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In this paper, the microstructure and mechanical properties of Al-6.5Si-5.5Cu-0.2Zr-0.01Sr-0.06Ti-0.2Ce cast aluminum alloys were investigated in multistage solid solution systems. The microstructure of the alloy was characterized using an optical microscope (OM), scanning electron microscope (SEM), energy-dispersive spectrometer (EDS), x-ray diffraction (XRD) and transmission electron microscope (TEM), respectively. The hardness and conductivity of the alloy were measured using a Vickers hardness and eddy current conductivity testers, respectively, and the tensile properties were described by a drawing machine. The results showed that the mechanical properties of the alloy are the worst under the four-stage solid solution system (G1). With the increase in multistage solution temperature and holding time, θ phase (Al2Cu) was gradually dissolved into α-Al matrix to enhance the effect of dislocation strengthening. When the solution temperature reached 510 °C, the mechanical properties of the alloy were the best, and the tensile strength and elongation were increased to 354.90 MPa and 9.02%, respectively. With the increase in temperature, eutectic Si agglomeration and large area of insoluble phase between metals were found, resulting in the decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

This study investigates the new surface development on AA6061 and AA5086 alloys considering the wire-arc additive manufacturing technique as a direct energy deposition (DED) process of wire. Two different quantities of MWCNTs, i.e., 0.01 (low) and 0.02 (high) g, with a constant nickel (Ni) weight (0.2 g) were pre-placed in the created square patterns. ER4043 filler was used as a wire for additive deposition, and an arc was generated through a tungsten inert gas (TIG) welding source. Furthermore, hardness and pin-on-disk wear-testing methods were employed to measure the changes at the surfaces with the abovementioned inducements. This work was designed to illustrate the hardness and the offered wear resistance in terms of mass loss of the AA6061 and AA5086 aluminum alloys with the function of nano-inducements. Two sliding distance values of 500 m and 600 m were selected for the wear analysis of mass loss from tracks. A maximum increase in hardness for AA6061 and AA5086 alloys was observed in the experiments, with average values of 70.76 HRB and 74.86 HRB, respectively, at a high mass content of MWCNTs. Moreover, the tribological performance of the modified surfaces improved with the addition of MWCNTs with Ni particles in a broader sense; the modified surfaces performed exceptionally well for AA5086 compared to AA6061 with 0.02 and 0.01 g additions, respectively. The system reported a maximum of 38.46% improvement in mass loss for the AA5086 alloy with 0.02 g of MWCNTs. Moreover, the morphological analysis of the developed wear tracks and the mechanism involved was carried out using scanning electron microscope (SEM) images. [ABSTRACT FROM AUTHOR]

Aluminum alloys are extensively used to manufacture mechanical components. However, when exposed to alkaline environments, like lubricants, refrigerants, or detergents, they can be corroded, reducing their durability. For this reason, the aim of this study is to investigate the influence of aggressive alkaline solutions (i.e., pH and presence of chlorides) on the corrosion resistance of three aluminum alloys (AA 5083-H111, AA 6082-T6, and AA 7075-T6) with and without anodizing treatments. Open circuit potential (EOCP) and anodic polarization measurements were carried out and typical corrosion parameters such as corrosion current density (icor) and corrosion rate (CR) were determined. Morphology of the corrosion attack and samples microstructure were investigated by scanning electron microscope. Results show that corrosion behavior of the three investigated alloys is influenced by (i) the aggressiveness of the testing environments; (ii) the thickness of the anodizing treatment; (iii) the alloy chemical composition; (iv) the distribution of intermetallic phases in the aluminum matrix. Moreover, three galvanic series have been built also testing other metallic alloys commonly used in mechanical applications, i.e., carbon steel (C40), stainless-steel (AISI 304), and Cu-based alloys (Cu-Ni alloy and CW 617 N, respectively). Results clearly indicate that galvanic series play a fundamental role when it is necessary to select an alloy for a specific environment, highlighting the thermodynamic conditions for corrosion occurrence. On the other hand, kinetic measurements and microstructural studies carried out on the three aluminum alloys stress the importance of the surface treatments and relevant thickness as well as the effect of metal exposure. Future work will involve the study of other surface treatments on aluminum alloys and the evaluation of their corrosion behavior in acidic environments. [ABSTRACT FROM AUTHOR]

Hot-dip aluminum alloy is widely used in the engineering fields. However, during the aluminum plating process, Fe inevitably enters and reaches a saturation state, which has a significant impact on the corrosion resistance and microstructure of the coating. Currently, adding Si during the hot-dip aluminum process can effectively improve the quality of the coating and inhibit the Fe-Al reaction. To understand the effect of Si content on the microstructure and electrochemical performance of Al-xSi-3.5Fe coating alloys, the microstructure and post-corrosion morphology of the alloys were analyzed using SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction). Through electrochemical tests and complete immersion corrosion experiments, the corrosion resistance of the coating alloys in 3.5 wt.% NaCl was tested and analyzed. The results show that the Al-3.5Fe coating alloy mainly comprises α-Al, Al3Fe, and Al6Fe. With the increase in Si addition, the iron-rich phase changes from Al3Fe and Al6Fe to Al8Fe2Si. When the Si content reaches 4 wt.%, the iron-rich phase is Al9Fe2Si2, and the excess Si forms the eutectic Si phase with the aluminum matrix. Through SKPFM (Scanning Kelvin Probe Force Microscopy) testing, it was determined that the electrode potentials of the alloy phases Al3Fe, Al6Fe, Al8Fe2Si, Al9Fe2Si2, and eutectic Si phase were higher than that of α-Al, acting as cathode phases to the micro-galvanic cell with the aluminum matrix, and the corrosion form of alloys was mainly galvanic corrosion. With the addition of silicon, the electrode potential of the alloy increased first and then decreased, and the corrosion resistance results were synchronous with it. When the Si content is 10 wt.%, the alloy has the lowest electrode potential and the highest electrochemical activity. [ABSTRACT FROM AUTHOR]

