Sample records for mg aluminum al

  1. First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys

    LIAO Fei


    Full Text Available Structural stabilities, mechanical properties and electronic structures of Al2Cu, Al2CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The results show that the cohesive energy (Ecoh decreases in the order MgZn2 > Al2CuMg > Al2Cu, whereas the formation enthalpy (ΔH decreases in the order MgZn2 > Al2Cu > Al2CuMg. Al2Cu can act as a strengthening phase for its ductile and high Young's modulus. The Al2CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic interaction in Al2Cu, Al2CuMg and MgZn2, and that improves the structural stability. In order to improve the alloys' performance further, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.

  2. Localized Corrosion Behavior of Al-Si-Mg Alloys Used for Fabrication of Aluminum Matrix Composites

    Pech-Canul, M. A.; Giridharagopal, R.; Pech-Canul, M. I.; Coral-Escobar, E. E.


    The relationship between microstructure and localized corrosion behavior in neutral aerated chloride solutions was investigated with SEM/EDAX, conventional electrochemical techniques, and with scanning Kelvin probe force microscopy (SKPFM) for two custom-made alloys with Si/Mg molar ratios of 0.12 and 0.49. In this order, Al3Fe, Al3Mg2, and Mg2Si intermetallics were identified in the first alloy and Al(FeMn)Si and Mg2Si particles in the second one. Anodic polarization curves and corrosion morphology showed that the alloy with higher Si/Mg molar ratio exhibited a better corrosion performance and evidence was shown that it had a more corrosion-resistant passive film. The corrosion process for both alloys in aerated 0.1 M NaCl solutions was localized around the Fe-rich intermetallics. They acted as local cathodes and produced dissolution of the aluminum matrix surrounding such particles. Mg2Si and Al3Mg2 exhibited anodic behavior. SKPFM was successfully used to map the Volta potential distribution of main intermetallics. The localized corrosion behavior was correlated with a large Volta potential difference between the Fe-rich intermetallics and the matrix. After immersion in the chloride solution, such Volta potential difference decreased.


    G.Y. Lin; Z.F. Zhang; H. Zhang; D.S. Peng; J. Zhou


    The hot deformation behaviors and mierostructures of Al-Zn-Mg-Cu-Cr aluminum alloy have been studied using thermal simulation test, optical microscopy and transmission electron microscopy. As a result, the true stress versus true strain curves and the microstructures under various deformation conditions are obtained. The microstructures gradually incline to dynamic-recrystallization with the deformation temperature rising and the recrystallization grains refine with the decrease of deformation temperature or with raising the strain rates. The quantitative relationship between the Zener-HoUomon parameter (Z) and average recrystallization grain size in the subsequent heat treatment is set up.

  4. Evaluation of Ultrasonic Nonlinear Characteristics in Heat-Treated Aluminum Alloy (Al-Mg-Si-Cu

    JongBeom Kim


    Full Text Available The nonlinear ultrasonic technique has been known to be more sensitive to minute variation of elastic properties in material than the conventional linear ultrasonic method. In this study, the ultrasonic nonlinear characteristics in the heat-treated aluminum alloy (Al-Mg-Si-Cu have been evaluated. For this, the specimens were heat treated for various heating period up to 50 hours at three different heating temperatures: 250°C, 300°C, and 350°C. The ultrasonic nonlinear characteristics of each specimen were evaluated by measuring the ultrasonic nonlinear parameter β from the amplitudes of fundamental and second harmonic frequency components in the transmitted ultrasonic wave. After the ultrasonic test, tensile strengths and elongations were obtained by the tensile test to compare with the parameter β. The heating time showing a peak in the parameter β was identical to that showing critical change in the tensile strength and elongation, and such peak appeared at the earlier heating time in the higher heating temperature. These results suggest that the ultrasonic nonlinear parameter β can be used for monitoring the variations in elastic properties of aluminum alloys according to the heat treatment.

  5. Studies on the Influence of Sintering Temperature on Crystalline Structures of Mg-Al Spinel Synthesized by Waste Aluminum Slag

    YU Yan; RUAN Yu-Zhong; WU Ren-Ping


    Mg-Al spinel is synthesized by using industrial waste-residue and basic magnesium carbonate in the aluminum factory as the main raw materials. The influence of sintering temperature on crystalline structure and microstructure of Mg-Al spinel has been mainly discussed. The crystalline structure of sample is characterized by using XRD, SEM and relevant analytical software. The experimental results show that compared to the conventional synthetic method, the application of waste aluminum slag as the raw material can greatly decrease the synthetic tem-perature. The content of Mg-Al spinel first increases and then decreases with the rise of sintering temperature, and its purity can reach as high as 96wt% at 1550 ℃, which is therefore determined to be the optimum synthetic temperature. SEM observations demonstrate that as the rise of sintering temperature, the grain of Mg-Al spinel grows up obviously with typical octahedral characteristic appearance.

  6. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments

    Holroyd, N. J. Henry; Scamans, G. M.


    Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack ("pop-in" vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies ( E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (alloys (>~0.8 wt pct), they are typically

  7. First principles calculations of formation energies and elastic constants of inclusions α-Al2O3, MgO and AlN in aluminum alloy

    Liu, Yu; Huang, Yuanchun; Xiao, Zhengbing; Yang, Chuge; Reng, Xianwei


    In this paper, the formation energies and elastic constants of α-Al2O3, MgO and AlN in both rock salt (cubic) and wurtzite (hexagonal) structures were investigated by first principles calculations. The results show that the formation energy being -17.8, -6.3, -3.06 and -3.46 eV/formula unit for α-Al2O3, MgO, AlN (rock salt) and AlN (wurtzite). It suggests that in the ground state, α-Al2O3 is relatively more stable than MgO and AlN. The elastic properties for a polycrystalline in the ground state were calculated with the obtained elastic constants, the elastic properties reveal the rock salt structure AlN is the hardest particles among all the inclusions, and all of these inclusions are classified as brittle materials, which is detrimental to the ductile nature of aluminum matrix. The calculated anisotropy index shows that the AlN (wurtzite) and α-Al2O3 have a lower degree of anisotropy compared with MgO and AlN (rock salt). The calculated results are in good agreement with the values of experimental and other works.

  8. Mechanical Behavior of Aluminum (AlSi10Mg)-RHA Composite

    S.D.Saravanan; M. Senthilkumar


    Rice Husk Ash (RHA) of three different particle size ranges (50 – 75 μm), (75 – 100μm) and (100 – 150μm) in 3, 6, 9 and 12 % by weight was reinforced with the aluminium alloy using stir cast route. The microstructure and mechanical properties of the fabricated composites were analyzed. The results reveal that the tensile strength, compressive strength and hardness of the aluminum alloy composites decrease with increase in particle size of RHA. But increase in the weight fractions of RHA parti...

  9. Natural Aging Behavior Of Friction Stir Welded Al-Zn-Mg-Cu Aluminum Alloys

    Kalemba I.


    Full Text Available The long term natural aging behavior of friction stir welded aluminum 7136-T76 and 7042 T6 extrusions was investigated. The microstructural characteristics and mechanical properties in the as-welded and six years naturally aged conditions were studied and correlated to a coupled thermal/material flow model of the joining process. Hardness profiles for the 7136 alloy taken along the mid-plane thickness of the workpiece displayed the characteristic W-shape. With natural aging, hardness recovery occurred on both sides of the weld, but the position of the hardness minima, particularly on the advancing side, shifted away from the weld centerline. The hardness profile for the 7042 alloy displayed U-shape in the as-welded condition and W-shape after natural aging. The hardness behavior upon natural aging correlated to the temperature profile developed during welding and the degree to which phase dissolution occurred in the regions adjacent to the stir zone.

  10. Influence of the selected structural parameter on a depth of intergranular corrosion of Al-Si7-Mg0,3 aluminum alloy

    L. Bernat


    Full Text Available The paper presents an influence of the Dendrite Arm Spacing (DAS microstructure parameter on the intergranular corrosion of AlSi7Mg aluminum alloy. The samples were subjected to the corrosion process for: 2,5; 12; 24; 48 and 96 hours in NaCl + HCl + H2O solution. It was noted that the DAS parameter significantly influenced on a distribution and depth of the intergranular corrosion of the hypoeutectic Al - Si - Mg silumin.

  11. Influence of Temperature on Mechanical Behavior During Static Restore Processes of Al-Zn-Mg-Cu High Strength Aluminum Alloy

    ZHANG Kun


    Full Text Available Flow stress behaviors of as-cast Al-Zn-Mg-Cu high strength aluminum alloy during static restore processes were investigated by: Isothermal double-pass compression tests at temperatures of 300-400℃, strain rates of 0.01-1 s-1, strains of 33% +20% with the holding times of 0~900 s after the first pass compression. The results indicate that the deformation temperature has a dramatical effect on mechanical behaviors during static restore processes of the alloy. (1 At 300 ℃ and 330 ℃ lower temperatures, the recovery during the deformation is slow, and deformation energy stored in matrix is higher, flow stresses at the second pass deformation decreased during the recovery and recrystallization, and the stress softening phenomena is observed. Stress softening is increased with the increasing holding time; Precipitation during the holding time inhibites the stress softening. (2 At 360 ℃ and 400 ℃ higher temperatures, the recovery during deformation is rapid, and deformation energy stored in matrix is lower. Solid solubility is higher after holding, so that flow stress at the second pass deformation is increased, stress hardening phenomena is observed. Stress hardening decreased with the increasing holding time duo to the recovery and recrystallization during holding period at 360 ℃; Precipitation during holding also inhibited the stress softening. However, Stress hardening remains constant with the increasing holding time duo to the reasanenal there are no recovery and recrystallization during holding period at 400 ℃.

  12. Electrochemical Codeposition of Al-Li-Mg Alloys at Solid Aluminum Electrode from LiCl-KCl-MgCl2 Molten Salt System

    Ye, Ke; Zhang, Mi Lin; Chen, Ye; Han, Wei; de Yan, Yong; Cao, Peng


    The electrochemical codeposition of Mg and Li at an aluminium electrode in LiCl-KCl (50:50 wt pct) melts containing different concentrations of MgCl2 at 893 K (620 °C) to form Al-Li-Mg alloys was investigated. Cyclic voltammograms showed that the potential of Li metal deposition at an Al electrode, before the addition of MgCl2, is more positive than that of Li metal deposition at an Mo electrode, which indicated the formation of an Al-Li alloy. The underpotential deposition of magnesium at an aluminium electrode leads to the formation of Al-Mg alloys, and the succeeding underpotential deposition of lithium on predeposited Al-Mg alloys leads to the formation of Al-Li-Mg alloys. Chronopotentiometric measurements indicated that the codeposition of Mg and Li occurs at current densities lower than -0.668 A cm-2 in LiCl-KCl-MgCl2 (8 wt pct) melts at an aluminium electrode. The chronoamperometric studies indicated that the onset potential for the codeposition of Mg and Li is -2.000 V, and the codeposition of Mg and Li at an aluminium electrode is formed into Al-Li-Mg alloys when the applied potentials are more negative than -2.000 V. X-ray diffraction and inductively coupled plasma analysis indicated that Al-Li-Mg alloys with different lithium and magnesium contents were prepared via potentiostatic and galvanostatic electrolysis. The microstructure of typical dual phases of the Al-Li-Mg alloy was characterized by an optical microscope and by scanning electron microscopy. The analysis of energy dispersive spectrometry showed that the elements of Al and Mg distribute homogeneously in the Al-Li-Mg alloy. The lithium and magnesium contents of Al-Li-Mg alloys can be controlled by MgCl2 concentrations and by electrolytic parameters.

  13. Tribological Behavior of Aluminum Alloy AlSi10Mg-TiB2 Composites Produced by Direct Metal Laser Sintering (DMLS)

    Lorusso, Massimo; Aversa, Alberta; Manfredi, Diego; Calignano, Flaviana; Ambrosio, Elisa Paola; Ugues, Daniele; Pavese, Matteo


    Direct metal laser sintering (DMLS) is an additive manufacturing technique for the production of parts with complex geometry and it is especially appropriate for structural applications in aircraft and automotive industries. Aluminum-based metal matrix composites (MMCs) are promising materials for these applications because they are lightweight, ductile, and have a good strength-to-weight ratio This paper presents an investigation of microstructure, hardness, and tribological properties of AlSi10Mg alloy and AlSi10Mg alloy/TiB2 composites prepared by DMLS. MMCs were realized with two different compositions: 10% wt. of microsize TiB2, 1% wt. of nanosize TiB2. Wear tests were performed using a pin-on-disk apparatus on the prepared samples. Performances of AlSi10Mg samples manufactured by DMLS were also compared with the results obtained on AlSi10Mg alloy samples made by casting. It was found that the composites displayed a lower coefficient of friction (COF), but in the case of microsize TiB2 reinforcement the wear rate was higher than with nanosize reinforcements and aluminum alloy without reinforcement. AlSi10Mg obtained by DMLS showed a higher COF than AlSi10Mg obtained by casting, but the wear rate was higher in the latter case.

  14. Thermal conductivity of diethylene glycol based magnesium-aluminum spinel (MgAl2O4-DG) nanofluids

    Żyła, Gaweł; Fal, Jacek; Gizowska, Magdalena; Perkowski, Krzysztof


    The paper presents the results of measurements of the thermal conductivity of MgAl_2O_4 -DG nanofluids. The dependence of the thermal conductivity on concentration of nanoparticles in various temperatures from 293.15 to 338.15 K with 15 K step was examined. Experimental data was modeled with existing theoretical models describing the effects of the concentration of particles on the thermal conductivity of the suspension. It was presented that thermal conductivity of MgAl_2O_4 -DG nanofluids increases proportional to volume concentration of nanoparticles.

  15. In-situ synthesis of MgAl{sub 2}O{sub 4} nanowhiskers reinforced 6061 aluminum alloy composites by reaction hot pressing

    Xing, Li; Zhang, Yaxuan; Shi, Chunsheng, E-mail:; Zhou, Yang; Zhao, Naiqin; Liu, Enzuo; He, Chunnian


    In-situ generated MgAl{sub 2}O{sub 4} nanowhiskers, with diameters ranging from 30 to 200 nm, reinforced 6061 aluminum alloy composites have been successfully synthesized by reaction hot pressing under a relatively low temperature (600 °C). The effects of temperature and pressure on the morphology of MgAl{sub 2}O{sub 4} whiskers, as well as microstructure, densification and mechanical properties of the composites were investigated in detail. The results indicate that the MgAl{sub 2}O{sub 4} nanowhiskers with aspect ratio about 10–50 are uniformly distributed and firmly bonded with the matrix. Most of the nanowhiskers acting as bridges penetrate into the Al particles to form a framework bearing and transferring extrinsic loads. The high-resolution transmission electron microscope observation reveals that the MgAl{sub 2}O{sub 4}/Al interface is clean, smooth and free from interfacial product, and the whiskers have well-bonded interfaces with matrix. Additionally, the composites, prepared by sintering at 600 °C under the pressure of 50 MPa, exhibit the optimal performance.

  16. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.


    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  17. Effect of geometrical stress concentrators on the current-induced suppression of the serrated deformation in an aluminum-magnesium AlMg5 alloy

    Shibkov, A. A.; Zolotov, A. E.; Zheltov, M. A.; Denisov, A. A.; Gasanov, M. F.; Kochegarov, S. S.


    The effect of an electric current on the band formation and the serrated deformation of planar specimens made of an aluminum-magnesium AlMg5 alloy and weakened by holes is experimentally studied. It is found that the concentration of elastic stress fields and the self-localized unstable plastic deformation field near a hole decreases the critical strain of appearance of the first stress drop and hinders the currentinduced suppression of band formation and the serrated Portevin-Le Chatelier deformation. These results are shown not to be related to the concentration of Joule heat near a hole.

  18. Tungsten inert gas (TIG welding of aluminum alloy EN AW-AlZn5.5MgCu

    J. Tušek


    Full Text Available The paper presents the results of tungsten inert gas (TIG welding of aluminium alloy 7075-T6 in the butt joint, with single-V edge preparation. The sample dimensions were 100 × 75 × 20 mm3. The TIG welding was done with 2 mm diameter filler wire made of 5183 (AlMg4,5Mn at four preheating temperatures. During the welding a temperature was measured at six locations with thermocouples. For successfully welded samples tensile test were done and microstructure of base metal, heat affected zone and weld was analysed. The welds brake at heat affected zone between base metal and the weld. The optimal preheating temperature was at 200 °C.

  19. Potential of an Al-Ti-MgAl2O4 Master Alloy and Ultrasonic Cavitation in the Grain Refinement of a Cast Aluminum Alloy

    Sreekumar, V. M.; Babu, N. H.; Eskin, D. G.


    A new grain refining master alloy containing MgAl2O4 and Ti was synthesized by in situ reaction of TiO2 particles in an Al-Mg melt. MgAl2O4 particles formed were distributed in the melt by ultrasonic cavitation processing. The obtained master alloy showed considerable (50 pct) grain refining ability in a commercial A357-type Al-Si alloy. Ultrasonication contributed further to 25 pct in the grain refinement. In comparison with a commercial Al-5 pct Ti-1 pct B master alloy, the efficiency of the new master alloy is less at a lower addition rate. Nevertheless, both master alloys performed similarly at higher additions. The strength and ductility of the inoculated and ultrasonicated alloy showed at least a 10 pct and a 50 pct increase, respectively, as compared with non-grain-refined alloy and a similar mechanical performance in comparison with the alloy inoculated with Al-5 pct Ti-1 pct B master alloy.

  20. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR


    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  1. Influence of pin structure on microstructure and mechanical properties of friction stir welded AA 6063 (AlMgSi 0.5) aluminum alloy

    Sayer, S.; Ceyhun, V. [Ege Univ., Izmir (Turkey)


    In this study, AA 6063 (AlMgSi0.5) Aluminum alloy plates were welded by a solid state welding procedure, friction stir welding (FSW). The influence of pin structure on the microstructure of the weld region and the mechanical properties of the joints were studied. It has been seen that the helical structure on pinscrew has an effective role on the formation of a zigzag line in the weld region. While rather long and uninterrupted zigzag lines in the weld region are obtained when right helical pinscrew is used, left helical pinscrew gave rise to shorter zigzag lines. While the zigzag line has no effect on the mechanical properties of the as-welded joint, heat treatment after the welding (PWHT) procedure seriously affects the strength of the joint due to the zigzag line formed in the weld region. The mechanical strength decreases with right helical pinscrew in PWHT, whereas, left helical pinscrew causes an increase in mechanical strength. (orig.)

  2. Degradation processes in Al/SiC{sub p}/MgAl{sub 2}O{sub 4} composites prepared from recycled aluminum with fly ash and rice hull ash

    Pech-Canul, M.I.; Escalera-Lozano, R.; Rendon-Angeles, J.C.; Lopez-Cuevas, J. [Cinvestav Saltillo, Carr. Saltillo-Mty. Km. 13, Saltillo, Coah, Mexico 25900 (Mexico); Pech-Canul, M.A. [Cinvestav Merida, Km. 6 Antigua Carr. a Progreso Apdo. Postal 73, Cordemex. Merida, Yuc., Mexico 97310 (Mexico)


    The degradation characteristics of Al/SiC{sub p}/spinel composites prepared with fly ash (FA) and rice hull ash (RHA) under environmental conditions were investigated. Composite specimens were prepared with recycled aluminum via reactive infiltration in the temperature range 1050-1150 C for 50-70 min and, in argon atmosphere at a pressure slightly above that of the atmospheric pressure. Results reveal that although both FA and RHA help in preventing SiC{sub p} dissolution and the subsequent chemical degradation of the composites, due to the interaction of native carbon in FA with liquid aluminum, FA-composites are susceptible to corrosion via Al{sub 4}C{sub 3}. Moreover, this phase accelerates the degradation process and increases the damage severity. The primary corrosion mechanism in both types of composites is attributed to microgalvanic coupling between the intermetallic Mg{sub 2}Si and the matrix. Accordingly, an appropriate control of the Si/(Si + Mg) molar ratio in the aluminum alloy hinders the Mg{sub 2}Si corrosion mechanism in both types of composites and a proper FA calcination prevents chemical degradation in FA composites. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  3. Hydrogenation properties of Mg-Al alloys

    Andreasen, Anders


    In this paper the properties of Mg-Al alloys in relation to hydrogen storage are reviewed. The main topics of this paper are materials preparation, hydrogen capacity, thermodynamics of hydride formation, and the kinetics of hydride formation and decomposition. Hydrogenation of Mg-Al leads...... to disproportionation with the formation of magnesium hydride and metallic aluminum as the final product. Experimental evidence renders this process reversible. It is observed that the enthalpy of hydride formation of magnesium is lowered upon alloying with Al due to a slightly endothermic disproportionation reaction....... Further, it is found that the kinetics of hydrogenation, as well dehydrogenation, may be significantly improved by alloying compared to pure Mg. The expense of these improvements of the hydrogenation/dehydrogenation properties is a lower gravimetric hydrogen density in the hydrogenated product, (C) 2008...

  4. Effect of Weld Characteristic on Mechanical Strength of Laser-Arc Hybrid-Welded Al-Mg-Si-Mn Aluminum Alloy

    Zhang, Chen; Gao, Ming; Jiang, Ming; Zeng, Xiaoyan


    Laser-arc hybrid welding (LAHW) was employed to improve the tensile properties of the joints of 8-mm-thick Al-Mg-Si-Mn alloy (AA6082) using Al-5Mg filler wire. The weld microstructures were examined by scanning electron microscope, electron backscattered diffraction, and transmission electron microscopy in detail. The LAHW joints with pore-free and high-tensile performances were obtained. The strength enhancement of the fusion zone and heat-affected zone in the LAHW joint was mainly attributed to the grain refinement strengthening and the precipitation strengthening, respectively. The microstructure characteristics were related to the effects of laser-arc interaction on the energy transfer within the molten pool. The arc caused the majority of laser energy to dissipate out of the keyhole, and then it reduced the heat input. The lower heat input refined the grain size, weakened the overaging effect, and thus improved the tensile strength.

  5. Combining Aluminum Heat Treat with Hot Isostatic Pressing:A Comparison of Structure, Properties, and Processing Routes for a Cast Al-Si-Mg Alloy

    Stephen J. Mashl


    Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal(R), a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response fiom that seen in conventional processing.This paper reviews the results of experiments performed to A1-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.

  6. Effect of trace La addition on the microstructures and mechanical properties of A356 (Al-7Si-0.35Mg) aluminum alloys

    Tsai, Y.-C.; Chou, C.-Y. [Department of Mechanical Engineering, National Central University, Jhongli, Taiwan (China); Lee, S.-L., E-mail: [Department of Mechanical Engineering/Institute of Materials Science and Engineering, National Central University, Jhongli, Taiwan (China); Lin, C.-K. [Department of Mechanical Engineering, National Central University, Jhongli, Taiwan (China); Lin, J.-C. [Department of Mechanical Engineering/Institute of Materials Science and Engineering, National Central University, Jhongli, Taiwan (China); Lim, S.W. [Renewable Energy R and D Center, Chung-Hsin Electric and Machinery Mfg. Corp., Taiwan (China)


    A356 hypoeutectic alloy is a heat-treatable Al-Si-Mg system with a normal composition of Al-7 wt.% Si and about 0.35 wt.% Mg which has widespread applications in the aerospace and automotive industries. The purpose of this study is to determine the influence of different amounts of La on the microstructures and mechanical properties of A356 alloys. The microstructures of as-cast samples were examined by using optical microscopy (OM), scanning electron microscopy (SEM) and image analysis. The mechanical properties were investigated by tensile test, and the quality index (Q = UTS + 150 x log (elongation)) was used to evaluate the modification efficiency of different La contents. The findings indicated that the modification efficiency in microstructures and mechanical properties of A356 alloy with 1.0 wt.% La are similar to those modified by the commercial modifier, 0.01 wt.% Sr. Furthermore, the results of thermal analysis reveal that there is no direct relationship between eutectic growth temperature and silicon morphology/modification rating.

  7. Investigation on the Interface Characteristics of Al/Mg Bimetallic Castings Processed by Lost Foam Casting

    Jiang, Wenming; Li, Guangyu; Fan, Zitian; Wang, Long; Liu, Fuchu


    The lost foam casting (LFC) process was used to prepare the A356 aluminum and AZ91D magnesium bimetallic castings, and the interface characteristics of the reaction layer between aluminum and magnesium obtained by the LFC process were investigated in the present work. The results indicate that a uniform and compact interface between the aluminum and magnesium was formed. The reaction layer of the interface with an average thickness of approximately 1000 μm was mainly composed of Al3Mg2 and Al12Mg17 intermetallic compounds, including the Al3Mg2 layer adjacent to the aluminum insert, the Al12Mg17 middle layer, and the Al12Mg17 + δ eutectic layer adjacent to the magnesium base. Meanwhile, the Mg2Si intermetallic compound was also detected in the reaction layer. An oxide film mainly containing C, O, and Mg elements generated at the interface between the aluminum and magnesium, due to the decomposed residue of the foam pattern, the oxidations of magnesium and aluminum alloys as well as the reaction between the magnesium melt and the aluminum insert. The microhardness tests show that the microhardnesses at the interface were obviously higher than those of the magnesium and aluminum base metals, and the Al3Mg2 layer at the interface had a high microhardness compared with the Al12Mg17 and Al12Mg17 + δ eutectic layers, especially the eutectic layer.

  8. Extrusion die geometry effects on the energy absorbing properties and deformation response of 6063-type Al-Mg-Si aluminum alloy

    Gbenebor, O. P.; Fayomi, O. S. I.; Popoola, A. P. I.; Inegbenebor, A. O.; Oyawale, F.

    The response of 6063-type Al-Mg-Si alloy to deformation via extrusion was studied using tool steel dies with 15°, 30°, 45°, 60° and 75° entry angles. Compressive loads were subjected to each sample using the AVERY DENISON machine, adapted to supply a compressive load on the punch. The ability of the extrudate to absorb energy before fracture was calculated by integrating numerically the polynomial relationship between the compressive stress and sample strains. Strain rate was calculated for each specimen and the deformation zone length was mathematically derived from the die geometry to decipher its influence on both lateral and axial deformations. Results showed that extruding with a 15° die was the fastest as a result of the low flow stress encountered. Outstanding compressive strength, plastic deformation, strain rate and energy absorbing capacity were observed for the alloy extruded with a 75° die angle. Increase in die angles led to a decrease in deformation zone length and samples deformed more in the axial direction than in the lateral except for the 45o die which showed the opposite; the sample also showed the least ductility.

  9. New scheme for cation distribution and electrical characterization of nanocrystalline aluminum doped magnesium ferrite MgAl{sub x}Fe{sub 2−x}O{sub 4}

    Zaki, H.M., E-mail: [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Physics, Faculty of Science, Zagazig University, Zagazig (Egypt); Al-Heniti, S.; Al Shehri, N. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia)


    MgAl{sub x}Fe{sub 2−x}O{sub 4} (x=0.0 up to 1 step 0.2) was prepared using co-precipitation method. The value of lattice constant is found to decrease with increasing Al{sup 3+} concentration. The particle size of the samples calculated using the Sherrer formula was obtained in the range of 15–28 nm. The two main bands corresponding to tetrahedral and octahedral sites were observed to be around 600 cm{sup −1} and 450 cm{sup −1}, respectively. These bands are shifted to high frequencies with more doping of Al{sup 3+} ions which may be attributed to the decrease in the mean radius of the tetrahedral and octahedral sites. The threshold frequency (ν{sub th}) for the electronic transition decreases with increasing the Al{sup 3+}content. The tetrahedral force constant (K{sub T}) increases continuously with Al{sup 3+} concentration.The bandwidth of the tetrahedral site is found to increase gradually with the Al{sup 3+} content. The validity of the proposed cation distribution is confirmed by considering the X-ray intensity ratios of diffraction lines sensitive to the tetrahedral and octahedral sites. DC conductivity measurements exhibited metallic and semiconductor-like behavior with temperature for all compositions. The decrease of Curie temperature with the increase of non-magnetic ions of aluminum indicates their preference to the octahedral sites as well and confirms the validity of the cation distribution.

