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Abstract A new cold worked, penetrative mechanical reinforcement method was evaluated for its potential to enhance joining between 2024-T3 aluminum matrix and glass fiber reinforced polymer (GFRP) for aerospace and automotive applications. In this study, the aluminum substrate surface was modified using a new cold working process which formed hooks directly from the substrate material. This surface was then treated with grit blast and Sol-Gel surface treatment before it was co-cured to both side of a GFRP, forming a single lap joint for testing. This type of joints was compared to a baseline bonded joint without mechanical reinforcement using the same surface treatment. The joint strength and fatigue performance of these sets of samples were experimentally evaluated under quasi-static and fatigue loading conditions. The bonded joints with penetrative mechanical reinforcements withstood greater peak load and higher strain prior to failure, as compared to non-reinforced bonded joints. Fatigue testing on the other hand showed better performance of non-reinforced joints over the reinforced ones. The failure surfaces of both quasi-static samples and fatigue samples were evaluated using a scanning electron microscope to determine failure mode(s). It was determined that the stress concentration at the base of reinforcements could be the main underlying cause for earlier onset of fatigue failure of reinforced samples. [ABSTRACT FROM AUTHOR]

Diluted magnetic semiconductor Ce doped Si films with p-type conduction by means of codoping of Al were fabricated with low-temperature molecular beam epitaxy. The uniformly distributed Ce as a magnetic ion is responsible for the disappearance of ferromagnetic nature. Therefore, the magnetotransport properties of the films were investigated if they have any p-f interaction between f electron in Ce and carrier in this DMS sample. The samples with lower carrier concentration (2 ×1019 cm-3 at 80 K) showed variable range hopping (VRH) conduction and VRH induced magnetoresistance (MR) was recognized. Samples with higher carrier concentration (7 ×1020 cm-3 at 80 K) showed a metallic conduction and a positive MR. The positive MR is attributed to the quantum correction on the conductivity due to the p-f exchange interaction induced spin splitting of the valence band. [ABSTRACT FROM AUTHOR]

While zero valent aluminum (ZVAl) is considered as a promising catalyst for Oxone activation, relevant studies are very limited and ZVAl is typically obtained by chemical-reagent grade aluminum. However, as aluminum is the third richest element on earth, many aluminum wastes (AWs) are readily available for preparing ZVAl without energy-intensive mining and metalworking. Herein, we propose for the first time to valorize AWs to prepare ZVAl via HCl-pretreatment; the resulting HCl-pretreated AW (HPAW) is evaluated for Oxone activation by decolorizing Amaranth (AMR) dye as a model test. Oxone activation behaviors by HPAW are investigated by examining various effects on AMR decolorization, including dosages of HPAW and Oxone, temperature, initial pH, and co-existing compounds. Even though electrons from HPAW can induce the formation of OH , the resulting OH could not effectively decolorize AMR. However, the electrons from HPAW can “activate” Oxone to generate SO 4 - , which completely and rapidly decolorizes AMR. This effective AMR decolorization is attributed to SO 4 - and also to OH derived from the reaction of water with SO 4 - . The Oxone activation by HPAW is much favorable under neutral conditions and at elevated temperatures, whereas the presence of co-existing compounds ( e.g. , NaCl and anionic surfactant) inhibits Oxone activation and then AMR decolorization significantly. HPAW can be also reused for Oxone activation even without regeneration. These features demonstrate that AW can be valorized easily by HCl-pretreatment and becomes an efficient heterogeneous catalyst for Oxone activation. [ABSTRACT FROM AUTHOR]

The dissimilar joints between 7A04 aluminum alloy rod and AZ31 magnesium alloy rod were produced by inertia friction welding. The effects of friction pressure on microstructure and mechanical properties of the joints were investigated. Results showed that intermetallic compounds (IMCs), mainly Al 12 Mg 17 and Al 3 Mg 2 , were formed at the interfaces. A large amount of microcracks were generated in IMCs interlayer. The thickness of IMCs layer decreased significantly with increasing friction pressure. The mechanical properties were assessed by tensile test and microhardness. The mechanical properties of joints largely lies on the characteristic of IMCs interlayers at the interface. The tensile strength of the joints increases remarkably with increasing friction pressure. The maximum tensile strength of 96 MPa was achieved under the friction pressure of 124 MPa. All the tensile specimens failed in quasi-cleavage fracture mode along the boundary between IMCs interlayer and Al base metal. [ABSTRACT FROM AUTHOR]