In the aircraft industry, the high-strength aluminum alloys AA7075 and AA2024 are extensively used for the manufacture of structural parts like stringers and skins, respectively. Additive manufacturing (AM) of the AA7075-T6 aluminum alloy via friction stir deposition to build continuously multilayered parts on a substrate of AA2024-T4 aluminum has not been attempted so far. Accordingly, the present work aimed to explore the applicability of building multilayers of AA7075-T6 alloy on a substrate sheet of AA2024-T4 alloy via the additive friction stir deposition (AFSD) technique and to optimize the deposition process parameters. The experiments were conducted over a wide range of feed rates (1–5 mm/min) and rotation speeds (200–1000 rpm). The axial deposition force and the thermal cycle were recorded. The heat input to achieve the AFSD was calculated. The AA7075 AFSD products were evaluated visually on the macroscale. The microstructures were also investigated utilizing an optical microscope and scanning electron microscope (SEM) equipped with an advanced EDS technique. As well as the presence phases, the mechanical performance of the deposited materials in terms of hardness and compressive strength was also examined. The results showed that the efficiency of the deposition process was closely related to the amount of heat generated, which was governed by the feeding rate, the rotational speed, and the downward force. AA7075 defect-free continuously multilayered parts were produced without any discontinuity defects at the interface with the substrate at deposition conditions of 1, 2, 3, and 4 mm/min and a constant 400 rpm consumable rod rotation speed (CRRS). The additively deposited AA7075-T6 layers exhibited a refined grain structure and uniformly distributed fragment precipitates compared to the base material (BM). The gain size decreased from 25 µm ± 4 for the AA7075-T6 BM to 1.75 µm ± 0.41 and 3.75 µm ± 0.78 for the AFSD materials fabricated at 1 and 4 mm/min deposition feeding rates, respectively, at 400 rpm/min. Among the feeding rates used, the 3 mm/min and 400 rpm rod rotation speed produced an AA7075 deposited part possessing the highest average hardness of 165 HV ± 5 and a compressive strength of 1320 MPa. [ABSTRACT FROM AUTHOR]

In this study, the effects of magnesium addition on the microstructure and comprehensive properties of Al-5Si-5.3Cu-0.3Sr-0.2Zr-0.2Y-0.06Ti alloys were investigated by optical microscope, scanning electron microscope, transmission electron microscope, hardness tester, and tensile testing machine. It is found that the addition of magnesium increases the number of undissolved particles in the alloy. However, on the one hand, magnesium addition refines the θ′ phase and increases its number density in the alloy. On the other hand, it generates a smaller Q′ phase. Both phases can enhance the precipitation strengthening and dislocation strengthening of the alloy. In addition, adding magnesium reduces the width of the precipitation-free zone (PFZ) and changes the distribution of grain boundary precipitates (GBPs). At 1% magnesium addition, the dislocation strengthening and precipitation strengthening effects of the θ′ and Q′ phases were the best, the width of PFZ was the smallest, and the GBPs were discontinuously arranged along the PFZ. Therefore, a high-strength, high-hardness, and intergranular corrosion-resistant cast aluminum alloy with dense structure, a tensile strength of 364.4 MPa, elongation of 4.87%, hardness of 145.4 HV, and intergranular corrosion grade of 3 was obtained. [ABSTRACT FROM AUTHOR]

The main aim of this research is to analyze the mechanical performances of the influence of silicon carbide (SiC) particles with AA6351 aluminum alloy. The aluminum metal matrix composites were prepared with liquefying stir casting to produce the metal matrix composites (MMCs). The following weight fractions are AA6351-0% SiC, AA6351-2.5% SiC, AA6351-5% SiC, and AA6351-7.5% SiC utilized to compose the MMCs. The mechanical performances like hardness, flexural, impact, compressive, and tensile studies were investigated on the processed MMCs. The scanning electron microscope (SEM) was employed to examine the strengthened particle of SiC. During the SEM examinations, uniformly dispersed SiC-strengthened particles were analyzed. The entire MMCs specimens achieve greater mechanical characteristics; the specimen fabricated with a maximum volume fraction of 7.5 wt% of SiC accumulates higher strength than the other volume fractions samples. The SiC plays a very tedious role in improving mechanical attributes. The fabricated MMCs were highly utilized in the applications of automotive and aerospace usages. This application is fully employed with lesser weight and maximum strength conditions to fulfill the mechanical performances. The stir-casting process was a highly efficient technique to compose better MMCs to achieve greater strength. [ABSTRACT FROM AUTHOR]

The oxide film on the scrap surface is one of the primary sources of oxide inclusions in the aluminum melt. Understanding the evolution of the oxide films in the aluminum melt is an important step for developing efficient recycling technologies and controlling the quality of the product. In the present study, we studied the evolution behavior of the oxide film in the aluminum melt. The oxide films were introduced via aluminum alloy scraps into the melt, and the micro-morphology and composition of the oxide film were analyzed by scanning electron microscope and energy spectrum. Results show that the oxide film on the surface of 1235 alloy foil, A356 alloy turning, and 5083 alloy scalping were broken into small flake oxide film and then transformed into minor granular oxide when the scraps were charged into commercial purity aluminum melt. However, in aluminum alloy melt containing magnesium, the oxide film remained an intact sheet shape up to a certain melt dwelling time. [ABSTRACT FROM AUTHOR]