  10. Control of Defects in Aluminum Gallium Nitride ((Al)GaN) Films on Grown Aluminum Nitride (AlN) Substrates


    like HEMTs . A nanolayer of AlGaN over GaN provides extra 2DEG charge density because of the piezoelectric effect of the AlGaN layer. The higher...Control of Defects in Aluminum Gallium Nitride ((Al) GaN ) Films on Grown Aluminum Nitride (AlN) Substrates by Iskander G. Batyrev, Chi-Chin Wu...Aluminum Gallium Nitride ((Al) GaN ) Films on Grown Aluminum Nitride (AlN) Substrates Iskander G. Batyrev and N. Scott Weingarten Weapons and

  11. Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    Bateni, Ali; Erdem, Emre; Repp, Sergej; Weber, Stefan; Somer, Mehmet


    Undoped and aluminum (Al) doped magnesium diboride (MgB2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB2. Above a certain level of Al doping, enhanced conductive properties of MgB2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  12. The Interplay of Al and Mg Speciation in Advanced Mg Battery Electrolyte Solutions.

    See, Kimberly A; Chapman, Karena W; Zhu, Lingyang; Wiaderek, Kamila M; Borkiewicz, Olaf J; Barile, Christopher J; Chupas, Peter J; Gewirth, Andrew A


    Mg batteries are an attractive alternative to Li-based energy storage due to the possibility of higher volumetric capacities with the added advantage of using sustainable materials. A promising emerging electrolyte for Mg batteries is the magnesium aluminum chloride complex (MACC) which shows high Mg electrodeposition and stripping efficiencies and relatively high anodic stabilities. As prepared, MACC is inactive with respect to Mg deposition; however, efficient Mg electrodeposition can be achieved following an electrolytic conditioning process. Through the use of Raman spectroscopy, surface enhanced Raman spectroscopy, (27)Al and (35)Cl nuclear magnetic resonance spectroscopy, and pair distribution function analysis, we explore the active vs inactive complexes in the MACC electrolyte and demonstrate the codependence of Al and Mg speciation. These techniques report on significant changes occurring in the bulk speciation of the conditioned electrolyte relative to the as-prepared solution. Analysis shows that the active Mg complex in conditioned MACC is very likely the [Mg2(μ-Cl)3·6THF](+) complex that is observed in the solid state structure. Additionally, conditioning creates free Cl(-) in the electrolyte solution, and we suggest the free Cl(-) adsorbs at the electrode surface to enhance Mg electrodeposition.

  13. Formation Mechanism of CaO-SiO2-Al2O3-(MgO) Inclusions in Si-Mn-Killed Steel with Limited Aluminum Content During the Low Basicity Slag Refining

    Wang, Kunpeng; Jiang, Min; Wang, Xinhua; Wang, Ying; Zhao, Haoqian; Cao, Zhanmin


    Pilot trails were carried out to study the formation mechanism of CaO-SiO2-Al2O3-(MgO) inclusions in tire cord steel. 48 samples were taken from 8 heats of liquid steel during secondary refining, which were subsequently examined by an automatic scanning electron microscope with energy dispersive spectrometer (SEM-EDS). Characteristics of thousands of oxide inclusions at different refining stages were obtained, including their compositions, sizes, morphologies, etc. Based on the obtained information of inclusions, details during formation of CaO-SiO2-Al2O3-(MgO) inclusions were revealed and a new mechanism was proposed, including their origin, formation, and evolution during the refining process. It was found that CaO-SiO2-Al2O3-(MgO) inclusions were initially originated from the CaO-SiO2-MnO-(MgO) inclusions, which were formed during BOF tapping by the coalescence between MnO-SiO2 deoxidation products and the emulsified slag particles because of violent flow of steel. This can be well confirmed by the evaluation of the formation thermodynamics of CaO-SiO2-MnO-(MgO) inclusions, which was proved very difficult to be produced by intrinsic reactions inside liquid steel. Because of chemical reactions between CaO-SiO2-MnO-(MgO) inclusions and molten steel, they were mainly changed into CaO-SiO2-MnO-Al2O3-(MgO) and partially into CaO-SiO2-Al2O3-(MgO), which may be detrimental to the cold drawing ability of coils. Based on this finding, improvements were made in industrial production during BOF tapping and secondary refining. The results indicated that such (CaO-SiO2)-based inclusions existed in conventional process were effectively decreased after the improvements.

  14. The anodic and cathodic dissolution of Al and Al-Cu-Mg alloy

    Mokaddem, M.; Volovitch, P. [Laboratoire de physicochimie des surfaces, UMR7045, Ecole Nationale Superieure de Chimie de Paris, ParisTech, 11, rue Pierre et Marie Curie, Paris (France); Rechou, F.; Oltra, R. [Institut CARNOT de Bourgogne, Electrochimie Interfaciale-Corrosion, UMR5209, Universite de Bourgogne, Dijon (France); Ogle, K., E-mail: kevin-ogle@enscp.f [Laboratoire de physicochimie des surfaces, UMR7045, Ecole Nationale Superieure de Chimie de Paris, ParisTech, 11, rue Pierre et Marie Curie, Paris (France)


    Atomic emission spectroelectrochemistry (AESEC) was used to monitor the release of Al from 99.99% aluminum (1199 alloy) and Al, Mg, and Cu from 2024 Al alloy in 30 g/l NaCl electrolyte as a function of pH. The cathodic dissolution of Al was demonstrated and attributed to an increase in the pH at the interface due to the water reduction reaction. The dissolution of Mg was also observed but was a more complex function of current probably depending on the interfacial pH and the Al dissolution rate. The detachment of copper-rich particles was observed as very rapid spectroscopic emission transients (peak width < 10 ms).

  15. Influence of Mg and Ti on the microstructure and electrochemical performance of aluminum alloy sacrificial anodes

    MA Jingling; WEN Jiuba; LI Xudong; ZHAO Shengli; YAN Yanfu


    The experiments focused on the influence of magnesium and titanium as additional alloying elements on the microstructure and electro-chemical behavior of Al-Zn-ln sacrificial anodes. The electrochemical behavior of the aluminum sacrificial anode with 3 wt.% sodium chlo-fide solution was studied by electrochemical impedance spectroscopy (EIS) tests. It was found that a microstructure with few precipitates and refined grains could be achieved by adding 1 wt.% Mg and 0.05 wt.% Ti to the Al-Zn-In alloy, resulting in the improved current capacity and efficiency of the alloy. The equivalent circuit based on the EIS experimental data revealed less corrosion and lower adsorbed corrosion pro-duction on the surface of the aluminum alloy with a combination of 1 wt.% Mg and 0.05 wt.% Ti, which suggested that the corrosion behav-ior seemed to be strongly related to the presence of precipitate particles in the aluminum alloy, and moderate amounts of precipitate particles could be beneficial to the electrochemical performance of the aluminum alloy sacrificial anode.

  16. Wettability of AlSi5Mg on Spodumene

    Fankhänel, Beate; Stelter, Michael; Voigt, Claudia; Aneziris, Christos G.


    The development of new filters for the aluminum industry requires investigations on the wettability of aluminum and its alloys on novel filter materials. The requested filter effects require not only an adequate wetting but also information about the interaction between the filter material and the metal. In the present work the wettability of an AlSi5Mg alloy on spodumene (LiAl[Si2O6]) containing substrates is investigated using the sessile drop technique. These measurements were carried out at 1223 K (950 °C) under vacuum. The spodumene-based substrates showed a completely different wetting behavior compared with an alumina substrate. The contact angel reduced more quickly and leveled out at a lower value (75 ± 2 deg) than in case of a pure alumina substrate (90 ± 1 deg). The reason for this behavior is a reaction between the LiAl(Si2O6) and the alloy droplet which supported deoxidation and formed a silica-rich reaction layer at the droplet/substrate interface.

  17. Grain Coarsening Behavior of Mg-Al Alloys with Mischmetal Addition


    Small addition of mischmetal (MM) into aluminum alloys can lead to grain refinement. However, it is still uncertain whether the same effect applies to Mg-Al alloys. This work indicated that small amount of mischmetal addition ranging from 0.1% to 1.2% (mass fraction) did not cause grain refinement in Mg-Al alloys. On the contrary, they tended to coarsen the grains. When added into Mg-Al alloys, MM reacted preferentially with Al to form Al11MM3 phase. As Al11MM3 phase mainly distributed within α-Mg grains than at grain boundaries, it had little effect in restricting grain growth. In addition, MM reacted with Al8(Mn, Fe)5 or ε-AlMn particles to form Al-MM-Mn compounds, thus it reduced the amount of heterogeneous nuclei in the melt and resulted in remarkable grain coarsening.



    The objective of the present work is to study the casting characteristics of various Al-Li alloys, which include fluidity and strengths of the alloys and their interaction with cast molds. Materials investigated are Al-Li-Mg and Al-Li-Cu-Mg alloys with Li content of 2.5 wt%. The results show that sand molds with resin binders are good for Al-Li casting. Ceramic coatings can further reduce the metal-mold interactions. However, the permeability is also reduced by coating. The fluidity of Li-bea...

  19. Enhanced properties of MgO-Al2O3 composite materials with Al powder addition under 1300 °C creep test and its mechanism analysis

    Jiang, Peng; Ma, Jiajia; Li, Yong; Yue, Dandan; Tong, Shanghao; Xue, Wendong


    The Al-MgO-Al2O3 composite samples were prepared with alumina (fused corundum and sintered alumina), high purity sintered magnesia and aluminum powder. Creep test was carried out at 1300 °C and studied. The results show that the creep rate of sample without aluminum addition decreases gradually. The creep properties of the MgO-Al2O3 composite material are improved by aluminum powder addition, with the sample demonstrating an increase creep rate. The physical properties of the samples are enhanced by aluminum powder addition as well. The mechanism of the improvement on the sample is analyzed by different characterization methods and kinetics calculations. Our results indicates that the AlN and MgAl2O4 spinel phases which are formed during the creep test are acting as the reinforcing phases and therefore enhance the creep performance of the samples.

  20. Coupled heat/mass-balance model for analyzing correlation between excess AlF3 concentration and aluminum electrolyte temperature

    HUANG Yong-bo; QU Xiang-dong; ZHOU Jie-min


    The influence of aluminum electrolyte component on its temperature is an important issue within the field of aluminum reduction with pre-baked cells. The characteristic correlation between excess AlF3 concentration and aluminum electrolyte temperature was explored through the modeling of heat and mass transfer processes in industrial pre-baked aluminum reduction cells. A coupled heat/mass-balance model was derived theoretically from the mass and energy balance of an electrolysis cell, and then was simplified properly into a practical expression. The model demonstrates that if environmental temperature and Al2O3 concentration keep constant, the excess AlF3 concentration decreases with the aluminum electrolyte temperature linearly and its decrease rate is dependent on the heat transfer property of aluminum electrolyte, side wall and cell shell. Secondly, experiments were conducted on site with two industrial cells in an aluminum electrolysis plant. Excess AlF3 concentration and aluminum electrolyte temperature were obtained simultaneously together with other parameters such as Al2O3, CaF2, MgF2 and LiF concentrations. Results show that the maximum absolute error between the tested value and the calculated value of excess AlF3 concentration using the proposed model is less than 2%. This reveals that the coupled heat/mass-balance model can appropriately characterize the correlation between excess AlF3 concentration and aluminum electrolyte temperature with good accuracy and practicability.

  1. An Investigation on Axial Deformation Behavior of Thin-Wall Unfilled and Filled Tube with Aluminum Alloy (Al-Si7Mg) Foam Reinforced with SiC Particles

    Kumaraswamidhas, L. A.; Rajak, Dipen Kumar; Das, S.


    The objective of this research is to produce superior quality aluminum alloy foam with low relative density and higher resistance against compression deformation. This investigation has studied crash energy capacities of unfilled and filled aluminum alloy foams in mild steel tubes. The foam has been prepared by the melt route process with an addition of 5wt.% silicon carbide particles. The fabricated aluminum alloy foams were characterized by field emission scanning electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and Material Pro analyzer. It was observed that the foam-filled tubes could absorb more energy as compared to the unfilled tubes before reaching the complete densification point. Also, the aluminum alloy foams had better energy absorption capacity during the crash or impact loading. This article demonstrates the excellent ability of aluminum alloy foam application in the field where there is a need to absorb crash energy. It is to be noted that the amount of energy absorption will be greater for low-density foam filled in thin-wall rectangular section tubes. We have seen an increasing trend in the application of aluminum foams inside the thin-wall mild steel tubes for maximum energy absorption.

  2. Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

    Tarakci, Mehmet, E-mail:


    The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

  3. Influence of Si on Interfacial Combination of SiCp/Al-Mg-Si Composite

    Han Jianmin; Li Ronghua; Li Mingwei; Cui Shihai; Li Weijing; Wang Jinhua


    The scanning electron microscopy (SEM) analysis results of Si distribution in the interface between SiC reinforcements and aluminum matrix of a stir casting SiCp/Al-Mg-Si composite were presented. Results show that there is Si precipitation deposit on the interface of the composite and Si connects with SiC reinforcements in one side and connects with aluminum matrix in the other side. Si phase plays as a connecting bridge, which contributes to the interfacial combination of SiCp/Al composite.

  4. Phosphatizing of Mg particles to improve the protective performance of Mg-rich primer on A2024 Al alloy

    Wang, Jianguo; Zuo, Yu; Tang, Yuming; Lu, Xiangyu


    Mg-rich primer as a new type protective coating provides cathodic protection for Al alloy. In this paper, a kind of phosphatizing surface treatment on Mg particles was studied in order to improve the protective performance of Mg-rich primer. After treated with phosphoric acid, a protective magnesium phosphate layer was formed on the surface of Mg particles, which had no negative influence on the cathodic protection of the Mg-rich primer for Al alloy. The coating resistance of the treated Mg-rich primer was bigger than that of untreated primer, meanwhile the coating capacitance of the treated Mg-rich primer was smaller than that of untreated primer, suggesting that the barrier effect of the primer was improved and the lifetime was extended. The magnesium phosphate layer could reduce the consumption rate of Mg particles. Meanwhile, the phosphate radicals transported to Al alloy substrate to form a product layer composed of magnesium phosphate and aluminum phosphate on the substrate surface, which decreased the corrosion rate of Al alloy and improved the protective performance of the primer.

  5. Susceptibility testing for welding of AlMg alloys intended for extrusion

    J. Borowski


    Full Text Available The objective of research was to determine the weldability, using Tungsten Inert Gas (TIG of extruded sections made of hard-deformable 5xxx series aluminum alloys with differing magnesium content, i.e. AlMg3, AlMg4,5, AlMg5, AlMg7. Welded joints were obtained as a result of a welding process consisting of several steps. Only welds characterized by very good appearance and quality were selected for tests. As a result of conducted research, TIG welding parameters were determined for sections with a thickness of 8 mm. It was observed that alloys of differing Mg content are characterized by high weldability and do not exhibit a significant reduction of the yield point. Moreover, joints exhibit uniform hardness distribution in the welded joint and heat-affected zone. Tensile strength is reduced.

  6. Influence of Al-Si Master Alloy on Microstructure and Property of Al-Mg-Si Alloy%Al-Si中间合金对Al-Mg-Si系合金组织性能的影响

    张建新; 高爱华


    The effects of Al-Si master alloy on microstructure and property of Al-Mg-Si system alloy were studied, and the mechanism of Si in influencing the microstructure and property of the alloy was discussed.The results indicate that Al-Si master alloy with 18% Si can refine the microstmcture of cast aluminum alloy and improve the mechanical properties.The corrosion resistance of Al-Mg-Si system alloy decreases with the increase of Si content in Al-Si master alloy, the corrosion resistance significantly decreases when more than 18%Si in Al-Si master alloy.The tensile strength of Al-Mg-Si system alloy improves with the increase of Si content in Al-Si master alloy, the tensile strength declines when Si content is above 20 %.%研究了Al-Si中间合金对Al-Mg-Si系铝合金组织性能的影响,并分析了Si的作用机理.结果表明:含18%Si的Al-Si中间合金对合金的铸态组织作用效果较好,并能合理改善材料的力学性能;随Al-Si中间合金中Si含量的增加,Al-Mg-Si系合金的耐腐蚀性下降,Si含量高于18%后下降显著;Al-Si中间合金中Si含量的增加,能提高Al-Mg-Si系合金的抗拉强度,Si含量高于20%后其抗拉强度开始下降.

  7. Effect on thickness of Al layer in poly-crystalline Si thin films using aluminum(Al) induced crystallization method.

    Jeong, Chaehwan; Na, Hyeon Sik; Lee, Suk Ho


    The polycrystalline silicon (poly-Si) thin films were prepared by aluminum induced crystallization. Aluminum (Al) and amorphous silicon (a-Si) layers were deposited using DC sputtering and plasma enhanced chemical vapor deposition method, respectively. For the whole process Al properties of bi-layers can be one of the important factors. In this paper we investigated the structural and electrical properties of poly-crystalline Si thin films with a variation of Al thickness through simple annealing process. All samples showed the polycrystalline phase corresponding to (111), (311) and (400) orientation. Process time, defined as the time required to reach 95% of crystalline fraction, was within 60 min and Al(200 nm)/a-Si(400 nm) structure of bi-layer showed the fast response for the poly-Si films. The conditions with a variation of Al thickness were executed in preparing the continuous poly-Si films for solar cell application.

  8. Interfacial reactions and wetting in Al-Mg sintered by powder metallurgy process

    Faisal, Heny; Darminto, Triwikantoro, Zainuri, M.


    Was conducted to analyze the effect of temperature variation on the bonding interface sintered composite Al-Mg and analyze the effect of variations of the density and hardness sinter. Research carried out by the base material powders of Al, Mg powder and solvent n-butanol. The method used in this study is a powder metallurgy, with a composition of 60% volume fraction of Al - 40% Mg. Al-Mg mixing with n-butanol for 1 hour at 500 rpm. Then the emphasis (cold comression) with a size of 1.4 cm in diameter dies and height of 2.8 cm, is pressed with a force of 20 MPa and held for 15 minutes. After the sample into pellets, then sintered at various temperatures 300 °C, 350 °C, 400 °C and 450 °C. Characterization is done by using the testing green density, sintered density, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), vickers microhardness, and press test. XRD data analysis done by using X'Pert High Score Plus (HSP) to determine whether there is a new phase is formed. Test results show that the sintered density increasing sintering temperature, the resulting density is also increasing (shrinkage). However, at a temperature of 450 °C decreased (swelling). With the increased sinter density, interfacial bonding getting Kuta and more compact so that its hardness is also increased. From the test results of SEM / EDX, there Mg into Al in the border area. At temperatures of 300 °C, 350 °C, 400 °C, the phase formed is Al, Mg and MgO. While phase is formed at a temperature of 450 °C is aluminum magnesium (Al3Mg2), Aluminum Magnesium Zinc (AlMg2Zn).

  9. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    Urgnani, J.; Di Chio, M.; Palumbo, M.; Feuerbacher, M.; Fernandez, J. F.; Leardini, F.; Baricco, M.


    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H2 absorption/desorption kinetics. In this paper, the interaction of H2 with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg38.5Al61.5, Mg69Al31 and Mg72Al28. For Mg72Al28, no significant changes in the microstructure have been obtained by rapid solidification. In Mg69Al31, a significant grain refinement has been observed, whereas, for Mg38.5Al61.5, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H2 absorption, leading to MgH2. After heating up to 430 °C the hydrogenated samples, a main desorption reaction from MgH2 has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  10. Hydrogen absorption and desorption in rapidly solidified Mg- Al alloys

    Urgnani, J; Di Chio, M; Palumbo, M; Baricco, M [Dipartimento di Chimica I.F.M. and NIS, Universita di Torino, via P. Giuria, 10125, Torino (Italy); Feuerbacher, M [Institut fuer Mikrostrukturforschung, Forschungszentrum Juelich GmbH, Leo-Brand- Strasse, 52428 Juelich (Germany); Fernandez, J F; Leardini, F, E-mail: jacopo.urgnani@unito.i [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049, Madrid (Spain)


    The addition of Al to Mg has been indicated as a suitable way to destabilise the hydride phase, in order to bring the absorption and desorption reactions close to reasonable temperatures and pressure values for hydrogen storage. Rapid solidification is known to refine the microstructure of Mg-Al alloys and it might improve the H{sub 2} absorption/desorption kinetics. In this paper, the interaction of H{sub 2} with rapidly solidified Mg-Al alloys have been studied for three different composition: Mg{sub 38.5}Al{sub 61.5}, Mg{sub 69}Al{sub 31} and Mg{sub 72}Al{sub 28}. For Mg{sub 72}Al{sub 28}, no significant changes in the microstructure have been obtained by rapid solidification. In Mg{sub 69}Al{sub 31}, a significant grain refinement has been observed, whereas, for Mg{sub 38.5}Al{sub 61.5}, the formation of a metastable hexagonal phase has been found. In all cases, a disproportionation reaction has been observed after H{sub 2} absorption, leading to MgH{sub 2}. After heating up to 430 deg. C the hydrogenated samples, a main desorption reaction from MgH{sub 2} has been observed, which brings again to the starting phases. Experimental results have been discussed on the basis of a thermodynamic assessment of the Mg-Al-H system.

  11. Effects of Mg content on aging behavior of sub-micron Al2O3p/Al-Cu-Mg composites

    JIANG Long-tao; ZHU De-zhi; CHEN Guo-qin; XIU Zi-yang; WU Gao-hui


    30%Al2O3p/Al-Cu-2.0Mg composite and Al2O3p/Al-Cu-2.5Mg composite with 0.3 μm-Al2O3 particles were fabricated.Age-hardening behaviors of two composites and the related matrix alloys were studied by means of Brinell-hardness measurement,DSC and TEM. The results show that the hardness of the composite is improved obviously because of the addition of sub-micron Al2O3 particles. But the hardness increment of Al2O3p/Al composite after aging is lower than that of the related matrix alloy.Moreover, the formation of GP region is suppressed by the addition of sub-micron Al2O3 particles, which broadens the exothermic peak of S' phase. The increment of Mg content has a different influence on accelerating the aging processes of aluminum alloys and the composites, and the hardness also increases.

  12. Interaction of hydrogen with an Mg-Al alloy (poster)

    Andreasen, A.; Andreasen, J.W.; Burkarl, R.;


    The properties of magnesium as a hydrogen storage medium may be positively altered by the addition of Al: thermodynamic properties, kinetics and heat transfer of the hydride bed can be improved. The interaction of hydrogen with a Mg-Al alloy pre-exposedto air has been studied with in-situ time...... energy for dehydrogenation of the Mg-Al alloy is found to be approx. 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg.Furthermore, it is found that Mg-Al is hydrogenated to MgH2 + Al and upon dehydrogenation a Mg-Al alloy is reformed. Pure Mg is not observed during...

  13. Microstructure and properties of Mg-Al binary alloys

    ZHENG Wei-chao


    Full Text Available The effects of different amounts of added Al, ranging from 1 % to 9 %, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  14. Microstructure and properties of Mg-Al binary alloys

    ZHENG Wei-chao; LI Shuang-shou; TANG Bin; ZENG Da-ben


    The effects of different amounts of added Al, ranging from 1% to 9%, on the microstructure and properties of Mg-Al binary alloys were investigated. The results showed that when the amount of added Al is less than 5%, the grain size of the Mg-Al binary alloys decreases dramatically from 3 097 μm to 151 μm with increasing addition of Al. Further addition of Al up to 9% makes the grain size decrease slowly to 111 μm. The α-Mg dendrite arms are also refined. Increasing the amount of added Al decreases the hot cracking susceptibility of the Mg-Al binary alloys remarkably, and enhances the micro-hardness of the α-Mg matrix.

  15. The formation of different Mg-Al LDHs (Mg/Al=2:1 under hydrothermal conditions and their application for Zn2+ ions removal

    Bankauskaite A.


    Full Text Available The formation of different Mg-Al LDHs (Mg/Al = 2:1 under hydrothermal conditions (200°C; 4-24 h was investigated in the 4MgCO3⋅Mg(OH2⋅5H2O - γ-Al2O3/Al(OH3 - H2O and Mg5(CO34(OH2•4H2O - γ-Al2O3 - H2O systems. It was determined that chemical nature of the initial Mg containing components changes the formation mechanism of the synthesis products during isothermal curing. Magnesium aluminum hydroxide hydrate is crystallized by using 4MgCO3⋅Mg(OH2⋅5H2O as starting material while hydroxide hydrate in the Mg5(CO34(OH2•4H2O presence. The sequence of the compounds formation is presented. It should be noted that different modifications of Al containing components have only a slight influence on the meixnerite-type LDH hydrothermal synthesis. It was determined that after 45 min of sorption all Zn2+ ions are incorporated into the crystal structure of hydrotalcite. It should be underlined that crystallinity of the latter compound do not change during ion exchange experiments. Thus, the latter compound can be used as adsorbent for Zn2+ ion removal. Synthesized samples were characterized by powder X-Ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, simultaneous thermal analysis (STA and scanning electron microscopy (SEM.

  16. As-cast microstructure of Al-Zn-Mg and Al-Zn-Mg-Cu alloys added erbium

    MAO Jian-wei; JIN Tou-nan; XU Guo-fu; NIE Zuo-ren


    The effects of different contents of rare earth element, and erbium, on the as-cast microstructures of Al-6Zn-2Mg and Al-6Zn-2Mg-1.8Cu alloys were studied by optical microscopy, scanning electron microscopy, X-ray diffractometry, transmission electron microscopy and EDS analysis. The results show that the netlike structure of as-cast alloys can be remarkably refined, and the distance of dendritic structure decreases, with Er addition. However, the improvement results on Al-Zn-Mg-Cu are not better than that of Al-Zn-Mg. Er and Al can interact to form Al3Er phase, which is coherent with α(Al) matrix, with trace Er addition to the Al-Zn-Mg alloy. The refinement effect of Al-Zn-Mg alloys is familiar with the formation and precipitation of coherent Al3Er phases. The ternary compound AlCuEr, similar with AlCuSc phase, will form when Er is added to Al-Zn-Mg-Cu alloy, which suppresses the formation of Al3Er phase and doesn't solve in the following heat treatment.

  17. Microstructures and mechanical properties of Al-Mg and Al-Zn-Mg based alloys containing minor scandium and zirconium

    尹志民; 姜锋; 潘青林; 郭飞跃; 朱大鹏; 宋练鹏; 曾渝; 王涛


    A series of Al-Mg and Al-Zn-Mg based alloys with and without Sc, Zr were prepared by ingot metallurgy. The mechanical properties and microstructures of the studied alloys under different treatment conditions were studied. In addition, the existing form and acting mechanism of minor Sc and Zr in Al-Mg and Al-Zn-Mg based alloys were analyzed and discussed. The following conclusions can be drawn. First, adding of minor Sc and Zr to those alloys can increase the strength of Al-Mg and Al-Zn-Mg based alloys by 25%, while the ductility can remain in 15% and 8%, respectively. Second, in Al-Mg and Al-Zn-Mg based alloys, minor Sc and Zr mainly exist in two forms of aluminides containing Sc and Zr, one is Al3(Sc,Zr)I precipitated from the melt during solidification, the other is Al3(Sc,Zr)Ⅱ precipitated during homogenization. The former is the most effective grain refiner for α(Al) solid solution matrix, and the latter is coherent with the matrix and can strongly pin dislocations and subboundaries, which can effectively restrain recrystallization of the alloys during hot deformation, annealing and solid solution. Third, strengthening caused by adding minor Sc and Zr to the studied alloys is mainly due to fine-grain strengthening, precipitation strengthening and substructure strengthening of Al3(Sc, Zr) caused by restraining recrystallization.