It has been shown in our previous effort in the development of an energy-based fatigue life prediction framework that, in order to obtain the fatigue toughness of a nonviscoplastic material at room temperature from the areas of hysteresis loops, a fatigue test need to be conducted at the ideal frequency to minimize the effect of nondamaging energy. For aluminum 6061-T6, the ideal frequency is 0.05 Hz. A fatigue test with such a low frequency requires extensive time to complete. Therefore, the present investigation focuses on modifying the energy-based framework in order to obtain the fatigue toughness from fatigue tests conducted at an arbitrary frequency higher than the ideal frequency. The fatigue toughness is calculated from the average strain range developed in a material during a fatigue test and the Ramberg–Osgood cyclic parameters. The measurement of average strain range by an extensometer associated with a nonviscoplastic test specimen at room temperature is independent of the test frequency. The cyclic parameters are obtained from the fatigue lives at two different stress ranges which are also independent of the test frequency at room temperature. Similar to the case of the previous framework, the modified framework is found to predict the room temperature fatigue life of aluminum 6061-T6 with a promising accuracy. [ABSTRACT FROM AUTHOR]

We have developed novel catalyst supports using aluminum etched with microchannels as microreactors. The novel catalyst support contains ∼1–3.5 μm microchannels (∼10,000–15,000 microchannels/mm 2 ) formed on the metal aluminum foil substrate by etching. Flow was through an applied porous membrane. The aim was to provide a reaction space with short controlled residence time and high catalytic activity. We confirmed whether reactions occur in the 1.7 μm membrane microchannels and evaluated the performance of this membrane compared with alumina granular. Methanol steam-reforming activity of the catalytic membrane shows it is an effective catalyst. Comparison with a crushed catalytic membrane shows that the reaction occurs in membrane microchannels. We deduce that there is no diffusive resistance at all temperatures because the membrane microchannel diffusive length is short compared with granular-type reactor channels. [ABSTRACT FROM AUTHOR]

For this study, seamless square tubes of aluminum alloys EN AW-6060 and EN AW-6082 were extruded with axial variable wall thickness by applying an axial moveable stepped mandrel. The microstructures in thick-walled and thin-walled sections of these tubes were investigated and correlated to the extrusion conditions. The results for EN AW-6060 revealed fibrous grains at low ram velocity ( v ram = 0.8 mm/s) and thus low strain rate. In these cases, peripheral coarse grains were also observed on the tube surfaces. Applying a higher v ram = 3.3 mm/s lead to a fully recrystallized microstructure. For EN AW-6082 the fibrous microstructure was predominant. This was attributed to the Mn-content of this alloy, which acts as an inhibitor for recrystallization. Only at the highest values of strain, strain rate and temperature a recrystallized microstructure was observed for this alloy. EBSD analyzes of boundary misorientation angles indicate that geometric dynamic recrystallization seems to be the predominant mechanism at low strain rates. The facts that the amount of low angle boundaries significantly decreased as subgrains were removed and the amount of high angle grain boundaries is increased revealed that recrystallization occurred at higher strain rates and strains. Furthermore, the transition areas, where the wall thickness was gradually reduced were investigated. Due to increasing strain and thus increasing strain rate, thin-walled tube segments show lower grain size than thick-walled sections. It was also revealed that the PCG layer thickness remained about constant with increased strain, but since the tube wall thickness was reduced, the recrystallized fraction increased for higher strains. [ABSTRACT FROM AUTHOR]

The objective of this research was to develop a powder metallurgy (PM) counterpart to the wrought aluminum alloy 2618 utilizing press-and-sinter technology. Each starting blend was prepared from a strategic combination of prealloyed aluminum coupled with elemental and master alloy additions and was processed through uni-axial die compaction coupled with controlled atmosphere sintering. All of the PM alloys responded well to sintering with near full theoretical density realized. The most desirable PM product contained minor additions of tin and silicon. Whereas tin imparted enhanced densification, silicon promoted appreciable gains in hardness and tensile properties. It was also determined that the beneficial effects of silicon persevered after prolonged thermal exposure at 260 °C provided that a nominal concentration of 0.2 wt% was maintained. The final press-and-sinter PM product offered mechanical properties and thermal stability that were comparable to the wrought target. [ABSTRACT FROM AUTHOR]