The effect of Ti content in various concentrations as an alloying element with Al on both microhardness and crystallization structure of aluminum–titanium alloys was studied, utilizing x-ray diffraction (XRD) and a scanning electron microscope (SEM). To study the electrochemical and corrosion performance of Al and its investigated alloys in 0.5 M solutions of HCl and H3PO4, two different techniques were used: extrapolation of Tafel plot and electrochemical impedance spectroscopy (EIS). Tafel plots and EIS revealed a similar trend. Generally, the rate of corrosion of the alloys was higher than that of Al. This investigation exhibited that the corrosion of Al alloying with Ti increased with an increase in both Ti content and temperature, which is due to reducing the growth of oxide film on the surface. Changes in the standard values of both entropy (ΔS) and enthalpy (ΔH), in addition to apparent activation energy (Ea) of corrosion processes of Al and its alloys in HCl and H3PO4, were evaluated. The evaluated data indicated negative values of ΔS, while the values of ΔH were positive. Besides, the decrease in ΔH value with the increase of Ti content in the alloy revealed that the dissolution of the studied alloys was fast. The positive values of ΔH were accompanied by an endothermic process. On the other hand, the activation energy (Ea) was decreased as a result of Al alloying with Ti in the two mentioned acids. Those results were supported by the corrosion current density (icorr.) and impedance parameters. By comparing the data obtained for both HCl and H3PO4 in all investigated electrodes, the corrosion current density (icorr.) in H3PO4 was lower than that in HCl. Such behavior can be ascribed to the aggressive attack of Cl¯ ions on the surfaces of the investigated electrodes, leading to pits formation. [ABSTRACT FROM AUTHOR]

This paper presents the new route of fabrication of H-AlSi24Cu3.8Mg0.8 alloy, assisted by ultrasonic vibration stirring and squeeze casting (UVSS). The primary objective of this investigation is to establish the tribological characteristics of the prepared aluminium alloy under dry, lubricated, and coated sliding conditions. Oil SAE20W40 is used as a lubricant and diamond-like carbon (DLC) is used as a coating. Under a load between 20 N and 50 N, a linear reciprocating tribometer (LRT) with a ball-on-plate geometry is used. Alloy was examined using an optical microscope, scanning electron microscope with EDS, 3D surface profilometer, Brinell hardness tester, and tensometer for pre- and postcharacterization of alloy, surface, and worn tracks. The DLC-coated condition yields the lowest wear and coefficient of friction. [ABSTRACT FROM AUTHOR]

Metal matrix composites (MMCs) are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. Therefore, they are used in different areas of industry, and the properties of this type of material are useful in engineering applications. Machining of such composites is of great importance to finalize the fabrication process with improved part quality. However, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine machinability characteristics. Effects of turning a metal matrix composite built of Al2O3 sinter, saturated with an EN AC-44000 AC-AlSi11 alloy, are presented in this paper. In the present study, a turning process of new metal matrix composites was carried out to determine the state-of-the-art material for various engineering applications. During the turning process, the cutting forces, a tool's wear, and surface roughness were investigated. Further, the SEM (scanning electron microscope) analysis of cutting inserts was performed. The influence of MMC structure on the machining process and surface roughness was studied. The Al2O3 reinforcements were used in different graininess. Effects of conventional turning of the metal matrix composite with Al2O3 sinter of FEPA (Federation of European Producers of Abrasives) 046 and FEPA 100 grade were compared. Results analysis of these tests showed the necessity of continuing research on turning metal matrix composites built of an AlSi alloy and Al2O3 ceramic reinforcement. The study showed the properties of MMCs that influenced machinability. In this paper, the influence of feed rate's value on surface roughness was carried out. The significant tool wear during the turning of the MMC was proved. [ABSTRACT FROM AUTHOR]

A recently developed solid-state joining technique called "friction stir spot welding" (FSSW) is used to combine metal alloys with low weldability. Significant experimental work for this study is concentrated on the FSSW of AA6063 and AA5083. The study involved fixture setup and welding pattern parameters for the sizes of the material, all of which were done on a milling machine. A cylindrical shoulder with a concave (10°) square pin profile was taken into consideration using various process parameters. The tool material is heat-treated high-carbon steel. The Taguchi L9 orthogonal array is employed for the experimental model. The influence of FSSW factors including spindle speed, time, and depth was studied, along with the relationship between tensile strength, hardness at the contact region, and hook development, which would be a nominal metallurgical pledge established in the welding zone among the interacting sheet plate. The hook structure was found in the area of contact, and thermomechanical effects were seen in the spot-welding area. It has been determined that the influencing variables are spindle speed and plunge depth. As a consequence, it was determined that a tool spindle speed of 1200 rpm, a time of 25 seconds, and a plunge depth of 0.10 mm offer better mechanical properties. The microstructural analysis of welded region was carried out using a scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

This study investigated the microstructure, hardness, tensile and tribological behaviour of a cooling slope Al--Si--Mg alloy following ECAP and T6 heat treatment. The optical and scanning electron microscopes were applied to investigate the microstructure of the as-cast material and heattreated ECAPed Al--Si--Mg alloy. The dry sliding wear test was tested with three different loads of 10 N, 50 N, and 100 N with constant sliding speed and sliding distance at 1.0 m/s and 9000 m, respectively, using the pin-on-disc tribometer. The hardness and tensile properties were evaluated through microhardness, UTS, and YS measurement for the as-cast Al--Si--Mg alloy, both heat-treated with and without ECAPed alloys. Moreover, wear rate and COF in the Al--Si--Mg alloy with different loads were analysed and linked with microstructural and strength behaviour after the ECAP process. Meanwhile, these analyses of results were correlated with the behaviour of the as-cast Al--Si--Mg aluminium alloy and heat-treated non-ECAPed alloy. Results demonstrated that a combination of ECAP processing and T6 heat treatment improves the mechanical behaviour, while the COF and wear rate are improved at a load of 100 N. [ABSTRACT FROM AUTHOR]

