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Convergent beam electron diffraction (CBED) was used to profile the thickness of aluminium alloys foils prepared by using the twinjet electropolishing method. The two-beam CBED condition was obtained by exciting the

The rise of heterocycle cations, a new class of stable cations, has fueled faster growth of research interest in heterocycle cation-attached anion exchange membranes (AEMs). However, once cations are grafted onto backbones, the effect of backbones on properties of AEMs must also be taken into account. In order to comprehensively study the influence of cations effect and backbones effect on AEMs performance, a series of AEMs were prepared by grafting spacer cations, heterocycles cations, and aromatic cations onto brominated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) or poly(vinylbenzyl chloride) (PVB) backbones, respectively. Spacer cation [trimethylamine (TMA), N,N-dimethylethylamine (DMEA)]-attached AEMs showed general ion transportation and stability behaviors, but exhibited high cationic reaction efficiency. Heterocycle cation [1-methylpyrrolidine (MPY), 1-methylpiperidine (MPrD)]-attached AEMs showed excellent chemical stability, but their ion conduction properties were unimpressive. Aromatic cation [1-methylimidazole (MeIm), N,N-dimethylaniline (DMAni)]-attached AEMs exhibited superior ionic conductivity, while their poor cations stabilities hindered the application of the membranes. Besides, it was found that PVB-based AEMs had excellent backbone stability, but BPPO-based AEMs exhibited higher OH- conductivity and cation stability than those of the same cations grafted PVB-based AEMs due to their higher water uptake (WU). For example, the ionic conductivities (ICs) of BPPO-TMA and PVB-TMA at 80 °C were 53.1 and 38.3 mS cm-1 , and their WU was 152.3 and 95.1 %, respectively. After the stability test, the IC losses of BPPO-TMA and PVB-TMA were 21.4 and 32.2 %, respectively. The result demonstrated that the conductivity and stability properties of the AEMs could be enhanced by increasing the WU of the membranes. These findings allowed the matching of cations to the appropriate backbones and reasonable modification of the AEM structure. In addition, these results helped to fundamentally understand the influence of cation effect and backbone effect on AEM performance.

Ecosystem degradation is a process during which different ecosystem components interact and affect each other. The microbial community, as a component of the ecosystem whose members often display high reproduction rates, is more readily able to respond to environmental stress at the compositional and functional levels, thus potentially threatening other ecosystem components. However, very little research has been carried out on how microbial community degradation affects other ecosystem components, which hampers the comprehensive understanding of ecosystems as a whole. In this study, we investigated the variation in a soil microbial community through the extinction gradient of an ectomycorrhizal species (Tricholomas matsutake) and explored the relationship between microbial community degradation and ectomycorrhizal species extinction. The result showed that during degradation, the microbial community switched from an interactive state to a stress tolerance state, during which the interactivity of the microbial community decreased, and the reduced community interactions with T.matsutake marginalized it from a large central interactive module to a small peripheral module, eventually leading to its extinction. This study highlights the mechanisms of T.matsutake extinction due to the loss of soil microbial community interactivity, offering valuable information about soil microbial community degradation and the plant ectomycorrhizal species conservation.

High salt content is one of the major problems for stewed products. To help address this issue, the effect of salt reduction on water migration in stewed ducks was investigated through diverse approaches, including water activity (Aw) and water-holding capacity (WHC) assay, as well as low-field nuclear magnetic resonance (LF-NMR) and scanning electron microscopy (SEM) observation. Our results showed that Aw value remained stable, while centrifugal loss decreased, and cooking loss increased significantly (p 0.05). The analysis of NMR indicated that, during the marinating stage, the proportion of immobilized water increased from 86.86%-89.66% (sodium chloride group) and 90.51% (salt-reduced group), respectively. After 2 h, the free water content became 0, and then became stable until the end of marinating. In the stewing stage, at the beginning 20 min, relaxation time of immobilized water decreased to about 35 ms and the ratio of immobilized water significantly reduced (p 0.05) by 5.38% (sodium chloride group) and 5.95% (salt-reduced group), respectively. Free water peak was detected upon stewing of 10 min, and 20 min later, there was no significant difference in the proportion of free water (p 0.05). In general, no significance was observed in water behavior and microstructure of stewed duck meat between the salt reduction group and sodium chloride group. In addition, SEM analysis revealed that marinating could expand the muscle fiber gap to accommodate more immobilized water. However, the fiber was looser at the initial stage of stewing and then became more compact. PRACTICAL APPLICATION: This work demonstrates potentially feasible to produce salt-reduced duck products.