Formation of linear polyenes -(CH=CH)- during thermal dehydration of thin layers (9-20 μm) of poly(vinyl alcohol) containing phosphotungstic-acid and aluminum-chloride catalysts was investigated. It was found that the concentration of long-chain ( n ≥ 8) polyenes in films containing phosphotungstic acid increased smoothly with increasing annealing time although the kinetics of the dehydration were independent of the film thickness. The polyene ( n ≥ 8) formation rate in films containing aluminum chloride dropped quickly with decreasing film thickness and increasing annealing time. As a result, long-chain polyenes practically did not form regardless of the annealing time for a film thickness of 11 μm. [ABSTRACT FROM AUTHOR]

Aluminum-doped zinc oxide (AZO) thin films are prepared by a low temperature (100 °C) aqueous solution deposition method with a subsequent UV post-deposition treatment at 140 °C. Film growth is governed by the retrograde solubility of zinc-ammine complexes at basic conditions (pH 11.4). Aluminum was introduced into the film as a dopant by co-precipitation, either using an aluminum metal foil or aluminum nitrate as a precursor. As the presence of Al ions in the solution influences the film morphology as well as the opto-electronic properties, different profiles of the dopant supply were examined and optimized with respect to the optical and electrical properties of the AZO layer. It was found that independent of the chosen aluminum precursor a linearly increasing dopant concentration in the solution is favorable for achieving dense, highly transparent (<8% absorption between 400 and 900 nm) AZO thin films with a lowest resistivity of 3.4 × 10−3 Ω cm. [ABSTRACT FROM AUTHOR]

Hot tearing has been an issue for many casting alloys, and much work has been devoted over the years to understanding the underlying mechanism, and to be able to mitigate it during casting. Unfortunately, the literature and therefore our understanding to date has been a bit muddled, as conflicting data and theories exist. In addition, many of the tests that have been developed to evaluate hot tearing have been qualitative in nature. Through the Light Metals Alliance, WPI's Metal Processing Institute and CANMET joined forces in 2006 to clarify our understanding of hot tearing and to enable us to control it during casting. This paper contains an overview of the authors' work; describes the quantitative test that was developed and discusses the processing variables that are needed to control and to mitigate hot tearing. [ABSTRACT FROM AUTHOR]

Abstract: Constitutive equations for sheet metals are important input data for the numerical simulation of forming processes. Their identification usually comes from uniaxial tensile tests at several orientations to the rolling direction and from equibiaxial tests. To characterize the kinematic part of the work hardening, strain path reversals are needed and different mechanical tests have been developed, such as tension–compression and simple shear. The aim of this work is to investigate the influence of the database used for identification, by using either bending–unbending or simple shear for strain path reversal. This study is performed both on an aluminum alloy and a TRIP steel. The presented results show that, for a limited strain range, the experiments are consistent. [Copyright &y& Elsevier]

Abstract: The process of multi-pass offset tube neck-spinning is simulated by adopting MARC, the 3D elasto-plastic finite element software. 6061T1 aluminum alloy (annealed) is taken as investigating material. The distribution of stress and strain, the dimensional accuracy, such as thickness reduction, linearity, ellipticity and axial elongation in different spinning passes during multi-pass offset tube neck-spinning are simulated theoretically and studied experimentally. It shows that the distribution of strain and stress is non-axisymmetric; the equivalent stress distributes and varies along axial direction section by section, and reaches the maximum at the opening end of the spun workpiece. The thickness reduction at the opening end, and the ellipticity and axial elongation of the spun workpiece increase with increasing spinning passes; the linearity of the forward path spinning is significantly smaller than that of the backward path spinning. The simulation result of the thickness distribution of the workpiece conforms well to the experimental result with maximum deviation less than 10%. It indicates that the FEA model established in this paper is reasonable and reliable. The automobile exhaust pipe with offset tube end is produced successfully based on theoretical analysis and experimental research. [Copyright &y& Elsevier]