Aluminium alloys have low density and good mechanical properties, making them suitable for the manufacture of mechanical structures where low weight is critical. However, when these alloys are subjected to elevated temperatures, their mechanical properties deteriorate significantly. The aim of this study is to investigate the effect of temperature on the mechanical properties of aluminium alloy, EN AC-Al Si12CuNiMg. For this purpose, an experimental investigation was performed at ambient and elevated temperatures on aluminium alloy samples prepared by casting. Tensile and hardness tests were carried out to characterize the mechanical properties of this material. Additionally, an optical microscope was used to examine the microstructures of this alloy. Finally, a scanning electron microscope was used to analyze the fracture modes of this material. The results show that the mechanical properties such as tensile strength, yield strength, and Young's modulus of this alloy dramatically decrease when the temperature exceeds 250oC. The microstructural investigation reveals several factors that are detrimental to the mechanical properties of this alloy. This includes coarse-grained structures, micro-pores, and several intermetallic compounds. Furthermore, fractography reveals a minor cleavage-like pattern and micro-cracks on the fracture surface of all failed samples under various temperatures, indicating semi-brittle fracture mode. [ABSTRACT FROM AUTHOR]

Aluminium alloys reinforced by nanoparticles are widely utilized in space vehicles, automotive components and industrial applications due to the unique characteristic of high stiffness to weight ratio. In this research, aluminium alloy 8011-TiC (Titanium Carbide) composites with a various weight percentage of reinforcement such as 5%, 7% and 9% wt.% were produced through stir casting technique. The contribution and uniform dispersion of TiC nano particles in Al 8011 was investigated through microstructural examination, mechanical and tribological behaviour. To sew up the uniform distribution of reinforcement particles over composite metal matrix alloy was investigated using Scanning and Optical Electron Microscope (OEM & SEM) depiction. The pattern of TiC content in the Al8011 alloy was observed through X-ray diffraction technique. Also, specimens are exposed to wear test as per ASTM G99 standard and the weight loss method is adopted. The result exhibits that tensile, yield strength properties and microhardness of nanocomposites particles to about increases by 35%, 170% and 150% respectively. The mechanical properties and wear resistance of 7% TiC yields better results compared with Al 8011 alloy and other compositions of augmentations. [ABSTRACT FROM AUTHOR]

This study was conducted with a high level of thoroughness. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM) were used to analyze the phase composition and microstructure of the AM-2024Al and the RO-2024Al. The hardness and porosity of the AM-2024Al, as well as the bonding strength between AM-2024Al and RO-2024Al, were also investigated. Furthermore, the corrosion and tribocorrosion properties and failure mechanisms of the AM-2024Al and the RO-2024Al were systematically and thoroughly compared and analyzed. The results of this comprehensive study revealed that the AM-2024Al displayed a similar phase structure and higher hardness in comparison to the RO-2024Al, and the AM-2024Al was compact and tightly bound to the RO-2024Al with a bonding strength of over 55.5 MPa. Furthermore, the AM-2024Al exhibited better corrosion resistance under PDP (potentiodynamic polarization) corrosion and similar wet sliding wear resistance under an approximate pure friction process (OCP corrosion, namely open circuit potential corrosion) and tribocorrosion compared with the RO-2024Al. These findings provide a high level of confidence in the potential of cold spraying additive manufacture 2024Al as a reliable way to repair damaged RO-2024Al. [Display omitted] • The tribocorrosion is first reported for the CS additive manufacturing 2024Al alloy. • The AM-2024Al exhibits superior anti-corrosion compared to the RO-2024Al. • The AM-2024Al has a comparable tribocorrosion resistance to the RO-2024Al. • Splats (AM-2024Al) and grains (RO-2024Al) are partly peeled during the tribocorrosion. • A plastic deformation layer was generated in the wear track surfaces of the two 2024Al. [ABSTRACT FROM AUTHOR]

The microstructure, phase composition, precipitates evaluation, casting, and mechanical properties of the novel cast Al-4Cu-2.1Er-1Mg-0.2Zr-0.2Cr-0.15Fe-0.15Si-0.1Ti alloy were analyzed using by optical microscope, scanning and transmission electron microscopes, differential scanning calorimetry, thermodynamic calculations, hot cracking and mechanical properties measurements. The positive effect of Cr as a substitution of Mn on plasticity and precipitation strengthening was demonstrated. The 0.2Zr, 0.2Cr and 0.1 Ti as a grain refiners provide a fine grain size of 25 μm in the as-cast state due to primary Al 75–80 Cu 10–12 Er 3–4 Cr 7 phase particles formation as a nucleation centers of Al. The hot cracking index (HCI) of the AlCuErMgCr alloy was 12–14 mm which is similar with HCI of the cast Al-Si-Cu-Mg alloys. The good casting properties in the AlCuErMgCr alloy achieved due to a fine grain structure and narrow solidification range. The contribution of the Al 3 (Zr,Er) (40 nm), Al 45 Cr 7 (6 nm), and S'(θ') (100/5 nm) precipitates is 38.5 MPa, 140.4 MPa, and 198.9 MPa and the calculated contribution from dislocation and precipitates is 262.3 MPa. The ultimate tensile strength (UTS) and elongation (El.) of the AlCuErMgCr alloy are 372 MPa and 6% which is higher in 16.6% and 150%, respectively, than in the Mn-containing alloy. Novel alloy has an excellent combination of yield strength (YS) and plasticity at 20–250°C. The YS and El. are 301 MPa and 6% and 225–250 MPa and 4.6–11.5% at 20 and 200–250°C, respectively. The rupture strength at 250°C after 100 h (σ 100 250) is 106 MPa. Mechanical and casting properties of the novel alloy are superior to the properties of commercial 201.0 (Al-Cu-Mn-Mg-Ag-Ti) alloy. • Cr, replacing Mn, had a positive impact on both plasticity and precipitation strengthening. • 0.2Zr, 0.2Cr, and 0.1Ti as grain refiners resulted in the formation of primary Al 75–80 Cu 10–12 Er 3–4 Cr 7 phase particles. • The AlCuErMgCr alloy displayed an ultimate tensile strength (UTS) of 372 MPa and an elongation (El.) of 6%. • The rupture strength at 250°C after 100 hours was determined to be 106 MPa. [ABSTRACT FROM AUTHOR]