Metabolic alterations are well documented in various cancers. Non‐small‐cell lung cancers (NSCLCs) preferentially use lactate as the primary carbon source, but the underlying mechanisms are not well understood. We developed a lactate‐dependent cell proliferation assay and found that dynamin‐related protein (DRP1), which is highly expressed in KRAS‐mutant NSCLC, is required for tumor cells to proliferate and uses lactate as fuel, demonstrating the critical role of DRP1 in the metabolic reprogramming of NSCLC. Metabolic and transcriptional profiling suggests that DRP1 orchestrates a supportive metabolic network to promote lactate utilization and redox homeostasis in lung cancer cells. DRP1 suppresses the production of reactive oxygen species (ROS) and protects cells against oxidative damage by enhancing lactate utilization. Moreover, targeting DRP1 not only reduces HSP90 expression but also enhances ROS‐induced HSP90 cleavage, thus inhibiting activation of mitogen activated protein kinase and PI3K pathways and leading to suppressed lactate utilization and increased ROS‐induced cell death. Taken together, these results suggest that DRP1 is a crucial regulator of lactate metabolism and redox homeostasis in KRAS‐mutant lung cancer, and that targeting lactate utilization by modulating DRP1 activity might be an effective treatment for lung cancer., Dynamin‐related protein (DRP1) is required for KRAS‐mutant lung cancer cells to proliferate and uses lactate as fuel, demonstrating the critical role of DRP1 in the metabolic reprogramming of lung cancer. DRP1 suppresses the production of reactive oxygen species and protects cells against oxidative damage by enhancing lactate utilization. Targeting lactate utilization by modulating DRP1 might be useful for the treatment of KRAS‐mutant lung cancer.

Hexavalent Chromium has been successfully employed for corrosion protection purposes in aerospace coatings for decades. However, legislation will restrict the use of Cr6+ in the future and therefore the aerospace sector needs to identify alternative environmentally friendly coatings for corrosion protection. Before implementation of newly developed systems into actual components is possible, rigorous and time-consuming testing practices are required to ensure the new systems can achieve the strict aerospace standards requirements. The emerging number of coating systems being developed, and the vast research conducted on the subject worldwide, make the selection of suitable replacements for industrial application challenging. In this work, differently pretreated aluminium AA2024 alloy surfaces are coated with conventional Cr6+ containing coating and compared to a number of industrial alternative coatings. Corrosion performance is assessed by real-time imaging while immersed, by EIS, and by standardised salt-spray tests. Results reveal that the performance ranking acquired by salt-spray tests (SST) can be readily replaced by short-term immersion tests, and the time to failure in SST can be estimated from key corrosion indicators arising from EIS measurements at specific immersion times.

The effects of applied current density, anodizing time and electrolyte temperature on the cell and pore morphology of anodic films and the voltage-time response obtained during galvanostatic anodizing of AA2024-T3 alloy in sulphuric acid electrolytes have been studied. Scanning electron microscopy was employed to observe the film morphology. Sponge-like porous structure was promoted by anodizing at relatively low current density and high electrolyte temperature. In contrast, linear porous structure was favoured under the converse conditions. Intermediate conditions resulted in films containing either sequential layers of the two morphologies or a morphology incorporating features of the two types; such conditions were associated with anodizing voltages in the range 25 to 35 V. The reasons for the morphological differences are proposed to be due to interactions between film growth stresses and stresses arising from oxygen evolution on the development of the alumina cells.