Abstract: The purpose of the present study is to propose a new technical method for arresting crack initiation at stop-drilled holes by drilling ancillary holes following the making of the stop-drilled holes. The main idea of the method is to reduce the stress concentration at the edges of stop-drilled holes. To confirm the effectiveness of the method, analyses were performed by using software for two-dimensional elastic problems based on the body-force method, and some experiments were carried out. The calculation results show that the existence of ancillary holes effectively reduced the stress concentration at the edges of the stop-drilled holes. A close distance between the stop-drilled hole and the ancillary holes resulted in lower stress concentration at the edge of the stop-drilled hole. Also, a considerable reduction of stress concentration was obtained by arranging for the diameter of the ancillary holes to be larger than that of the stop-drilled holes. Consecutively, the experimental results showed that the fatigue initiation life was in good agreement with the calculation results. [Copyright &y& Elsevier]

The LHC Accelerator Research Program (LARP) is currently developing 4 m long Nb3 Sn quadrupole magnets for a possible upgrade of the LHC Interaction Regions (IR). In order to provide a reliable test bed for the fabrication and test of long Nb,3Sn coils, LARP has started the development of the long racetrack magnet LRS01. The magnet is composed of two 3.6 m long racetrack coils contained in a support structure based on an aluminum shell pre-tensioned with water-pressurized bladders and interference keys. For the phase-one test of the assembly procedure and loading operation, the structure was pre-stressed at room temperature and cooled down to 77 K with instrumented, solid aluminum "dummy coils". Mechanical behavior and stress homogeneity were monitored with strain gauges mounted on the shell and the dummy coils. The dummy coils were replaced with reacted and impregnated Nb3 Sn coils in a second assembly procedure, followed by cool-down to 4.5 K and powered magnet test. This paper reports on the assembly and loading procedures of the support structure as well as the comparison between strain gauge data and 3-D model predictions. [ABSTRACT FROM AUTHOR]

Results of experimental studies and numerical modeling of high strain rate of aluminum alloy AK4-1 (analog AU2GN) have been presented. Using Split Hopkinson Pressure Bar (SHPB) method stress-strain curves under compression and tension have been obtained. On the basement of these results appropriate parameters of some constitutive equations have been calculated. Strength and deformation material failure properties, dynamic crack resistance, dynamic friction factor for material pair aluminum-titanium have been obtained by carrying out of modificated SHPB tests. A verification of the constitutive equations has been realized by dynamic indentation method and modified Taylor test. [ABSTRACT FROM AUTHOR]

To estimate the strain rate dependence of the dynamic flow stress of aluminum alloys, 2017-O and - T4, high strain rate and rate reduction tests are performed at strain rates ranging from about 1000/sec to 30000/sec. A steep increase in the flow stress is observed for 2017-O at the strain rate of about 3000/sec. For 2017-T4, the above phenomenon is observed at the strain rate above about 10000/sec. A simplified model for dislocation kinetics under dynamic plastic deformation is employed which can represent a transition in the rate controlling mechanism of dislocation motion from a thermally activated process to a viscous drag. It is expected that the steep increase in the flow stress observed at high strain rates is attributed to the rate dependence of the viscous drag on the dislocation motion. [ABSTRACT FROM AUTHOR]

Abstract   We provide a convenient recipe for fabricating reliable superconducting microbolometers as acoustic phonon detectors with sub-nanosecond response, using image-reversal optical lithography and dc-magnetron sputtering, and our recipe requires no chemical or plasma etching. Our approach solves the traditional problem for granular aluminium bolometers of unreliable (i.e., non-Ohmic) electrical contacts by sequentially sputtering the granular aluminium film and then a palladium capping layer. We use dc calibration data, the method of Danilchenko et al. (Acta Phys. Pol. A 103(4):325, [2003]) and direct nanosecond-pulsed photoexcitation to obtain the microbolometer’s characteristic current, thermal conductance, characteristic relaxation time, and heat capacity. We also demonstrate the use of the deconvolution algorithm of Edwards et al. (J. Phys. E Sci. Instrum. 22:582, [1989]) to obtain the phonon flux in a heat pulse experiment with nanosecond resolution. [ABSTRACT FROM AUTHOR]

