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On the microstructure and texture evolution in 17-4 PH stainless steel during laser powder bed fusion: Towards textural design

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Journal of Materials Science & Technology 2022年第22期117卷 183-195页

作者： M.S.Moyle N.Haghdadi X.Z.Liao S.P.Ringer S.Primig school of Materials Science&Engineering UNSW SydneyNSW 2052Australia australian centre for microscopyµanalysis The University of SydneyNSW 2006Australia school of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneyNSW 2006Australia

Additive Manufacturing (AM) of metals allows the production of parts with complex designs, offeringadvanced properties if the evolution of the texture can be controlled. 17-4 precipitation hardening (PH)stainless steel is a high strength, high corrosion resistance alloy used in a range of industries suitable forAM, such as aerospace and marine. Despite 17-4 PH being one of the most common steels for AM, thereare still gaps in the understanding of its AM processing–structure relationships. These include the natureof the matrix phase, as well as the development of texture through AM builds under different processingconditions. We have investigated how changing the laser power and scanning strategy affects the microstructure of 17-4 PH during laser powder bed fusion. It is revealed that the matrix phase is δ-ferritewith a limited austenite presence, mainly in regions of the microstructure immediately below melt pools.Austenite fraction is independent of the printing pattern and laser power. However, reducing the timebetween adjacent laser passes during printing results in an increase in the austenite volume fraction.Another effect of the higher laser power, as well as additional remelting within the printing strategy, isan increase in the average grain size by epitaxial ferrite grain growth across multiple build layers andthe development of a mosaic type microstructure. Changes to the scanning strategy have significant impacts on the textures observed along the build direction, while (100) texture along the scanning directionis observed consistently. Mechanisms for texture formation and the mosaic structure are proposed thatpresents a pathway to the design of texture via AM process control.

关键词： Additive manufacturing 17-4 PH stainless steel Microstructure Texture

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Tribological behaviour of fused deposition modelling printed short carbon fibre reinforced nylon composites with surface textures under dry and water lubricated conditions

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Friction 2022年第12期10卷 2045-2058页

作者： Ming LUO Siyu HUANG Ziyan MAN Julie M.CAIRNEY Li CHANG school of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydney NSW 2006Australia australian centre for microscopy and microanalysis The University of SydneySydney NSW 2006Australia

Fused deposition modelling(FDM)printed short carbon fibre reinforced nylon(SCFRN)composites were fabricated.The friction and wear behaviour of printed materials were systematically investigated under both dry sliding and water lubricated conditions.The results showed that with short fibre enhancements,the printed SCFRN achieved a lower friction coefficient and higher wear resistance than nylon under all tested conditions.Further,under water lubricated conditions,the printed SCFRN exhibited a low,stable friction coefficient due to the cooling and lubricating effects of water.However,the specific wear rate of the printed specimens could be higher than that obtained under dry sliding conditions,especially when the load was relatively low.The square textured surface was designed and created in the printing process to improve materials’tribological performance.It was found that with the textured surface,the wear resistance of the printed SCFRN was improved under dry sliding conditions,which could be explained by the debris collection or cleaning effect of surface texture.However,such a cleaning effect was less noticeable under lubricated conditions,as the liquid could clean the surface effectively.On the other hand,surface textures could increase the surface area exposed to water,causing surface softening due to the higher water absorption rate.As a result,the samples having surface textures showed higher wear rates under lubricated conditions.The work has provided new insights into designing wear resistant polymer materials using three-dimensional(3D)printing technologies,subjected to different sliding conditions.