The effect of scandium content on the structure and properties of alloy Al – 4.5% Zn – 4.5% Mg – 1% Cu – 0.12% Zr is determined. The microstructure of the alloy is studied with identification of the phases using an optical microscope and scanning and transmission electron microscopes. The Vickers hardness and the yield strength under heating are determined. The phase diagram is plotted and the nonequilibrium crystallization is described using the Thermo-Calc software and the TTAL5 database. It is shown that addition of 0.1% scandium contributes substantially enough into the growth of the hardness after 3-h annealing at 450°C and into the yield strength after 20-h aging at 175°C. The compositions studied are recommended as a base for designing new refractory alloys based on the Al – Zn – Mg – Cu system. [ABSTRACT FROM AUTHOR]

The aluminium alloy will improve its strength further with addition of reinforcement on considering its applications to produce much lighter weight to high strength parts. This work examines the addition of silicon carbide at varying levels of 12%, 14% and 16% in 6061 aluminium alloy. In addition, magnesium and copper are added to aid the strength of the Aluminium Metal Matrix Composite. The process parameters are optimized for the wear rate of the composites through Taguchi technique together with design of experiments. The percentage of SiC addition, load applied (30N, 60N and 90N) and sliding distance (500m, 1000m and 1500m) are the parameters taken into consideration for this wear analysis. It was observed that sliding distance was the most influencing factor, among others, while investigating the wear behaviour with ANOVA. Microstructure analysis performed with a scanning electron microscope on worn surfaces shows that SiC particles influence the wear rate of the composites. [ABSTRACT FROM AUTHOR]

The beryllium bronze guide sleeve and the aluminum alloy valve body are assembled to form a beryllium bronze-aluminum alloy stepped hole which requires multiple positioning and tool changes during machining, resulting in lower machining efficiency and accuracy. The geometry error and surface quality of beryllium bronze-aluminum alloy stepped holes after reaming were studied in this research. The geometric error (cylindricity, concentricity and verticality) and diameters of the stepped holes were measured by using a three-coordinate measuring machine. The experimental results show that the PCD forming cutters has high geometric error and diameter stability when reaming beryllium bronze-aluminum alloy stepped holes. Under various cutting parameters, the cylindricity of stepped holes was guaranteed to be within 6μm, and the concentricity of stepped holes was guaranteed to be within 6μm, and verticality of stepped holes was guaranteed to be within 2μm. With the increase of spindle speed and feed per tooth, the diameters of beryllium bronze holes increase while the diameters of aluminum alloy holes decrease and then increase. As the cutting allowance increases, the diameters of the beryllium bronze holes and aluminum alloy holes decrease. The laser confocal microscope and scanning electron microscope were used to detect and analyze the surface quality of beryllium bronze-aluminum alloy stepped holes after reaming. The experimental results show that the surface roughness of the beryllium bronze-aluminum alloy stepped holes reamed by using the PCD forming cutter were less than 0.3μm, and the surface roughness of the beryllium holes were slightly larger than the aluminum holes. The fourth group of experimental parameters (spindle speed 1290r/min, feed per tooth 0.01mm/z, cutting allowance 0.06mm) was selected as the actual processing parameters. There are cavities on the surface of the initial stepped holes before reaming and the cavities basically disappear after reaming, so the surface quality of the beryllium bronze-aluminum alloy stepped holes has been greatly improved. [ABSTRACT FROM AUTHOR]

In this study, the paint layer was removed on the surface of 5083 aluminum alloy using laser cleaning and mechanical grinding. The microstructure and performance of experimental samples were carefully investigated using scanning electron microscope, energy disperse spectroscopy and other methodologies. The results showed that compared with mechanical grinding, laser cleaning can improve the surface paint coating of aluminum alloy more effectively. The surface of the matrix formed uniformly distributed volcanic craters and small holes emerged at the spot junction after laser cleaning. The carbon and oxygen content on the substrate surface after laser cleaning was much lower than that after mechanical grinding. In addition, the corrosion resistance and coating adhesion of the substrate were obviously improved using laser cleaning. It was closely associated with refinement of the grains and reduction in surface roughness. We concluded that laser cleaning can be widely used to replace mechanical grinding in manufacturing on the premise of meeting industrial needs. [ABSTRACT FROM AUTHOR]

Aluminum alloy 6061(AA6061) sheets of 4 mm in thickness are joined by laser wire-filling welding (LWFW) using the ER4047 welding wire. Microstructure and alloy element distributions near the fusion line are characterized and are investigated by optical microscope, scanning electron microscope, energy dispersive spectrometer. The results showed that the well-formed welded joints are obtained with a few thermal cracks near the fusion line. The coarse grain and a reduction in the weight ratio of magnesium to silicon can be observed, when the welding speed decreases under constant laser power. The thermal crack is caused by the decrease of the weight fraction of magnesium and the proportion of silicon content has an effect on the microhardness of welded joints. By properly controlling the welding speed, the various properties of AA6061 LWFW joints can be balanced. [ABSTRACT FROM AUTHOR]