Abstract: Chemical etching is employed as micromachining manufacturing process to produce micron-size components. The process applies a strong chemical etchant solution to remove unwanted part in the workpiece material. It is basically a corrosion-controlled process. Chemical etching process has a long history and accepted one of the important nontraditional machining processes during the last half century. The method is widely applied to machine geometrically complex parts from thin and flat of any material. It is also used to reduce weight of the workpiece materials. In this study, aluminium was machined by well-known chemical etchant, ferric chloride (FeCl3) at different etching temperature. The effects of selected chemical etching parameters on depth of etch and surface finish quality were investigated. It was observed that FeCl3 was very useful chemical etching for aluminium etching. [Copyright &y& Elsevier]

Abstract: A solid electrolyte type nitrogen oxides (NO x ) gas sensor was fabricated by applying an Al3+ cation conducting solid electrolyte with the KNO3-doped (Gd0.4Nd0.6)2O3 solid solution and Al metal as the auxiliary sensing electrode and the reference electrode, respectively. A rapid, reproducible and continuous sensor response was obtained with obeying the theoretical Nernst relationship for NO and NO2 gases at the temperature as low as 250°C, one of typical temperature of emitted gases. [Copyright &y& Elsevier]

Hot deformation of 7050 aluminium alloy with coarse elongated grains has been investigated by tensile tests conducted at 340 and 460°C and the strain rate of 10 × 10–4–10 × 10–1 s–1. When the 7050 aluminium alloy was conducted at 460°C and 10 × 10–2 s–1, the maximum elongation of 273% is achieved and large plastic deformation was carried out at an almost constant stress. The microstructure evolution under the deformation condition is characterised using OM, SEM, EBSD and TEM in detail. The results show that the microstructure evolution is realised by continuous dynamic recrystallisation in coarse grains. The increase in misorientation is proportional to the increase in the true strain, and the k value, the increasing rate of average misorientation angle, is 157°. The primary hot deformation mechanisms of the 7050 aluminium alloy are localised grain boundary sliding and dislocation gliding, which can increase the grain boundary misorientation continuously. [ABSTRACT FROM AUTHOR]

Abstract: The HANARO fuel element is made of a cylindrical fuel meat, top and bottom aluminum end plugs and an aluminum cladding with eight longitudinal fins. The fuel meat of each fuel element consists of a dispersion of small particles of a high density uranium silicide (U3Si) compound in a continuous aluminum matrix. To verify the irradiation performance of the HANARO fuel at a high power and a high burnup, in-pile irradiation tests were performed in the HANARO core. Detailed non-destructive and destructive post-irradiation examinations were conducted. It was verified through the irradiation tests that the HANARO fuel maintains a proper in-pile performance and integrity even at a high power of 121kW/m and up to a high burnup of 85at.% U-235. [Copyright &y& Elsevier]

Abstract: Most polymeric tribological components are inherently insulative, resulting in susceptibility to failure from frictional heating at the PV limit, which is typically reported as a product of the heat flux terms pressure (P) and sliding speed (V). This letter reports on the design of a tribological composite for increased thermal conductivity and PV limit. The control sample is an unfilled compositionally graded sample, consisting of a PEEK bulk with an integral PEEK/PTFE tribological solid lubricant surface layer. One composite sample is a compositionally graded PEEK bulk containing 10vol.% aluminum foam, and the other is a 10vol.% indium filled PEEK/PTFE bulk sample. Tribological experiments are conducted on a thrust washer tribometer instrumented with 13 thermocouples. At failure, the unfilled sample had a temperature rise of 170K. Under the same conditions, the aluminum and indium filled samples had temperature rises of 37K and 115K, respectively. They also had 250% and 40% higher PV limits, respectively than the unfilled sample. As designed, the continuity of the aluminum foam was found to be substantially more effective than the particle dispersion of the indium at dissipating thermal energy. [Copyright &y& Elsevier]

Abstract: Aluminum alloys 2014-T6, 2024-T3, 6061-T6, 7050-T7451, and 7075-T6 were thermally exposed at different times (1min to 20 days) and temperatures 177–482°C (350–900F). This study was conducted to simulate the effects of heat damage on aluminum alloys and to determine the correlations existing between the static mechanical and electrical conductivity properties. Results indicate that at the temperatures below 260°C (500F) all five alloys showed clear correlations between the mechanical and physical properties. [Copyright &y& Elsevier]

