.chemical_element ,General Chemistry ,engineering.material ,Microstructure ,Copper ,Corrosion ,Cerium ,chemistry ,Aluminium ,engineering ,General Materials Science - Abstract
De-alloying of S-phase in AA2024-T3 in the presence chlorides, is well-known. However, it is unclear how rare earth mercaptoacetate inhibitors affect this process when immersed in a 0.1. M NaCl solution. This paper analyses data obtained using EPMA on AA2024-T3 surfaces before and after a 16. min immersion period. Cerium and praseodymium mercaptoacetate inhibited the de-alloying process of S-phase particles. Although no significant change in composition was observed for cathodic intermetallics, each appeared to participate in local corrosion reactions as evidenced by the development of surface oxides. Clustering between S-phase and one of the Cu-containing intermetallic domains was also evident.
- Published
- 2015
36. Microstructure and corrosion of AA2024
- Author
-
Maria Forsyth, Reza Parvizi, and Anthony E. Hughes
- Subjects
Laser Scanning Microscopy ,Materials science ,Materials processing ,Atomic force microscopy ,business.industry ,General Chemical Engineering ,Metallurgy ,chemistry.chemical_element ,General Chemistry ,Microstructure ,Corrosion ,Fatigue crack nucleation ,chemistry ,Aluminium ,General Materials Science ,Aerospace ,business - Abstract
AA2024-Tx is one of the most common high-strength aluminium alloys used in the aerospace industry. This article reviews current understanding of the microstructure of sheet AA2024-T3 and chronicles the emergence of new compositions for constituent particles as well as reviews older literature to understand the source of the original compositions. The review goes on to summarise older and more recent studies on corrosion of AA2024-T3, drawing attention to areas of corrosion initiation and propagation. It pays particular attention to modern approaches to corrosion characterisation as obtained through microelectrochemical techniques and physicochemical characterisation, which provide statistical assessment of factors that contribute to corrosion of AA2024. These approaches are also relevant to other alloys.
- Published
- 2015
37. Atom Probe Tomography Study of the Nanoscale Heterostructure around an Al20Mn3Cu2 Dispersoid in Aluminum Alloy 2024
- Author
-
Reza Parvizi, Anthony E. Hughes, Ross K. W. Marceau, Mike Y. Tan, and Maria Forsyth
- Subjects
Materials science ,Hydrogen ,Alloy ,Metallurgy ,chemistry.chemical_element ,Surfaces and Interfaces ,Atom probe ,engineering.material ,Condensed Matter Physics ,Microstructure ,Corrosion ,law.invention ,Electrochemical noise ,chemistry ,Aluminium ,law ,Electrochemistry ,engineering ,General Materials Science ,Spectroscopy ,Hydrogen embrittlement - Abstract
Atom probe tomography (APT) has been used to investigate the surface and sub-surface microstructures of aluminum alloy 2024 (AA2024) in the T3 condition (solution heat treated, cold worked, and naturally aged to a substantially stable condition). This study revealed surface Cu enrichment on the alloy matrix, local chemical structure around a dispersoid Al20Mn3Cu2 particle including a Cu-rich particle and S-phase particle on its external surface. Moreover, there was a significant level of hydrogen within the dispersoid, indicating that it is a hydrogen sink. These observations of the nanoscale structure around the dispersoid particle have considerable implications for understanding both corrosion and hydrogen embrittlement in high-strength aluminum alloys.