The rearrangement and expression of immunoglobulin genes are regulated by enhancers and their binding transcriptional factors that activate or suppress the activities of the enhancers. The immunoglobulin κ (Igκ) gene locus has three important enhancers: the intrinsic enhancer (Ei), 3′ enhancer (E3′), and distal enhancer (Ed). Ei and E3′ are both required for Igκ gene rearrangement during early stages of B‐cell development, whereas optimal expression of the rearranged Igκ gene relies on both E3′ and Ed. The transcription factor YY1 affects the expression of many genes involved in B‐cell development, probably by mediating interactions between their enhancers and promoters. Herein, we found that YY1 binds to the E3ʹ enhancer and suppresses Igκ expression in B lymphoma cells by epigenetically modifying the enhancer. Knocking down YY1 enhanced Igκ expression, which was associated with increased levels of E2A (encoded by the TCF3 gene) and its binding to the E3ʹ enhancer. Moreover, in germinal centre B cells and plasma cells, YY1 expression was reversely associated with Igκ levels, implying that YY1 might facilitate antibody affinity maturation in germinal centre B cells through the transient attenuation of Igκ expression.

Purpose To investigate the acoustic radiation due to eddy current-cryostat interactions and perform a qualitative analysis on noise reduction methods. Methods In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate the noises from both the warm bore wall vibration and the gradient coil assembly. For the SPL reduction of the warm bore wall vibration, we first improved the active shielding of the gradient coil, thus reducing the eddy current on the warm bore wall. A damping treatment was then applied to the warm bore wall to control the acoustic radiation. Results Initial simulations show that the SPL of the warm bore wall is higher than that of the gradient assembly with typical design shielding ratios at many frequencies. Subsequent simulation results of eddy current control and damping treatment application show that the average SPL reduction of the warm bore wall can be as high as 9.6 dB, and even higher in some frequency bands. Conclusions Combining eddy current control and suggested damping scheme, the noise level in a MRI system can be effectively reduced. This article is protected by copyright. All rights reserved.

An experimental protocol (workflow) has been developed for time-lapse x-ray nanotomography (nano-CT) imaging of environmentally driven morphological changes to materials. Two case studies are presented. First, the leaching of nanoparticle corrosion inhibitor pigment from a polymer coating was followed over 14 days, while in the second case the corrosion damage to an AA2099 aluminium alloy was imaged over 12 hours. The protocol includes several novel aspects relevant to nano-CT with the use of a combination of x-ray absorption and phase contrast data to provide enhanced morphological and composition information, and hence reveal the best information to provide new insights into the changes of different phases over time. For the pigmented polymer coating containing nominally strontium aluminium polyphosphate, the strontium-rich components within the materials are observed to leach extensively whereas the aluminium-rich components are more resistant to dissolution. In the case of AA2099 it is found that the initial grain boundary corrosion is driven by the presence of copper-rich phases and is then followed by the corrosion of grains of specific orientation.

Background Emerging reports demonstrated that PIWI‐interacting RNAs (piRNAs) played an indispensable role in tumorigenesis. However, it still remains elusive whether piR‐1245 in gastric juice specific in stomach could be employed as a biomarker for gastric cancer (GC). The present work is aiming at exploring the possibility of piR‐1245 in gastric juice as a potential marker to judge for diagnosis and prognosis of gastric cancer. Methods Gastric juice was collected from 66 GC patients and 66 healthy individuals. Quantitative real‐time reverse transcriptase polymerase chain reaction (qRT‐PCR) was employed to measure the levels of piR‐1245 expression. Then, the pattern of piR‐1245 expression in gastric juice was determined between GC patients and healthy individuals. A receiver operating characteristic (ROC) curve was constructed for distinguishing GC from healthy individuals. Results Gastric juice piR‐1245 levels in GC were higher than those of controls (P

The protective film formed in a defect by leaching of lithium oxalate from model organic coatings during neutral salt spray exposure has been investigated. A scribed area of about 1 mm width was introduced on the coated AA2024-T3 aluminium alloy. The scribed area was examined before and after exposure in neutral salt spray environment for 4, 8, 24 and 168 h by scanning and transmission electron microscopies. It was found that the lithium oxalate was able to leach from the organic coating during neutral salt spray exposure and it promoted the formation of a film that provided effective corrosion protection to the alloy. The typical film morphology consists of three different layers, including a relatively compact layer near the alloy substrate, a porous middle layer and a columnar outer layer. Variation of the film morphology was also observed at different locations of the scribed alloy surface, which may be related to the difference of local concentration of lithium species. Electron energy loss spectroscopy detected lithium, aluminium and oxygen in the film. Although the film showed the varied morphologies in different regions of the scribed area, the alloy substrate was protected from corrosion when the film was formed. Copyright © 2016 John Wiley & Sons, Ltd.