关键词： fused deposition modelling(FDM) short carbon fibre reinforced nylon(SCFRN)composites transfer film friction and wear

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Cationic and Anionic Antimicrobial Agents Co‑Templated Mesostructured Silica Nanocomposites with a Spiky Nanotopology and Enhanced Biofilm Inhibition Performance

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Nano-Micro Letters 2022年第5期14卷 181-191页

作者： Yaping Song Qiang Sun Jiangqi Luo Yueqi Kong Bolin Pan Jing Zhao Yue Wang Chengzhong Yu australian Institute for Bioengineering and Nanotechnology The University of QueenslandBrisbaneQLD 4072Australia centre for microscopy and microanalysis University of QueenslandBrisbaneQLD 4072Australia Australia centre for Water and Environmental Biotechnology University of QueenslandBrisbaneQLD 4072Australia school of Chemistry and Molecular Engineering East China Normal UniversityShanghai 200241People’s Republic of China

Silica-based materials are usually used as delivery systems for antibacterial applications.In rare cases,bactericidal cationic surfactant templated silica composites have been reported as antimicrobial agents.However,their antibacterial efficacy is limited due to limited control in content and structure.Herein,we report a“dual active templating”strategy in the design of nanostructured silica composites with intrinsic antibacterial performance.This strategy uses cationic and anionic structural directing agents as dual templates,both with active antibacterial property.The cationic-anionic dual active templating strategy further contributes to antibacterial nanocomposites with a spiky surface.With controllable release of dual active antibacterial agents,the spiky nanocomposite displays enhanced anti-microbial and anti-biofilm properties toward Staphylococcus epidermidis.These findings pave a new avenue toward the designed synthesis of novel antibacterial nanocomposites with improved performance for diverse antibacterial applications.

关键词： Antibacterial surfactants Spiky nanoparticles Antibacterial Anti-biofilm Mesostructured nanocomposites

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Correlation between precipitates evolution and mechanical properties of Al-Sc-Zr alloy with Er additions

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Journal of Materials Science & Technology 2022年第4期99卷 61-72页

作者： Li Liu Jian-Tang Jiang Xiang-Yuan Cui Bo Zhang Liang Zhen Simon P.Ringer school of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China China-Ukraine Institute of Welding Guangdong Academy of SciencesGuangzhou 510651China school of Aerospace Mechanical and Mechatronic Engineeringand Australian Centre for Microscopy and MicroanalysisThe University of SydneyNew South Wales 2006Australia school of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

Correlation between precipitates evolution and mechanical properties of Al-Sc-Zr alloy with Er additions during isothermal ageing were investigated by microhardness measurements,transmission electron microscopy,atom probe tomography and density functional theory-based simulations.The results demonstrate that the Er additions significantly improve the hardness during elevated temperature ageing,especially at 400℃.This is mainly because Er additions increase the nucleation rate of the Al_(3)(Er,Sc,Zr)precipitates,resulting in a higher density of fine and uniform dispersion of L1_(2)structured nanoparticles.First-principles calculations demonstrate that the second nearest neighboring solute-solute interactions for the species Sc,Zr and Er are energetically favored–a key feature to rationalize the observed precipitate structure and the underlying formation mechanism.The sequential formation of the core/shell precipitates in the Er-free alloy and core/double-shell precipitates in the Er-containing alloy arises due to the different solute-solute and solute-vacancy interaction energies,and the relative diffusivities of the Er,Sc and Zr species in Al.These results shed light on the beneficial effects of Er additions on the agehardening behavior of Al-Sc-Zr alloy and provide guidance for designing the ageing treatments for the Al-Sc-Zr(-Er)alloys.

关键词： Al alloys Isothermal ageing Microhardness Transmission electron microscopy Atom probe tomography First-principles calculations

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Comments by opponents on the British Medical Association’s guidance on non-therapeutic male circumcision of children seem one-sided and may undermine public health

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World Journal of Clinical Pediatrics 2023年第5期12卷 244-262页