- Published
- 2014
38. The application of multiscale quasi 4D CT to the study of SrCrO4 distributions and the development of porous networks in epoxy-based primer coatings
- Author
-
S. Sellaiyan, Ivan S. Cole, George Thompson, James Carr, Yushuang Yang, Anthony E. Hughes, A. Trinchi, Peter D. Lee, Tiqiao Xiao, and F.F. Chen
- Subjects
Materials science ,General Chemical Engineering ,Mineralogy ,Electrolyte ,Fractal dimension ,Diffusion ,Strontium chromate ,chemistry.chemical_compound ,Materials Chemistry ,Cluster (physics) ,Electron computed tomography ,Dissolution ,X-ray computed tomography ,Fractal networks ,Chromate conversion coating ,Organic Chemistry ,Epoxy ,Fick's laws of diffusion ,Chromate ,Surfaces, Coatings and Films ,Chemical engineering ,chemistry ,visual_art ,Chemical Engineering(all) ,visual_art.visual_art_medium ,Inhibited primers - Abstract
Transport paths for inhibitor release within a model strontium chromate (SrCrO4) inhibited/epoxy primer have been studied using a combination of tomography techniques. It has been found that the SrCrO4 particles form independent clusters within the model primer. The clusters have a range of fractal dimensions with the largest clusters (a few hundred microns in size) having a fractal dimension of 2.36. Leaching of the SrCrO4 from the primer appears to be initially through direct dissolution of particles in contact with the electrolyte but changes to diffusion through void pathways created by dissolution of the SrCrO4 phase. No evidence was found for the diffusion of chromate ions through the epoxy. Transport through such clusters does not follow Fickian diffusion, which has traditionally been employed to describe inhibitor release dynamics. Release kinetics typically follow a tm behaviour where t is time and m is an index which would be 0.5 for Fickian diffusion. Thus the overall release with time will evolve, being initially the result of direct dissolution, then at intermediate times, be dominated by transport through the fractal network and at the final stage go to zero since all the strontium chromate will be dissolved from the cluster connected to the surface. Clusters not connected to the surface remain undissolved and form additional reservoirs for further release in when local damage occurs in their vicinity. This new model of inhibitor transport creates new strategies for the development of self-healing properties for coatings.
- Published
- 2014
39. Rare Earth Elements: Overview of Mining, Mineralogy, Uses, Sustainability and Environmental Impact
- Author
-
Seng Lim, Chris Vernon, Nawshad Haque, and Anthony E. Hughes
- Subjects
geography ,geography.geographical_feature_category ,Wind power ,rare earth ,business.industry ,Natural resource economics ,Energy consumption ,Management, Monitoring, Policy and Law ,Renewable energy ,Greenhouse gas ,Sustainability ,lcsh:Q ,Environmental impact assessment ,Mountain pass ,Electricity ,lcsh:Science ,business ,Geology ,mining, mineralogy, recycling, life cycle assessment ,Nature and Landscape Conservation - Abstract
Rare earths are used in the renewable energy technologies such as wind turbines, batteries, catalysts and electric cars. Current mining, processing and sustainability aspects have been described in this paper. Rare earth availability is undergoing a temporary decline due mainly to quotas being imposed by the Chinese government on export and action taken against illegal mining operations. The reduction in availability coupled with increasing demand has led to increased prices for rare earths. Although the prices have come down recently, this situation is likely to be volatile until material becomes available from new sources or formerly closed mines are reopened. Although the number of identified deposits in the world is close to a thousand, there are only a handful of actual operating mines. Prominent currently operating mines are Bayan Obo in China, Mountain Pass in the US and recently opened Mount Weld in Australia. The major contributor to the total greenhouse gas (GHG) footprint of rare earth processing is hydrochloric acid (ca. 38%), followed by steam use (32%) and electricity (12%). Life cycle based water and energy consumption is significantly higher compared with other metals.
- Published
- 2014
40. Comparative study of protection of AA 2024-T3 exposed to rare earth salts solutions
- Author
-
Santiago J. Garcia, T. Markley, Anthony E. Hughes, and Johannes M. C. Mol
- Subjects
Chemistry ,Scanning electron microscope ,General Chemical Engineering ,Rare earth ,Inorganic chemistry ,Intermetallic ,chemistry.chemical_element ,General Chemistry ,Chloride ,Corrosion ,Ion ,Dibutyl phosphate ,Cerium ,medicine ,General Materials Science ,medicine.drug - Abstract
The inhibitive effects of the dibutyl phosphate anion in cerium dibutylphosphate [Ce(dbp)3] on AA 2024-T351 immersed in 0·05M NaCl were evaluated by comparison with immersion in cerium chloride (CeCl3) in 0·05M NaCl as well as 0·05M NaCl alone. Scanning electron microscopy and energy dispersive X-ray hyperspectral mapping were used to examine the surfaces after exposure to the different inhibitor solutions. It was found that the dibutylphosphate anion produced additional inhibition for the matrix and the S phase intermetallic particles. The most significant mode of corrosion in the absence of inhibitors was in the form of rings of corrosion product. CeCl3 largely suppressed the formation of the rings of corrosion product, and the Ce(dbp)3 entirely eliminated them (for the time scales investigated here), indicating the additional inhibitive action of the dibutylphosphate anion.