Abstract: The present study demonstrates different approaches towards MIC identification in three real cases of technological equipment failures. In the first case the failure of carbon steel heat exchanger as a result of tubes, lids, tube sheets, and connection pipes clogging was investigated. Chemical analysis of cooling water and precipitates, as well laboratory screening of deposits for bacteria, revealed that activity of iron-oxidizing bacteria present in cooling water led to heat exchanger blockage. The second case is related to MIC detection on floating roofs made of magnesium–aluminum alloy following a 3-weeks hydro-test. Corrosion tests carried out on the original and sterilized water used in hydro-test confirmed MIC process. In the third case the potential of MIC occurrence in engine cooling system made of cast aluminum alloy and filled with 20% ethylene glycol coolant solution was evaluated. The simulation tests allowed determining the real causes of the severe corrosion attack of examined system, including MIC high probability. [Copyright &y& Elsevier]

Abstract: Dry machining and high speed machining are increasingly attempted because of their impact on manufacturing cost. However, these processes generate dust that can be harmful. Environmental regulations require that manufacturers reduce manufacturing hazards, hence the need to develop environmentally conscious processes and cutting strategies that will help them to achieve that goal. This work investigates the turning of the 6061-T6 aluminium alloy, and 1018 and 4140 steels, using carbide cutting tools. The cutting tool geometry and the cutting speed are varied and their effect on dust formation and chip formation studied. The size of the dust particle investigated is 2.5μm and under (PM2.5). A new dust unit, which can be used as an ecological factor, is introduced to compare the dust emissivity of the tested materials. This dust unit is then related to the cutting conditions, and experimental models are developed. A correlation is established between the chip formation, the tool lead angle, the cutting speed, and the dust emission, in order to determine the conditions required for minimal dust emission. [Copyright &y& Elsevier]

Abstract: The nucleation kinetics of individual grains during solidification of an aluminium alloy are experimentally investigated by X-ray diffraction at a synchrotron source. The investigated aluminium alloy contained solute titanium along with micrometer size TiB2 particles, which act as substrates for heterogeneous nucleation of aluminium grains during solidification. The nucleation rate of aluminium grains during solidification is measured by different cooling rates ranging from 1 to 40K/min. The measurements indicate that for the continuous cooling, the nucleation rate strongly decreases with time. The nucleation process is complete for solid fractions below 30% for all cooling rates. The maximum nucleation rate significantly increases with increasing cooling rates. [Copyright &y& Elsevier]

Abstract: A kinetic study of dissolution reaction of Al can waste was conducted for the synthesis of aluminum isopropoxide (AIP). With the used Al can and isopropyl alcohol (IPA) as reactants, the reaction was examined at the condition of 3molIPA/mol Al of stoichiometric ratio, adding 10−3 molHgI2/mol Al for catalyst and no agitation at the reaction temperature ranging from 70 to 82°C. After 17h, the reaction gave a 75% yield. A two-stage dissolution mechanism was proposed in which the dissolution rate is determined first by a chemical reaction and then by ash layer diffusion. On the basis of the shrinking core model with the shape of flat plate, the first dissolution rate of Al can was controlled by chemical reaction. The concentration of isopropyl alcohol was added to the reaction at the stoichiometric ratio, then it was largely changed through the dissolution reaction. Therefore, since the conversion rate of isopropyl alcohol varies greatly depending on the reaction time, it was included as an integral term of the reaction time. By using the Arrhenius expression, the apparent activation energy of the first chemical reaction step was determined to be 92.4kJmol−1. In the second stage, the dissolution rate is controlled by diffusion control through the ash layer. The apparent activation energy of the second step was determined to be 174.9kJmol−1. [Copyright &y& Elsevier]

Abstract: The praseodymium-aluminium perovskite–praseodymium oxide, PrAlO3–Pr2O3, and praseodymium-aluminium perovskite–praseodymium hexaluminate, PrAlO3–PrAl11O18, eutectics have been recently obtained by the micro-pulling down method. The aim of this work was determination of the chemical composition and electronic structure examination of the above-mentioned eutectics. [Copyright &y& Elsevier]