  18. Substitution of lithium for magnesium, zinc, and aluminum in Li{sub 15}Si{sub 4}: crystal structures, thermodynamic properties, as well as {sup 6}Li and {sup 7}Li NMR spectroscopy of Li{sub 15}Si{sub 4} and Li{sub 15-x}M{sub x}Si{sub 4} (M=Mg, Zn, and Al)

    Baran, Volodymyr; Faessler, Thomas F. [Department Chemie, Technische Universitaet Muenchen, Garching (Germany); Wuellen, Leo van [Department of Physics, University of Augsburg (Germany)


    An investigation into the substitution effects in Li{sub 15}Si{sub 4}, which is discussed as metastable phase that forms during electrochemical charging and discharging cycles in silicon anode materials, is presented. The novel partial substitution of lithium by magnesium and zinc is reported and the results are compared to those obtained for aluminum substitution. The new lithium silicides Li{sub 14}MgSi{sub 4} (1) and Li{sub 14.05}Zn{sub 0.95}Si{sub 4} (2) were synthesized by high-temperature reactions and their crystal structures were determined from single-crystal data. The magnetic properties and thermodynamic stabilities were investigated and compared with those of Li{sub 14.25}Al{sub 0.75}Si{sub 4} (3). The substitution of a small amount of Li in metastable Li{sub 15}Si{sub 4} for more electron-rich metals, such as Mg, Zn, or Al, leads to a vast increase in the thermodynamic stability of the resulting ternary compounds{sub .} The {sup 6,7}Li NMR chemical shift and spin relaxation time T{sub 1}-NMR spectroscopy behavior at low temperatures indicate an increasing contribution of the conduction electrons to these NMR spectroscopy parameters in the series for 1-3. However, the increasing thermal stability of the new ternary phases is accompanied by a decrease in Li diffusivity, with 2 exhibiting the lowest activation energy for Li mobility with values of 56, 60, and 62 kJ mol{sup -1} for 2, Li{sub 14.25}Al{sub 0.75}Si{sub 14}, and 1, respectively. The influence of the metastable property of Li{sub 15}Si{sub 4} on NMR spectroscopy experiments is highlighted. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Formation of aluminum titanate with small additions of MgO and SiO{sub 2}

    Guedes-Silva, Cecilia Chaves; Ferreira, Thiago dos Santos; Genova, Luis Antonio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio Machado de Souza, E-mail: [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Geociencias


    The formation of aluminum titanate was investigated by isothermal treatments of samples obtained from equimolar mixtures of alumina and titania, containing small amounts of silica and magnesia. Results of differential thermal analysis and Rietveld refinements of data collected by X-ray powder diffraction (XRPD) showed that additions of silica in amounts used in this work did not influence the formation of aluminum titanate. However, the presence of magnesia favored the formation of aluminum titanate in two steps, first one by incorporating Mg{sup 2+} into Al{sub 2}TiO{sub 5} lattice during its initial formation, and the second one by accelerating the Al{sub 2}TiO{sub 5} formation, contributing to large quantities of this phase. MgO doped samples have also developed a more suitable microstructure for stabilizing of Al{sub 2}TiO{sub 5}, what make them promising for applications such as thermal barriers, internal combustion engines and support material for catalyst. (author)

  20. Production of metallic nanopowders (Mg, Al by solar carbothermal reduction of their oxides at low pressure

    J. Puig


    Full Text Available The carbothermal reduction of MgO and Al2O3 in argon flow at low pressure allows to lower the onset temperature of metal vapor formation. Thermodynamic calculations indicate that metal formation begins at 1400 and 1700 K for a primary vacuum (1000 Pa, respectively, for Mg and Al. In the experimental section, concentrated solar energy was used for the process heating in order to favor energy savings. The products of the reaction between MgO or Al2O3 and 2 varieties of carbon (graphite, carbon black in flowing argon atmosphere at a total pressure of around 1000 to 1600 Pa were studied using X-ray diffraction, and microstructure observations revealed the formation of metallic nanopowders with some by-products. Metallic conversions close to 45 wt% and 52 wt%, respectively, for Mg and Al, were obtained. The low conversion yield of the carbothermal reduction of MgO can be attributed to a backward reaction reforming MgO powder and to a sintering process between oxide particles at high temperature. Aluminum production challenge is to avoid formation of undesired by-products: Al2O, Al4C3 and Al-oxycarbides. Advantages and weaknesses of the used process are described and some improvements are proposed to increase metallic yields.

  1. Diffusion bonding of Al7075 alloy to titanium aluminum vanadate alloy

    Alhazaa, Abdulaziz Nasser

    The aluminum alloy (Al7075) and titanium alloy (Ti-6Al-4V) are used in a variety of applications in the aerospace industry. However, the high cost of Ti-6Al-4V alloy has been a major factor which has limited its use and therefore, the ability to join Al7075 alloy to Ti-6Al-4V alloy can provide a product that is less costly, but retains the high strength and light weight properties necessary for the transport industry. However, the large difference in the physical properties between these two alloys prevents the use of conventional joining techniques such as fusion welding to join these dissimilar alloys. Therefore, the diffusion bonding technique was used to join Al7075 alloy to Ti-6Al-4V alloy with the objective of minimizing microstructural changes of the two alloys during the bonding process. In this thesis, solid state and liquid phase bonding processes were undertaken. Solid state bonding was employed without interlayers and was successful at 510°C and 7 MPa. The bond interface showed an absence of the oxides due to the dissolution of oxygen into the titanium solution. Bonds made using copper interlayers at a temperature sufficient enough to form eutectic liquid formation between copper and aluminum were produced. The intermetallics theta(Al2Cu), S(Al2CuMg) and T(Al2Mg3Zn3) were identified at the aluminum interface while Cu3Ti2 intermetallic was identified at the titanium interface. Bonds made using tin based alloys interlayers and copper coatings were successful and gave the highest shear strength. The eutectic formation on the Al7075 alloy was responsible for joint formation at the aluminum interface while the formation of Sn3Ti5 intermetallic was responsible for the joint formation at titanium interface. The corrosion rate of the bonds decreased with increasing bonding time for joints made using the tin based interlayer in 3% NaCl solution. However, the presence of copper within the joint increased the corrosion rate of the bonds and this was attributed to

  2. Interaction of hydrogen with an Mg-Al alloy (poster)

    Andreasen, A.; Andreasen, J.W.; Burkarl, R.


    The properties of magnesium as a hydrogen storage medium may be positively altered by the addition of Al: thermodynamic properties, kinetics and heat transfer of the hydride bed can be improved. The interaction of hydrogen with a Mg-Al alloy pre-exposedto air has been studied with in-situ time...... energy for dehydrogenation of the Mg-Al alloy is found to be approx. 160 kJ/mol. This is not significantly higher than for pure and fully activated Mg.Furthermore, it is found that Mg-Al is hydrogenated to MgH2 + Al and upon dehydrogenation a Mg-Al alloy is reformed. Pure Mg is not observed during...... dehydrogenation, suggesting that the formation of Mg-Al is fast compared to the liberation of hydrogen fromMgH2. From thermodynamical calculations using the semi-empirical Miedema model a slightly lower heat of hydride formation is found. Based on comparison with previous experiments on Mg exposed to air...


    Achmad Sulhan Fauzi


    Full Text Available This article describes the results of research on the use of transition alumina for improving the performance of ceramics. Synthesis has been made of gradual changes materials (Functionally Graded Materials, FGM aluminum titanate (AT / corundum based on transition alumina powders with the addition of MgO as a stabilizer of AT as much as 2 wt.%. Samples without the addition of MgO was also made for comparison. Transition alumina with and without the addition of MgO were calcined at a temperature of 1100C for 1 hour to become ?-alumina. The powder mixture was compacted at a pressure of 49.3 MPa and then prasintered at a temperature of 1100C for 1 hour, then repeatedly infiltrated with infiltrator TiCl3 solution (20% which prepared by dissolving the Ti metal powders into HCl. Furthermore, the material sintered at temperatures of 1500C with a holding time for 3 hours. Physical character of materials showed an increase in density and decrease in porosity of the material due to the addition of MgO. Phase identification results obtained from the content of AT and corundum phases which gradual in depth, indicating that FGM has been formed. These results were supported by analysis of x-ray diffraction pattern showing the formation of a solid solution Al2 (1-x + MgxTi1 xO5 which marked by the shifting of the peak of AT phase in FGM samples with the addition of MgO. Tulisan ini menjelaskan hasil penelitian tentang penggunaan alumina transisi untuk meningkatkan performa keramik. Telah dilakukan sintesis bahan ubahan gradual (Functionally Graded Material, FGM aluminum titanat (AT/korundum berbahan dasar serbuk alumina transisi dengan penambahan MgO sebagai penstabil AT sebanyak 2 wt.%. Sampel tanpa tambahan MgO juga dibuat sebagai pembanding. Alumina transisi dengan dan tanpa penambahan MgO dikalsinasi pada temperatur 1100C selama 1 jam sehingga menjadi ?-alumina. Serbuk campuran dikompaksi pada tekanan 49,3 MPa lalu diprasinter pada temperatur 1100C selama

  4. Elastic and Thermodynamic Properties of Complex Mg-Al Intermetallic Compounds via Orbital-Free Density Functional Theory

    Zhuang, Houlong; Chen, Mohan; Carter, Emily A.


    Magnesium-aluminum (Mg-Al) alloys are important metal alloys with a wide range of engineering applications. We investigate the elastic and thermodynamic properties of Mg, Al, and four stoichiometric Mg-Al compounds including Mg17Al12 , Mg13Al14 , and Mg23Al30 , and MgAl2 with orbital-free density-functional theory (OFDFT). We first calculate the lattice constants, zero-temperature formation energy, and independent elastic constants of these six materials and compare the results to those computed via Kohn-Sham DFT (KSDFT) benchmarks. We obtain excellent agreement between these two methods. Our calculated elastic constants of hexagonal close-packed Mg and face-centered-cubic Al are also consistent with available experimental data. We next compute their phonon spectra using the force constants extracted from the very fast OFDFT calculations, because such calculations are computationally challenging using KSDFT. This is especially the case for the Mg23Al30 compound, whose 3 ×3 ×3 supercell consists of 1431 atoms. We finally employ the quasiharmonic approximation to investigate temperature-dependent thermodynamic properties, including formation energies, heat capacities, and thermal expansion of the four Mg-Al intermetallic compounds. The calculated heat capacity and thermal expansion of both Mg and Al agree well with experimental data. We additionally find that Mg13Al14 and MgAl2 are both unstable, consistent with their absence from the equilibrium Mg-Al phase diagram. Our work demonstrates that OFDFT is an efficient and accurate quantum-mechanical computational tool for predicting elastic and thermodynamic properties of complicated Mg-Al alloys and also should be applicable to many other engineering alloys.

  5. Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

    Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.


    An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

  6. The softening effect of heat-treated strengthened Al-Zn-Mg alloy in welding process

    Zhang, Xiaohong; Chen, Jingqing; Zhang, Kang; Chen, Hui


    Weld joint softening occurs during the welding process of heat-treatable aluminum alloys and strongly influences the mechanical properties. In this work, the softening of heat-treated Al-Zn-Mg alloy was studied in the multipass welding process. By Gleeble-3500 thermal-mechanical simulator, the heat treatment and tensile test with welding thermal cycles were carried out to simulate the microstructure evolution and mechanical softening during multipass welding. After that, the softening mechanism of the HAZ was analyzed by microstructure analysis. The results indicate that the heat-treated Al-Zn-Mg alloy exhibited obvious softening after several thermal cycles with peak temperature higher than 200∘C, and this phenomenon is worse with increasing peak temperature. Based on the microstructure analysis, it was found that the reinforcement phase changes according to the applied thermal cycles, which strongly affects the strength of Al-Zn-Mg alloys.

  7. Effect of Sc on Precipitation Hardening of AlSi6Mg Alloy


    The effect of Sc on precipitation hardening of AlSi6Mg was studied. Zr was previously reported that it increased the effectiveness of Sc in wrought aluminum in many areas so Zr was also used together with Sc in this study.Different levels of Sc and Zr additions were added to AlSi6Mg before casting in the permanent mold. The samples were precipitation hardened at different aging temperatures and for various aging time before testing for tensile strength and hardness. It was found that Sc addition into Al6SiMg can change its response to age hardening. Additions of Sc and Sc with Zr increased both yield strength and hardness for both aging temperatures. In addition, Sc was found to modify eutectic Si to obtain fibrous morphology. This effect of Sc on eutectic silicon modification has never been reported before.

  8. Elevated temperature properties of Mg- 12Li-Al-MgO composites

    WEI Xiao-wei; HUANG Qing-min


    The compressive creep of Mg-12Li-Al-MgO particulate composites was investigated, which were produced by the reaction of reinforcement materials (B2O3) with Mg-12Li-Al alloy melt in the temperature range of 100-190 ℃ and under different compressive stress in the range of 40-70 MPa with special apparatus. The content of MgO particulates is about 0, 5%, 10%,15%(volume fraction) in Mg-12Li-Al alloy respectively. The results reveal that the creep resistance of the particulate composites is increased with increasing the content of MgO particulates and considerable improvementin creep resistance is observed in Mg-12Li-Al-MgO composites. However, over all range of temperatures and stresses, the creep data for these composites can be correlated using an empirical equation εs =Aσnexp(-Q/RT), where n is 4.93 and Q is about 78.1 kJ/mol for Mg-14Li-Al alloy and n is between 7.48 and 9.47 and Q is 111.2-137.3 kJ/mol for Mg-12Li-Al-MgO composites. The different compressive creep behavior of the composites is associated with the different material constant A. The compressive creep rate is controlled by the lattice diffusion of Li and dislocation climb.

  9. {sup 26}Al-containing acidic and basic sodium aluminum phosphate preparation and use in studies of oral aluminum bioavailability from foods utilizing {sup 26}Al as an aluminum tracer

    Yokel, Robert A. [College of Pharmacy, 511C Pharmacy Building 725 Rose Street, University of Kentucky Medical Center, Lexington, KY 40536-0082 (United States) and Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536-0305 (United States)]. E-mail:; Urbas, Aaron A. [Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055 (United States); Lodder, Robert A. [College of Pharmacy, 511C Pharmacy Building 725 Rose Street, University of Kentucky Medical Center, Lexington, KY 40536-0082 (United States); Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055 (United States); Selegue, John P. [Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055 (United States); Florence, Rebecca L. [College of Pharmacy, 511C Pharmacy Building 725 Rose Street, University of Kentucky Medical Center, Lexington, KY 40536-0082 (United States)


    We synthesized {sup 26}Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down ({approx}3000- and 850-fold) to prepare {approx}300-400 mg of each SALP. The {sup 26}Al was incorporated at the beginning of the syntheses to maximize {sup 26}Al and {sup 27}Al equilibration and incorporate the {sup 26}Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used to characterize the two SALP samples and some intermediate samples. Multi-elemental analysis (MEA) was used to determine Na, Al and P content. Commercial products were included for comparison. Satisfactory XRD analyses, near infrared spectra and MEA results confirmed that we synthesized acidic and basic SALP, as well as some of the syntheses intermediates. The {sup 26}Al-containing acidic and basic SALPs were incorporated into a biscuit material and a processed cheese, respectively. These were used in oral bioavailability studies conducted in rats in which the {sup 26}Al present in blood after its oral absorption was quantified by accelerator mass spectrometry. The results showed oral Al bioavailability from acidic SALP in biscuit was {approx}0.02% and from basic SALP in cheese {approx}0.05%, lower than our previous determination of Al bioavailability from drinking water, {approx}0.3%. Both food and water can appreciably contribute to the Al absorbed from typical human Al intake.

  10. Electrodeposition of Mg-Li-Al-La Alloys on Inert Cathode in Molten LiCl-KCl Eutectic Salt

    Han, Wei; Chen, Qiong; Sun, Yi; Jiang, Tao; Zhang, Milin


    Electrochemical preparation of Mg-Li-Al-La alloys on inert electrodes was investigated in LiCl-KCl melt at 853 K (580 °C). Cyclic voltammograms (CVs) and square wave voltammograms (SWVs) show that the existence of AlCl3 or AlF3 could promote La deposition on an active Al substrate, which is predeposited on inert electrodes. All electrochemical tests show that the reduction of La3+ is a one-step reduction process with three electrons exchanged. The reduction of La(III)→La(0) occurred at -2.04 V, and the underpotential deposition (UPD) of La was detected at -1.55 V ( vs Ag/AgCl). The same phenomena concerning La UPD were observed on two inert cathodes, W and Mo. In addition, Mg-Li-Al-La alloys were obtained by galvanostatic electrolysis on the W cathode from La2O3 in LiCl-KCl-MgCl2-KF melts with aluminum as the anode. X-ray diffraction (XRD) measurements indicated that various phases like the Al2La, Al12Mg17, and βLi phase (LiMg/Li3Mg7) existed in the Mg-Li-Al-La alloys. The distribution of Mg, Al, and La in Mg-Li-Al-La alloys from the analysis of a scan electron micrograph (SEM) and energy dispersive spectrometry (EDS) indicated that the elements Mg, Al, and La distributed homogeneously in the alloys.

  11. Effect of Change in Strain Path During Cold Rolling on the Evolution of Microstructure and Texture in Al and Al-2.5%Mg

    Bhattacharjee, P. P.; Saha, S.; Gatti, J. R.


    The effect of change in strain path during cold rolling on the evolution of microstructure and texture is investigated. For this purpose, high purity aluminum and Al-2.5%Mg alloy are deformed ( 90% reduction in thickness) by unidirectional and cross cold rolling. Irrespective of the alloy system, copper-type texture is observed in unidirectional processed materials, while strong brass ({011}) texture is developed during cross rolling. Unidirectionally rolled aluminum showed higher HAGB fraction, but similar HAGB spacing as compared to the cross-rolled aluminum after 90% reduction in thickness. At the same time, the internal misorientation in the cross-rolled 2N-Al is higher than in the unidirectionally rolled material. In contrast, Al-2.5% Mg alloy processed differently in both ways shows similar HAGB fraction, spacing, and internal misorientation distribution. These observations indicate that microstructure evolution due to strain path change is more strongly affected by dynamic recovery as compared to texture evolution.

  12. Hydrogen reversibility of LiBH₄-MgH₂-Al composites.

    Hansen, Bjarne R S; Ravnsbæk, Dorthe B; Skibsted, Jørgen; Jensen, Torben R


    The detailed mechanism of hydrogen release in LiBH4-MgH2-Al composites of molar ratios 4 : 1 : 1 and 4 : 1 : 5 are investigated during multiple cycles of hydrogen release and uptake. This study combines information from several methods, i.e., in situ synchrotron radiation powder X-ray diffraction, (11)B magic-angle spinning (MAS) NMR, Sievert's measurements, Fourier transform infrared spectroscopy and simultaneous thermogravimetric analysis, differential scanning calorimetry and mass spectroscopy. The composites of LiBH4-MgH2-Al are compared with the behavior of the LiBH4-Al and LiBH4-MgH2 systems. The decomposition pathway of the LiBH4-MgH2-Al system is different for the two investigated molar ratios, although it ultimately results in the formation of LiAl, Mg(x)Al(1-x)B2 and Li2B12H12 in both cases. For the 4 : 1 : 1-molar ratio, Mg(0.9)Al(0.1) and Mg17Al12 are observed as intermediates. However, only Mg is observed as an intermediate in the 4 : 1 : 5-sample, which may be due to an earlier formation of Mg(x)Al(1-x)B2, reflecting the complex chemistry of Al-Mg phases. Hydrogen release and uptake reveals a decrease in the hydrogen storage capacity upon cycling. This loss reflects the formation of Li2B12H12 as observed by (11)B NMR and infrared spectroscopy for the cycled samples. Furthermore, it is shown that the Li2B12H12 formation can be limited significantly by applying moderate hydrogen partial pressure during decomposition.

  13. Effect of Ca addition on the corrosion behavior of Mg-Al-Mn alloy

    Yang, Jiang; Peng, Jian; Nyberg, Eric A.; Pan, Fu-sheng


    The microstructures and corrosion resistance of magnesium-5 wt% aluminum-0.3 wt% manganese alloys (Mg-Al-Mn) with different Ca additions (0.2-4 wt%) were investigated. Results showed that with increasing Ca addition, the grain of the alloys became more refined, whereas the corrosion resistant ability of the alloys initially increased and then decreased. The alloy with 2 wt% Ca addition exhibited the best corrosion resistance, attributed to the effect of the oxide film and (Mg,Al)2Ca phases which were discontinuously distributed on the grain boundaries. These phases acted as micro-victims, they preferentially corroded to protect the α-Mg matrix. The oxide film formed on the alloy surface can hinder the solution further to protect the α-Mg matrix.

  14. Mg-Al Alloys Manufactured by Casting and Hot Working Process


    Mechanical properties of Mg-Al based alloys at different fabrication state, namely as-cast, hot rolled, and annealed, were investigated to develop the alloys that are suitable for the casting/hot working process. Experimental results indicated that the castability such as hot cracking resistance tends to improve with increasing the aluminum content. However, the elongation at elevated temperatures was observed to decrease as the Al content increases, implying difficulties in hot forming. A small amount of Zr additions could significantly enhance the room temperature mechanical properties of hot-rolled Mg-6%Al-1%Zn alloy. The tendency of remarkable grain coarsening at high temperatures was effectively reduced by the Zr additions. TEM analyses suggested that very fine Al3Zr precipitates formed in the Zr-added alloy are responsible for the obtained results.

  15. Evolution of Fe Bearing Intermetallics During DC Casting and Homogenization of an Al-Mg-Si Al Alloy

    Kumar, S.; Grant, P. S.; O'Reilly, K. A. Q.


    The evolution of iron (Fe) bearing intermetallics (Fe-IMCs) during direct chill casting and homogenization of a grain-refined 6063 aluminum-magnesium-silicon (Al-Mg-Si) alloy has been studied. The as-cast and homogenized microstructure contained Fe-IMCs at the grain boundaries and within Al grains. The primary α-Al grain size, α-Al dendritic arm spacing, IMC particle size, and IMC three-dimensional (3D) inter-connectivity increased from the edge to the center of the as-cast billet; both α c-AlFeSi and β-AlFeSi Fe-IMCs were identified, and overall α c-AlFeSi was predominant. For the first time in industrial billets, the different Fe-rich IMCs have been characterized into types based on their 3D chemistry and morphology. Additionally, the role of β-AlFeSi in nucleating Mg2Si particles has been identified. After homogenization, α c-AlFeSi predominated across the entire billet cross section, with marked changes in the 3D morphology and strong reductions in inter-connectivity, both supporting a recovery in alloy ductility.

  16. Magnesium-Based Sacrificial Anode Cathodic Protection Coatings (Mg-Rich Primers for Aluminum Alloys

    Michael D. Blanton


    Full Text Available Magnesium is electrochemically the most active metal employed in common structural alloys of iron and aluminum. Mg is widely used as a sacrificial anode to provide cathodic protection of underground and undersea metallic structures, ships, submarines, bridges, decks, aircraft and ground transportation systems. Following the same principle of utilizing Mg characteristics in engineering advantages in a decade-long successful R&D effort, Mg powder is now employed in organic coatings (termed as Mg-rich primers as a sacrificial anode pigment to protect aerospace grade aluminum alloys against corrosion. Mg-rich primers have performed very well on aluminum alloys when compared against the current chromate standard, but the carcinogenic chromate-based coatings/pretreatments are being widely used by the Department of Defense (DoD to protect its infrastructure and fleets against corrosion damage. Factors such as reactivity of Mg particles in the coating matrix during exposure to aggressive corrosion environments, interaction of atmospheric gases with Mg particles and the impact of Mg dissolution, increases in pH and hydrogen gas liberation at coating-metal interface, and primer adhesion need to be considered for further development of Mg-rich primer technology.

  17. Influence of Mg Content on Deformability of AlMg Alloys during Extrusion

    Leśniak D.


    Full Text Available In this study the research on deformability of AlMg alloys with high Mg contents in extrusion was carried out. The different shapes from AlMg alloys containing 3.5%, 4.5% and 5.5% of Mg were extruded on 500 T semi-industrial press by using one-hole and multi-hole flat dies. The extrudates surface quality was under investigations in relation with the temperature-speed parameters of the extrusion process. The metal exit speed was estimated depending on the extrudates shape, wall thickness and Mg content. The alloy’s border solidus and liquidus temperatures were also determined.

  18. Degradation of Al/SiCp composites produced with rice-hull ash and aluminum cans.

    Escalera-Lozano, R; Gutiérrez, C A; Pech-Canul, M A; Pech-Canul, M I


    The use of recycling aluminum from beverage containers and rice-hull ash (RHA) offers to be an attractive alternative for the economic production of Al/SiCp composites. However, corrosion phenomena in the composites represent technological barriers yet to be resolved before they can be exploited to their full potential. A simple methodology involving characterization by XRD, SEM, EDX, FTIR and ICP was designed in order to investigate the causes of the rapid degradation in a humid environment of Al/SiCp composites produced with RHA and aluminum cans. Results reveal that the use of RHA was beneficial to avoid degradation through the formation and subsequent hydration of the Al4C3 phase. However with condensed moisture acting as an electrolyte, localized corrosion took place with aggressive damage manifested by the disintegration of the composite into a powdery mixture. The relevant corrosion mechanism was mainly attributed to microgalvanic coupling between the Mg2Si intermetallic compound and the matrix (although other phases such as SiC, Si, MgAl2O4 could also work as microcathodes).

  19. Microstructure and Mechanical Properties of an Al-Li-Mg-Sc-Zr Alloy Subjected to ECAP

    Anna Mogucheva


    Full Text Available The effect of post-deformation solution treatment followed by water quenching and artificial aging on microstructure and mechanical properties of an Al-Li-Mg-Sc-Zr alloy subjected to equal-channel angular pressing (ECAP was examined. It was shown that the deformed microstructure produced by ECAP remains essentially unchanged under solution treatment. However, extensive grain refinement owing to ECAP processing significantly affects the precipitation sequence during aging. In the aluminum-lithium alloy with ultrafine-grained (UFG microstructure, the coarse particles of the S1-phase (Al2LiMg precipitate on high-angle boundaries; no formation of nanoscale coherent dispersoids of the δ′-phase (Al3Li occurs within grain interiors. Increasing the number of high-angle boundaries leads to an increasing portion of the S1-phase. As a result, no significant increase in strength occurs despite extensive grain refinement by ECAP.

  20. Order-Disorder Transition and Phase Separation in the MgB2 Metallic Sublattice Induced by Al Doping.

    Brutti, S; Gigli, G


    MgB2 is a superconductor constituted by alternating Mg and B planar layers: doping of both the sublattices has been observed experimentally to destroy the outstanding superconductive properties of this simple material. In this study we present the investigation by first principles methods at atomistic scale of the phase separation induced by aluminum doping in the MgB2 lattice. The calculations were performed by Density Functional Theory in generalized gradient approximation and pseudopotentials. Orthorhombic oP36 supercells derived by the primitive hR3 MgB2 cell were built in order to simulate the aluminum-magnesium substitution in the 0-50% composition range. The computational results explained the occurrence of a phase separation in the Mg1-xAlxB2 system. The miscibility gap is predicted to be induced by an order-disorder transition in the metallic sublattice at high Al concentration. Indeed at 1000 K aluminum substitution takes place on random Mg sites for concentration up to 17% of the total metallic sites, whereas at Al content larger than 31% the substitution is energetically more favorable on alternated metallic layers (Mg undoped planes alternate with Mg-Al layers). The formation of this Al-rich phase lead at 50% doping to the formation of the double omega Mg1/2Al1/2B2 ordered lattice. From 17 to 31% the two phases, the disordered Mg1-xAlxB2 (x MgB2 occurs in parallel with the collapse of the superconductive properties of the material.