Evaluation of inorganic and organic compounds as corrosion inhibitors of Cu-Zn alloys in H2SO4 and HNO3 solutions was studied using potentiodynamic and impedance spectroscopy along with scanning electron microscope (SEM) and energy dispersive X-Ray analyzer (EDX) investigations. The corrosion inhibition of Cu-Zn alloys was investigated in oxy acid solutions using inorganic potassium permanganate and di-hydrogen phosphate, amino acids as environmentally safe materials, commercial cooling water, and green tea extracts. Both potassium permanganate and di-hydrogen phosphate improve the corrosion resistance of Cu-Zn alloys. Phosphate appears more effective as corrosion inhibitor for Cu-Zn alloys than permanganate. The inhibition efficiency (IE%) of the different amino acids such as valine, leucine and lysine was also calculated. The experimental results have shown that amino acid-like lysine can be used as an efficient corrosion inhibitor for the Cu-Zn alloys in oxy acid solutions. This may be due to the presence of two amino groups adsorbed together. For lysine, inhibition efficiency, IE%, of ~87 and ~59 is for H2SO4 and ~96.3 and 54.9 for HNO3 for alloy I and II respectively are observed. Due to the composition of green water have a great effect on the inhibition action on Cu-Zn alloys which reaching 91.8 and 96.5% for Alloy I and 95.4 and 87.1% for Alloy II in 0.5 M H2SO4 and HNO3 respectively. Although benzotriazole, in cooling water, is an excellent inhibitor suitable for use in a wide variety of environments, it has toxic properties. So, much of the recent researches have focused on formulating new and more environmentally acceptable preservation solutions. The green tea, as plant extract, will be very environmentally friendly. The EDX confirm the formation of a protective layer on the Cu-Zn alloys containing aluminum in Alloy II. This sequence reflects the beneficial effects of Al in Alloy II. The presence of 2.43% Al in Alloy II improves the corrosion resistance due to the formation of thin, transparent, stable and self - healing Al2O3 layer. This confirmed the results obtained from the potentiodynamic polarization measurements and EIS methods. [ABSTRACT FROM AUTHOR]

Contact line movement over laser-textured metal alloy surfaces depends on the texture, droplet state, inversion of wettability, and liquid flow rate. Ordered and anisotropic textures were created by a nanosecond pulse laser on aluminum-magnesium alloy surfaces. Microrelief was studied on a profilometer and scanning electron microscope. Changes in wetting properties and the characteristics of spreading were obtained. To implement wetting cycles, liquid was dispensed with a syringe pump using the bottom-up method. The results provide new, in-depth knowledge to understand the mechanisms of the contact line movement on laser-textured metal surfaces. We have shown that by creating a texture with given parameters (ordered or anisotropic), it is possible to predict a change in wettability from superhydrophilic to hydrophobic, as well as a droplet state. In this paper, we have demonstrated that the contact angle hysteresis determines not only the deviation of the contact angle from equilibrium, but also the adhesion force between the droplet and the surface, a droplet state (Wenzel or Cassie-Baxter), and the wetting anisotropy of local areas on laser-textured alloy. We have recorded two states of the droplet on formed textures: the Wenzel with air cushions on anisotropic and the Wenzel with complete filling of cavities with water on ordered textures. [ABSTRACT FROM AUTHOR]

AlSi10Mg alloys reinforced by TiC particles were fabricated on 5052 aluminum alloys by laser additive manufacturing. The surface morphology, microstructure, microhardness, and tensile properties of the alloys fabricated with different processing parameters were investigated by optical microscope (OM), scanning electron microscope (SEM), Vickers hardness tester, and high-precision electronic universal testing machine. The results show that appropriate laser energy input leads to uniform distribution of TiC particles in the alloy. Fine needle-like TiC particles are precipitated from the grain boundary, which is beneficial to the improvement of mechanical properties of the alloy. The optimum process parameters are found to be 2500–3500 W for laser power, 600 mm/min for scanning velocity, and 2.0 mm for hatch spacing. For lower or higher laser energy input, aggregations are formed in the coatings. At the optimum processing parameters, the maximum microhardness and tensile strength of the TiC/AlSi10Mg alloys are much higher than those of others, which are 139.1 HV0.05 and 278.8 MPa, respectively. A large number of dimples have been found on the fracture surface of the alloys, which indicates the fracture mechanism of the alloy is ductile fracture. [ABSTRACT FROM AUTHOR]

In this study, we systematically investigated several typical interfaces of the T-phase (a precipitated phase in 2024 alloy), namely the T(200)/Al(403), T(101)/Al( 4 ‾ 03) and T(200)/Al(301) interface and analyzed interface properties through first-principles calculations and HAADF-STEM (High-angle annular dark-field scanning transmission electron microscope) observations. The calculation results show that AlMn- terminated interface is the most thermodynamically stable of the different terminal interfaces in T(200)/Al(403) and T(101)/Al( 4 ‾ 03) interface. Therefore, we also speculate that the T precipitated phase forms interface with aluminum matrix through the AlMn- terminated. By investigating the DOS(density of states) and the electron density difference of the interface, we prove that Al–Mn covalent bond is formed on the outer surface of the T phase. In addition, this work provides some basis for the analysis of the T phase and T/Al interface from an energy point of view through various data, which helps us to further investigate the properties of the interface. • Characterization of T(Al 20 Cu 2 Mn 3) precipitated phases in 2024 aluminum matrix by HAADF-STEM and EDS mapping. • For the first time and systematically, first-principle calculations were performed for different interfaces of T-phase, and their various properties were analyzed. • Three different interface calculations show that the AlMn- terminated interface is the most thermodynamically stable. • The (101) T / / (4 ‾ 03) A l interface is more stable. [ABSTRACT FROM AUTHOR]