作者： Stephen Moreton Guy Cox Mark Sheldon Stefan A Bailis Jeffrey D Klausner Brian J Morris CircFacts Warrington WA51HYCheshireUnited Kingdom australian centre for microscopyµanalysis and school of aeronautical Mechanical and Mechatronic EngineeringUniversity of SydneySydney 2006New South WalesAustralia Medical Humanities and Bioethics Program Feinberg School of MedicineNorthwestern UniversityChicagoIL 60661United States Cornerstone Therapy&Recovery Center St.PaulMN 55101United States Department of Medicine Population and Public Health SciencesKeck School of MedicineUniversity of Southern CaliforniaLos AngelesCA 90089United States school of Medical Sciences University of SydneySydney 2006New South WalesAustralia

The British Medical Association(BMA)guidance on non-therapeutic circumcision(NTMC)of male children is limited to ethical,legal and religious issues.Here we evaluate criticisms of the BMA’s guidance by Lempert et al.While their arguments promoting autonomy and consent might be superficially appealing,their claim of high procedural risks and negligible benefits seem one-sided and contrast with high quality evidence of low risk and lifelong benefits.Extensive literature reviews by the American Academy of Pediatrics and the United States Centers for Disease Control and Prevention in developing evidence-based policies,as well as risk-benefit analyses,have found that the medical benefits of infant NTMC greatly exceed the risks,and there is no reduction in sexual function and pleasure.The BMA’s failure to consider the medical benefits of early childhood NTMC may partly explain why this prophylactic intervention is discouraged in the United Kingdom.The consequence is higher prevalence of preventable infections,adverse medical conditions,suffering and net costs to the UK’s National Health Service for treatment of these.Many of the issues and contradictions in the BMA guidance identified by Lempert et al stem from the BMA’s guidance not being sufficiently evidence-based.Indeed,that document called for a review by others of the medical issues surrounding NTMC.While societal factors apply,ultimately,NTMC can only be justified rationally on scientific,evidence-based grounds.Parents are entitled to an accurate presentation of the medical evidence so that they can make an informed decision.Their decision either for or against NTMC should then be respected.

关键词： Circumcision,Male Child Infections Risk Policy Public health

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Condensed point defects enhance thermoelectric performance of rare-earth Lu-doped GeTe

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Journal of Materials Science & Technology 2023年第20期151卷 227-233页

作者： Wan-Yu Lyu Wei-Di Liu Meng Li Xiao-Lei Shi Min Hong Tianyi Cao Kai Guo Jun Luo Jin Zou Zhi-Gang Chen centre for Future Materials University of Southern QueenslandSpringfieldQueensland 4300Australia school of Chemistry and Physics Queensland University of TechnologyBrisbaneQueensland 4000Australia australian Institute for Bioengineering and Nanotechnology The University of QueenslandBrisbaneQueensland 4072Australia school of Physics and Materials Science Guangzhou UniversityGuangzhou 510006China school of Materials Science and Engineering Shanghai UniversityShanghai 200444China school of Mechanical and Mining Engineering The University of QueenslandBrisbaneQueensland 4072Australia centre for microscopy and microanalysis The University of QueenslandBrisbaneQueensland 4072Australia

Heavy rare-earth element doping can effectively strengthen phonon scattering,suppress the lattice thermal conductivity,and enhance the overall thermoelectric performance of GeTe.However,the large electronegativity difference between rare-earth elements(such as La,Eu,and Gd)and Ge refrains the doping limit of rare-earth elements below 1 mol.%in GeTe.Here,compared with other rare earth elements,Lu was found to have a relatively small radius and electronegativity difference with Ge,which can induce a high doping level in GeTe.The result shows that Lu doping effectively reduces the lattice thermal conductivity from 0.77 W^(−1) m K^(−1) of GeTe to 0.35 W m^(−1) K^(−1) of Ge_(0.98)Lu_(0.02)Te at 673 K,and further induces a high zT value of 1.5 in Ge_(0.98)Lu_(0.02)Te at 673 K.Extra Sb alloying optimizes the carrier concentration from 1.02×10^(21) cm^(−3) of Ge_(0.98)Lu_(0.02)Te to 1.77×10^(20) cm^(−3) of Ge0.90Lu0.02Sb0.08Te,which results in a reasonable power factor of 33.82μW cm^(−1) K^(−2) and a low electrical thermal conductivity of 0.75 W m^(−1) K^(−1) at 673 K in Ge_(0.90)Lu_(0.02)Sb_(0.08)Te.Correspondingly,a peak zT of 1.75 at 673 K and an average zT of 0.92 within the temperature range of 303–723 K are obtained in Ge_(0.9)Lu_(0.02)Sb_(0.08)Te.This study indicates that Lu and Sb co-doping can effectively boost the thermoelectric performance of GeTe-based thermoelectric materials.