  1. Microstructural evolution of Mg-7Al-2Sn Mg alloy during multi-directional impact forging

    M.G. Jiang


    Full Text Available Multi-directional impact forging (MDIF was applied to a Mg-7Al-2Sn (wt.% Mg alloy to investigate its effect on the microstructural evolution. MDIF process exhibited high grain refinement efficiency. After MDIF 200 passes, the grain size drastically decreased to 20 µm from the initial coarse grains of ~500 µm due to dynamic recrystallization (DRX. Meanwhile, original grain boundaries remained during MDIF and large numbers of fine spherical β-Mg17Al12 particles dynamically precipitated along the original grain boundaries with high Al concentration, acting as effective pinning obstacles for the suppression of DRXed grain growth. Besides, micro-cracks nucleated during MDIF and propagated along the interface between the remained globular or cubic Al-Mn particles and Mg matrix.

  2. Preparation of SiC–MgAl2O4–Y3Al5O12-MWCNTs nanocomposites by spark plasma sintering

    Zharikov, E. V.; Kapustin, V. V.; Faikov, P. P.; Popova, N. A.; Barmin, A. A.; Ivanov, A. V.; Rizakhanov, R. N.


    Fabrication a composite materials based on silicon carbide (SiC) reinforced with multi-walled carbon nanotubes (MWCNTs) with addition of magnesium alumina spinel MgAl2O4, and yttrium aluminum garnet Y3Al5O12 by spark plasma sintering are presented. Two series of composites differing by the particle size of starting SiC were prepared. Mechanical characteristics of composites including microhardness, fracture toughness and flexural strength are determined.

  3. Preparation of Al-Mg Alloy Electrodes by Using Powder Metallurgy and Their Application for Hydrogen Production

    Wen-Nong Hsu


    Full Text Available The choice of an electrode is the most critical parameter for water electrolysis. In this study, powder metallurgy is used to prepare aluminum-magnesium (Al-Mg alloy electrodes. In addition to pure Mg and Al electrodes, five Al-Mg alloy electrodes composed of Al-Mg (10 wt%, Al-Mg (25 wt%, Al-Mg (50 wt%, and Al-Mg (75 wt% were prepared. In water electrolysis experiments, the pure Al electrode exhibited optimal electrolytic efficiency. However, the Al-Mg (25 wt% alloy was the most efficient when the anticorrosion effect and materials costs were considered. In this study, an ultrasonic field was applied to the electrolysis cell to improve its efficiency. The results revealed that the current increased by approximately 23.1% when placed in a 30 wt% KOH solution under the ultrasonic field. Electrochemical polarization impedance spectroscopy (EIS was employed to evaluate the effect of the ultrasonic field on the reduction of polarization resistance. The results showed that the concentration impedance in the 30 wt% KOH electrolyte decreased markedly by 44%–51% Ω.

  4. Anisotropic Mechanical Behavior of AlSi10Mg Parts Produced by Selective Laser Melting

    Tang, Ming; Pistorius, Petrus Christiaan


    AlSi10Mg cylinders produced by laser powder-bed fusion have somewhat different yield behavior for cylinders with XY orientation and Z orientation. Earlier yielding for Z-oriented samples is likely related to micro-residual stress, resulting from the difference in thermal expansion of the aluminum matrix and cellular silicon. Smaller tensile reduction in area of Z-oriented samples is related to tearing along the softer region at the boundaries of melt pools, where the silicon cell spacing is larger. Indentation measurements confirmed the lower hardness at the edges of melt pools.

  5. Microstructural evolution during friction stir welding of AlSi1MgMn alloy

    M. Janjić


    Full Text Available This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6 obtained through the Friction Stir Welding (FSW process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.

  6. Slag-Resistance of MgAlON Spinel


    The slag-resistance and microstructural changes after the slag tests of MgAlON spinel containing different amount of nitrogen were studied by means of crucible slag-resistant experiment, SEM and EDS in the work. The results show that the slag-resistance of MgAlON is dependent on the nitrogen content, and the optimum amount is 2.88%. The structure is not changed although the grains have been permeated by some silicon, calcium and iron. A glass phase which contained nitrogen formed in the metamorphic layer. The glass can improve the ability of the slag-resistance of MgAlON because of its higher viscosity.

  7. Unique Structural Properties of the Mg-Al Hydrotalcite Solid Base Catalyst : An In Situ Study using Mg and Al K-edge XAFS during Calcination and Rehydration

    Koningsberger, D.C.; Bokhoven, J.A. van; Roelofs, J.C.A.A.; Jong, K.P. de


    The changes in the layered structure of Mg-Al hydrotalcite (Mg/Al=2) during heat treatment have been investigated by using in situ XAFS simultaneously at the Mg and Al K-edges. The development of unique in situ instrumentation allowed the coordination environments at both the Mg and Al centers to be

  8. Reactivity of Mg-Al hydrotalcites in solid and delaminated forms in ammonium carbonate solutions

    Stoica, Georgiana; Santiago, Marta; Abelló, Sònia; Pérez-Ramírez, Javier


    Treatment of Mg-Al hydrotalcites (LDHs, layered double hydroxides) in aqueous (NH 4) 2CO 3 at 298 K leads to composites of dawsonite, hydrotalcite, and magnesium ammonium carbonate. The mechanism and kinetics of this transformation, ultimately determining the relative amounts of these components in the composite, depend on the treatment time (from 1 h to 9 days), the Mg/Al ratio in the hydrotalcite (2-4), and on the starting layered double hydroxide (solid or delaminated form). The materials at various stages of the treatment were characterized by inductive coupled plasma-optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, infrared spectroscopy, thermogravimetry, and nitrogen adsorption at 77 K. The progressive transformation of hydrotalcite towards crystalline dawsonite and magnesium ammonium carbonate phases follows a dissolution-precipitation mechanism. A gradual decrease of the Mg/Al ratio in the resulting solids was observed in time due to magnesium leaching in the reacting medium. Dawsonite-hydrotalcite composite formation is favored at high aluminum contents in the starting hydrotalcite, while the formation of magnesium ammonium carbonate is favored at high Mg/Al ratios. The synthetic strategy comprising hydrotalcite delamination in formamide prior to aqueous (NH 4) 2CO 3 treatment is more reactive towards composite formation than starting from the bulk solid hydrotalcite.

  9. Melt Protection of Mg-Al Based Alloys

    María J. Balart


    Full Text Available This paper reports the current status of Mg melt protection in view to identify near-future challenges, but also opportunities, for Mg melt protection of Mg-Al based alloys. The goal is to design and manufacture sustainable Mg alloys for resource efficiency, recycling and minimising waste. Among alternative cover gas technologies for Mg melt protection other than SF6: commercially available technologies containing―HFC-134a, fluorinated ketone and dilute SO2―and developed technologies containing solid CO2, BF3 and SO2F2, can potentially produce toxic and/or corrosive by-products. On the other hand, additions of alkaline earth metal oxides to Mg and its alloys have developed a strong comparative advantage in the field of Mg melt protection. The near-future challenges and opportunities for Mg-Al based alloys include optimising and using CO2 gas as feedstock for both melt protection and grain refinement and TiO2 additions for melt protection.

  10. Aluminum drinking water treatment residuals (Al-WTRs) as sorbent for mercury: Implications for soil remediation.

    Hovsepyan, Anna; Bonzongo, Jean-Claude J


    The potential of readily available and non-hazardous waste material, aluminum drinking water treatment residuals (Al-WTRs), to efficiently sorb and immobilize mercury (Hg) from aqueous solutions was evaluated. Al-WTR samples with average specific surface area of 48m(2)/g and internal micropore surface area of 120m(2)/g were used in a series of batch sorption experiments. Obtained sorption isotherms indicated a strong affinity of Hg for Al-WTRs. Using the Langmuir adsorption model, a relatively high maximum sorption capacity of 79mg Hg/g Al-WTRs was determined. Sorption kinetic data was best fit to a pseudo-first-order model, while the use of the Weber-Morris and Bangham models suggested that the intraparticle diffusion could be the rate-limiting step. Also, Al-WTRs effectively immoblized Hg in the pH range of 3-8. The results from these short-term experiments demonstrate that Al-WTRs can be effectively used to remove Hg from aqueous solutions. This ability points to the potential of Al-WTRs as a sorbent in soil remediation techniques based on Hg-immobilization.

  11. Homogenization of alloys in the system Al-Mg-Sc

    Drits, M. E.; Toropova, L. S.; Bykov, Yu. G.


    A reduction in homogenizing anneal temperature and a reduction in soaking time leads to an increase in yield point for alloys of the system Al-Mg-Sc. The optimum homogenizing schedule for alloys of this system is heating to 400°C and soaking for up to 10 h. This homogenizing schedule provides an alloy structure of fine coherent ScAl3-phase precipitates and dissolution of excess β-phase precipitates.

  12. Effects of MgO Nano Particles on Microstructural and Mechanical Properties of Aluminum Matrix Composite prepared via Powder Metallurgy Route

    Baghchesara, Mohammad Amin; Abdizadeh, Hossein; Baharvandi, Hamid Reza

    The objective of the present investigation was to evaluate the microstructural and mechanical properties of Al/nano MgO composite prepared via powder metallurgy method. Pure atomized aluminum powder with an average particle size of 1μm and MgO particulate with an average particle size between 60 to 80 nm were used. Composites containing 1.5, 2.5 and 5 percent of volume fraction of MgO were prepared by powder metallurgy method. The specimens were pressed by Cold Isostatic Press machine (CIP), subsequently were sintered at 575, 600 and 625°C. After sintering and preparing the samples, mechanical properties were measured. The results of microstructure, compression and hardness tests indicated that addition of MgO particulates to aluminum matrix composites improves the mechanical properties.

  13. Effect of ScAl/sub 3/ phase dispersity on hardening of A1-6. 3% Mg-0. 21% Sc alloy

    Drits, M.E.; Bykov, Y.G.; Toropova, L.S.


    This paper reports on attempts to evaluate the quantitatively separate influence exerted on the hardening of an aluminum alloy containing 6.3% Mg and 0.21% Sc by both particles of the ScAl/sub 3/ phase exhibiting a different degree of dispersity and also the substructure which is formed in the alloy after hot deformation. The binary aluminum alloy containing 6.3% of Mg after hot deformation has a fully recrystallized structure, while the aluminum alloy containing 6.5% of Mg and Sc is recrystallized. It is concluded that: the magnitude of substructure hardening of the A1-6.3% Mg-0.21% Sc alloy is similar, irrespective of the dispersity of coherent ScAl/sub 3/ particles; and, hardening of the alloy, which is governed by coherent ScAl/sub 3/-phase segregations less than 20 mm in diameter, significantly exceeds the effect of substructure hardening.

  14. Microstructure Evolution and Mechanical and Corrosion Behavior of Accumulative Roll Bonded Mg-2%Zn/Al-7075 Multilayered Composite

    Anne, Gajanan; Ramesh, M. R.; Shivananda Nayaka, H.; Arya, Shashi Bhushan; Sahu, Sandeep


    Multilayered composite of Mg-2%Zn/Al-7075 was developed by accumulative roll bonding (ARB) of wrought Mg-2%Zn and aluminum 7075 alloy. The Mg-2%Zn/Al-7075 multilayered composite exhibited density of 2295 kg/m3 and an average grain size of 1 and 1.3 μm in Mg-2%Zn and Al-7075 layers, respectively. A thorough microstructural characterization was performed on the composites by scanning electron microscope, electron backscatter diffraction (EBSD), transmission electron microscope and phase analysis by x-ray diffraction. In addition, mechanical properties were evaluated by microhardness and tensile tests. Corrosion behavior of the multilayered composite was examined using electrochemical polarization test. EBSD analysis showed the presence of ultrafine grains with high-angle grain boundaries. The composite exhibited a significant improvement in ultimate tensile strength ( 1.82 times) and elongation ( 1.5 times) as compared with Mg-2%Zn alloy, after four-pass ARB process.

  15. Study of Microbiologically Induced Corrosion Action on Al-6Mg-Zr and Al-6Mg-Zr-Sc


    The corrosion behaviors of Al-6Mg-Zr and Al-6Mg-Zr-Sc in the sulfate-reducing bacteria (SRB) solution in anaerobic environment were studied using electrochemical, microbiological, and surface analysis methods. It was found that the oxide film was more compact owing to the addition of Sc resulting in the open circuit potential shifting by about 100mV positively. On the other hand, it was seen that the pitting sensitivity of Al-6Mg-Zr-Sc alloy in SRB solution decreased and its microbiologically influenced corrosion resistance was improved. Pitting corrosion occurring on the surface of the two alloys under the comprehensive action of the metabolism of SRB was observed by SEM. It was obtained by EDS that the corrosion degree increased with time and corrosion was furthered by deposition of the product.

  16. Solid-state 27Al nuclear magnetic resonance investigation of three aluminum-centered dyes

    Mroué, Kamal H.


    We report the first solid-state 27Al NMR study of three aluminum phthalocyanine dyes: aluminum phthalocyanine chloride, AlPcCl (1); aluminum-1,8,15,22-tetrakis(phenylthio)-29H,31H-phthalocyanine chloride, AlPc(SPh)4Cl (2); and aluminum-2,3-naphthalocyanine chloride, AlNcCl (3). Each of these compounds contains Al3+ ions coordinating to four nitrogen atoms and a chlorine atom. Solid-state 27Al NMR spectra, including multiple-quantum magic-angle spinning (MQMAS) spectra and quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) spectra of stationary powdered samples have been acquired at multiple high magnetic field strengths (11.7, 14.1, and 21.1 T) to determine their composition and number of aluminum sites, which were analyzed to extract detailed information on the aluminum electric field gradient (EFG) and nuclear magnetic shielding tensors. The quadrupolar parameters for each 27Al site were determined from spectral simulations, with quadrupolar coupling constants (CQ) ranging from 5.40 to 10.0 MHz and asymmetry parameters (η) ranging from 0.10 to 0.50, and compared well with the results of quantum chemical calculations of these tensors. We also report the largest 27Al chemical shielding anisotropy (CSA), with a span of 120 ± 10 ppm, observed directly in a solid material. The combination of MQMAS and computational predictions are used to interpret the presence of multiple aluminum sites in two of the three samples.

  17. Thermal stability of Al-Mg-Sc-Zr alloy

    ZHAO Wei-tao; YAN De-sheng; RONG Li-jian


    The thermal stability of Al3(Sc,Zr) precipitates in the cold worked Al-Mg-Sc-Zr alloy after elevated temperature exposure was investigated. The evaluation was conducted using room temperature tensile, Vicker's hardness, optical metallography and scanning electron microscope (SEM) with the backscatter. The results show that the Al3(Sc,Zr) precipitates and mechanical properties have no obvious change, and the grains keep elongated along the working direction as that in cold worked sample after exposure at 300 ℃ for 1 000 h. The coarsening of Al3(Sc,Zr) precipitates occurs and is no longer effective on the recrystallization resistance, and partial recrystallization is observed after 400 ℃ exposure. In particular, after 500 ℃ exposure, the hardness decreases drastically and the alloy has fully recrystallized due to the obvious coarsening of Al3(Sc,Zr) precipitates.

  18. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    Li, Shuo [School of Materials Science and Technology, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian Distract, Beijing 100083 (China); Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States); Bhushan, Bharat, E-mail: [Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States)


    Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  19. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg alloys

    M. Kaczorowski


    Full Text Available The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM and transmission (TEM electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.

  20. Structural Evolvement of Heating Treatment of Mg/Al-LDH and Preparation of Mineral Mesoporous Materials

    CHEN Tianhu; XU Huifang; WANG Yifeng; QING Chengsong; FAN Mingde; CHEN Gang


    Although hydrotalcite, or layered double hydroxides (LDHs), is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/Al-LDH is evaluated by XRD, TEM and N2-BET analyses. The results indicate that the magnesium-aluminum LDH with carbonate as interlayer anion,periclase-like oxides was formed at temperatures of 400-800℃. Meanwhile, 2-3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase-like formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of (Mg, Al)-oxide nano-crystals and nanopores among the nano-crystals. When heating temperature exceeds 1000, the periclase-like (Mg, Al)-oxide is transformed into a composite with periclase (MgO) and spinel phases.The periclase can be re-hydrolyzed and dissolved in HCl solution. After acid treatment, the sample with a high surface area is composed of spinel nano-crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition.

  1. Characterization of Al-Mg Alloy Aged at Low Temperatures

    Yi, Gaosong; Cullen, David A.; Littrell, Kenneth C.; Golumbfskie, William; Sundberg, Erik; Free, Michael L.


    Long-term aged [343 K (70 °C) for 30 months and natural exposure for over 10 years] Al 5456 H116 samples were characterized using electron backscatter diffraction (EBSD), scanning transmission electron microscopy (STEM), state-of-the-art energy-dispersive X-ray spectroscopy (EDS) systems, and small-angle neutron scattering (SANS). ASTM G-67 mass loss tests of the sensitized Al 5456 alloy samples were conducted. Intragranular Mg-rich precipitates, such as Guinier-Preston (GP) zones, were confirmed in Al 5456 H116 aged at 343 K (70 °C) for 30 months, and the volume of these precipitates is 1.39 pct. β' phase is identified at the grain boundary of a navy ship sample, while high-resolution STEM results reveal no intragranular precipitates. Intergranular corrosion (IGC) of Al 5456 was found to be related to the continuity of intergranular precipitates.

  2. Mechanical property, biocorrosion and in vitro biocompatibility evaluations of Mg-Li-(Al)-(RE) alloys for future cardiovascular stent application.

    Zhou, W R; Zheng, Y F; Leeflang, M A; Zhou, J


    Mg-Li-based alloys were investigated for future cardiovascular stent application as they possess excellent ductility. However, Mg-Li binary alloys exhibited reduced mechanical strengths due to the presence of lithium. To improve the mechanical strengths of Mg-Li binary alloys, aluminum and rare earth (RE) elements were added to form Mg-Li-Al ternary and Mg-Li-Al-RE quarternary alloys. In the present study, six Mg-Li-(Al)-(RE) alloys were fabricated. Their microstructures, mechanical properties and biocorrosion behavior were evaluated by using optical microscopy, X-ray diffraction, scanning electronic microscopy, tensile tests, immersion tests and electrochemical measurements. Microstructure characterization indicated that grain sizes were moderately refined by the addition of rare earth elements. Tensile testing showed that enhanced mechanical strengths were obtained, while electrochemical and immersion tests showed reduced corrosion resistance caused by intermetallic compounds distributed throughout the magnesium matrix in the rare-earth-containing Mg-Li alloys. Cytotoxicity assays, hemolysis tests as well as platelet adhesion tests were performed to evaluate in vitro biocompatibilities of the Mg-Li-based alloys. The results of cytotoxicity assays clearly showed that the Mg-3.5Li-2Al-2RE, Mg-3.5Li-4Al-2RE and Mg-8.5Li-2Al-2RE alloys suppressed vascular smooth muscle cell proliferation after 5day incubation, while the Mg-3.5Li, Mg-8.5Li and Mg-8.5Li-1Al alloys were proven to be tolerated. In the case of human umbilical vein endothelial cells, the Mg-Li-based alloys showed no significantly reduced cell viabilities except for the Mg-8.5Li-2Al-2RE alloy, with no obvious differences in cell viability between different culture periods. With the exception of Mg-8.5Li-2Al-2RE, all of the other Mg-Li-(Al)-(RE) alloys exhibited acceptable hemolysis ratios, and no sign of thrombogenicity was found. These in vitro experimental results indicate the potential of Mg-Li-(Al

  3. Effect of ScAl/sub 3/ phase dispersity on hardening of Al-6. 3 pct Mg-0. 21 pct Sc alloy

    Drits, M.E.; Bykov, IU.G.; Toropova, L.S.


    The relative contributions of disperse coherent ScAl/sub 3/ segregations and of the substructure to the hardening of an aluminum alloy containing 6.3 pct Mg and 0.21 pct Sc are evaluated quantitatively. It is shown that the extent of substructure hardening is independent of the dispersity of coherent ScAl/sub 3/ particles and, consequently, of the homogenizing treatment. The contribution of coherent ScAl/sub 3/ segregations less than 20 nm in diameter to the hardening of the alloy significantly exceeds that of substructure hardening. 9 references.

  4. In Situ Observation of MgO Inclusions in Liquid Iron-Aluminum Alloys

    Mu, Haoyuan; Zhang, Tongsheng; Yang, Liang; Xavier, Rodrigo R.; Fruehan, Richard J.; Webler, Bryan A.


    This study showed that MgO inclusions can be stable in liquid iron with elevated Al and it illustrated an important role of vaporization in the evolution of inclusions. Previous studies have shown that dissolved Al reduces MgO from slags and refractories, leading to spinel (MgAl2O4) inclusions. The elevated Al content of newer steels raises the possibility that MgO inclusions can be stable. In this work, MgO inclusions were produced and observed in an Fe-Al alloy. The inclusions in the liquid alloy at 1873 K (1600 °C) were observed in situ with a Confocal Laser Scanning Microscope (CLSM). Two types of experiments were performed: one where only a metal sample was melted and the other where the sample was in contact with a liquid, MgO-saturated slag. When no slag was present, the MgO inclusions shrank and disappeared at 1873 K (1600 °C). No inclusions were observed in situ during cooling or in post-CLSM analysis. When the MgO-saturated slag was present, the inclusion sizes were essentially constant and MgO was observed on the surface of post-CLSM samples. Analysis of the results showed that MgO can be stable in 1873 K (1600 °C), but that its presence depends on the rate of removal of Mg due to vaporization and the supply of Mg due to slag/metal or refractory/metal reactions.

  5. Divorced Eutectic Solidification of Mg-Al Alloys

    Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo


    We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed -Mg phase followed by the nucleation of the -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.

  6. Quantitative procedure for evaluation of microstructure of cast Mg-Al-Ca-Sr magnesium alloy

    T. Rzychoń


    Full Text Available In this paper the microstructural characterization of ingot MRI-230D magnesium alloy and quantitative procedure for evaluation of microstructure are presented. The optical and scanning electron microscopy were used to study the morphology of microstructural compounds in this alloy. The X-ray diffraction was used to determination of phase composition. The as-cast microstructure of MRI-230D magnesium alloy containing aluminum, calcium and strontium consists of the dendritic α-Mg and such intermetallic compounds as: Al2Ca, Al4Sr and AlxMny. In the purpose quantitative description of microstructure semi-automatic procedures using Met-Ilo image analysis were developed. Prepared semi-automatic procedures allow a fast determination of phase content in MRI-230D alloy using light microscopy and will be useful in the quality control of MRI-230D ingots.

  7. Rapidly solidified Mg-Al-Zn-rare earth alloys

    Chang, C.F.; Das, S.K.; Raybould, D.


    Among the light metal alloys, magnesium is the lightest structural material except for beryllium, and yet magnesium alloys have not seen extensive use because of their poor strength and corrosion resistance. Rapid solidification technology offers a possible solution to these problems. A number of Mg-Al-Zn alloys containing rare earth (RE) elements (e.g. Ce, Pr, Y, and Nd) have been investigated using rapid solidification processing for possible structural applications. The processing consists of planar flow or jet casting into ribbons, pulverization of ribbon to powder, and consolidation of powder into bulk shapes. The mechanical properties of some of these alloys show attractive combinations of strength, ductility and corrosion resistance. The microstructures of these alloys are correlated with their mechanical properties. The rapidly solidified Mg-Al-Zn-RE alloys show great potential for applications in automotive and aerospace industries. 7 references.

  8. Study on Mg/Al Weld Seam Based on Zn–Mg–Al Ternary Alloy

    Liming Liu


    Full Text Available Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA welding. An infrared thermography system was used to measure the temperature of the welding pool during the welding process to investigate the solidification process. It was found that the mechanical properties of the welded joints were improved with the increasing of the Al content in the Zn–xAl filler metals, and when Zn–30Al was used as the filler metal, the ultimate tensile strength could reach a maximum of 120 MPa. The reason for the average tensile strength of the joint increasing was that the weak zone of the joint using Zn–30Al filler metal was generated primarily by α-Al instead of MgZn2. When Zn–40Al was used as the filler metal, a new transition zone, about 20 μm-wide, appeared in the edge of the fusion zone near the Mg base metal. Due to the transition zones consisting of MgZn2- and Al-based solid solution, the mechanical property of the joints was deteriorated.

  9. Nano-ZnO Particles’ Effect in Improving the Mechanical Response of Mg-3Al-0.4Ce Alloy

    Sravya Tekumalla


    Full Text Available Magnesium based nanocomposites, due to their excellent dimensional stability and mechanical integrity, have a lot of potential to replace the existing commercial Al alloys and steels used in aerospace and automotive applications. Mg-Al alloys are commercially used in the form of AZ (magnesium-aluminum-zinc and AM (magnesium-aluminum-manganese series in automobile components. However, the Mg17Al12 phase in Mg-Al alloys is a low melting phase which results in a poor creep and high temperature performance of the alloys. Rare earth additions modify the phase and hence improve the properties of the materials. In this paper, Ce and nano ZnO particles were added to Mg-Al alloys to attain a favorable effect on their properties. The developed materials exhibited promising properties in terms of thermal expansion coefficient (CTE, hardness, and tensile strength. Further, the ZnO addition refined the microstructure and helped in obtaining a uniform distribution, however without grain size refinement. The increased addition of ZnO and the improvement in the distribution led to an enhancement in the properties, rendering the materials suitable for a wide spectrum of engineering applications.

  10. Microstructure and crystal growth direction of Al-Mg alloy

    Ti-jun Chen


    Full Text Available The microstructures and crystal growth directions of permanent mould casting and directionally solidified Al-Mg alloys with different Mg contents have been investigated. The results indicate that the effect of Mg content on microstructure is basically same for the alloys prepared by these two methods. The primary grains change from cellular crystals to developed columnar dendrites, and then to equiaxed dendrites as the Mg content is increased. Simultaneously, both the cellular or columnar grain region and the primary trunk spacing decrease. All of these changes are mainly attributed to the constitutional supercooling resulting from Mg element. Comparatively, the cellular or columnar crystals of the directionally solidified alloys are straighter and more parallel than those of the permanent mould casting alloys. These have straight or wavy grain boundaries, one of the most important microstructure characteristics of feathery grains. However, the transverse microstructure and growth direction reveal that they do not belong to feathery grains. The Mg seemingly can affect the crystal growth direction, but does not result in the formation of feathery grains under the conditions employed in the study.

  11. Environmentally Benign Neem Biodiesel Synthesis Using Nano-Zn-Mg-Al Hydrotalcite as Solid Base Catalysts

    Karthikeyan Chelladurai


    Full Text Available Hydrotalcite, also known as aluminum-magnesium layered double hydroxide (LDH or anionic clay, is a synthetic compound that was broadly investigated in the past decade due to its many potential applications. In this work, we present an environmentally benign process for the transesterification (methanolysis of neem oil to fatty acid methyl esters (FAME using Zn-Mg-Al hydrotalcites as solid base catalysts in a heterogeneous manner. The catalysts were characterized by XRD, FT-IR, TPD-CO2, and the BET surface area analysis. It is well-known that the catalytic performance of hydrotalcite is dramatically increased through the incorporation of Zn into the surface of Mg-Al hydrotalcite material. The optimized parameters, 10 : 1 methanol/oil molar ratio with 7.5 g catalysts reacted under stirring speed 450 rpm at 65°C for 4 h reaction, gave a maximum ester conversion of 90.5% for the sample with Zn-Mg-Al ratio of 3 : 3 : 1.