Abstract: Component materials in the steam environment of energy generation systems have severe problems of erosion caused by the impingement of water droplets. An evaluation of the resistance of such materials to erosion is very important in the maintenance of power plant systems and to prolong the life span of the components. A water-jet peening system, which is normally used for surface treatment technology, is based on the phenomenon of erosion damage. Parameters associated with water droplet impingement which dominate erosion rates are less controllable when a water-jet system is used. In this study, the use of a water-jet apparatus for erosion tests was conducted on an aluminum alloy to determine the effective parameters for erosion damage which are dependent on water pressure and the stand off distance between the nozzle and specimen. Parameters such as impact velocity, impact frequency and diameter of water droplets were examined by observations of craters formed on a thin aluminum film. Erosion damage was characterized with respect to incubation period and damage depth rate. Optimum surface treatment conditions were evaluated for an incubation period and damage depth rate after the incubation period. The incubation period and damage depth rate were greatly affected by the velocity and impact frequency of water droplets and the surface treatment technology should be sustained by the optimum impingement conditions which are controlled by the water pressure and stand off distance of the nozzle in the water-jet apparatus. [Copyright &y& Elsevier]

Abstract: When bubbles collapse near solid surfaces, cavitation damage can occur. Two are the already known erosion mechanisms: liquid micro-jets impingement and shock waves. These micro-jets and shock waves are responsible for material loss from the surface, basically by wear failure. In the rotating disk device, a disk with cavitation inducers and specimens fixed on it rotates inside a water chamber to provide cavitating flow. In this work, a new concept of the horizontal rotating disk device is presented and discussed, as well as some preliminary results obtained from its operation. This new compact apparatus is tested with the aim to observe its performance in generating bubbles and to cause erosion. The damage in the specimens is measured by mass loss and surface observations by photographs of the tested specimen surface obtained by scanning electronic microscope, which are shown and discussed. After 15h working in cavitating conditions, pure aluminum and brass were eroded by the cavitation phenomenon, resulting in pitting formation and mass loss. Also, 1020 mild steel specimen was investigated for 5h. The new presented version of the equipment is cheaper and more compact than the preceding ones, resulting in advantages related to initial costs and losses in power transmission. The specimens of aluminum, brass and steel, were eroded by cavitation although in the aluminum the mass loss was lower than expected. The brass specimen was eroded as expected. The erosion mechanism is possibly due to bubbles collapse and water jet impact perpendicular to the specimen surface, producing circular erosion craters. Burned circular craters were also seen in the aluminum specimen. [Copyright &y& Elsevier]

Abstract: Severe plastic deformation (SPD) is an efficient approach for the production of bulk ultra-fine grained or nanostructured materials that involves plastic deformation to very high strain. The Equal Channel Angular Extrusion (ECAE) is a deformation process, which realizes the concept of SPD as such that the above-mentioned structures can be obtained. In this paper, the experimental research on multi-pass ECAE process of a widely used aluminum 6061 alloy is conducted and the mechanical properties after ECAE process are investigated. To study the effect of pre-extrusion heat treatment on the mechanical properties, different heat treatment scenarios are conducted to obtain un-aged and aged samples. Sixteen passes of ECAE process at room temperature are done without any rotation of the workpiece and the relationship of mechanical properties with number of extrusion passes was identified. In addition, mechanical properties including yield strength (YS) and the strain hardening exponent after the processing are investigated to determine the effect of the number of ECAE passes on the mechanical properties of the extruded samples. Results of the uniaxial tensile testing reveal that the YS of un-aged samples increased by ∼70% while aged samples exhibit an increase of ∼150% in YS after four passes of ECAE. There is a significant increase in the strain hardening exponent of the samples subjected to the different heat treatment configurations due to severe plastic deformation after multi-pass ECAE. The fracture surface of the tensile bars after uniaxial tensile testing was examined using scanning electron microscope (SEM) and the comparison of the fracture surfaces of the un-aged and aged specimens were presented. [Copyright &y& Elsevier]

Abstract: Both gravity casting and squeeze casting were carried out previously on an aluminium alloy (LM6) and a zinc alloy (ZA3) with different casting temperatures. Tensile, impact and density measurement were conducted. It was found that generally, samples taken from the bottom of the squeeze casting mould gave higher tensile strength, higher impact strength and higher density values. This study was carried out to determine the effect of solidification time on the mechanical properties of the castings. Two analytical methods were used: a steady-state heat flow model and Garcia''s virtual model. It was found that similar results were obtained with both analytical methods. Casting samples taken from the lower part of the squeeze casting mould were found to have a significantly shorter solidification time. For both types of alloys, it was found that generally the shorter the solidification time of the casting, the higher is its density, impact energy, yield strength and ultimate tensile strength (UTS). This study had therefore contributed to a better understanding of the mechanical properties obtained previously from different casting processes. [Copyright &y& Elsevier]