- Published
- 2014
41. The use of cerium and praseodymium mercaptoacetate as thiol-containing inhibitors for AA2024-T3
- Author
-
Rainier Catubig, Ivan S. Cole, Anthony E. Hughes, Bruce Hinton, and Maria Forsyth
- Subjects
chemistry.chemical_classification ,Materials science ,Chromate conversion coating ,Praseodymium ,General Chemical Engineering ,Inorganic chemistry ,Alloy ,chemistry.chemical_element ,General Chemistry ,engineering.material ,Corrosion ,Cerium ,chemistry ,Aluminium ,visual_art ,Thiol ,engineering ,Aluminium alloy ,visual_art.visual_art_medium ,General Materials Science - Abstract
The susceptibility of the aluminium alloy, AA2024-T3, to localised corrosion as well as the toxicity of chromate inhibitors are both well known facts. In this paper the effect on the corrosion of AA2024-T3 of the thiol-containing mercaptoacetate, when coupled with cerium or praseodymium is examined. Potentiodynamic polarisation and SEM/EDXS were used to analyse the inhibiting behaviour of the compounds cerium mercaptoacetate and praseodymium mercaptoacetate. Both inhibitors were predominantly cathodic inhibitors with increasing anodic inhibition after 24 h of immersion. A mechanism of film formation and corrosion protection was also proposed.
- Published
- 2014
42. Towards chromate-free corrosion inhibitors: structure–property models for organic alternatives
- Author
-
Michael Breedon, Ivan S. Cole, David A. Winkler, Timothy G. Harvey, Amanda S. Barnard, Anthony E. Hughes, and Frank R. Burden
- Subjects
Chromate free ,Materials science ,Chromate conversion coating ,Modelling methods ,Metallurgy ,Environmental Chemistry ,Structure property ,Biochemical engineering ,Pollution ,Corrosion - Abstract
Progressive restrictions on the use of toxic chromate-based corrosion inhibitors present serious technical challenges. The most critical of these is the lack of non-toxic ‘green’ alternatives that offer comparable performance, particularly on corrosion-prone aluminium alloys such as the 2000 and 7000 series. In this study we used computational modelling methods to investigate the properties of a range of small organic, potentially safer inhibitors and their interactions with technologically relevant alloy surfaces. We have generated robust and predictive computational models of corrosion inhibition for a structurally related data set of organic compounds from the literature. Our studies have correlated molecular features of the inhibitor molecules with inhibition and identified those features that have the greatest impact on experimentally determined corrosion inhibition. This information can be used to drive guided decision making for in silico or experimental screening of molecules for their corrosion inhibition efficiency, while considering more carefully their environmental consequences.
- Published
- 2014
43. Reducing ZnO nanoparticle cytotoxicity by surface modification
- Author
-
Terence W. Turney, Cenchao Shen, Ming-Deng Luo, Anthony E. Hughes, Paul F.A. Wright, Bryce Feltis, and Lisandra L. Martin
- Subjects
Materials science ,Cell Survival ,Surface Properties ,Inorganic chemistry ,Metal Nanoparticles ,chemistry.chemical_element ,Nanoparticle ,Protein Corona ,Zinc ,Surface coating ,Solubility ,chemistry ,Cell Line, Tumor ,PEGylation ,Biophysics ,Humans ,Surface modification ,General Materials Science ,Zinc Oxide ,Cytotoxicity ,Intracellular - Abstract
Nanoparticulate zinc oxide (ZnO) is one of the most widely used engineered nanomaterials and its toxicology has gained considerable recent attention. A key aspect for controlling biological interactions at the nanoscale is understanding the relevant nanoparticle surface chemistry. In this study, we have determined the disposition of ZnO nanoparticles within human immune cells by measurement of total Zn, as well as the proportions of extra- and intracellular dissolved Zn as a function of dose and surface coating. From this mass balance, the intracellular soluble Zn levels showed little difference in regard to dose above a certain minimal level or to different surface coatings. PEGylation of ZnO NPs reduced their cytotoxicity as a result of decreased cellular uptake arising from a minimal protein corona. We conclude that the key role of the surface properties of ZnO NPs in controlling cytotoxicity is to regulate cellular nanoparticle uptake rather than altering either intracellular or extracellular Zn dissolution.