  12. Analysis of Al-Mg casting alloys crystallization with use of „ATND” method

    T. Ciućka


    Full Text Available The paper presents results of non-ferrous metals crystallization tests performed with use of the ATND method. Such tests are performed in the Institute of Chipless Technology, Academy of Technology and Humanities in Bielsko-Biala. Method of analysis of non-ferrous metals crystallization gives complete picture of arisen structural components of alloys. Particular structural components of alloys investigated with use of the ATND method were verified in x-ray microanalysis, what unequivocally confirmed their presence. Below are presented in graphical form (crystallization diagrams results of crystallization process obtained from the ATND method. In crystallization diagrams of AlMg10 and AG51 alloys are shown curves (thermal curve and its derivative, voltage curve and its derivative. Crystallizable individual structural components of the investigated alloys are reflected on curves of the method in form of characteristic peaks. The tests were performed with AlMg10 and AlMg5Si1 aluminum-magnesium alloys casting. Moreover, the paper presents structures of the investigated alloys with marked structural components identified with use of x-ray microanalysis.

  13. Synthesis and characterization of Mn intercalated Mg-Al hydrotalcite.

    Yang, Chengxue; Liao, Libing; Lv, Guocheng; Wu, Limei; Mei, Lefu; Li, Zhaohui


    Mn intercalated hydrotalcite was prepared using a reconstruction method. And Mn intercalation was confirmed by XRD, FTIR, and thermal analyses. The different valences of Mn were present as determined by XPS. Calcination slightly promoted the isomorphic replacement of Mn(2+) and Mn(3+) for Mg(2+) and Al(3+), especially the replacement of Mn(2+) for Mg(2+) and Al(3+), and to some extent, reduced Mn intercalation. Ultrasonic treatment significantly increased Mn intercalation in permanganate form (Mn(7+)), and promoted the replacement of Mn(2+) for Mg(2+) and Al(3+). XRF analysis showed that ultrasonic treatment decreased the unbalanced layer charge of Mn intercalated hydrotalcite, while prolonged calcination increased it. These results may provide guidance on the preparation and application of Mn intercalated hydrotalcite. Extended calcination time and ultrasonic vibration increased the interlayer spacing of hydrotalcite, as a result of reduction in layer charge. As the layer charge was not completely balanced after Mn intercalation, a certain amount of CO3(2-) was re-adsorbed into the interlayer space. Mn-hydrotalcites with different layer charges, different contents of Mn with varying valences are expected to have different performances in the process of adsorption, degradation, and catalysis.

  14. Ageing processes in Al-Cu-Mg alloys with different Cu/Mg ratios

    Macchi, C. [IFIMAT, UNCentro and CONICET, Pinto, Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto, Tandil (Argentina); Ferragut, R.; Dupasquier, A. [LNESS and CNISM, Politecnico di Milano, Como (Italy); Polmear, I.J. [Emeritus Professor, Department of Materials Engineering, Monash University, Melbourne, Vic. (Australia)


    Three age-hardenable Al-Cu-Mg alloys with different Cu/Mg ratios were studied by means of positron annihilation lifetime spectroscopy and Vickers hardness as a function of the artificial ageing time at 175 C. Complementary information on the decomposition sequence was obtained by means of differential scanning calorimetry. The results are discussed in terms of the different structures that are formed during the precipitation sequence of the supersaturated solid solution. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Tensile property of Al-Si closed-cell aluminum foam

    YU Hai-jun; YAO Guang-chun; LIU Yi-han


    Al-Si closed-cell aluminum foams of different densities were prepared by molten body transitional foaming process. The tensile behavior of Al-Si closed-cell aluminum foam was studied and the influence of relative densities on the tensile strength and elastic modulus was also researched. The results show that the fracture surfaces of Al-Si closed-cell aluminum foam display quasi-cleavage fiacture consisting of brittle cleavages and ductile dimples. The tensile strength and elastic modulus are strictly affected by the relative density of Al-Si closed-cell aluminum foam. With increasing relative density, the tensile strength increases and the strain at which the peak strength is measured also increases; in addition, the elastic modulus increases with increasing relative density.




    Full Text Available En un esfuerzo por desarrollar una nueva aleación con aplicación estructural, se ha desarrollado una aleación base Aluminio aleada con magnesio, silicio y zinc. La investigación pretende correlacionar la microestructura y con el tratamiento térmico. La aleación AlMgSiZn, fue elegida para ese propósito debido a la presencia de precipitados tanto en la matriz del aAl, como en los límites de grano, los cuales permiten una excelente relación entre la dureza y la resistencia mecánica. En lo que respecta a la microestructura, esta fue caracterizada bajo condición de colada y después de ser tratada térmicamente por envejecimiento. Este tratamiento fue realizado en dos etapas, la primera a 450ºC durante 3 horas que corresponde al tratamiento de homogeneización: y la segunda al proceso de envejecimiento artificial llevado a cabo a 160ºC durante 1hr. Los resultados indican la presencia de dendritas de aAl, además un eutéctico binario y partículas de Mg7Zn3 adentro de las regiones interdendríticas. El eutéctico y las partículas fueron modificados por el tratamiento de envejecido. Las observaciones realizadas con el microscopio electrónico de transmisión en especímenes con y sin tratamientos térmicos, demostraron una distribución uniforme de precipitados con diversas morfologías, tales como cúbico, esférico y plaqueta: para la matriz de aAl, los cuales no fueron detectados durante las observaciones en el microscopio electrónico de barrido.

  17. Performance of Mg-14Li-1Al-0.1Ce as anode for Mg-air battery

    Ma, Yibin; Li, Deyu [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Li, Ning [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin; Huang, Xiaomei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China)


    In this research, a new Mg-air battery based on Mg-14Li-1Al-0.1Ce was prepared and the battery performance was investigated by constant current discharge test. The corrosion behavior of Mg, AZ31 and Mg-Li-Al-Ce were studied by self-corrosion rate measurement and potentiodynamic polarization measurement. The characteristics of Mg-Li-Al-Ce after discharge were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that Mg-Li-Al-Ce is more active than Mg and AZ31. The self-corrosion rate is found to be in the order: Mg-Li-Al-Ce < Mg < AZ31. It has been observed that the Mg-air battery based on Mg-Li-Al-Ce offers higher operating voltage, anodic efficiency and capacity than those with Mg and AZ31. SEM and EIS results show that the discharge product of Mg-Li-Al-Ce is loosely adhered to the alloy surface, and thus Mg-Li-Al-Ce could keep high discharge activity during discharge. (author)

  18. The Effect of Aluminum Content and Processing on the Tensile Behavior of High Pressure Die Cast Mg Alloys

    Deda, Erin M.

    Due to their high specific strength and good castability, magnesium alloys are desirable for use in weight reduction strategies in automotive applications. However, the mechanical properties of high pressure die cast (HPDC) magnesium can be highly variable and dependent on location in the casting. To better understand the relationship between microstructure and tensile properties, the influence of alloying and section thickness on the microstructural features and tensile properties of Mg-Al and Mg-Al-Mn alloys is quantified. This investigation provides experimental input to modeling activities for the development of an Integrated Computational Materials Engineering capability, to assess and quantify the impact of microstructure on the tensile behavior of HPDC Mg AM series (magnesium-aluminum-manganese) alloys. As a result of this work, it is found that with increasing aluminum content, the yield strength increases and the ductility decreases. Increasing the plate thickness results in a decrease in both the yield strength and ductility. HPDC components have varying microstructural features through the plate thickness, developing a "skin" and "core". The grain size, beta-Mg 17Al12 phase, and solute content are all quantified through the thickness of the plates. By quantifying microstructural variations, a physics-based model has been developed which is able to predict the effects of alloying and plate thickness on yield strength. The primary factors affecting strengthening are accounted for using a linear superposition model of solid solution, grain size, and dispersion hardening. This model takes into account through-thickness microstructure gradients that exist in HPDC components by using a composite model to incorporate the skin and core changes. The yield strength in these alloys is dominated by grain boundary strengthening and solute hardening effects. In order to isolate the effects of eutectic phases, shrinkage porosity and oxide films on strength and

  19. First principles predictions of intrinsic defects in aluminum arsenide, AlAs : numerical supplement.

    Schultz, Peter Andrew


    This Report presents numerical tables summarizing properties of intrinsic defects in aluminum arsenide, AlAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz, 'First principles predictions of intrinsic defects in Aluminum Arsenide, AlAs', Materials Research Society Symposia Proceedings 1370 (2011; SAND2011-2436C), and intended for use as reference tables for a defect physics package in device models.

  20. Foaming behaviour of Al-Si-Cu-Mg alloys

    Kim, A. [Kongju National University (Korea). Dept. of Mechanical Engineering; Cho, S.S. [Chungnam National University, Daejeon (Korea). School of Materials Engineering; Lee, H.J. [Hanbat National University, Daejeon (Korea). Dept. of Building Service Engineering


    The powder metallurgical route was utilised to obtain the Al-5Si-4Cu-4Mg (alloy 544) and Al-3Si-2Cu-2Mg (alloy 322) foams. Various steps such as centrifugal atomisation, mixing alloy powder and foaming agent (1 wt-%TiH{sub 2}), cold compaction of mixture, hot extrusion and foaming in a preheated furnace were performed. Foaming behaviour of the alloys was investigated by digital microscopy, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) mapping in this study. It was found that alloy 544 takes a shorter period of time to initiate pore nucleation than alloy 322. Alloy 544 had a higher pore growth rate than alloy 322 at the same pre-set furnace temperature. In both alloys, crack-like pore nucleation occurred between aluminium alloy powders elongated in a direction parallel to the extrusion direction. Both alloys showed the same foaming sequence of crack-like pore nucleation, spherical pore growth, coalescence of neighbouring pores and collapse of pores adjacent to the free surface of specimen. The time required to start pore nucleation decreased with the increase of foaming temperature. The cell walls of both alloys consisted of {alpha}-Al phase and eutectic phase. (author)

  1. MgCoAl and NiCoAl LDHs synthesized by the hydrothermal urea hydrolysis method: Structural characterization and thermal decomposition

    Chagas, L.H., E-mail: [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); Instituto Nacional de Metrologia Qualidade e Tecnologia, Divisão de Metrologia de Materiais, 25250-020 Duque de Caxias, RJ (Brazil); De Carvalho, G.S.G.; Do Carmo, W.R. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); San Gil, R.A.S. [Universidade Federal do Rio de Janeiro, Instituto de Química, 21949-900 Rio de Janeiro, RJ (Brazil); Chiaro, S.S.X. [PETROBRAS-CENPES, 21941-915 Rio de Janeiro, RJ (Brazil); Leitão, A.A.; Diniz, R. [Universidade Federal de Juiz de Fora, Departamento de Química, Grupo de Físico-Química de Sólidos e Interfaces, 36036-330 Juiz de Fora, MG (Brazil); De Sena, L.A.; Achete, C.A. [Instituto Nacional de Metrologia Qualidade e Tecnologia, Divisão de Metrologia de Materiais, 25250-020 Duque de Caxias, RJ (Brazil)


    Highlights: • We synthesized MgCoAl and NiCoAl LDHs by the urea hydrolysis method. • Aluminum rich and crystalline materials have been formed. • The calcination of the LDHs generated mixed oxides with high surface areas. - Abstract: Layered double hydroxides (LDHs) with Mg/Co/Al and Ni/Co/Al were synthesized for the first time by the urea hydrolysis method. The experimental conditions promoted aluminum rich and crystalline materials. The formation of LDHs was investigated by powder X-ray diffraction (XRD), chemical analysis, solid state nuclear magnetic resonance with magic angle spinning ({sup 27}Al-MAS-NMR), simultaneous thermogravimetric/differential thermal analysis (TGA/DTA), FTIR spectroscopy, scanning electron microscopy (SEM), and N{sub 2} adsorption–desorption experiments. A single phase corresponding to LDH could be obtained in all the investigated compositions. Thermal calcination of these LDHs at 500 °C resulted in the formation of solid solutions in which Al{sup 3+} was dissolved. All the calcined materials have rock-salt like structures and high surface areas.

  2. The intermittency of plasticity in an Al3%Mg alloy

    Bougherira, Y; Entemeyer, D; Fressengeas, C; Lebyodkin, M A [Laboratoire de Physique et Mecanique des Materiaux, Universite Paul Verlaine-Metz, CNRS, Ile du Saulcy, 57045 Metz (France); Kobelev, N P; Lebedkina, T A, E-mail: Youcef.bougherira@univ-metz.f [Institute of Solid State Physics, Russian Ac. Sci., 142432 Chernogolovka (Russian Federation)


    Statistics of acoustic emission accompanying plastic deformation and of stress serrations caused by the Portevin-Le Chatelier effect are studied during tension of an Al3%Mg alloy at room temperature. Power-law distributions of acoustic emission reflecting self-organization of dislocations and intermittency of plastic flow are found, irrespective of the strain rate, both before and after the critical strain for the onset of the serrated flow. In contrast, several regimes including both power-law and peaked distributions are observed at the macroscopic scale of stress serrations, depending on the applied strain rate.

  3. Development of Low Cost, High Performance AlZn4.5Mg1 Alloy 7020


    MPa) U.T.S. (MPa) El. (%) Data Reference 7005-T651 290 (42) 370 (54) 15 typical [6] 6061 -T651 300 (44) 337 (49) 19 experiment [15] 7018...Aluminum Association chemical composition limits [14]. Alloy Si Fe Cu Mn Mg Cr Ni Zn Ti V Zr Date 6061 0.40 0.8 0.7 0.15 0.40 0.15...Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys, ( aluminium /standards/international-registration), The Aluminum

  4. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    Li, Shuo; Bhushan, Bharat


    Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  5. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001) magnetic tunnel junctions

    Belmoubarik, Mohamed; Sukegawa, Hiroaki; Ohkubo, Tadakatsu; Mitani, Seiji; Hono, Kazuhiro


    We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001) magnetic tunnel junctions (MTJs) on their spin-dependent transport properties. The tunnel magnetoresistance (TMR) ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm) induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  6. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001 magnetic tunnel junctions

    Mohamed Belmoubarik


    Full Text Available We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001 magnetic tunnel junctions (MTJs on their spin-dependent transport properties. The tunnel magnetoresistance (TMR ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  7. Al-Mg-Sc-Zr合金的再结晶%Recrystallization of Al-Mg-Sc-Zr Alloys

    张永红; 尹志民; 张杰; 潘青林; 彭志辉


    研究了添加微量Sc,Zr的Al-Mg合金的再结晶行为,结果表明:Al-Mg-Sc-Zr合金的再结晶起始温度为400℃,细小、弥散、与基体共格的析出相对位错和亚晶的钉扎作用是合金再结晶温度大幅度提高的主要原因,再结晶形核机制为亚晶聚合机制.%The recrystalization behavior of Al-Mg alloys with Sc and Zr additives was studied.It is found that the recrystallization of the alloy began at 400℃.The main reason of the great increase of recrystallization temperature is attributed to that the dislocations and subgrain boundaries.The recrystallizing nucleation mechanism was the subgrain boundary merging mechanism in the alloy are pinned by ultrafine dispersed coherent precipitates.

  8. The interface bonding mechanism and related mechanical properties of Mg/Al compound materials fabricated by insert molding

    Liu, J.C.; Hu, J.; Nie, X.Y. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Li, H.X., E-mail: [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Du, Q. [SINTEF Materials and Chemistry, Trondheim (Norway); Zhang, J.S.; Zhuang, L.Z. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)


    To overcome the shortcomings of magnesium alloys such as low strength at an elevated temperature and poor corrosion resistance, the fabrication of Mg/Al compound materials has attracted more and more attention in the recent years. Among the various fabrication methods such as diffusion bonding, friction-stir welding, and fusion welding, insert molding technique has shown some advantages such as low production cost, short processing time and the ability of producing complex shape. However, there are only a few documents about this preparation method. In this paper, the corresponding study is carried out via inserting 6061 aluminum alloy into AZ31 magnesium alloy melt. The interface bonding mechanism and its mechanical behavior are investigated as well. It has been found that a good metallurgical bonding can be formed at the interface, which consists of three layers, i.e., Al{sub 3}Mg{sub 2}, Al{sub 12}Mg{sub 17}, and Al{sub 12}Mg{sub 17}+(Mg) eutectic structure. The average shear strength is 20 MPa, which is close to the reported shear strength of the samples prepared by other methods. This research provides a new insight for the fabrication of Mg/Al compound materials.

  9. Microstructure and mechanical properties of spray-deposited Al-Si-Fe-Cu-Mg alloy containing Mn


    Al-20Si-5Fe-3Cu-lMg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited hypereutectic Al-Si alloy were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, TEM (Transmission Electron Microscope) and HREM (High-resolution Electron Microscope), DSC (Differential Scanning Calorimetry), microhardness measurement, and tensile tests. The effects of Mn on the microstructural evolution of the highsilicon aluminum alloy after extrusion and heat treatment have been examined. The results show that two kinds of phases, i.e. S (Al2CuMg) and σ(Al5Cu6Mg2), precipitated from matrix and improved the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300℃). The tensile test results indicate that the spray-deposited Al-20Si-SFe-3Cu-1Mg alloy has better strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.

  10. Secondary precipitation in Al-Zn-Mg-(Ag) alloys

    Macchi, C.E.; Somoza, A.; Dupasquier, A.; Polmear, I.J


    Secondary ageing of age-hardenable aluminium alloys occurs at temperatures below the solvus of GP zones after a preliminary ageing at a higher temperature. The phenomenon has technological interest, as it may be included in heat treatments giving a substantial benefit on the mechanical properties. In the present work, positron annihilation lifetime spectroscopy (PALS) is applied in combination with Vickers hardness measurements for an investigation on secondary ageing of Al-4wt.%Zn-3wt.%Mg-xAg, where x=0, 0.1, 0.2, 0.3, 0.5 wt.%. Ageing regimes have been characterised by the substantially different evolutions that are observed. The results shed light on the interplay between the formation of coherent solute aggregates (clusters or GP zones) and the precipitation of semi-coherent or incoherent precipitates, which are in competition to control the hardening effects. PALS data show that secondary ageing in the ternary Al-Zn-Mg alloys produces coherent aggregates even in the presence of a well-developed stage of semi-coherent or incoherent precipitation that is obtained if the alloys are first aged to peak hardness. In the presence of Ag, on the contrary, the effects of coherent aggregation during secondary ageing are observed only if the preliminary ageing is interrupted well before reaching peak hardness.

  11. Property Criteria for Automotive Al-Mg-Si Sheet Alloys

    Ramona Prillhofer


    Full Text Available In this study, property criteria for automotive Al-Mg-Si sheet alloys are outlined and investigated in the context of commercial alloys AA6016, AA6005A, AA6063 and AA6013. The parameters crucial to predicting forming behavior were determined by tensile tests, bending tests, cross-die tests, hole-expansion tests and forming limit curve analysis in the pre-aged temper after various storage periods following sheet production. Roping tests were performed to evaluate surface quality, for the deployment of these alloys as an outer panel material. Strength in service was also tested after a simulated paint bake cycle of 20 min at 185 °C, and the corrosion behavior was analyzed. The study showed that forming behavior is strongly dependent on the type of alloy and that it is influenced by the storage period after sheet production. Alloy AA6016 achieves the highest surface quality, and pre-ageing of alloy AA6013 facilitates superior strength in service. Corrosion behavior is good in AA6005A, AA6063 and AA6016, and only AA6013 shows a strong susceptibility to intergranular corrosion. The results are discussed below with respect to the chemical composition, microstructure and texture of the Al-Mg-Si alloys studied, and decision-making criteria for appropriate automotive sheet alloys for specific applications are presented.

  12. Improvement of warm formability of Al-Mg sheet alloys containing coarse second-phase particles

    Arne; K; DAHLE; Amit; K; GHOSH


    Several alloying elements involving Zr, Cu, Zn and Sc were added to Al-Mg sheet alloys in order to obtain an excellent combination of high strength and good high-temperature formability. Microstruc-tural examination showed that coarse intermetallic particles were formed in the microstructure and their amounts changed with variations of the alloying elements. During warm rolling of thermome-chanical treatments prior to warm deformation, the coarse particles initiated cracks, decreasing the warm formability. For healing the crack damage and further improving the warm formability, a process of hot isothermal press was developed and optimized to the sheet alloys. With this process, the biaxial stretch formability at 350℃ was improved by 22% for an aluminum alloy containing a large amount of coarse particles.

  13. Corrosion Resistance of the Superhydrophobic Mg(OH)2/Mg-Al Layered Double Hydroxide Coatings on Magnesium Alloys

    Zhang, Fen; Zhang, Changlei; Zeng, Rongchang; Song, Liang; Guo, Lian; Huang, Xiaowen


      Coatings of the Mg(OH)2/Mg-Al layered double hydroxide (LDH) composite were formed by a combined co-precipitation method and hydrothermal process on the AZ31 alloy substrate in alkaline condition...

  14. Secondary ageing in an Al-Cu-Mg alloy with high Cu/Mg ratio

    Dupasquier, A.; Folegati, P. [Politecnico di Milano (Italy). Ist. di Fisica della Materia; Ferragut, R. [Politecnico di Milano (Italy). Ist. di Fisica della Materia; IFIMAT, Univ. Nacional del Centro de la Provincia de Buenos Aires and CICPBA, Tandil (Argentina); Massazza, M.; Riontino, G. [Ist. Nazionale di Fisica della Materia, Dipt. di Chimica I.F.M., Univ. di Torino (Italy); Somoza, A. [IFIMAT, Univ. Nacional del Centro de la Provincia de Buenos Aires and CICPBA, Tandil (Argentina)


    The mechanisms governing secondary ageing (structural transformations occurring at low temperature after a heat treatment at higher temperature) were investigated by combined measurements of positron lifetimes, Vickers microhardness measurements and differential scanning calorimetry (DSC) on a laboratory alloy (Al-4.5 wt.% Cu-0.56 wt.% Mg). The results show that hardening occurs at a much slower rate than in case of primary ageing at RT. The positron lifetime data suggest that the hardening rate is controlled by slow release of vacancies from Cu-rich clusters formed during the initial high temperature treatment. The hardening stage is concomitant with an increase of the positron lifetime, and has probably the same origin, which is the formation of solute clusters containing vacancies and Mg as essential components. The formation at low temperature of new structures is also demonstrated by DSC. (orig.)

  15. A study of Al-Sc-Zr alloys in the aluminum-rich region

    Toropova, L.S.; Kamardinkin, A.N.; Kindzhibalo, V.V.; Tyvanchuk, A.T. (AN SSSR, Institut Metallurgii, Moscow (USSR))


    Alloys in the ternary system Al-Sc-Zr along a section of approximately 1.0 pct Sc and 0.8 pct Zr were investigated by X-ray diffraction and electron probe analyses. It is found that phases Al3Sc and Al3Zr are in equilibrium with the alpha solid solution of aluminum. The contents of zirconium and scandium in the phase Al3Sc are determined as a function of their concentrations in the alloy.

  16. Effects of Be, Sr, Fe and Mg interactions on the microstructure and mechanical properties of aluminum based aeronautical alloys

    Ibrahim, Mohamed Fawzy

    The present work was carried out on a series of heat-treatable aluminum-based aeronautical alloys containing various amounts of magnesium (Mg), iron (Fe), strontium (Sr) and beryllium (Be). Tensile test bars (dendrite arm spacing ~ 24mum) were solutionized for either 5 or 12 hours at 540°C, followed by quenching in warm water (60°C). Subsequently, these quenched samples were aged at 160°C for times up to 12 hours. Microstructural assessment was performed. All heat-treated samples were pulled to fracture at room temperature using a servo-hydraulic tensile testing machine. The results show that Be causes partial modification of the eutectic silicon (Si) particles similar to that reported for Mg addition. Addition of 0.8 wt.% Mg reduced the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, without Sr, a peak corresponding to the formation of a Be-Fe phase (Al8Fe2BeSi) was detected at 611°C. The Be-Fe phase precipitates in a script-like morphology. A new quinary eutectic-like reaction was observed to take place near the end of solidification of high Mg, high Fe, Be-containing alloys. This new reaction is composed mainly of fine particles of Si, Mg2Si, pi-Al 8Mg3FeSi6 and (Be-Fe) phases. The volume fraction of this reaction decreased with the addition of Sr. The addition of Be has a noticeable effect on decreasing the beta-phase length, or volume fraction, this effect may be limited by adding Sr. Beryllium addition also results in the precipitation of the beta-phase in a nodular form, which reduces the harmful effects of these intermetallics on the alloy mechanical properties. Increasing both Mg and Fe levels led to an increase in the amount of the pi-phase; increasing the iron content led to an increase in the volume fraction of the partially soluble beta- and pi-phases, while Mg2Si particles were completely dissolved. The beta-phase platelets were observed to undergo changes in their morphology due to the

  17. Fracture toughness of Al-4%Mg/Al{sub 2}O{sub 3}p composites

    Pestes, R.H. [Hewlett-Packard, Camus, WA 98607 (United States); Kamat, S.V. [Mechanical and Materials Engineering Department, Washington State University, Pullman, WA 99164-2920 (United States); Hirth, J.P. [Mechanical and Materials Engineering Department, Washington State University, Pullman, WA 99164-2920 (United States)


    Fracture toughness tests were carried out on Al-4%Mg/Al{sub 2}O{sub 3}p composites containing different sizes and volume fractions of alumina particulates. The results indicated that the fracture toughness was dependent on the interparticle spacing provided the particulate size was below a critical size. The critical particle size corresponds to the situation wherein the energy release rate on particulate cracking is sufficient to trigger dynamic unstable crack extension. ((orig.))

  18. Mg/O2 Battery Based on the Magnesium-Aluminum Chloride Complex (MACC) Electrolyte

    Vardar, Galin; Smith, Jeffrey G.; Thomson, Travis


    Mg/O2 cells employing a MgCl2/AlCl3/DME (MACC/DME) electrolyte are cycled and compared to cells with modified Grignard electrolytes, showing that performance of magnesium/oxygen batteries depends strongly on electrolyte composition. Discharge capacity is far greater for MACC/DME-based cells, while...... substantially and likely explains the poor rechargeability. An additional impedance rise consistent with film formation on the Mg negative electrode suggests the presence of detrimental O2 crossover. Minimizing O2 crossover and bypassing charge transfer through the discharge product would improve battery...

  19. The electrochemical behaviors of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn in sodium chloride solution

    Lv, Yanzhuo; Liu, Min; Xu, Yan; Cao, Dianxue; Feng, Jing


    The electrochemical oxidation behaviors of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn electrodes in 0.7 mol L-1 NaCl solution are investigated by methods of potentiodynamic polarization, potentiostatic oxidation, electrochemical impedance spectroscopy and scanning electron microscopy. The phase composition of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn alloys is analyzed conducted by X-ray diffraction. The performances of Mg-8Li-3Al-0.5Zn and Mg-8Li-3Al-1.0Zn as the anode of Mg-H2O2 semi fuel cells are determined. The effect of Zn content on the corrosion resistant of these Mg-Li-based alloys is studied. It is found that the Mg-8Li-3Al-0.5Zn electrode has higher discharge activity and less corrosion resistance than that of Mg-8Li-3Al-1.0Zn electrode in 0.7 mol L-1 NaCl solution. The Mg-H2O2 semi fuel cell with Mg-8Li-3Al-0.5Zn anode presents a maximum power density of 100 mW cm-2 at room temperature, which is higher than that of Mg-8Li-3Al-1.0Zn anode (80 mW cm-2). The performance of semi fuel cell with the Mg-8Li-3Al-0.5Zn electrode is better than that with Mg-8Li-3Al-1.0Zn electrode, especially at higher current density (>30 mA cm-2).