One of the main bottleneck issues for room-temperature antiferromagnetic spintronic devices is the small signal read-out owing to the limited anisotropic magnetoresistance in antiferromagnets. However, this could be overcome by either utilizing the Berry-curvature-induced anomalous Hall resistance in noncollinear antiferromagnets or establishing tunnel junction devices based on effective manipulation of antiferromagnetic spins. In this work, we demonstrate the giant piezoelectric strain control of the spin structure and the anomalous Hall resistance in a noncollinear antiferromagnetic metal - D019 hexagonal Mn3Ga. Furthermore, we built tunnel junction devices with a diameter of 200 nm to amplify the maximum tunneling resistance ratio to more than 10% at room-temperature, which thus implies significant potential of noncollinear antiferromagnets for large signal-output and high-density antiferromagnetic spintronic device applications., Comment: 16 pages, 5 figures

The effect of thermal exposure at 70 and 100 °C on intergranular corrosion (IGC) susceptibility of AA5083 alloy has been studied. At both temperatures, metastable β′ phase has been detected at grain boundaries. The thermal exposure resulted in sensitized microstructure in the alloy and, consequently, increased mass loss values during the nitric acid mass loss test (NAMLT). The sensitization of the alloy is related to the formation of the β′ phase. The as-received O temper alloy showed relatively high resistance to IGC and exhibited a discontinuous distribution of the β′ phase precipitates at grain boundaries. After exposure at 70 °C for 480 h, the size of β′ phase precipitate at the grain boundaries slightly increased, resulting in an increased mass loss. After exposure at 100 °C for 240 h, the alloy became severely sensitized due to the more continuous distribution of β′ phase precipitate along the grain boundaries.

Localized corrosion in an AA2099-T83 aluminum–lithium alloy has been correlated with localized plastic deformation (LPD) introduced by cold working. The high population density of dislocations in the slip bands associated with LPD promoted preferential precipitation of needle-shaped T1 (Al2CuLi) phase during artificial aging. Consequently, preferential attack of the electrochemically active T1 phase in corrosive environment resulted in selective corrosion of the bands, leading to the development of the characteristic morphology of narrow, parallel volume of corrosion. Copyright © 2015 John Wiley & Sons, Ltd.

It was revealed that an AA5083 alloy had been severely sensitized after 40 years in service at ground atmosphere temperature. The degree of sensitization of the various regions through the alloy plate thickness is different, which is associated with the non-uniform distribution of Mg through the plate thickness. The alloy plate exhibits Mg-rich bands that promoted the heterogeneous distribution of Mg-containing precipitates. The composition of these precipitates ranges from that for low Mg content intermetallics to that of the β′ phase. Structure characterization revealed the β′ phase and a cubic Al-Mg phase that has lower magnesium contents compared to the β phase.

From readily available propargylic amines, 1,2,5-trisubstituted imidazoles are efficiently obtained through a cascade reaction catalyzed by AgOTf or promoted by molecular iodine. The AgOTf-catalyzed reaction involves nucleophilic addition of propargylic amine to ketenimine, a silver-catalyzed electrophilic cyclization reaction of alkyne, and a tautomerism/isomerism/metal-H exchange cascade. The iodine-mediated counterpart yields 5-formyl-1,2-disubtituted imidazoles, which presumably includes a cascade hydrolysis/oxidation reaction. Furthermore, the presented protocol can be scaled up and the resultant 1,2,5-trisubstituted imidazole can be converted into fused indeno[1,2-d]imidazole.