- Published
- 2014
44. Leaching properties of chromate-containing epoxy films using radiotracers, PALS and SEM
- Author
-
Akira Uedono, James Sullivan, Stephen Buckman, S. Sellaiyan, Suzanne V. Smith, and Anthony E. Hughes
- Subjects
Aqueous solution ,Materials science ,Chromate conversion coating ,Scanning electron microscope ,General Chemical Engineering ,Positron Lifetime Spectroscopy ,Organic Chemistry ,Epoxy ,Surfaces, Coatings and Films ,Corrosion ,Chemical engineering ,visual_art ,Materials Chemistry ,Aluminium alloy ,visual_art.visual_art_medium ,Leaching (metallurgy) ,Composite material - Abstract
Model chromate-containing epoxy primer (CEP) films were applied to aluminium alloy substrates using doctor blades. The effect of exposure to NaCl solution on the chromate-containing epoxy film was followed by monitoring the leaching behaviour of Cr. The continuous leaching of chromate inhibitor from the epoxy film is a self-healing characteristic that is designed to prevent corrosion of the aluminium alloy substrate. The CEP films were doped with 51 Cr chromate inhibitor ( t 1/2 = 27.7 days), were exposed to NaCl solutions over time, and the 51 Cr gamma emission was used to monitor its release from the film into the aqueous solution. Pulsed beam positron lifetime spectroscopy and scanning electron microscopy (SEM) were used to probe structural changes that might transport properties of chromate species in the epoxy matrix. Positron Annihilation Lifetime Spectroscopy (PALS) was used to determine changes to free volumes at the nano scale in the films and SEM was used to ascertain the chromate distribution and structural scales at the micron level and above. Both PALS and SEM studies were preformed as a function of exposure time. It was found that a SrCrO 4 depletion zone was formed at the surface as a result of the complete dissolution of the inhibitor particles, suggesting that transport of the Sr 2+ and CrO 4 2− might be through a network of channels created by the voids remaining in the epoxy matrix.
- Published
- 2014
45. Microstructure characterisation and reconstruction of intermetallic particles
- Author
-
A.M. Glenn, F.F. Chen, Ivan S. Cole, Anthony E. Hughes, Jason A. Osborne, and Erik Sapper
- Subjects
Range (particle radiation) ,Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,Metals and Alloys ,Intermetallic ,General Medicine ,engineering.material ,Microstructure ,Surfaces, Coatings and Films ,Corrosion ,Mechanics of Materials ,visual_art ,Materials Chemistry ,Pitting corrosion ,Aluminium alloy ,visual_art.visual_art_medium ,engineering ,Environmental Chemistry ,Particle ,Composite material - Abstract
Pitting corrosion is associated with the distribution and composition of intermetallic (IM) particles. However, quantitatively studying the relationship between alloy corrosion and IM particle property remains a challenging topic. In this paper, a computational method is presented for IM particle characterisation and reconstruction based on backscattered scanning electron micrographs of aluminium alloy AA2024-T3. The reconstructed mapping of IM particles provides a 2D map of the intermetallic distribution that conforms to empirical statistical data but is generated randomly. This enables a range of statistically identical virtual microstructures which are generated in order to determine variability in pitting models as well as for systematic variation of input parameters in a sensitivity analysis (e. g., concentration of a given alloying element) used to deduce new microstructural maps for modified compositions. IM particle spatial distribution patterns are analysed based on the reconstruction maps to study the clustering properties of different types of IM particles. The presented approach provides a quantitative tool for studying the relationship between alloy corrosion and the distribution and composition of a range of IM particles.
- Published
- 2013
46. Designing molecular protection: new paradigm for developing corrosion resistant materials uniting high throughput studies, multiscale modelling and self-repair
- Author
-
Ivan S. Cole and Anthony E. Hughes
- Subjects
Computer science ,General Chemical Engineering ,Component (UML) ,Self repair ,Corrosion resistant ,Forensic engineering ,General Materials Science ,General Chemistry ,Biochemical engineering ,Protection system ,Throughput (business) ,Field (computer science) ,Variety (cybernetics) - Abstract
Over the past decade, three technologies, high throughput studies, multiscale modelling (MSM) and self-repair, have entered the field of corrosion science. MSM links processes from 106 to 10−7 m and allows an understanding of how metal protection systems interact with the environment and with surface electrochemical processes. Potentially MSM has the ability to accurately predict component life and so permit virtual design. In virtual design, a huge range of possible design (including molecular designs) can be assessed on a PC before selecting the best performing inhibitor for a specific application. High throughput experimentation permits many tests to be undertaken at one time. As well as allowing a huge range of inhibitors to be tested under a variety of conditions, it allows the inhibitors of the one family with subtly different molecular configurations to be tested. Self-repair is based on the principle that no matter how well we design and construct a material, it will always develop defects...