  20. Effects of Melt-to-Solid Insert Volume Ratio on the Microstructures and Mechanical Properties of Al/Mg Bimetallic Castings Produced by Lost Foam Casting

    Jiang, Wenming; Fan, Zitian; Li, Guangyu; Yang, Li; Liu, Xinwang


    A356 aluminum and AZ91D magnesium alloys, which act as a solid insert and a melt, respectively, were used to prepare Al/Mg bimetallic castings using the lost-foam casting process, and the effects of the melt-to-solid volume ratio (VR) on the microstructures, mechanical properties, and fractographies of the Al/Mg bimetallic castings were investigated in this paper. Obtained results show that the average thickness of the reaction layer between aluminum and magnesium significantly increased with increasing VR, and a compact and uniform interface was obtained with a VR of 14.6. The reaction layers of all the bimetallic castings obtained by different VRs mainly consisted of the Al12Mg17 + δ eutectic layer close to the magnesium matrix, the Al12Mg17 + Mg2Si intermediate layer as well as the Al3Mg2 + Mg2Si layer next to the aluminum base. The microhardnesses of reaction layers of all the bimetallic castings with different VRs were considerably higher than those of the magnesium and aluminum matrix alloys, particularly the Al3Mg2 layer. Excessive thick reaction layer and pore defects remarkably weakened the bonding strength of the bimetallic castings, especially pore defects, and a relative maximum shear strength was obtained with a VR of 14.6. The fractographs of the push-out samples showed a change in the fracture surface from a mixed brittle and ductile fracture nature to that of a brittle fracture nature with the increase of VR.

  1. An Investigation of Laser Assisted Machining of Al_2O_3 Particle Reinforced Aluminum Matrix Composite


    The Al 2O 3 particles reinforced aluminum matrix composite (Al 2O 3p/Al) are more and more widely used for their excellent physical and chemical properties. However, their poor machinability leads to severe tool wear and bad machined surface. In this paper laser assisted machining is adopted in machining Al 2O 3p/Al composite and good result was obtained. The result of experiment shows in machining Al 2O 3p/Al composites the cutting force is reduced in 30%~50%, the tool wear is reduced in 20%~30% an...

  2. Synthesis of AlPO4-5 and CrAPO-5 using aluminum dross.

    Kim, Jun; Biswas, Kalidas; Jhon, Ki-Won; Jeong, Soon-Yong; Ahn, Wha-Seung


    AlPO(4)-5 and its chromium-containing analogue, CrAPO-5, were prepared using aluminum dross in the presence of triethylamine as a structure directing agent; both Al dross powder and an extracted precipitate from Al dross in an alkali solution were used as an aluminum source. These materials were characterized by XRD, BET surface area measurement, SEM, EDX, XRF, ESR, and UV-vis spectroscopy. Their textural properties were found close to those of the corresponding reference samples prepared using pure Al(OH)(3). CrAPO-5 samples prepared from the aluminum dross were tested as a catalyst for liquid phase oxidation of tetralin using t-butyl hydroperoxide as an oxidizing agent, which showed virtually identical catalytic performances to that obtained by a reference CrAPO-5 catalyst.

  3. Electroless Growth of Aluminum Dendrites in NaCl-AlCl3 Melts

    Li, Qingfeng; Hjuler, H.A.; Berg, Rolf W.


    The spontaneous growth of aluminum dendrites after deposition was observed and examined in sodium chloride-aluminumchloride melts. The concentration gradient of AlCl3 in the vicinity of the cathode surface resulting from electrolysisconstitutes a type of concentration cell with aluminum dendrites...... as electrodes. The short-circuit discharge of thecell is found to be the driving force for the growth of aluminum dendrites. Such a concentration gradient is proposed to beone of the causes for dendrite formation in the case of metal deposition....

  4. Rapid Solidification: Selective Laser Melting of AlSi10Mg

    Tang, Ming; Pistorius, P. Chris; Narra, Sneha; Beuth, Jack L.


    Rapid movement of the melt pool (at a speed around 1 m/s) in selective laser melting of metal powder directly implies rapid solidification. In this work, the length scale of the as-built microstructure of parts built with the alloy AlSi10Mg was measured and compared with the well-known relationship between cell size and cooling rate. Cooling rates during solidification were estimated using the Rosenthal equation. It was found that the solidification structure is the expected cellular combination of silicon with α-aluminum. The dependence of measured cell spacing on calculated cooling rate follows the well-established relationship for aluminum alloys. The implication is that cell spacing can be manipulated by changing the heat input. Microscopy of polished sections through particles of the metal powder used to build the parts showed that the particles have a dendritic-eutectic structure; the dendrite arm spacings in metal powder particles of different diameters were measured and also agree with literature correlations, showing the expected increase in secondary dendrite arm spacing with increasing particle diameter.

  5. Deformation of nanocrystalline binary aluminum alloys with segregation of Mg, Co and Ti at grain boundaries

    Zinovev, A. V.; Bapanina, M. G.; Babicheva, R. I.; Enikeev, N. A.; Dmitriev, S. V.; Zhou, K.


    The influence of the temperature and sort of alloying element on the deformation of the nanocrystalline (NC) binary Al alloys with segregation of 10.2 at % Ti, Co, or Mg over grain boundaries has been studied using the molecular dynamics. The deformation behavior of the materials has been studied in detail by the simulation of the shear deformation of various Al bicrystals with the grain-boundary segregation of impurity atoms, namely, Ti, Co, or Mg. The deformation of bicrystals with different grain orientation has been studied. It has been found that Co introduction into grain boundaries of NC Al has a strengthening effect due to the deceleration of the grain-boundary migration (GBM) and difficulty in the grain-boundary sliding (GBS). The Mg segregation at the boundaries greatly impedes the GBM, but stimulates the development of the GBS. In the NC alloy of Al-Ti, the GBM occurs actively, and the flow-stress values are close to the values characteristic of pure Al.

  6. Anomalous hexagonal superstructure of aluminum oxide layer grown on NiAl(110) surface

    Krukowski, Pawel; Chaunchaiyakul, Songpol; Minagawa, Yuto; Yajima, Nami; Akai-Kasaya, Megumi; Saito, Akira; Kuwahara, Yuji


    A modified method for the fabrication of a highly crystallized layer of aluminum oxide on a NiAl(110) surface is reported. The fabrication method involves the multistep selective oxidation of aluminum atoms on a NiAl(110) surface resulting from successive oxygen deposition and annealing. The surface morphology and local electronic structure of the novel aluminum oxide layer were investigated by high-resolution imaging using scanning tunneling microscopy (STM) and current imaging tunneling spectroscopy. In contrast to the standard fabrication method of aluminum oxide on a NiAl(110) surface, the proposed method produces an atomically flat surface exhibiting a hexagonal superstructure. The superstructure exhibits a slightly distorted hexagonal array of close-packed bright protrusions with a periodicity of 4.5 ± 0.2 nm. Atomically resolved STM imaging of the aluminum oxide layer reveals a hexagonal arrangement of dark contrast spots with a periodicity of 0.27 ± 0.02 nm. On the basis of the atomic structure of the fabricated layer, the formation of α-Al2O3(0001) on the NiAl(110) surface is suggested.

  7. Influence of Basicity and MgO on Fluidity and Desulfurization Ability of High Aluminum Slag

    Wang, Ping; Meng, Qing-min; Long, Hong-ming; Li, Jia-xin


    The viscosity of experimental slag, which was mixed based on the composition of a practical blast furnace slag, was measured in this paper. The influence of Al2O3 and MgO content, basicity R2 = w(CaO)/w(SiO2) on the fluidity of slag was studied. The stepwise regression analysis in SPSS was used to reveal the relationship between sulfur distribution coefficient LS and slag composition as well as furnace temperature. The results show that increasing of MgO up to 12% can decrease the slag viscosity. The w(MgO) should be controlled below 8% when there is 20% Al2O3 in the slag. Temperature of hot metal and content of CaO in slag are the two dominant factors on the desulfurization capacity of slag.

  8. Abrasion resistant low friction and ultra-hard magnetron sputtered AlMgB14 coatings

    Grishin, A. M.


    Hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric AlMgB14 ceramic target. X-ray amorphous AlMgB14 films are very smooth. Their roughness does not exceed the roughness of Si wafer and Corning glass used as the substrates. Dispersion of refractive index and extinction coefficient were determined within 300 to 2500 nm range for the film deposited onto Corning glass. Stoichiometric in-depth compositionally homogeneous 2 μm thick films on the Si(100) wafer possess the peak values of nanohardness 88 GPa and Young’s modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth. Friction coefficient was found to be 0.06. The coating scratch adhesion strength of 14 N was obtained as the first chipping of the coating whereas its spallation failure happened at 21 N. These critical loads and the work of adhesion, estimated as high as 18.4 J m-2, surpass characteristics of diamond like carbon films deposited onto tungsten carbide-cobalt (WC-Co) substrates.

  9. Fretting Fatigue Experiment and Analysis of AlSi9Cu2Mg Alloy

    Jun Wang


    Full Text Available An investigation was carried out in order to study the fretting fatigue behavior of an AlSi9Cu2Mg aluminum alloy. The fretting fatigue tests of AlSi9Cu2Mg were performed using a specially designed testing machine. The failure mechanism of fretting fatigue was explored by studying the fracture surfaces, fretting scars, fretting debris, and micro-hardness of fretting fatigue specimens using scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDX, and micro Vickers hardness test techniques. The experimental results show that the fretting fatigue limit (42 MPa is significantly reduced to approximately 47% of the plain fatigue limit (89 MPa under 62.5 MPa contact pressure. Furthermore, the fretting fatigue life decreases with increasing alternating stress and increasing contact pressure. The examination results suggest that the stress concentrates induced by oxidation-assisted wear on the contact interface led to the earlier initiation and propagation of crack under the fretting condition.

  10. Early solute clustering in an AlZnMg alloy

    Dupasquier, A.; Iglesias, M.M. [Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Ist. Nazionale di Fisica della Materia (Italy); Ferragut, R. [Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Ist. Nazionale di Fisica della Materia (Italy); IFIMAT, UNCentro and CICPBA, Tandil (Argentina); Macchi, C.E.; Somoza, A. [IFIMAT, UNCentro and CICPBA, Tandil (Argentina); Massazza, M.; Riontino, G. [Ist. Nazionale di Fisica della Materia (Italy); Dipt. di Chimica IFM, Univ. di Torino, Torino (Italy); Mengucci, P. [Ist. Nazionale di Fisica della Materia (Italy); Dipt. di Fisica e Ingegneria dei Materiali e del Territorio, Univ. Politecnica delle Marche, Ancona (Italy)


    Within the framework of an extended investigation programme addressing the development of methods for enhancing the quality of aluminium alloys, decomposition processes were studied for a laboratory system having the same main alloying elements of the commercial alloy 7020 (Al, 2.1 at. % Zn, 1.5 at % Mg). Positron annihilation spectroscopy (PAS), microhardness measurements, DSC, SAXS and TEM were combined to observe the evolution of this alloy at 150 C and at room temperature (RT) after a solution treatment at 480 C; in the RT case, also after preliminary ageing at 150 C. The results show: a) presence of vacancy rich clusters (VRC) formed during quenching; b) early formation of GP(I) zones at RT; c) changing chemical composition of GP(I) zones during RT ageing; d) rapid dissolution of GP(I) at 150 C and incipient loss of coherency after 1 hour; e) recovery of GP(I) at RT after interrupted ageing at 150 C. (orig.)

  11. Cast Aluminum Alloys for High Temperature Applications Using Nanoparticles Al2O3 and Al3-X Compounds (X = Ti, V, Zr)

    Lee, Jonathan A.


    In this paper, the effect of nanoparticles Al2O3 and Al3-X compounds (X = Ti, V, Zr) on the improvement of mechanical properties of aluminum alloys for elevated temperature applications is presented. These nanoparticles were selected based on their low cost, chemical stability and low diffusions rates in aluminum at high temperatures. The strengthening mechanism at high temperature for aluminum alloy is based on the mechanical blocking of dislocation movements by these nanoparticles. For Al2O3 nanoparticles, the test samples were prepared from special Al2O3 preforms, which were produced using ceramic injection molding process and then pressure infiltrated by molten aluminum. In another method, Al2O3 nanoparticles can also be homogeneously mixed with fine aluminum powder and consolidated into test samples through hot pressing and sintering. With the Al3-X nanoparticles, the test samples are produced as precipitates from in-situ reactions with molten aluminum using conventional permanent mold or die casting techniques. It is found that cast aluminum alloy using nanoparticles Al3-X is the most cost effective method to produce high strength aluminum alloys for high temperature applications in comparison to nanoparticles Al2O3. Furthermore, significant mechanical properties retention in high temperature environment could be achieved with Al3-X nanoparticles, resulting in tensile strength of nearly 3 times higher than most 300- series conventional cast aluminum alloys tested at 600 F.

  12. Microstructure development in Al-Cu-Ag-Mg quaternary alloy

    Zhou, Bin; Froyen, L.


    The solidification behaviour of multi-component and multi-phase systems has been largely investigated in binary and ternary alloys. In the present study, a quaternary model system is proposed based on the well known Al-Cu-Ag and Al-Cu-Mg ternary eutectic alloys. The quaternary eutectic composition and temperature were determined by EDS (Energy Dispersive Spectrometry) and DSC (Differential Scanning Calorimetry) analysis, respectively. The microstructure was then characterised by SEM (Scanning Electron Microscope). In the DSC experiments, two types of quaternary eutectics were determined according to their phase composition. For each type of eutectic, various microstructures were observed, which result in different eutectic compositions. Only one of the determined eutectic compositions was further studied by the controlled growth technique in a vertical Bridgeman type furnace. In the initial part of the directionally solidified sample, competing growth between two-phase dendrites and three-phase eutectics was obtained, which was later transformed to competing growth between three-phase and four-phase eutectics. Moreover, silver enrichment was measured at the solidification front, which is possibly caused by Ag sedimentation due to gravity and Ag rejection from dendritic and three-phase eutectic growth, and its accumulation at the solidification front.

  13. The Influence of Nickel and Tin Additives on the Microstructural and Mechanical Properties of Al-Zn-Mg-Cu Alloys

    Haider T. Naeem


    Full Text Available The effects of nickel and nickel combined tin additions on mechanical properties and microstructural evolutions of aluminum-zinc-magnesium-copper alloys were investigated. Aluminum alloys containing Ni and Sn additives were homogenized at different temperatures conditions and then aged at 120°C for 24 h (T6 and retrogressed at 180°C for 30 min and then reaged at 120°C for 24 h (RRA. Comparison of the ultimate tensile strength (UTS of as-quenched Al-Zn-Mg-Cu-Ni and Al-Zn-Mg-Cu-Ni-Sn alloys with that of similar alloys which underwent aging treatment at T6 temper showed that gains in tensile strengths by 385 MPa and 370 MPa were attained, respectively. These improvements are attributed to the precipitation hardening effects of the alloying element within the base alloy and the formation of nickel/tin-rich dispersoid compounds. These intermetallic compounds retard the grain growth, lead to grain refinement, and result in further strengthening effects. The outcomes of the retrogression and reaging processes which were carried on aluminum alloys indicate that the mechanical strength and Vickers hardness have been enhanced much better than under the aging at T6 temper.

  14. Role of cerium, lanthanum, and strontium additions in an Al-Si-Mg (A356) alloy

    Nabawy, Ahmed M.; Samuel, Agnes M.; Samuel, Fawzy H. [Universite du Quebec, Chicoutimi (Canada). Dept. des Sciences Appliquees; Alkahtani, Saleh A.; Abuhasel, Khaled A. [Salman Bin Abdulaziz Univ., Riyadh (Saudi Arabia). Mechanical Engineering Dept.


    The effects of individual and combined additions of cerium (Ce), lanthanum (La), and strontium (Sr) on the eutectic modification and solidification characteristics of an Al-Si-Mg (A356) aluminum alloy were investigated using optical microscopy and thermal analysis techniques. Addition of Ce, La, and Sr resulted in different depression levels of the eutectic nucleation temperature and eutectic growth undercooling, generating modified eutectic structures exhibiting different levels of modification. Microstructural results showed that the best modification levels using individual additions were achieved by Sr which produced a fine fibrous eutectic structure, followed by La, which produced a refined lamellar structure, with Ce providing the lowest level of modification. On the other hand, a combined addition of Ce and Sr provided the highest modification level, with the production of a very fine fibrous eutectic silicon structure. In general, the addition of Sr helped to further increase the refinement obtained in the alloys containing La or Ce + La additions. In the latter alloy, the main intermetallic phases observed were La(Al,Si){sub 2} and Al{sub 20}(La,Ce)Ti{sub 2}Si. The improved modification levels were found to be proportional to the depression in the eutectic nucleation temperature and the eutectic growth undercooling. A high cooling rate also improved the modification level by at least one level.

  15. Preparation of Al-Sr Master Alloy in Aluminum Electrolysis Cell


    Al-Sr master alloy was prepared by using liquid aluminum cathode and a mixture of Na3AlF6- SrCO3 as the basic molten salt electrolyte in a laboratory electrolysis cell.The effects of electrolyte composition,electrolysis temperature,cathodic current density and the electrolytic duration on Sr content of Al-Sr alloy were studied.Through laboratory experiments,the parameters for smooth electrolytic reaction were proposed.

  16. Effect of mischmetal and yttrium on microstructures and mechanical properties of Mg-Al alloy

    张诗昌; 魏伯康; 蔡启舟; 王立世


    The effect of yttrium and mischmetal(MMs) on the as-cast and solid solution treated structures of Mg-Al alloys with different Al-contents was investigated. The results show that the MMs in Mg-Al alloy existed in rodAl4 (Ce, La)compound while Y in Mg-Al alloy in polygonal Al2 Y compound. The amount of Mg17 Al12 in Mg-Al al-loy is decreased with increasing Y or MMs addition, and Mg17 Al12 intermetallic compound is changed from continu-ous network to discontinuous one. The Al4 (Ce, La) and Al2 Y compounds are not dissolved into Mg-Al alloy matrixduring solid solution treatment so that their high heat stability can be exhibited. The experiment of mechanical prop-erties indicate that elongation and impact toughness of the Mg-Al-Y alloy with polygonal Al2 Y compound are higherthan those of Mg-Al-MMs alloy with rod Al4 (Ce, La) compound.

  17. Influence of Ni content on physico-chemical characteristics of Ni, Mg, Al-Hydrotalcite like compounds

    Alexandre Carlos Camacho Rodrigues


    Full Text Available The physico-chemical properties of a series of Ni,Mg,Al-HTLC with Al/(Al+Mg+Ni = 0.25 and low Ni/Mg ratios were studied by means of X-ray diffraction (XRD, thermogravimetric (TGA and thermodifferential (DTA analysis, N2 physissorption and temperature programmed reduction (TPR. The as-synthesized materials were well-crystallized, with XRD patterns typical of the HTLCs in carbonate form. Upon calcination and dehydration the dehydroxilation of the layers with concurrent decomposition of carbonate anions produced mixed oxides with high surface area. XRD analysis indicated that the different nickel and aluminum oxides species are well-dispersed in a poor-crystallized MgO periclase-type phase. As observed by TPR, the different Ni species showed distinct interactions with Mg(AlO phase, which were influenced by both nickel content and calcination temperature. Regardless of the the nickel content, the reduction of nickel species was not complete as indicated by the presence of metallic dispersions.

  18. Effects of homogenization on microstructures and properties of a new type Al-Mg-Mn-Zr-Ti-Er alloy

    He, L.Z., E-mail: [Key Lab of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, Liaoning (China); Li, X.H. [Chalco Ruimin Corporation, Limited, Fuzhou 350015 (China); Liu, X.T.; Wang, X.J.; Zhang, H.T.; Cui, J.Z. [Key Lab of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University, Shenyang 110004, Liaoning (China)


    Research highlights: These new type alloys are very potential for increased use in aerospace and automobile industries. However, most of published reports have focused on the effects of Cu, Sc, Zr, Ag, rare metals and Si additions, Portevin-LeChatelier effect, corrosion properties, friction stir welding and superplasticity in 5000-series aluminum alloy, few investigated on Er and stepped homogenization on the precipitation of dispersoids in Al-Mg-Mn alloy. The purpose of this work was to study the effects of Er and homogenization treatment on mechanical properties and microstructural evolution in new type Al-Mg-Mn-Er alloy. - Abstract: Microstructural evolutions and mechanical properties of Al-Mg-Mn-Zr-Ti-Er alloy after homogenization were investigated in detail by optical microscope (OM), scanning electronic microscope (SEM), transmission electronic microscope (TEM), energy dispersive spectrum (EDS) and tensile test. A maximum tensile strength is obtained when the alloy homogenized at 510 deg. C for 16 h. With increasing preheating temperature (200-400 deg. C), the strength of the alloy finial homogenized at 490 deg. C for 16 h increases. When the preheating temperature is {>=}300 deg. C, the strengths of the two-step homogenized alloys are higher than those of the single homogenized alloys. The preheating stage plays an important role in the microstructures and properties of the final homogenized alloy. Many fine (Mn,Fe)Al{sub 6} precipitates when the preheating temperature is 400 deg. C. ErAl{sub 3} phase cannot be observed during preheating stage. Plenty of fine (Mn,Fe)Al{sub 6} and ErAl{sub 3} precipitate in finial homogenized alloy when the preheating temperature is {>=}300 deg. C. The Al-Mg-Mn-Zr-Ti-Er alloy is effectively strengthened by substructure and dispersoids of (Mn,Fe)Al{sub 6} and ErAl{sub 3}.

  19. Effect of reaction time and (Ca+Mg)/Al molar ratios on crystallinity of Ca-Mg-Al layered double Hydroxide

    Heraldy, E.; Nugrahaningtyas, K. D.; Sanjaya, F. B.; Darojat, A. A.; Handayani, D. S.; Hidayat, Y.


    Ca-Mg-Al Layered Double Hydroxides (Ca-Mg-Al-LDH) compounds were successfully synthesized from brine water and AlCl3.6H2O as the starting materials by coprecipitation method. The product result was characterized by X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR). The effects of the reaction time and the molar ratios of the raw material on the crystallinity of Ca-Mg-Al-LDH were examining. Results show that increasing reaction time (30; 60 and 90 min.) could improve the crystallinity and monodispersity of layered double hydroxide compounds particles. The well-defined Ca-Mg- Al-LDH could be prepared with (Ca+Mg)/Al molar ratios 0.5.

  20. Effects of Mg content on pore structure and electrochemical corrosion behaviors of porous Al-Mg alloys

    何文远; 肖逸锋; 吴靓; 许艳飞; 钱锦文; 贺跃辉; 郑学军


    Porous Al-Mg alloys with different nominal compositions were successfully fabricated via elemental powder reactive synthesis, and the phase composition, pore structure, and corrosion resistance were characterized with X-ray diffractometer, scanning electron microscope and electrochemical analyzer. The volume expansion ratio, open porosity and corrosion resistance in 3.5% (mass fraction) NaCl aqueous solution of the alloys increase at first and then decrease with the increase of Mg content. The maxima of volume expansion ratio and open porosity are 18.3% and 28.1% for the porous Al-56%Mg (mass fraction) alloy, while there is the best corrosion resistance for the porous Al-37.5% Mg (mass fraction) alloy. The pore formation mechanism can be explained by Kirkendall effect, and the corrosion resistance can be mainly affected by the phase composition for the porous Al-Mg alloys. They would be of the potential application for filtration in the chloride environment.

  1. First-principles study on Al4Sr as the heterogeneous nucleus of Mg2Si

    Xia, Zhi; Li, Ke


    The interfacial structure, electronic structure, work of adhesion and interfacial energy of the Al4Sr(100)/Mg2Si(100) interface have been studied with first-principles calculations to clarify the heterogeneous nucleation potential of the Al4Sr particle for a primary Mg2Si phase. Eight models of the Al4Sr(100)/Mg2Si(100) interface with OT and HCP stacking were adopted for the interfacial model geometries. The results show that the Al-Mg terminations of HCP and Al-Si terminations of OT stacking, with lower interfacial spacing and higher interfacial adhesion, are the most favorable structures after relaxation. Al-Mg- and Al-Si-terminated interfaces, with a lower interfacial distance, form chemical bonds more easily. Metallic bonds are formed near the Al-Mg-terminated interface, while the Al-Si-terminated interface exhibits predominantly covalent bond characteristics. Moreover, the calculated interfacial energies of both terminations are negative in conditions involving excess Mg atoms. The interfacial energies of Al-Si are lower than those of Al-Mg termination, indicating that the Al-Si-terminated interface is more stable. From thermodynamic analysis, we discover that the Al4Sr particle can be an effective heterogeneous nucleation substrate for Mg2Si in a Mg-Al-Si alloy melt.

  2. Silicon spheroidization treatment of thixoformed Al-Si-Mg alloys

    Ogris, E.; Uggowitzer, P.J. [Eidgenoessische Technische Hochschule, Zurich (Switzerland). Inst. of Metallurgy; Luechinger, H. [SAG-Aluminium Lend GmbH und Co KG and THIXALLOY trademark Components GmbH und Co KG, Lend (Austria)


    Al-Si-Mg alloys are commonly used in the automobile industry because of their outstanding mechanical properties and corrosion resistance. The need of lighter and safer cars is the driving force behind research in the area of high strength light metal safety part applications. The strength level can be tuned by varying the amount of alloyed magnesium. Usually if strength is increased, ductility will decrease. Following the demands of the automotive industry, safety parts should have a minimum fracture elongation of 15% and a minimum yield strength of 150 MPa. The huge hurdle is the 15% fracture elongation which can not be reached by sand or die casting, but some relatively new alternative casting technologies, like Thioxocasting or New Rheocasting, yield encouraging ductility values. Recent research activity has focused on increasing strength and ductility, but so far the results have not yet been satisfying. This paper presents investigations on the spheroidization process of eutectic silicon and its positive effect on mechanical properties. It is shown that the spheroidization process is already finished after minutes of exposure to heat treatment. Metallographical and quantitative microstructural analysis is used to describe the growth and spheroidization process of the silicon crystals. Specimens of THIXALLOY trademark 630 (A356) thixocast components were heat treated for varied periods of time, aged and tested. Results show amazing improvements of ductility and strength in comparison to the as cast state. Maximum values of 18% fracture elongation and 230 MPa yield strength are reached. (orig.)

  3. Heat treatment of AlSi9Mg alloy

    J. Pezda


    Full Text Available Processes of crystallization of alloys have decisive impact on structure of castings, and the same their utility characteristics. Knowledge about those processes constitutes a source of information to development of preparation of liquid metal and control of alloy preparation process within industry. Method of Thermal-Voltage-Derivative Analysis (ATND, developed by Faculty of Chipless Forming Technology enables registration of temperature and voltage curves, on which one can observe thermal and voltage effects being result of crystallization of phases and eutectic mixtures present on these curves in form of characteristic “peaks”. Temperature value read offs for these characteristic points become a basis to taking regression analysis aimed at obtaining of mathematical dependences illustrating effect of changes of these values on change of impact resistance of dispersion hardened AK9 alloy. The paper presents an attempt of implementation of Thermal-Voltage-Derivative Analysis method to determination of temperature of hyperquenching and ageing processes of AK9 (AlSi9Mg silumin. Investigated alloy had undergone typical treatments of refining and modification, and next the heat treatment. Temperature range for the heat treatment has been determined on base of ATND melting curves.

  4. The effect of Al on thermal stability and kinetics of decomposition of MgH{sub 2} prepared by mechanochemical reaction at different conditions

    Ershova, O.G.; Dobrovolsky, V.D., E-mail:; Solonin, Y.M.; Khyzhun, O.Y.; Koval, A.Y.