Abstract: Embossing and restoration are utilized to improve the mechanical properties of sheet metal. By subjecting the sheet to these techniques, the section modulus of the sheet metal is increased. Moreover, strain hardening is locally introduced on the sheet. With these strengthening methods, sheet metal of thinner gage can be utilized with remarkable improvement in mechanical properties, such as strength and rigidity. In this paper, embossing and restoration process are conducted to different aluminum alloy sheets. The effects of these techniques to the yield strength, tensile strength, total elongation and bending strength of the sheets are investigated. Also, the effects of bulge height during embossing and of forming condition on these mechanical properties of formed specimens are examined. The effectiveness of these forming techniques on strengthening the sheets is likewise discussed. [Copyright &y& Elsevier]

Abstract: Constant amplitude fatigue tests at R =0.1, conducted on the aircraft aluminum alloy 2024 T3, have revealed an appreciable surface hardness increase of the alloy at the nano- and meso-scale during fatigue. The observed surface hardness changes could be monitored with confidence by means of nanoindentations. The degree of hardening increases with increasing number of fatigue cycles following exponential relations. With increasing fatigue stress level degree of hardening increases as well. The observed results provide a basis for developing concepts to early detect and also monitor fatigue damage accumulation in aluminum aircraft structures based on measurements of the material’s hardness changes by means of nanoindentations. [Copyright &y& Elsevier]

Abstract: A new method for micropatterning of metallic patterns on porous anodic oxide film of aluminium is described. The porous anodic oxide film was impregnated with organic dye and palladium ions before the hydrothermal pore-sealing. The surface layers formed during the pore-sealing, i.e. outer acicular hydroxide layer and a compact intermediate sub-layer trap the palladium ion underneath the layers. Exposing the palladium enriched area by the help of laser beam followed by electroless nickel deposition results the deposition of nickel on the laser-exposed part. Thickness of the deposits can be up to about 2–3μm, after about the 20min of immersion in electroless nickel plating bath. The metallic micropatterns, formed by the method are crack free, smooth and uniform over extended length. [Copyright &y& Elsevier]

Abstract: We studied the aluminum-induced early alteration of cultured diatom frustules in a series of laboratory experiments. Ashed frustules of the diatom Thalassiosira punctigera were exposed to natural seawater at varying dissolved aluminum (Al) concentrations (without addition, 100 nM and 500 nM Al) for periods of up to 6 months both in batch incubations and in flow-through chambers. These Al concentrations are representative of levels commonly found in pore waters in the marine environment. In general, the aluminum content of the frustules increased with time of exposure. A maximum increase of the aluminum to silicon mole ratio from 1.23×10−3 (day 0) to 3.14×10−3 was observed after 14 days of incubation at 500 nM Al. Time series with incubation times from 1 to 21 days at 100 nM Al confirm that the aluminum is rapidly associated with the diatom frustule. The uptake of Al during incubation goes along with a shift in pore structure towards smaller pores. The structural association of aluminum and silicon in biogenic silica was investigated using X-ray absorption spectroscopy at the Al–K-edge. Al–K-edge X-ray adsorbtion near edge spectra (XANES) of incubated diatom frustules demonstrate that most aluminum is present in tetrahedral coordination regardless of the Al concentration of the seawater and the duration of exposure. Al–K-edge EXAFS spectroscopy indicates the structural incorporation of aluminum into the Si framework. The results from X-ray absorption spectroscopy at the Al–K-edge, the textural changes of diatom frustules during incubation and wet chemical data are all consistent with the formation of an aluminosilicate phase on the surface of the diatom frustules. The precipitation this surface phase occurred under experimental conditions mimicking those prevailing at the sediment–water interface. We propose that the documented reaction pathway contributes to the rapid post-mortem aluminum enrichment of diatom frustules at the sediment–water interface. [Copyright &y& Elsevier]