Linear friction welding may be used to join titanium alloys to stainless steel for a variety of applications. After welding, a crevice is often observed close to the edges and, in aqueous wet environments, a galvanic couple is formed between the two materials. If corrosion resistance is a requirement, the combined presence of a crevice and a galvanic couple is a concern. In this study, the behaviour of galvanically coupled titanium alloy and stainless steel has been investigated, both for planar electrodes and under simulated crevice conditions. In both cases, it was found that a significant driving force between the two materials develops over time to progress corrosion on the stainless steel, but the high specific impedance of the titanium surface limits the current flow. Consequently, it is concluded that galvanic coupling between titanium and stainless steel is only of concern if the area of the titanium largely exceeds the area of the steel, and only under complete immersion conditions in a sufficiently conductive electrolyte.

Antiferromagnets naturally exhibit three obvious advantages over ferromagnets for memory device applications: insensitivity to external magnetic fields, much faster spin dynamics (~THz) and higher packing density due to the absence of any stray field. Recently, antiferromagnetic spintronics emerges as a cutting-edge field in the magnetic community. The key mission of this rapidly rising field is to steer the spins or spin axes of antiferromagnets via external stimuli and then realize advanced devices based on their physical property changes. Herein, the state of the art of antiferromagnetic spintronics is presented. Subsequently, the history of ferromagnetic/ferroelectric multiferroic composites is briefly revisited. Finally, we introduce an ultralow-power, long-range, and magnetic-field-insensitive approach for harnessing antiferromagnetic spins based on our recent experimental progress, i.e., piezoelectric strain control. Relevant theoretical and experimental studies have formed an attractive new branch in antiferromagnetic spintronics, which we coin as antiferromagnetic piezospintronics., Comment: 22 pages, 6 figures. To be appearing in Advanced Electronic Materials as a Progress Report

Aluminium extrusions used for heat transfer applications are exposed to corrosive environments, which can eventually lead to perforation of the tube by pitting. In this study, the effect of microstructure on the corrosion behaviour of extruded AA3XXX series alloys has been investigated. It was revealed that pits developed were purely crystallographic and a drop testing procedure was developed to simulate the seawater acetic acid test in a laboratory environment. The drop testing experiment has been successfully employed to study the early stages of pitting for different surface finishes. Selected pits were studied with in-SEM nanotomography. Stable pits initiated on areas free of second-phase particles, in the vicinity of grain boundaries. When the corrosion front reached a grain boundary plane, pit propagation was interrupted in the direction perpendicular to the plane and the corrosion front followed grain boundaries, corroding one grain body more than its neighbour. A mechanistic understanding of crystallographic pitting corrosion has been developed. Copyright © 2013 John Wiley & Sons, Ltd.

The filiform corrosion behaviour of hot-rolled AA3104 aluminium alloy was investigated in the presence of a near-surface deformed layer produced by hot rolling. Through detailed examination of microstructure of the near-surface deformed layer and observation of the propagation behaviour of filiform corrosion, it was found that lateral development of surface-active filiform corrosion in the deformed layer was promoted by magnesium oxide in bands and manganese-containing dispersoids. Further, successive-pitting filiform corrosion was observed along the underlying grain boundaries of the bulk alloy, which develops into crystallographic corrosion of the grain interiors. Copyright © 2013 John Wiley & Sons, Ltd.

Materials ultramicrotomy has been progressed at Manchester for many years, enabling generation of suitably thin specimens for transmission electron microscopy. In addition, the remaining block specimen from which thin, electron transparent specimens have been generated also provides the basis for specimen preparation for high resolution backscattered electron imaging in the scanning electron microscope. This knowledge allows generation of serial sections of appropriate specimens that are oxide- and contamination-free for high resolution observation in the backscattered imaging mode. With recent instrumental developments, i.e. the GATAN 3View System, enabling ultramicrotomy to be performed in-SEM, relatively rapid sectioning and imaging can now be performed with ready reconstruction of electron tomographs. Further, correlative microscopy can be undertaken by utilising the GATAN XuM system in the same scanning electron microscope, enabling non-destructive X-ray tomography in addition to destructive electron tomography. The in-SEM, serial sectioning of selected aluminium alloys is considered here, as well as correlation of the X-ray and electron tomography approaches on the penetration of localised corrosion into an AA2024 T351 aluminium aerospace alloy. Copyright ?? 2013 John Wiley & Sons, Ltd. Copyright ?? 2013 John Wiley & Sons, Ltd.