    This work is directed at decreasing decomposition temperature of MgH{sub 2}. In accordance with the theoretical predictions, hydride of solid solution of Al in Mg should decompose at lower temperature compared to that of MgH{sub 2}, and numerous experiments indicate that thermodynamic stability of the hydride depends on methods and conditions of its synthesis. Therefore, the goal of this article is to study the possibility of obtaining the hydride of solid solution of aluminum in magnesium by different technological approaches. Three mechanical composite alloys derived by the different approaches are studied employing the X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermodesorption spectroscopy (TDS) methods. XRD Rietveld analysis reveals that the hydrogenation of a Mg + 10 wt% Al powder by means of reactive milling in the hydrogen atmosphere as well as hydrogenation of the powder from the gaseous phase after milling the powder for 20 h in the argon atmosphere leads to formation of aluminum-free MgH{sub 2} hydride and the Mg{sub 17}Al{sub 12} phase. Our TDS studies (at P{sub H2} = 0.1 MPa) indicate that additives of 10 wt% Al to magnesium do not lead to decreasing the decomposition temperature of MgH{sub 2} prepared by mechanochemical reaction at the different conditions. - Highlights: • Three mechanical alloys with 10% wt. Al additives to Mg have been synthesized. • Hydrogen-sorption properties and thermal stability of the alloys are studied at 1 bar H{sub 2}. • Al additives to Mg do not influence decomposition temperature of MgH{sub 2} phase of the alloys. • Al additives do not improve kinetics of process of hydrogen desorption from MgH{sub 2} phase.

  5. Activating Mg acceptors in AlN by oxygen: first principles calculations

    Wu, R Q


    First principles calculations based on density functional theory (DFT) are performed to study the electronic properties of Mg acceptors in AlN at the presence of oxygen. It is found that Mg and O tend to form complexes like Mg-O, Mg$_2$-O, Mg$_3$-O and Mg$_4$-O which have activation energies about 0.23 eV lower than that of Mg (except of the passive Mg-O). The lower activation energies originate from the extra states over valence band top of AlN induced by the passive Mg-O. By comparing to the well-established case of GaN, it is possible to fabricate Mg and O codoped AlN without MgO precipitate. These results suggest the possibility of achieving higher hole concentration in AlN by Mg and O codoping.

  6. Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process


    High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC) and Y-block shaped metal mold(Permanent mold Casting; PC) C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of t...

  7. Microstructural characterization of an Al-li-mg-cu alloy by correlative electron tomography and atom probe tomography.

    Xiong, Xiangyuan; Weyland, Matthew


    Correlative electron tomography and atom probe tomography have been carried out successfully on the same region of a commercial 8090 aluminum alloy (Al-Li-Mg-Cu). The combination of the two techniques allows accurate geometric reconstruction of the atom probe tomography data verified by crystallographic information retrieved from the reconstruction. Quantitative analysis of the precipitate phase compositions and volume fractions of each phase have been obtained from the atom probe tomography and electron tomography at various scales, showing strong agreement between both techniques.

  8. An Experimental Investigation of Effects of Fluxes (Na3AlF6 and K2TiF6), Element Alloys (Mg), and Composite Powders ((Al + TiC)CP and (Al + B4C)CP) on Distribution of Particles and Phases in Al-B4C and Al-TiC Composites

    Mazaheri, Younes; Emadi, Rahmatollah; Meratian, Mahmood; Zarchi, Mehdi Karimi


    The wettability, incorporation, and gravity segregation of TiC and B4C particles into molten aluminum are important problems in the production of Al-TiC and Al-B4C composites by the casting techniques. In order to solve these problems, different methods consisting of adding the Na3AlF6 and K2TiF6 fluxes and Mg (as the alloying element) into the molten aluminum and injection of the (Al + TiC)CP and (Al + B4C)CP composite powders instead of B4C and TiC particles are evaluated. In this work, the conditions of sample preparation, such as particle addition temperature, stirring speed, and stirring time, are determined after many studies and tests. Microstructural characterizations of samples are investigated by scanning electron microscopy equipped with energy dispersive spectroscopy (EDS) and X-ray diffractometry. The results show better distribution and incorporation of TiCp and B4Cp in aluminum matrix when the fluxes are used, as well as EDS analysis of the interface between the matrix and reinforcement-strengthened formation of the different phases such as Al4C3 in the Al-TiC composites and Al3BC, TiB2 in the Al-B4C composites.

  9. An Experimental Investigation of Effects of Fluxes (Na3AlF6 and K2TiF6), Element Alloys (Mg), and Composite Powders ((Al + TiC)CP and (Al + B4C)CP) on Distribution of Particles and Phases in Al-B4C and Al-TiC Composites

    Mazaheri, Younes; Emadi, Rahmatollah; Meratian, Mahmood; Zarchi, Mehdi Karimi


    The wettability, incorporation, and gravity segregation of TiC and B4C particles into molten aluminum are important problems in the production of Al-TiC and Al-B4C composites by the casting techniques. In order to solve these problems, different methods consisting of adding the Na3AlF6 and K2TiF6 fluxes and Mg (as the alloying element) into the molten aluminum and injection of the (Al + TiC)CP and (Al + B4C)CP composite powders instead of B4C and TiC particles are evaluated. In this work, the conditions of sample preparation, such as particle addition temperature, stirring speed, and stirring time, are determined after many studies and tests. Microstructural characterizations of samples are investigated by scanning electron microscopy equipped with energy dispersive spectroscopy (EDS) and X-ray diffractometry. The results show better distribution and incorporation of TiCp and B4Cp in aluminum matrix when the fluxes are used, as well as EDS analysis of the interface between the matrix and reinforcement-strengthened formation of the different phases such as Al4C3 in the Al-TiC composites and Al3BC, TiB2 in the Al-B4C composites.

  10. Corrosion mechanism of MgO-C and MgO-C-Al refractories used in stainless steel electric arc furnace; Mecanismo de corrosion a refractarios de MgO-C y MgO-C-Al en horno electrico

    Pena, P.; Aza, A. H. de; Contreras, L.; Garcia-Crrodeguas, R.; Aza, S. de; Almagro, J. F.; Luna, C.; Guerrero Barranco, M.; Ferrer, F. J.


    This article presents the results of a post-mortem study of various MgO-C and MgO-C-Al pieces that are used in the electric furnaces at the Acerinox factory in Cadiz. From the chemical, thermal, mineralogical and microstructural characterization of the materials prior to use and post-mortem it has been established that, in both types of refractories, the corrosion has lead to the formation of reaction layers with different chemical and mineralogical composition, as a function of temperature and oxygen partial pressure, ranging from the hot to the cold face and strongly depending on the zone of the electric furnace where the piece is situated. Changes in graphite content have been observed in both types of materials by X-ray diffraction. These changes have been quantified by Differential Thermal Analysis. In MgO-C-Al refractories it has been observed the formation of small amounts of C{sub 3}Al{sub 4} inside the pieces and MgAl{sub 2}O{sub 4} in the refractories hot face. Keeping in mind the obtained results and the phase equilibrium diagram of Mg-C-Al-O it has been established a corrosion mechanism for both types of materials. It cannot be established by the present results that additions of Al ({approx}{approx} 2 % in weight) improve the performance of MgO-C materials. (Author)

  11. Fabrication and heat treatment of high strength Al-Cu-Mg alloy processed using selective laser melting

    Zhang, Hu; Zhu, Haihong; Nie, Xiaojia; Qi, Ting; Hu, Zhiheng; Zeng, Xiaoyan


    The proposed paper illustrates the fabrication and heat treatment of high strength Al-Cu-Mg alloy produced by selective laser melting (SLM) process. Al-Cu-Mg alloy is one of the heat treatable aluminum alloys regarded as difficult to fusion weld. SLM is an additive manufacturing technique through which components are built by selectively melting powder layers with a focused laser beam. The process is characterized by short laser-powder interaction times and localized high heat input, which leads to steep thermal gradients, rapid solidification and fast cooling. In this research, 3D Al-Cu-Mg parts with relative high density of 99.8% are produced by SLM from gas atomized powders. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 276 MPa and 402 MPa, respectively, along with fracture strain of 6%. The effect of solution treatment on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the SLMed Al-Cu-Mg samples can be greatly enhanced through proper heat treatment. After T4 solution treatment at 540°C, under the effect of precipitation strengthening, the tensile strength and the yield strength increase to 532 MPa and 338 MPa, respectively, and the elongation increases to 13%.

  12. Laser cladding of a Mg based Mg-Gd-Y-Zr alloy with Al-Si powders

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin


    In the present work, a Mg based Mg-Gd-Y-Zr alloy was subjected to laser cladding with Al-Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg2Si, Mg17Al12 and Al2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg2Si, Mg17Al12 and Al2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from -1.77 V for the untreated alloy to -1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10-5 A cm-2 to 1.64 × 10-6 A cm-2. The results show that laser cladding is an efficient method to improve surface properties of Mg-Rare earth alloys.

  13. Electrochemical Deposition of Aluminum from NaCl-AlCl3 Melts

    Li, Qingfeng; Hjuler, H. A.; Berg, Rolf W.


    Electrochemical deposition of aluminum from NaAlCl4 melts saturated with NaCl onto a glassy carbon electrode at175°C has been studied by voltammetry, chronoamperometry, and constant current deposition. The deposition of aluminumwas found to proceed via a nucleation/growth mechanism, and the nucle......Electrochemical deposition of aluminum from NaAlCl4 melts saturated with NaCl onto a glassy carbon electrode at175°C has been studied by voltammetry, chronoamperometry, and constant current deposition. The deposition of aluminumwas found to proceed via a nucleation/growth mechanism......, and the nucleation process was found to be progressive.The morphology of aluminum deposits was examined with photomicroscopy. It was shown that depending on the currentdensities (c.d.) applied, three types of aluminum deposits could be obtained, namely, spongy deposits formed at lower c.d.(below 0.7 mA/cm2), smooth...... layers deposited at intermediate c.d. (between 2 and 10 mA/cm2), and dendritic or porous depositsobtained at high c.d. (above 15 mA/cm2). However, the smooth aluminum deposits were about five times more voluminousthan the theoretical value. The spongy deposits were formed due to difficulties...

  14. Melt Processing and Characterization of Al-SiC Nanocomposite, Al, and Mg Foam Materials

    Ahmed M. Nabawy


    Full Text Available In the present work, metallic foams of Al, Mg and an Al-SiC nanocomposite (MMNC have been fabricated using a new manufacturing technique by employing melt infiltration assisted with an electromagnetic force. The aim of this investigation was to study and to develop a reliable manufacturing technique consisting of different types of metallic foams. In this technique, an electromagnetic force was used to assist the infiltration of Al-SiC slurry and of pure liquid metal into a leachable pattern of NaCl, thus providing perfect cellular structures with micro-sized porosities. A high frequency induction coil unit equipped with a vacuum chamber and a hydraulic press was used to manufacture the foam materials. Microstructures of the produced foam materials were explored by using Field Emission Scanning Electron Microscopy (FESEM. The mechanical behavior of the manufactured foams was investigated by applying compression testing. The results indicate a high applicability of the new technique in producing metallic foams of pure metals and of a metal matrix nanocomposite . The produced foam materials displayed isotropic cellular structures with excellent compressive behaviors. Microstructure measurements indicate that the average pore size and strut thickness that can be achieved are in the ranges of 100–500 μm and 50–100 μm, respectively. The produced foam of the Al-SiC nanocomposite material provided the highest strength of 50 MPa prior to the densification stage, which equates to 25 times, and 10 times higher than the strength levels that were obtained by Al, and Mg foams, respectively.

  15. Effect of the partial substitution of Mg by Al on the crystal structure and hydrogenation behavior of La2Mg17

    ZHANG Qing'an; WANG Changchun; SI Tingzhi


    The effect of the partial substitution of Mg by Al on the crystal structure of La2Mg17 has been investigated. It was found that the La2Mg17 phase disappears after the partial substitution of Mg by Al. The La2(Mg0.9Al0.1)17 alloy contains La(Mg,Al)12 and La(Mg,Al)2. Further increasing the Al content, the La2(Mg0.8Al0.2)17 alloy consists of La(Mg,Al)12, La(Mg,Al)2, and Mg. The La(Mg0.93Al0.07)12 phase in the La2(Mg0.9Al0.1)17 alloy crystallizes with the ThMn12-type structure in space group I4/mmm (No.139). The lattice parameters were determined to be a = 1.03246(7) nm and c = 0.59410(6) nm. In the ThMn12-type structure, Al atoms occupy 8f site but the Al content is limited. Moreover, the hydrogenation characteristics have also been compared. La2Mg17 decomposes into LaH3 and MgH2 under hydrogen, but the La(Mg0.93Al0.07)12 phase can be hydrogenated into LaH3, MgH2, and La3Al11 at 473 K.

  16. Pengaruh Variasi Lama Waktu Hidrogenasi terhadap Pembentukan Metal Hidrida pada Paduan MgAl

    Nasrul Arif Pradana


    Full Text Available Paduan berbasis magnesium (Mg merupakan salah satu paduan yang dapat digunakan sebagai Hydrogen Storage Material. Pemaduan Magnesium dengan aluminium bertujuan untuk menurunkan energi aktivasi proses reaksi hidrogen dengan paduan Mg-Al. Paduan Mg-Al dengan komposisi Mg-42 at.% Al disintesa melalui proses milling dengan waktu 40 jam yang menghasilkan solid solution MgAl. Serbuk hasil milling disintering dengan temperatur 600oC dengan holding time selama 2 jam dalam lingkungan argon sehingga terbentuk fase Mg17Al12. Serbuk Mg17Al12 kemudian dihidrogenasi pada tekanan 1MPa, temperatur 4000C dengan variasi lama waktu hidrogenasi 1, 2 , dan 3 jam. Analisis difraksi sinar-X mengidentifikasi adanya faseMgH2 dengan perkiraan % wt sebesar  1.242%, 3.082% dan 4.2% setelah dilakukan proses hidrogenasi selama 1 , 2 dan 3 jam.

  17. Aluminum and phosphorus separation: application to preparation of target from brain tissue for {sup 26}Al determination by accelerator mass spectrometry

    Brauer, Russell D.; Robertson, J. David; Sharma, Pankaj; Yokel, Robert A. E-mail:


    Acid digested brain containing 4 mg added {sup 27}Al was ashed at 1000 deg. C to prepare an Al{sub 2}O{sub 3} target for accelerator mass spectrometry (AMS) analysis of {sup 26}Al. A glass-like material usually resulted which was thought to be aluminum (Al) oxyphosphate. The separation of Al and phosphate was investigated. Al, but not phosphate, was bound by a cation exchange resin (AG 50-X8). Hydrofluoric acid eluted the Al from the resin. Removal of phosphate from acid digested brain by this method produced an amorphous material after ashing that was easier to recover from the porcelain crucible and had a higher AMS beam current. This procedure to separate Al from phosphate may have utility in other applications.

  18. MgAl2O4 Ultrafiltration Ceramic Membrane Derived from Mg-Al Double Alkoxide%铝镁双醇盐制备MgAl2O4尖晶石陶瓷超滤膜

    张国昌; 陈运法; 吴振江; 谢裕生


    Spinel (MgAl2O4) ultrafiltration membranes were prepared on porous α-Al2O3 plates via the sol-gel route. Mg-Al double alkoxide [MgAl2(iprO)s] was first synthesized as the precursor, then hydrolyzed and peptized in aqueous solution. The gel layer was coated from the colloidal sol on the intermediate layer (α-Al2O3), which was formerly prepared to modify the porous substrate, and then thermally treated at 900℃. The processing parameters such as pH, temperature and sol composition during the sol preparation were optimized for controlling particle size. The pore size of the 2μm thick top layer is about 13 nm as estimated by both the BSA (Bovine Serum Albumin)retention test and an empirical equation.The water permeability of the obtained spinel membrane is 55~143 kg/(min.cm2.Pa).

  19. Comparative study of Mg/Al- and Zn/Al-layered double hydroxide-perindopril erbumine nanocomposites for inhibition of angiotensin-converting enzyme

    Hussein Al Ali SH


    Full Text Available Samer Hasan Hussein Al Ali,1 Mothanna Al-Qubaisi,2 Mohd Zobir Hussein,1,3 Maznah Ismail,2,4 Zulkarnain Zainal,1 Muhammad Nazrul Hakim51Department of Chemistry, Faculty of Science, 2Laboratory of Molecular Biomedicine, Institute of Bioscience, 3Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 4Department of Nutrition and Health Science, 5Department of Biomedical Science, Faculty of Medicine and Health Science, Universiti Putra Malaysia, Selangor, MalaysiaAbstract: The intercalation of a drug active, perindopril, into Mg/Al-layered double hydroxide for the formation of a new nanocomposite, PMAE, was accomplished using a simple ion exchange technique. A relatively high loading percentage of perindopril of about 36.5% (w/w indicates that intercalation of the active took place in the Mg/Al inorganic interlayer. Intercalation was further supported by Fourier transform infrared spectroscopy, and thermal analysis shows markedly enhanced thermal stability of the active. The release of perindopril from the nanocomposite occurred in a controlled manner governed by pseudo-second order kinetics. MTT assay showed no cytotoxicity effects from either Mg/Al-layered double hydroxide or its nanocomposite, PMAE. Mg/Al-layered double hydroxide showed angiotensin-converting enzyme inhibitory activity, with 5.6% inhibition after 90 minutes of incubation. On incubation of angiotensin-converting enzyme with 0.5 µg/mL of the PMAE nanocomposite, inhibition of the enzyme increased from 56.6% to 70.6% at 30 and 90 minutes, respectively. These results are comparable with data reported in the literature for Zn/Al-perindopril.Keywords: magnesium, aluminum, layered double hydroxide, perindopril erbumine, ion exchange, angiotensin-converting enzyme, Chang cells line

  20. Band filling and interband scattering effects in MgB2: carbon versus aluminum doping.

    Kortus, Jens; Dolgov, Oleg V; Kremer, Reinhard K; Golubov, Alexander A


    We argue, based on band structure calculations and the Eliashberg theory, that the observed decrease of T(c) of Al and C doped MgB2 samples can be understood mainly in terms of a band filling effect due to the electron doping by Al and C. A simple scaling of the electron-phonon coupling constant lambda by the variation of the density of states as a function of electron doping is sufficient to capture the experimentally observed behavior. Further, we also explain the long standing open question of the experimental observation of a nearly constant pi gap as a function of doping by a compensation of the effect of band filling and interband scattering. Both effects together generate a nearly constant pi gap and shift the merging point of both gaps to higher doping concentrations, resolving the discrepancy between experiment and theoretical predictions based on interband scattering only.

  1. Effect of strontium on crystallization of Mg2Si phase in Al-Si-Mg casting alloys

    廖恒成; 丁毅; 孙国雄


    Optical microscope and SEM were used to observe the changes of the microstructure of Al-11.6%Si-0.4%Mg alloys with varying strontium additions and the effect of strontium on the crystallization of Mg2Si phase was discussed. It is found that Mg2Si phase nucleates on the surfaces of the eutectic silicon flakes in the unfully modified alloys, growing as meshwork or bamboo-shoot shape, however, very few and fine Mg2Si particles phase are isolated at the boundaries of the eutectic cells in the fully modified alloys. Strontium has an important influence on the crystallization of Mg2Si phase in Al-Si-Mg casting alloys and it is thought to be related to the increase of the amount of dendritic α phase and the modifying degree of eutectic silicon phase.

  2. MgAl2O4–-Al2O3 solid solution interaction: mathematical framework and phase separation of -Al2O3 at high temperature

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal


    Although existence of MgAl2O4–-Al2O3 solid solution has been reported in the past, the detailed interactions have not been explored completely. For the first time, we report here a mathematical framework for the detailed solid solution interactions of -Al2O3 in MgAl2O4 (spinel). To investigate the solid solubility of -Al2O3 in MgAl2O4, Mg–Al spinel (MgO–Al2O3; = 1, 1.5, 3, 4.5 and an arbitrary high value 30) precursors have been heat treated at 1000°C. Presence of only non-stoichiometric MgAl2O4 phase up to = 4.5 at 1000°C indicates that alumina (as -Al2O3) present beyond stoichiometry gets completely accommodated in MgAl2O4 in the form of solid solution. → alumina phase transformation and its subsequent separation from MgAl2O4 has been observed in the Mg–Al spinel powders ( > 1) when the 1000°C heat treated materials are calcined at 1200°C. In the mathematical framework, unit cell of MgAl2O4 (Mg8Al16O32) has been considered for the solid solution interactions (substitution of Mg2+ ions by Al3+ ions) with -Al2O3. It is suggested that combination of unit cells of MgAl2O4 takes part in the interactions when > 5 (MgO–Al2O3).

  3. Effects of RE on the Microstructure of Mg-8Zn-4Al Magnesium Alloys


    The effects of RE on the microstrcture of as-cast Mg-8Zn-4Al magnesium alloys were investigated. The results show that the solidification range of Mg-8Zn-4Al-xRE alloys increases with RE additions. A binary eutectic reaction can arise and produce a new phase (Mg3Al4Zn2RE) and the temperature of phase transformation point of the new phase is 412.85C. In Mg-8Zn-4Al-1.5RE alloy, a small amount of Mg3Al4Zn2RE phase and ε phases are found besides α(Mg),ψ and τ phases. Also microstructures of Mg-8Zn-4Al alloys can be refined by addition of 1.5 % RE obviously.

  4. Precise lattice location of substitutional and interstitial Mg in AlN

    Amorim, Lígia Marina; Pereira, Lino Miguel da Costa; Decoster, Stefan; Silva, Daniel José; Silva, Manuel Ribeiro da; Gottberg, Alexander; Correia, João Guilherme; Temst, Kristiaan; Vantomme, André


    The lattice site location of radioactive $^{27}$Mg implanted in AlN was determined by means of emission channeling. The majority of the $^{27}$Mg was found to substitute for Al, yet significant fractions (up to 33%) were also identified close to the octahedral interstitial site. The activation energy for interstitial Mg diffusion is estimated to be between 1.1 eV and 1.7 eV. Substitutional Mg is shown to occupy ideal Al sites within a 0.1 Å experimental uncertainty. We discuss the absence of significant displacements from ideal Al sites in the context of the current debate on Mg doped nitride semiconductors.

  5. Evolution of Mg-5Al-0.4Mn microstructure after rare earth elements addition

    A. Żydek


    Full Text Available Mg-5Al-0.4Mn-xRE (x = 0, 1, 2, 3 wt.% magnesium alloys were prepared successfully by casting method. The microstructure wasinvestigated by light microscopy. The influence of rare earth (RE elements on the area fraction of eutectic was analysed. The obtainedresults revealed that the as-cast Mg-5Al-0.4Mn alloy consist of α - Mg matrix and eutectic α + γ (where γ is Mg17Al12. However, whilerare earth elements were added to the Mg-Al type alloy, Al11RE3 precipitates were formed. The amount of the Al11RE3 precipitatesincreased with increasing addition of RE, but the amount of γ - Mg17Al12 decreased.

  6. Preparation, Characterization, and Catalytical Application of MgCoAl-Hydrotalcite-Like Compounds

    Kai Yan; Xianmei Xie; Jinping Li; Xiulan Wang; Zhizhong Wang


    MgCoAl-hydrotalcite-like compounds (MgCoAl-HTLcs) were synthesized using the copre-cipitation method of variable pH values. The effect of each factor on the preparation of HTLcs was discussed systematically, which included pH values, mole ratios of Mg2+ to Co2+, the concentrations of the solution, and the temperature and time of the hydrothermal treatment. Besides, the thermal decomposition of MgCoAl-HTLcs was discussed. X-ray diffraction, thermogravimetric analysis, and FT-IR spectroscopy were performed to characterize the MgCoAl-HTLcs samples. The results showed that when the pH = 7.6-8.5 or 5.5-6.2, atomic ratios of (Mg2++Co2+)/Al3+ = 2 and Mg2+/Co2+ ranging from 1.00 to 2.00, temperature and time of hydrothermal treatment being 110 ℃ and 6 h, unique MgCoAl-HTLcs with high crystallinity could be obtained. When the calcination temperature was up to 250 ℃, the MgO phase was detected coexisting with Al2O3 and MgAl2O4 was highly spreaded on the derived mixed oxides. The synthesis reaction of benzoin methyl ether with methanol and benzaldehyde was chosen to study the catalytic activity of MgCoAl-HTLcs. The catalyst showed high activity and high stability in the synthesis of benzoin methyl ether in the feasible condition.

  7. Ethanol steam reforming over Mg-Al mixed-oxide catalysts

    Coleman, L.J.; Hudgins, R.R.; Silveston, P.L.; Croiset, E. [Waterloo Univ., ON (Canada). Dept. of Chemical Engineering


    Eight magnesium-aluminium (Mg-Al) mixed oxides and magnesium oxide (MgO) and aluminium oxide (Al{sub 2}O{sub 3}) were studied in order to identify the most effective Mg-Al mixed oxide for hydrogen production via ethanol steam reforming. Co-precipitated precursors were calcinated to prepare the Mg-Al mixed oxides. Activity and selectivity of the mixed oxides for ethanol steam reforming were evaluated at 773 and 923 K. Results showed that all catalysts performed poorly during the steam reforming reaction, and produced low rates of hydrogen, carbon monoxide (CO) and carbon dioxide (CO{sub 2}). Catalysts with an MgAl{sub 2}O{sub 4} spinel crystal structure gave the best performance at both reaction temperatures. However, carbon deposits were discovered on all catalysts for reactions performed at 923 K. Co-precipitation resulted in more effective contact between the Mg and Al in the form of Mg-Al LDO and MgAL{sub 2}O{sub 3}. The absence of pure oxides suggested that Mg and Al were chemically coupled in the mixed oxide catalysts. Results of the study showed that the catalyst with an atomic ratio of 0.66 Mg1Al2 was the most active and achieved the highest rates of production for hydrogen. 14 refs., 3 tabs., 1 fig.

  8. Effect of Mg on microstructures and properties of Al-Mg-Si-Cu aluminium alloys for automotive body sheets

    LIU Hong; SONG Wen-ju; ZHAO Gang; LIU Chun-ming; ZUO Liang


    The effects of variation of Mg content on microstructures,the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy,optical metallographic analysis,tensile and Ericsson tests.The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si,with an increment of Mg content,the strength enhances,the specific elongation and Erisson values of alloys decrease,and the number of Mg2 Si constituent increases and that of Al(MnFe)Si type constituents reduces.Al-MgSi-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint bake cycle (I.e.artificial aging at 170 ℃ for 30 min immediately after the solution treatment and quenching).Suitable Mg content should be controlled in the range of 0.8% and 1.2 % (mass fraction).

  9. Corrosion Behavior of Novel Mg-9Li-7Al-1Sn and Mg-9Li-5Al-3Sn-1Zn Alloys in NaCl Aqueous Solution

    Kumar, Vinod; Shekhar, Rajiv; Balani, Kantesh


    Corrosion behavior of two multiphase Mg-Li-Al-based alloys in 0.6 M NaCl aqueous solution is investigated by hydrogen gas evolution measurement and electrochemical test. This paper reports, for the first time, the comparison of hydrogen evolution and Tafel extrapolation results of Mg-Li-Al-based alloys. The corrosion rate of Mg-9Li-7Al-1Sn is observed to be reasonably higher when compared to that of Mg-9Li-5Al-3Sn-1Zn, and both the alloys have shown higher corrosion rate than that of Mg-3Al-1Zn alloy (AZ31B). The micro-galvanic corrosion of primary precipitates and hcp α-phase (Mg-rich) is not as severe as was observed in case of the secondary precipitates and bcc β-phase (Li-rich). Corrosion mechanism of multiphase Mg-Li-Al-based alloys in chloride solution, which has not been adequately reported in the literature, is lucidly articulated based on the early stages of corrosion, film morphology, and in situ hydrogen bubble study.

  10. Effect of Al and Mg Doping on Optical Properties of ZnO Thin Films Prepared by Spin Coating

    G. T Yusuf


    Full Text Available This paper investigated the influence of aluminum and magnesium doping on the optical and electrical properties of zinc oxide (ZnO thin films for solar cell application. Zinc acetate dehydrates was used as starting material. Aluminum chloride and tin chloride were added to each solution to serve as dopants. X-ray diffractions were analyzed by X-ray diffraction (XRD which revealed crystalline and hexagonal wurtzite structure. All the films showed more than 80% transparency in the visible region. The optical band gap of undoped ZnO thin film was found to be 3.12ev while that of Al-doped and Mg-doped ZnO film was estimated to be 3.16eV and 3.26eV respectively. The resistivity of the films measured were 2.51×10–4 Ω cm for Al-doped, 2.53×10–4 Ω cm for mg-doped and 2.61×10-4 Ω cm for undoped ZnO respectively. The quality of the films deposited in this work is a promising window layer component of a solar cell. The variation in the band gap observed in this work could be explained by Burstein–Moss effect which was fully explained in the discussion section of this work.