Hot forming technique has served as a solution to overcome the poor formability of aluminum alloys at room temperature (RT). However, it also causes high energy consumption and a prolonged period of processing cycle. Apart from hot forming, warm forming is an alternative method for improving formability. In this work, warm forming processes for aluminum alloys were classified into two categories, including a conventional warm forming of T6-temper alloy (WF-T6) and a novel pre-hardening warm forming (PHF) process. Based on an Al–Zn–Mg–Cu alloy, warm tensile tests and Erichsen tests were performed to investigate the flow behavior and drawability, and Vickers hardness tests were used to evaluate the post-forming property. Superior formability and post-forming hardness were obtained at 200 ℃ in PHF process compared with WF-T6 process, which achieved a drawability 15% higher than that of O-temper alloy at RT, and a post-forming hardness superior to that of T6-temper blank. Against common sense, due to the particularity of the phase transition mechanism in PHF process, the temperature at 180 ℃ exhibited lower yield flow stress and post-forming hardness than 200 ℃. In addition, it is interesting to find that the inducement to the loss of hardness after forming at 250 ℃ was absolutely different in these two processes. Electron backscatter diffraction (EBSD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) tests were employed to characterize the microstructure evolution, and the engineering potential of these two processes was discussed. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, aluminum alloy doped with Mg, In, Sn and Bi (Al-0.02Mg-0.01Sn-0.004Bi-0.003In) is prepared via melting and casting process. The influence of rare earth elements Bi and In on electrochemical performance of aluminum alloy anode is studied. The self-corrosion of hydrogen evolution and the electrochemical performance are investigated for the prepared alloy in 4 M NaOH electrolyte. The scanning electron microscope is used to study the surface morphology of the prepared alloy after discharge. It shows that synergistic effect between the alloy elements significantly reduces the self-corrosion rate of aluminum anode. Discharge experiments display that the prepared alloy outputs high capacity density and energy density of 2857.14 A h kg−1 and 4805.71 W h kg−1 at a high discharge rate (50 mA cm−2), respectively. It can also obtained considerable anodic utilization of 95.94 %. The prepared aluminum alloy is a desirable candidate anode material for the high-performance Al-air battery. • The prepared alloy exhibits an equiaxed grain structure with an average grain size of 70 µm. • The prepared alloy outputs high capacity density and energy density. • The prepared alloy has low self-corrosion rate of hydrogen evolution. • The prepared alloy has considerable anodic utilization of 95.94 %. [ABSTRACT FROM AUTHOR]

Ce-based imidazole complex (Ce-IM/ZIF-8) nanoparticles (NPs) were fabricated by doping cerium ions (Ce3+ /Ce4+) in zeolite imidazolate framework-8 (ZIF-8) through a one-pot co-precipitation method. The stimuli-responsive release of Ce3+/Ce4+ species from the Ce-IM/ZIF-8 NPs under acidic conditions was confirmed by UV–Vis spectroscopy. Electrochemical impedance spectroscopy and scanning electron microscope were applied to evaluate the corrosion inhibition efficiency of Ce-IM/ZIF-8 NPs on bare aluminum alloy, and it demonstrates that the released Ce3+/Ce4+, Zn2+ ions and imidazole could absorb on the surface of Al alloy by chelating effect, forming a compact corrosion barrier on the Al substrate. Furthermore, the Ce-IM/ZIF-8 NPs were encapsulated into epoxy (EP) resin to obtain a composite coating, and it is found that when the NPs addition amount was 1 wt%, the EP-based composite coating exhibits excellent corrosion barrier and promising self-healing ability, with its impedance at 0.01 Hz maintaining 2.2 × 108 Ω·cm2 even after 6 cycles of aging tests (720 h), which could be ascribed to the synergistic inhibition of released Ce ions and imidazole molecules on Al substrate beneath the defective coating. A kind of cerium-centered ZIF-8 NPs with surface modified by Ce-imidazole complex (Ce-IM/ZIF-8) was synthesized, which not only realized pH stimuli-responsive release of Ce3+/Ce4+ ions to repair the damaged passive film on Al alloy, but also improved the anti-corrosion property of EP coating. [Display omitted] • Ce-IM decorated ZIF-8 NPs was synthesized by one-pot co-precipitation method. • Ce-IM/ZIF-8 NPs can release Ce3+, Zn2+ ions and imidazole upon acid stimulus. • Ce3+ ions and imidazole present synergistic inhibition effect on Al corrosion. • Ce-IM/ZIF-8 NPs exhibit excellent self-healing ability to EP coating defects. [ABSTRACT FROM AUTHOR]

This paper discusses the effect of stanum (Sn) addition on the physical properties of Al-5.5Zn-2.0Mg-xSn (where x = 0.1 - 2.0 wt. %) alloys. These alloys were prepared using conventional casting techniques. The phases, microstructures, hardness and electrical resistivity of as-cast and heat-treated Al-5.5Zn-2.0Mg-xSn alloys were characterised using a con focal laser scanning microscope (CLSM), an x-ray diffractometer (XRD), a four point probe resistivity meter and a scanning electron microscope (SEM). The hardness of heat-treated Al-5.5Zn-2.0Mg-xSn alloys was much better than that of as-cast alloys mainly due to the dispersive distribution of Mg2Sn phase in the aging-treated alloy. The calculated hardness values for both as-cast and heat treated Al-5.5Zn-2.0Mg-xSn alloys suggest that the decrease of hardness value with increasing Sn contents can be ascribed to formation of more Mg2Sn intermetallic compound in these alloys. Electrical resistivity measurement shows a decrease in both as-cast and heat-treated alloys with decreasing Sn content in these alloys. It was concluded that the addition of Sn gives a strong influence on the formation of strengthening precipitates and electron mobility in the Al-5.5Zn-2.0Mg-xSn alloys. [ABSTRACT FROM AUTHOR]

In this article, the effect of aging time in Al-Li-Hf alloy was studied. The samples were homogenized at 600°C and aged from 0.166 to 100 h at 190°C in thermal oil. According to scanning electron microscope (SEM) images, the effect of aging in the intermetalic precipitates changes its morphology as well as composition. For as cast alloys small Hf-Li precipitates with high Hf content exist. When considering aging samples the size precipitates increases, as does Hf content, from 30.74% for 1 h to 59.85% for 100 h. For an aging time of 100 h, the microhardness Vickers show better values which can be attributed to the Hf-Li solubility into the Al matrix to the point where their precipitation of intermetalic precipites and further cause changes in the dendritic arm spacing. [ABSTRACT FROM AUTHOR]