关键词： Thermoelectric Rare-earth Thermal conductivity Carrier concentration

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Optimal array alignment to deliver high performance in flexible conducting polymer-based thermoelectric devices

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Journal of Materials Science & Technology 2022年第29期124卷 252-259页

作者： Shengduo Xu Meng Li Min Hong Lei Yang Qiang Sun Shuai Sun Wanyu Lyu Matthew Dargusch Jin Zou Zhi-Gang Chen school of Mechanical and Mining Engineering The University of QueenslandBrisbaneQueensland4072Australia centre for Future Materials University of Southern QueenslandSpringfield CentralQueensland4300Australia school of Materials Science&Engineering Sichuan UniversityChengdu 610064China centre for microscopy and microanalysis The University of QueenslandBrisbaneQueensland4072Australia school of Chemistry and Physics Queensland University of TechnologyBrisbaneQueensland4000Australia

Flexible thermoelectric devices(F-TEDs)show great potentials to be applied in curved surface for power generation by harvesting low-grade energy from human body and other heat sources.However,their power generation efficiency is constrained by both unsatisfactory constituent materials performance and immature device design.Here,we used an optimal alignment of vertically-aligned poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)arrays to assemble a 2.7×3.2 cm^(2)F-TEDs,exhibiting a maximum power output of 10.5μW.Such a high performance can be ascribed to the outstanding power factor of 198μW m^(-1)K^(-2)by the synergetic effect of both high charge mobility and optimal oxidation level and the optimized array alignment that maximizes the temperature difference utilization ratio across the TE legs.Particularly,optimized leg distance of 6 mm and leg length of 12 mm are determined to realize a high temperature difference utilization ratio of over 95%and a record-high output power density of 1.21μW cm^(-2)under a temperature difference of 30 K.Further,reliable bending(1000 cycles)and stability(240 h)tests indicate the outstanding mechanical robustness and environmental stability of the developed F-TEDs.This study indicates our reasonable device design concept and facile material treatment techniques secure high-performance F-TEDs,serving as a reference for other flexible energy harvesting devices with wide practical applications.

关键词： Flexible thermoelectric device Performance optimization TE array alignment Optimized power density

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Effect of Small Addition of Sc on the Microstructural Evolution in Al-15Ag Alloy

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Journal of Materials Science & Technology 2005年第5期21卷 630-634页

作者： Zhiguo CHEN Ziqiao ZHENG Simon P.Ringer school of Materials Science and Engineering Central South University Changsha 410083 China australian Key centre for microscopy & microanalysis The University of Sydney 2006 NSW Australia

The effect of small addition of Sc on the microstructural evolution in Al-15Ag alloy was investigated by Monte Carlo simulation and transmission electron microscopy （TEM）. Monte Carlo simulation results indicate that Ag clustering is suppressed by the addition of Sc during the initial ageing stage, and there is a little chemical repulsion between Ag atoms and Sc atoms. TEM observations show that the morphology of γ′ precipitation can be modified by the small addition of Sc, which does result in a refinement of γ′ precipitates in Al-15Ag-0.2Sc. The mechanism by which trace Sc affect the microstructure is to reduce the ledge density of γ′precipitates.