The generation of dark appearance on an anodized AA6063-T6 aluminium alloy profile has been investigated. Plan and cross-sectional views of the anodic films of normal and dark samples revealed a distinct layer, of 1–2 µm thickness, decorated with characteristic features in the outer film regions of the dark sample, contrasting with typical porous anodic film of the normal sample. Additionally, it was revealed that the alloy substrate of the dark sample was over-aged and the characteristic features in the outer film regions of the dark sample are related to preferential anodizing of coarsened β′ (Mg2Si) precipitates. Further, it is suggested that the over-aged microstructure is not the sufficient condition for the occurrence of dark appearance, and the anodizing conditions in the early stages also play an important role in the generation of dark appearance. Copyright © 2013 John Wiley & Sons, Ltd.

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.

Differences between chromate conversion coatings and sol–gel coatings formed on aluminium and aluminium–copper alloys are highlighted with respect to the formation of cracks, the effect of the substrate composition on coating thickness and the influence of curing in air on coating re-growth. For sol–gel coatings, it is shown that (i) cracking can be eliminated by inclusion of a sufficient amount of organic moieties, (ii) the coating thickness is unaffected by copper and (iii) coating re-growth occurs readily after curing. These attributes are shown to contrast with the significantly different behaviours of chromate conversion coatings. Copyright © 2012 John Wiley & Sons, Ltd.

Sequential sectioning and sequential imaging by scanning electron microscopy have been employed to obtain three-dimensional images of an AA2024-T3 aluminium alloy after exposure to sodium chloride solution. The three-dimensional arrangement of intermetallic particles within the alloy was disclosed, indicating that groupings of intermetallics are preferential sites for corrosion initiation due to the combined presence of defects such as cracks or voids and local differences in electrochemical potential. Three-dimensional imaging enabled the study of the dealloying process occurring on the S-phase particles (Al-Cu-Mg) during corrosion, revealing the details of a copper-rich sponge-like structure. Initially, dealloying proceeds by initial formation of a copper-rich nanoporous layer containing significant amounts of residual aluminium and magnesium. Subsequently, the layer dealloys further, increasing the free volume of the porous structure. At later stages of dealloying, some copper metal clusters detach from the substrate and oxidize. Copyright ?? 2012 John Wiley & Sons, Ltd. Copyright ?? 2012 John Wiley & Sons, Ltd.

Kashin-Beck disease (KBD) is an endemic degenerative osteoarthropathy, but the mechanisms underlying its pathogenesis remains unclear. This study compares antioxidant capacity and lipid peroxidation using a novel model, in which rats were administered a selenium-deficient diet for 4 weeks prior to their exposure to T-2 toxin for 4 weeks. Changes in cell morphology and empty chondrocyte lacunae indicative of cell death, as well as cartilage proteoglycan loss in the deep zone of articular cartilage of knee joints were observed in rats with selenium-deficient diet plus T-2 toxin treatment. These changes were similar to those observed previously in KBD. The levels of thiobarbituric acid reactive substances (TBARS), indicative of lipid peroxidation in serum and cartilage, were significantly increased in all experimental groups compared to the normal diet group, while the levels of antioxidants, measured as total antioxidant capacity (T-AOC), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidases (GPX), in serum and cartilage were significantly lower than that in the normal diet group. The mRNA expression of those antioxidants in cartilage tissue was significantly reduced by T-2 toxin alone or by selenium-deficient diet plus T-2 toxin treatment. These results indicate that increasing TBARS and decreasing antioxidants in serum and cartilage by T-2 toxin treatment with a selenium-deficient nutritional status may alter oxidative stress in joint tissues and contribute to the pathological process of cartilage damage in KBD.