- Published
- 2013
47. Unravelling the corrosion inhibition mechanisms of bi-functional inhibitors by EIS and SEM–EDS
- Author
-
Johannes M. C. Mol, Santiago J. Garcia, Anthony E. Hughes, and T. Markley
- Subjects
Materials science ,Aqueous solution ,Scanning electron microscope ,General Chemical Engineering ,Inorganic chemistry ,Energy-dispersive X-ray spectroscopy ,chemistry.chemical_element ,General Chemistry ,Inorganic ions ,Chloride ,Corrosion ,Cerium ,chemistry ,visual_art ,Aluminium alloy ,visual_art.visual_art_medium ,medicine ,General Materials Science ,medicine.drug - Abstract
In this work the corrosion inhibition effect of aluminium alloy AA2024-T3 in aqueous solution by an inorganic cerium salt (i.e. cerium chloride) and an organic one (i.e. cerium dibutyl phosphate) is presented. The research involved long term immersion tests (up to 8 d) followed up by EIS. The analysis was complemented by a systematic selection of the most probable equivalent circuits and scanning electron microscope analysis combined with X-ray energy dispersive spectroscopy. This study highlights the different corrosion protection mechanisms of organic and inorganic ions. A model of protection is suggested based on the combination of techniques.
- Published
- 2013
48. A consistent description of intermetallic particle composition: An analysis of ten batches of AA2024-T3
- Author
-
Anthony E. Hughes, Allan James Morton, A.M. Glenn, A Moffatt, Rudi G Buchheit, and Nicolas Craig Wilson
- Subjects
Particle composition ,Chemistry ,visual_art ,Metallurgy ,Materials Chemistry ,Aluminium alloy ,visual_art.visual_art_medium ,Intermetallic ,Surfaces and Interfaces ,General Chemistry ,Electron microprobe ,Condensed Matter Physics ,Surfaces, Coatings and Films - Published
- 2013
49. Grain-stored energy and the propagation of intergranular corrosion in AA2xxx aluminium alloys
- Author
-
Yinghua Ma, George Thompson, Xiaorong Zhou, Teruo Hashimoto, C. Luo, Peter Skeldon, and Anthony E. Hughes
- Subjects
Materials science ,Metallurgy ,chemistry.chemical_element ,Surfaces and Interfaces ,General Chemistry ,Intergranular corrosion ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Corrosion ,chemistry ,Aluminium ,visual_art ,Phase (matter) ,Materials Chemistry ,Aluminium alloy ,visual_art.visual_art_medium ,Lithium ,Grain boundary ,Electron backscatter diffraction - Abstract
In the present study, intergranular corrosion (IGC) in AA2024 and AA2099 aluminium alloys was investigated. The IGC propagation path was examined using scanning and transmission electron microscopies. Further, electron backscatter diffraction was employed to investigate the relationship between the grain structure and the IGC susceptibility. It was found that IGC could occur at grain boundaries where second phase precipitates were absent. It was also revealed that IGC occurred at the grain boundaries that surround grains of relatively high-stored energy, and corrosion was not confined within the region immediately adjacent to the grain boundaries but had developed into the grains of relatively high-stored energy, suggesting that IGC propagated within the grains that have relatively high levels of defects. Copyright © 2013 John Wiley & Sons, Ltd.
- Published
- 2013
50. Investigation into the Influence of Carbon Contamination on the Corrosion Behavior of Aluminum Microelectrodes and AA2024-T3
- Author
-
Aaron Torpy, A.M. Glenn, Tim H. Muster, D. Lau, Colin M. MacRae, J. Ward, Anthony E. Hughes, and Nick Wilson
- Subjects
Materials science ,Carbon contamination ,Renewable Energy, Sustainability and the Environment ,Metallurgy ,chemistry.chemical_element ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Microelectrode ,chemistry ,Aluminium ,Materials Chemistry ,Electrochemistry ,Corrosion behavior - Published
- 2013
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