关键词： Aluminium alloys Ageing Microstructure Scandium

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Enhanced High-Temperature Cycling Stability of Garnet-Based All Solid-State Lithium Battery Using a Multi-Functional Catholyte Buffer Layer

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Nano-Micro Letters 2024年第7期16卷 59-73页

作者： Leqi Zhao Yijun Zhong Chencheng Cao Tony Tang Zongping Shao WA school of Mines:Minerals Energy and Chemical EngineeringCurtin UniversityPerthWA 6102Australia

The pursuit of safer and high-performance lithium-ion batteries(LIBs)has triggered extensive research activities on solid-state batteries,while challenges related to the unstable electrode-electrolyte interface hinder their practical implementation.Polymer has been used extensively to improve the cathode-electrolyte interface in garnet-based all-solid-state LIBs(ASSLBs),while it introduces new concerns about thermal stability.In this study,we propose the incorporation of a multi-functional flame-retardant triphenyl phos-phate additive into poly(ethylene oxide),acting as a thin buffer layer between LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)cathode and garnet electro-lyte.Through electrochemical stability tests,cycling performance evaluations,interfacial thermal stability analysis and flammability tests,improved thermal stability(capacity retention of 98.5%after 100 cycles at 60℃,and 89.6%after 50 cycles at 80℃)and safety characteristics(safe and stable cycling up to 100℃)are demonstrated.Based on various materials characterizations,the mechanism for the improved thermal stability of the interface is proposed.The results highlight the potential of multi-functional flame-retardant additives to address the challenges associated with the electrode-electrolyte interface in ASSLBs at high temperature.Efficient thermal modification in ASSLBs operating at elevated temperatures is also essential for enabling large-scale energy storage with safety being the primary concern.

关键词： Solid-state battery Cathode electrolyte interlayer Flame-retardant additive Cycling stability Interfacial stability

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The role of aluminium in the preservation of microbial biosignatures

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Geoscience Frontiers 2019年第3期10卷 1125-1138页

作者： Alan Levett Emma J.Gagen Hui Diao Paul Guagliardo Llew Rintoul Anat Paz Paulo M.Vasconcelos Gordon Southam school of Earth and Environmental Sciences University of Queensland centre for microscopy and microanalysis University of Queensland centre for microscopy Characterisation and Analysis University of Western Australia school of Chemistry Physics & Mechanical EngineeringQueensland University of Technology

Demonstrating the biogenicity of presumptive microfossils in the geological record often requires supporting chemical signatures, including isotopic signatures. Understanding the mechanisms that promote the preservation of microbial biosignatures associated with microfossils is fundamental to unravelling the palaeomicrobiological history of the material. Organomineralization of microorganisms is likely to represent the first stages of microbial fossilisation and has been hypothesised to prevent the autolytic degradation of microbial cell envelope structures. In the present study, two distinct fossilisation textures(permineralised microfossils and iron oxide encrusted cell envelopes)identified throughout iron-rich rock samples were analysed using nanoscale secondary ion mass spectrometry(NanoSIMS). In this system, aluminium is enriched around the permineralised microfossils, while iron is enriched within the intracellularly, within distinct cell envelopes. Remarkably,while cell wall structures are indicated, carbon and nitrogen biosignatures are not preserved with permineralised microfossils. Therefore, the enrichment of aluminium, delineating these microfossils appears to have been critical to their structural preservation in this iron-rich environment. In contrast,NanoSIMS analysis of mineral encrusted cell envelopes reveals that preserved carbon and nitrogen biosignatures are associated with the cell envelope structures of these microfossils. Interestingly, iron is depleted in regions where carbon and nitrogen are preserved. In contrast aluminium appears to be slightly enriched in regions associated with remnant cell envelope structures. The correlation of aluminium with carbon and nitrogen biosignatures suggests the complexation of aluminium with preserved cell envelope structures before or immediately after cell death may have inactivated autolytic activity preventing the rapid breakdown of these organic, macromolecular structures.Combined, these results highlight that aluminium may play an important role in

关键词： Aluminium Microfossils Biosignatures NanoSIMS Organomineralisation

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