In 1996, it was found that the Beilby layer on rolled aluminium sheet could be imaged in the transmission electron microscope (TEM) on ultramicrotomed cross sections of the sheet surface. Following from this observation, we have examined Beilby layers on all types of aluminium surfaces that have been subject to high shear processing treatments such as rolling, grinding or machining. The layers are microcrystalline rather than amorphous, and they strongly influence properties like corrosion resistance and reflectance. Preferential precipitation in these deformed surface layers results in their electrochemical activation and it is responsible for the development of underfilm corrosion in most architectural and automotive alloys. More recently, it has been possible to directly image Beilby layers on ultramicrotomed stubs using the new generation of low kilovoltage high-resolution scanning electron microscopes and to carry out high-resolution TEM of sections cut from precisely located surface features. The paper presents an overview of all the recent investigations of high shear induced Beilby layers on aluminium alloys and discusses their control of surface properties.

In the present study, controlled reheating and breakdown rolling experiments have been carried out and the thickness, structure and uniformity of the resultant near-surface deformed layer have been characterised by scanning and transmission electron microscopy. High aspect ratio rolling, coupled with an increased rolling speed and rough and worn roll surfaces results in a high degree of interaction between the work roll and work pieces. This generates a shingled surface appearance with a high population of transverse surface cracks and a relatively thick near-surface deformed layer. In contrast, relatively low aspect ratio rolling, coupled with a reduced rolling speed and freshly ground work roll surfaces generates a relatively thin near-surface deformed layer. The thickness of the near-surface deformed layer varies across the alloy surface and is directlv related to the shingles, the surface cracks and the distribution of coarse intermetallics.

In the present study, the effects of mechanical polishing on the microstructure and corrosion behaviour of AA7075 aluminium alloy are investigated. It was found that a nano-grained, near-surface deformed layer, up to 400 nm thickness, is developed due to significant surface shear stress during mechanically polishing. Within the near-surface deformed layer, the alloying elements have been redistributed and the microstructure of the alloy is modified; in particular, the normal MgZn2 particles for T6 are absent. However, segregation bands, approximately 10-nm thick, containing mainly zinc, are found at the grain boundaries within the near-surface deformed layer. The presence of such segregation bands promoted localised corrosion along the grain boundaries within the near-surface deformed layer due to microgalvanic action. During anodic polarisation of mechanically polished alloy in sodium chloride solution, two breakdown potentials were observed at −750 mV and −700 mV, respectively. The first breakdown potential is associated with an increased electrochemical activity of the near-surface deformed layer, and the second breakdown potential is associated with typical pitting of the bulk alloy. Copyright © 2009 John Wiley & Sons, Ltd.

Oxide films grown anodically at the surface of superpure aluminium are used as standards to assess the accuracy of the thickness (d XPS ) determined using the Beer-Lambert treatment of the Al 2p metal and oxide peak intensities. For the fitting conditions employed, the value of d XPS is found to be very close to the true film thickness for films

The effectiveness of carboxylic acid functionalized plasma polymers (PPs) as adhesion promotion pretreatments for aluminium is investigated. Plasma polymers of acrylic acid have been deposited onto AA6016 aluminium alloy and subsequently bonded with an amine-hardened epoxy-based adhesive formulation to make single lap shear (SLS) joints. Bond durability was investigated by testing joints after storage in water at 60 °C for 1 week. A combination of tensile testing of the SLS joints and locus of failure determination, by transmission electron microscopy and imaging XPS, was used to assess the PP pretreatment performance relative to the commercially applied chromic acid anodizing process. All non-aged joints failed in the adhesive, but after ageing of the joints in water a reduced failure stress was measured and areas of failure near to the aluminium oxide surface were visible. The locus of failure was determined through comparison of transmission electron micrographs, of ultramicrotomed sections transverse to the fracture surface, and XPS images of the surface. Failure was identified at both the PP/aluminium oxide and the PP/adhesive interfaces. It is anticipated that further application of this fractography approach will facilitate the optimization of PP adhesion promotion pretreatments to improve on the promising results obtained in this initial study.