Fully lamellar (FL) Ti–46.5Al–2Cr–1.5Nb–1V (at%) alloy is used to study the relationship between microstructure and fracture toughness. A heat treatment process is adopted to control the microstructural parameters of the studied alloy. Fracture toughness experiments and scanning electron microscope (SEM) in-situ straining experiments are carried out to determine the influence of lamellar spacing and grain size on the fracture toughness of FL TiAl alloys. It is found that ligament length depends on the lamellar spacing, and fracture toughness varies non-monotonously with the increase of grain size. The results are ascribed to the competition between the microcrack nucleation and microcrack propagation. Finally a semi-empirical relationship between the fracture toughness and microstructure parameters was established. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, hot cracking in Al–(1–4.5%) Cu direct-chill (DC) cast billet was investigated by means of controlled DC casting followed by structure examination. No hot cracks were found in the billets of alloys containing more than 4% Cu. The hot tear surfaces of the DC cast billets with different compositions were observed in a scanning electron microscope. The porosity fraction measurement was also performed. It was found that decreasing the copper concentration from 3 to 1% caused a decrease in the amount of eutectic observed on the hot tear surface. Special features appeared on the hot tear surface of an Al–1% Cu alloy in which the hot tear predominantly propagated through the solid phase, i.e., bridged grain boundary. A solute-rich (eutectic) path along grain boundaries ahead of the hot-crack tip was observed in billets with hot tears, which could be an evidence of crack healing. The porosity concentrated in the center of the billet and its amount was lower in alloys with high hot tear susceptibility and in alloys not susceptible to hot tearing. Increased casting speed lead to increasing porosity. [Copyright &y& Elsevier]

A method of accurate serial sectioning has been designed for three-dimensional texture measurement in aluminium alloy sheet. Using this method, determination of three dimensional texture in an AA6111-T4P sheet has been carried out by electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM) from the sheet surface to 1/3 of the thickness. Optimal conditions for specimen preparation and SEM operation have been investigated to ensure minimum planar displacement or rotation among sections. It has been demonstrated that in the AA6111-T4P sheet the {001}<100> (cube), {011}<100> (Goss) and {011}<455> (P*) orientations are the major texture components. The through thickness averaged cube and Goss components are aligned parallel to the rolling direction forming a banded structure, and the bands of the cube and Goss are distributed alternately in the transverse direction. The variation in grain size is very limited compared with the texture components. [ABSTRACT FROM AUTHOR]

Strong adhesive bonding between carbon fibre reinforced polymer (CFRP) and aluminium (Al) alloy substrates is essential for structural integrity of modern aircrafts. This study reports a simple and effective method to increase the adhesion interface strength between CFRP and Al alloy substrates by means of a combined sandblasting and resin pre-coating (RPC) process. The RPC technique is used to maximize the full potential of surface abrasion from sandblasting by sealing all micro-cavities and wetting the entire surface and sub-surface openings over the Al substrate and CFRP. The RPC solution consisting of around 90 wt% of acetone and 10 wt% of resin (without hardener) takes resin into the surface micro-openings and effectively increases the wettability of bond surfaces. Based on single lap shear tests, over 170.2% of improvement in the shear strength has been achieved by the combined sandblasting and RPC method in compared with the adhesive joints without any surface treatment. The surface roughness, contact angle measurements and Scanning Electron Microscope (SEM) observations are conducted to investigate the wettability and microstructural details, confirming the effectiveness of the RPC technique. [ABSTRACT FROM AUTHOR]

The microstructural and wear properties of laser-cladding WC/Ni-based layer on Al–Si alloy were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and wear-testing. The results show that, compared with the original specimen, the microhardness and wear resistance of the cladding layer on an Al–Si alloy were remarkably improved, wherein the microhardness of the layer achieved 1100 HV and the average friction coefficient of the layer was barely 0.14. The mainly contributor to such significant improvement was the generation of a WC/Ni-composite layer of Al–Si alloy during laser cladding. Two types of carbides, identified as M7C3 and M23C6, were found in the layer. The wear rate of the layer first increased and then decreased with the increase in load; when the load was 20 N, 60 N and 80 N, the wear rate of layer was1.89 × 10−3 mm3·m−1, 3.73 × 10−3 mm3·m−1 and 2.63 × 10−3 mm3·m−1, respectively, and the average friction coefficient (0.14) was the smallest when the load was 60 N. [ABSTRACT FROM AUTHOR]

High entropy alloy (HEA) is an emerging class of materials that shows promising potential for many applications. Numerous HEAs have been synthesized and characterized over the past twenty years, however only limited researches have been done on the welding process of HEAs. In this research, AlCoCrFeNi High Entropy Alloys and Al-6061 plates are welded by using the explosive welding technique. In order to characterize the morphology and the composition of the compound, a scanning electron microscope was utilized. The weldability window was calculated in order to verify the weldabilty of the AlCoCrFeNi to Al-6061, and three different conditions were selected to perform the experiments. In all the experiments the AlCoCrFeNi and Al-6061 were properly welded together. However, some cracks were observed in the welded samples obtained in high velocity collision. The results suggest that the explosive welding technique is potentially a good method for joining high entropy alloys to other metals. • AlCoCrFeNi High Entropy Alloys and Aluminum plats are welded by using the explosive welding technique. • The weldability window was calculated in order to verify the weldabilty of the AlCoCrFeNi to Aluminium. • The Sample with the stand of distance of 1 mm shows a straight interface. [ABSTRACT FROM AUTHOR]