  11. Evolution of intermetallic phases of Al-Zn-Mg-Cu alloy during heat treatment

    FAN Xi-gang; JIANG Da-ming; MENG Qing-chang; LI Nian-kui; SUN Zhao-xia


    Al-Zn-Mg-Cu alloy is a favorable choice for aerospace applications requiring good combination of strength and toughness,which is greatly influenced by the coarse intermetallic particles. The evolution of intermetallic particles in an Al-Zn-Mg-Cu alloy during heat treatment was studied by field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffractometry(XRD).The results show that there are lamellar eutectic structure (α(Al)+Mg(Zn,Al,Cu)2) and Al7Cu2Fe particles in the solidified structure.The Al7Cu2Fe particles are embedded in the eutectic structure. The content of eutectic structure decreases with the increase of holding time and disappears after 24 h. The size and morphology of Al7Cu2Fe particles exhibit no change during the heat treatment. It is found that the Al2CuMg phase is formed during the treatment at 460 ℃. A transformation process from the primary eutectic phase Mg(Zn,Al,Cu)2 to Al2CuMg is observed, and the transformation mechanism and kinetics are analyzed. The Al2CuMg constituents form in the primary Mg(Zn,Al,Cu)2 phase, and grow along the eutectic microstructure.

  12. Behavior of oxide at diffusion-bonded interface of Al-Mg-Si series 6063 alloy. 1st Report. Diffusion-bonding mechanism of aluminium alloys by transmission electron microscopy; Al-Mg-Si kei 6063 gokin no kakusan setsugo kaimen ni okeru sankabutsu no kyodo. 1. Toka denshi kenbikyo kansatsu ni yoru Al gokin no kakusan setsugo kiko no kento

    Ikeuchi, K.; Matsuda, F. [Osaka University, Osaka (Japan). Welding Research Institute; Kotani, K. [Industrial Research Institute of Aichi Prefecture, Aichi (Japan)


    Transmission electron microscopic observation and a joint strength test were carried out on diffusion-bonded interface of Al-Mg-Si series 6063 alloy to investigate behavior of the surface oxide film and its effect on the bonding strength. The test pieces are made of the Al-Mg-Si series 6063 alloy and industrial pure aluminum 1080 cut out from a rod as a reference material. The bonded surface was applied with electrolytic grinding or wire brush finish. Analysis of electron diffraction diagram revealed formation of Al2MgO4 on the bonded interface of the 6063 alloy in either case of the electrolytic grinding or the wire brush finish. However, it was not possible to derive the electron diffraction diagram from oxide film on the bonded interface of pure aluminum, and the oxide film was thought amorphous. Tensile strength of the diffusion-bonded joint of the 6063 alloy approached the strength of the base material at considerably lower bonding temperature and with smaller bonding deformation than in pure aluminum in either case of the bonded surface electrolytically ground or wire-brush finished. This was thought to have been caused from difference in behavior of the oxide film. 16 refs., 12 figs., 3 tabs.

  13. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy

    G.A. Young; J.R. Scully


    It is well established that Al-Zn-Mg-(Cu) aluminum alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are commonly used to increase HEAC resistance at the expense of strength. Overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). When freshly bared coupons of AA 7050 are exposed to 90 C, 90% RH air, hydrogen ingress follows inverse-logarithmic-type kinetics and is equivalent for underaged (HEAC susceptible) and overaged (HEAC resistant) tempers. However, when the native oxide is allowed to form (24 hrs in 25 C, 40% RH lab air) prior to exposure to 90 C, 90% RH air, underaged alloy shows significantly greater hydrogen ingress than the overaged alloy. Humid air is a very aggressive environment producing local ({approx}1{micro}m) hydrogen concentrations in excess of 10,000 wt. ppm at 90 C. In the copper bearing alloy, overaging also effects the apparent diffusivity of hydrogen. As AA 7050 is aged from underaged {yields} peak aged {yields} overaged, the activation energy for hydrogen diffusion increases and the apparent diffusivity for hydrogen decreases, In the low copper alloy, overaging has little effect on hydrogen diffusion. Comparison of the apparent activation energies for hydrogen diffusion and for K independent (stage II) crack growth

  14. High Active Zn/Mg-Modified Ni–P/Al2O3 Catalysts Derived from ZnMgNiAl Layered Double Hydroxides for Hydrodesulfurization of Dibenzothiophene

    Feng Li


    Full Text Available A series of ZnMgNiAl layered double hydroxides (LDHs containing 20 wt.% Ni and different Zn/Mg molar ratios were prepared by a coprecipitation method, and then were introduced with H2PO4− via a microwave-hydrothermal method. With the resulting mixtures as the precursors, Zn/Mg-modified ZnMgNi–P/Al2O3 catalysts were prepared. The Zn/Mg molar ratio affected the formation of Ni2P and Ni12P5 in nickel phosphides. The ZnMgNi–P/Al2O3 catalyst with a Zn/Mg molar ratio of 3:1 exhibits the best dibenzothiophene hydrodesulfurization (HDS activity. Compared with the Ni–P/Al2O3 catalyst prepared from the impregnation method, the ZnMgNi–P/Al2O3 catalyst shows a higher HDS activity (81.6% vs. 54.3% and promotes the direct desulfurization of dibenzothiophene.

  15. Effect of nano Al(Sc{sub x-1}Zr{sub x}) precipitates on the mechanical and corrosion behavior of Al-2.5 Mg alloys

    Ahmad, Z.; Aleem, B.J. Abdul [Mechanical Engineering Department, KFUPM, Dhahran 31261 (Saudi Arabia)


    Microanalytical, mechanical, and corrosion studies were undertaken to investigate the effect of nano-precipitates of Al(Sc{sub x-1}Zr{sub x}) on the mechanical and corrosion characteristics of Al 2.5 alloy containing 0, 0.15, 0.3, 0.6, and 0.9 wt% of Sc with 0.15 wt% Zr. Addition of 0.3% Sc significantly increased the yield strength due to small precipitates sizes (5-19 nm) and the high coherency of the nano-particles. Largest contributor to the strength was grain boundary strengthening caused by pinning of grain boundary precipitates. The alloys showed a good resistance to corrosion in 3.5 wt% neutral chloride solution. The alloy offered a high passivation tendency because of homogeneous coherent nano Al(Sc{sub x-1}Zr{sub x}) precipitates. The nano precipitates interfaces and homogeneously distributed Al{sub 3}Sc precipitates offer a high degree of corrosion resistance to Al 2.5 Mg Sc alloys compared to conventional aluminum alloys, such as Al 6061 and Al6013. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Improved Hydrogen Storage Properties of Mg(BH4)2-Mg(AlH4)2 Combined Systems

    Xiao, Haoyuan; Leng, Haiyan; Yu, Zhigang; Li, Qian; Chou, Kuo-Chih

    Magnesium borohydride and Magnesium alanate were synthesized by mechanochemical metathesis reaction. The thermal decomposition behaviors of Mg(BH4)2-nMg(AlH4)2(n=0.5,1) systems were investigated as potential hydrogen storage materials. The results showed that the systems started to desorb H2 at 120 °C and desorbed 3.9 wt.% and 4.9 wt.% H2 below 300 °C when n equals 0.5 and 1, respectively, while individual Mg(BH4)2 started to desorb H2 at 250 °C and desorbed only 0.82 wt.% H2. Because of the exist of the Mg(AlH4)2, the isothermal desorption kinetics of Mg(BH4)2 in the Mg(BH4)2-0.5Mg(AlH4)2 systems was 50% faster than that of pristine Mg(BH4)2. In addition, the re-hydrogenation rates also increased 49.4% and 37.9%.

  17. Tribological Characteristics of Single-phase AlMgB14 and Nanocomposite AlMgB14-TiB2 Superhard Coatings

    Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Zhu, Dong [Eaton Corporation; Cook, Bruce A [Ames Laboratory; Elmoursi, Alaa A [Eaton Corporation


    This study investigated the friction and wear characteristics of AlMgB14 and AlMgB14-TiB2 superhard coatings, produced by pulse laser deposition (PLD) and physical vapor deposition (PVD), respectively. Tests were conducted under unidirectional and reciprocating sliding against AISI 52100 bearing steel in both dry and oil-lubricated conditions. The AlMgB14 coating exhibited an encouraging but short-lived low friction stage (u = 0.2) in dry sliding. The AlMgB14-TiB2 coating reduced the wear rates by one order of magnitude for itself and three orders of magnitude for the counterface compared with the uncoated M2 tool steel in dry sliding. This nanocomposite coating also demonstrated significant extension (>2.5X) of the low friction (non-scuffing) stage in a lubricant starvation sliding.

  18. Development and evaluation of Al-Ti-C master alloys as grain refiner for aluminum

    Hadia, M.A. [Aluminum Co. of Egypt, Nag Hammadi (Egypt); Ghaneya, A.A.; Niazi, A. [Assiut Univ. (Egypt)


    A series of Al-Ti-C master alloys with different amounts of titanium and carbon (Al-3.5%Ti-0.5%C, Al-3.5%Ti-0.7%C and Al-5%Ti-1%C) has been developed by adding activated graphite to molten Al-Ti binary alloys. The micro-structures of the developed alloys were investigated. The efficiency of the produced alloys as aluminum grain refiner was evaluated. The effects of the following factors were investigated: addition rate of each master alloy, the pouring temperature of the refined metal and the holding time before pouring. Also, the contact time for each refiner was studied. The results were significant and the refiner Al-5%Ti-1%C was the most effective.

  19. Corrosion and Discharge Behaviors of Al-Mg-Sn-Ga-In in Different Solutions

    Xiong, Hanqing; Yin, Xiang; Yan, Yang; Dai, Yilong; Fan, Sufeng; Qiao, Xueyan; Yu, Kun


    Al-0.5 wt.%Mg-0.08 wt.%Sn-0.05 wt.%Ga-0.05 wt.%In and Al-0.5 wt.%Mg-0.08 wt.%Sn-0.05 wt.%Ga alloys were prepared by melting, casting and cold rolling. Corrosion and discharge behaviors of the two experimental alloys were investigated by electrochemical measurement, self-corrosion rate measurement, air battery testing, and scanning electron microscopy. The results showed that Al-Mg-Sn-Ga-In alloy exhibited higher electrochemical activity than Al-Mg-Sn-Ga alloy in 2 M NaCl solution, while it showed lower electrochemical activity than Al-Mg-Sn-Ga alloy in 4 M NaOH solution. By comparison with the air battery based on Al-Mg-Sn-Ga alloy, the battery with Al-Mg-Sn-Ga-In alloy cannot exhibit better discharge performance in 4 M NaOH electrolyte. However, the performance of the air battery based on Al-Mg-Sn-Ga-In alloy was greatly improved due to the In-rich inclusions and the uniform corroded morphology in 2 M NaCl electrolyte. Thus, Al-Mg-Sn-Ga-In alloy was a good anode material for Al-air battery in 2 M NaCl electrolyte.

  20. Inclusions, Porosity, and Fatigue of AlSi10Mg Parts Produced by Selective Laser Melting

    Tang, Ming

    Additive manufacturing (AM) has experienced remarkable growth in the past decade with applications in both rapid prototyping and rapid manufacturing for functional end-usable parts. As one of the most promising AM processes, selective laser melting (SLM) can be used to fabricate metal products line by line and layer upon layer within a powder bed system. Such process allows the building of parts with customized shapes, which brings higher design flexibility than traditional casting and wrought manufacturing. In this work, AlSi10Mg powder is chosen as the raw material for producing parts by SLM, since aluminum alloys are widely used in automotive and aerospace industries thanks to an excellent combination of low density and competitive mechanical properties. However, there remain multiple drawbacks which limit further applications of aluminum parts produced by SLM: lack of prediction of solidification microstructure, few studies on fatigue properties, and cost and time caused by the limited production rate. All these issues were studied in this work and summarized as follows: Rapid movement of the melt pool (at a speed around 1 m/s) in SLM of metal powder directly implies rapid solidification. In this research, the length scale of the as-built microstructure of parts built with the alloy AlSi10Mg was measured and compared with the well-known relationship between cell size and cooling rate. Cooling rates during solidification were estimated using the Rosenthal equation. It was found that the solidification structure is the expected cellular combination of silicon with alpha-aluminum. The dependence of the measured cell spacing on the calculated cooling rate follows the well-established relationship for aluminum alloys. The implication is that cell spacing can be manipulated by changing the heat input. Microscopy of polished sections through particles of the metal powder used to build the parts showed that the particles have a dendritic-eutectic structure; the

  1. Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

    REN Qing-li; LUO Qiang


    The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD,TEM,IR and DSC. Moreover,based on the DSC test results,the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

  2. Characteristics of physicochemical interactions in the aluminum-rich region of the system Al-Sc-Mn

    Drits, M.E.; Toropova, L.S.; Gushchina, F.L.


    The aluminum-rich part of the Al-Sc-Mn phase diagram has been investigated by differential thermal, microstructural, and X-ray phase analyses and by scanning electron microscopy. It is found that the part of the system studied is characterized by an invariant eutectic transformation at 649 plus or minum 2 C. Two binary compounds, Al3Sc and Al6Mn, are in equilibrium with aluminum solid solution. No ternary compounds have been detected in the system studied. It is also shown that scandium substantially reduces the solubility of manganese in aluminum.

  3. Thermal diffusivity of Al-Mg based metallic matrix composite reinforced with Al2O3 ceramic particles

    Cruz-Orea, A.; Morales, J. E.; Saavedra S, R.; Carrasco, C.


    Thermal diffusivities of Al-Mg based metallic matrix composite reinforced with ceramic particles of Al2O3 are reported in this article. The samples were produced by rheocasting and the studied operational condition in this case is the shear rate: 800, 1400 and 2000 rpm. Additionally, the AlMg base alloy was tested. Measurements of thermal diffusivity were performed at room temperature by using photoacoustic technique.

  4. Layered Double Hydroxides with Hydrotalcite-type Structure Containing Fe3+, Al3+ and Mg2+


    Layered double hydroxides(LDHs) with hydrotalcite-type structure containing Fe3+, Al3+ and Mg2+ were prepared by means of a coprecipitation method. The products were characterized by element analysis, X-ray powder diffraction and transmission electron microscopy. It was found that even if the molar ratio of n(Fe+Al)/n(Fe+Al+Mg)>0.33, yet a pure hydrotalcite-like compound(HTlc) phase was gained when n(Fe)/n(Al+Mg+Fe)≤0.30 and n(Al)/n(Al+Mg+Fe)≤0.30; the Al(OH)3 phase appeared in the products when n(Al)/n(Al+Mg+Fe)>0.30; and an amorphous phase emerged when n(Fe)/n(Al+Mg+Fe)>0.33. These results show that there is no concentration superposition effect between Fe3+ and Al3+ on the crystalline state of the produced samples. In our previous work, the concentration superposition effect between Zn2+ and Mg2+ in the synthesis of Zn-Mg-Al-LDHs was found. For the prepared Fe-Al-Mg-LDHs samples, the value of lattice parameter a is between 0.30-0.32 nm; and the value of lattice parameter c is between 2.30-2.47 nm, the basal spacing is in the range of 0.76-0.83 nm. When the ratio of n(Fe)/n(Al) is a constant, the values of a and c increase with the increase of the Mg2+ content of the produced samples. The mean particle size and the mean crystal grain were determined by virtue of a particle-size instrument, XRD-Scherrer formula and TEM method, respectively.

  5. Pressureless infiltration of Si3N4 preforms with an Al-2wt %Mg alloy


    The pressureless infiltration process to synthesize a silicon nitride composite was investigated. An Al-2wt%Mg alloy was infiltrated into silicon nitride preforms in the atmosphere of nitrogen. It is possible to infiltrate the Al-2wt%Mg alloy in silicon nitride preforms. The growth of the composite with useful thickness wasfacilitated by the presence of magnesium powder at the interface and by flowing nitrogen. The microstructure of the Si3N4-Al composite has been characterized using scanning electron microscope.During the infiltration of Si3N4 preforms, Si3N4 reacted with aluminium to form silicon and AlN. Thesilicon produced during the growth consumed in the formation of MgSiAlO, MgSiAlN and Al3.27Si0.47 type phases. The growth of the composite was found to proceed in two ways, depending on the oxide content in the initial preforms. First, less oxide content preforms gave rise to MgAlSiO and MgAlSiN type phases after infiltration. Second, more oxide content preforms gave rise to AlN-Al2O3 solid solution phase(AlON). The AlON phase was only present in the composite, containing 10% aluminium in the silicon nitride preforms before infiltration.

  6. Electrochemical Deposition and Dissolution of Aluminum in NaAlCl4 Melts

    Li, Qingfeng; Hjuler, H.A.; Berg, Rolf W.


    Effects of the additives MnCl2, sulfide, and their combined influence on aluminum deposition and dissolution inNaAlCl4 saturated with NaCl have been studied by polarization measurements, galvanostatic deposition, and current reversalchronopotentiometry (CRC). The solubility of MnCl2 was found...... to be 0.086 ± 0.006 m/o in the melt at 175°C. Aluminum-manganesealloys can be deposited in NaAlCl4 saturated with both NaCl and MnCl2, resulting in a slight increase incathodic overpotentials. The codeposition of the binary alloys at current densities below 4 mA/cm2 gave rise to formationof deposits so...

  7. Hydrothermal synthesis and characterization of polycrystalline gadolinium aluminum perovskite (GdAlO3, GAP

    N. Girish H.


    Full Text Available Gadolinium aluminum perovskite (GdAlO3, GAP is a promising high temperature ceramic material, known for its wide applications in phosphors. Polycrystalline gadolinium aluminum perovskites were synthesized using a precursor of co-precipitate gel of GdAlO3 by employing hydrothermal supercritical fluid technique under pressure and temperature ranging from 150 to 200 MPa and 600 to 700 °C, respectively. The resulted products of GAP were studied using the characterization techniques, such as powder X-ray diffraction analysis (XRD, infrared spectroscopy (IR, scanning electron microscopy (SEM and energy dispersive analysis of X-ray (EDX. The X-ray diffraction pattern matched well with the reported orthorhombic GAP pattern (JCPDS-46-0395.

  8. A study on atomic diffusion behaviours in an Al-Mg compound casting process

    Liu, Yongning; Chen, Yiqing; Yang, Chunhui


    Al and Mg alloys are main lightweight alloys of research interest and they both have superb material properties, i.e., low density and high specific strength, etc. Being different from Al alloys, the corrosion of Mg alloys is much more difficult to control. Therefore to combine merits of these two lightweight alloys as a composite-like structure is an ideal solution through using Al alloys as a protective layer for Mg alloys. Compound casting is a realistic technique to manufacture such a bi-metal structure. In this study, a compound casting technique is employed to fabricate bi-layered samples using Al and Mg and then the samples are analysed using electron probe micro-analyzer (EPMA) to determine diffusion behaviours between Al and Mg. The diffusion mechanism and behaviours between Al and Mg are studied numerically at atomic scale using molecular dynamics (MD) and parametric studies are conducted to find out influences of ambient temperature and pressure on the diffusion behaviours between Al and Mg. The results obtained clearly show the effectiveness of the compound casting process to increase the diffusion between Al and Mg and thus create the Al-base protection layer for Mg.

  9. Effect of Mg or Ag addition on the evaporation field of Al.

    Aruga, Yasuhiro; Nako, Hidenori; Tsuneishi, Hidemasa; Hasegawa, Yuki; Tao, Hiroaki; Ichihara, Chikara; Serizawa, Ai


    It is known that the distribution of the charge-states as well as the evaporation field shift to higher values as the specimen temperature is decreased at a constant rate of evaporation. This study has explored the effect of Mg or Ag addition on the evaporation field of Al in terms of the charge state distribution of the field evaporated Al ions. The fractional abundance of Al(2+) ions with respect to the total Al ions in Al-Mg alloy is lower than that in pure Al, whereas it shows higher level in the Al-Ag alloy at lower temperatures. The temperature dependence of the fractional abundance of Al(2+) ions has been also confirmed, suggesting that Al atoms in the Al-Mg alloy need lower evaporation field, while higher field is necessary to evaporate Al atoms in the Al-Ag alloy, compared with pure Al. This tendency is in agreement with that of the evaporation fields estimated theoretically by means of measurements of the work function and calculations of the binding energy of the pure Al, Al-Mg and Al-Ag alloys.

  10. Mechanism of scandium influence on strength and heat resistance increase in Al-Mg alloys

    Drits, M.E.; Pavlenko, S.G.; Toropova, L.S.; Bykov' , Yu.G.; Ber, L.B. (AN SSSR, Moscow. Inst. Metallurgii)


    An attempt is made to study the strengthening nature in the Al-Mg-Sc alloy system. The problems of the temperature stability of the non-crystallized structure of the Al-6.5% Ng alloy and the nature of secondary extractions in these alloys caused by scandium presence, are studied. The alteration of the fluidity limit of the Al-6.5% Mg-Se alloys depending on the annealing temperature for various types of intermediate products is shown. Doping of the Al-6.5% Mg alloy with scandium brings about a considerable increase of strength properties, as a result of formation of the ScAl/sub 3/ phase.

  11. Effect of magnesium and nickel coatings on the wetting behavior of alumina toughened zirconia by molten Al-Mg alloy

    Sharifi, H.; Khavandi, A. R.; Divandari, M.; Hasbullah, M. I.


    The wettability of alumina toughened zirconia (ZTA) by Al-Mg alloy was investigated using the sessile drop technique. The effects of nickel coating, magnesium content, nitrogen atmosphere, and processing temperature on the contact angle between the molten alloy and the substrate were determined. Likewise, the effect of these factors on the wetting properties was studied. The results showed that the nickel coating on the ceramic substrate caused a significant reduction in solid/liquid surface energy and the contact angle decreased obviously. The presence of magnesium in the molten aluminum alloy in nitrogen atmosphere reduced the contact angle effectively. The presence of magnesium in the alloy must be at a minimum amount of 2wt%-3wt%. Moreover, it was suggested that some chemical reactions in the Al-Mg-N system led to the production of Mg3N2 and AlN compositions. These compositions improved the wetting properties of the systems by reducing the surface energy of the molten. It was shown that increasing the temperature is also an effective factor for the enhancement of wetting properties.

  12. From Powders to Dense Metal Parts: Characterization of a Commercial AlSiMg Alloy Processed through Direct Metal Laser Sintering

    Eleonora Atzeni; Elisa Paola Ambrosio; Riccardo Canali; Manickavasagam Krishnan; Flaviana Calignano; Diego Manfredi


    In this paper, a characterization of an AlSiMg alloy processed by direct metal laser sintering (DMLS) is presented, from the analysis of the starting powders, in terms of size, morphology and chemical composition, through to the evaluation of mechanical and microstructural properties of specimens built along different orientations parallel and perpendicular to the powder deposition plane. With respect to a similar aluminum alloy as-fabricated, a higher yield strength of about 40% due to the v...

  13. Effect Of SiC Particles On Sinterability Of Al-Zn-Mg-Cu P/M Alloy

    Rudianto H.


    Full Text Available Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565°-580°C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn2, CuAl2 and Mg2Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.

  14. The Microstructure, Texture and Mechanical Properties of the Rolled Al/Mg/Al Clad Sheets

    Nie, Huihui; Liang, Wei; Zheng, Liuwei; Ren, Xiaoxia; Chi, Chengzhong; Fan, Haiwei


    Two types of three-layered Al/Mg/Al clad sheets were fabricated by hot rolling. The first (sheet A) underwent a single pass with a small rolling reduction of 33% and the second (sheet B) underwent four passes with a large rolling reduction of 71%, and both were subsequently annealed at 200 °C for 1 h. Microstructural examination and tensile tests on the fabricated sheets revealed that 17.8-μm-thick intermetallic compound layers (IMCLs) appeared at AZ31/5052 interfaces in sheet B while none were observed in sheet A. The AZ31 layers in sheets A and B exhibited basal textures with intensities of 15.1 and 9.8, respectively, and only sheet A exhibited tensile twins (TTs) in the AZ31 layer. Recrystallization resulting in grains was preferred near the AZ31/5052 interface and the intersections between TTs. Owing to its larger rolling reduction, more extensive recrystallization was observed in the sheet B component layers than in sheet A. Sheet B exhibited better mechanical properties with a much higher ultimate tensile strength (UTS) than sheet A (230 versus 102 MPa) and a slightly larger elongation (19 versus 17%).This indicates that texture intensities and the extent of recrystallization of component layers have a significant effect upon the mechanical properties of clad sheets.

  15. [A Fluorescent Chemical Sensor Based on MgAl-8-HQ LDH Composite Particle for the Selective Detection of Fe3+].

    Yang, Lei; Yao, Qi; Yuan, Xue-hua; Yang, Yan-ling


    In order to achieve the highly selective and Simple detection for ferric ion, strong-fluorescent 8-hydroxyquinoline (8-HQ) Mg-Al layered double hydroxide(Mg(χ)Al-8-HQ LDH) was designed and prepared by 8-HQ's intercalation and ready coordination based on adjustment of Al3+ on Mg-Al layered double hydroxides (MgAl LDH) laminates. Meanwhile its structure and property were characterized by IR, XRD, UV-Vis and fluorescent spectrometer. IR analysis showed coordinate bonds of C-O-Al and C-N-Al between 8-HQ and Al3+ were generated. XRD revealed that 8-HQ had already inserted in MgAl LDH laminates, and it made (003) diffraction peaks move to low 2θ angle direction, and the diffraction peak intensity was enhanced with the molar ratio of Mg and Al increasing. Because the coordination reaction between 8-HQ and Al3+ in MgAl LDH laminates took place, it induced the absorption peak of 8-HQ at 314 nm disappeared, at the same time the transition absorption peak at 376 nm between metal ions and ligands appeared. As demonstrated by fluorescence spectroscopic analysis, fluorescence intensity of Mg(χ)Al-8-HQ LDH increased with the content of Al3+ reducing, when the molar ratio of Magnesium and Aluminium ion is 4 : 1, its fluorescence intensity enhanced more significantly than 8-hydroxyquinoline aluminum. Through the research on the influence of metal ions on the fluorescence spectra of Mg4 Al-8-HQ LDH particle, it was found that the particle to metal ions exhibited significant selection and difference, especially with high selectivity for Fe3+ ion. The effect of [Fe3+] on the color and fluorescence intensity of Mg4Al-8-HQ LDH particle solution was further studied, and the results showed that the solution varied from light yellow to dark green with the content of Fe3+ in 10(-6) to 10(-2) mol x L(-1) increasing, so it can implement colorimetric sensing for Fe3+ in the above range. And at the same time its fluorescence intensity significantly decreased, and its fluorescence could be

  16. Corrosion behavior of an Al-6Mg-Sc-Zr alloy

    XU Guangxing; TAO Binwu; LIU Jianhua; LI Songmei


    The corrosion behavior of an Al-6Mg-Sc-Zr alloy was studied and compared with that of an Al-6Mg-Zr alloy.The addition of scandium into the Al-6Mg-Zr alloy reduced the susceptibility to exfoliation corrosion. By using the constant load tensile method in a 3.5 wt.% NaCl solution, the resistance to SCC of the Al-6Mg-Sc-Zr alloy was higher than that of the Al-6Mg-Zr alloy. When the specimens were not applied with an anodic current, the Al-6Mg-Sc-Zr alloy was resistance to SCC and no brittle cracking was found on the fracture surface. When an anodic current was applied, the Al-6Mg-Sc-Zr alloy specimens failed as a result of accelerated corrosion rather than SCC. It was believed that the addition of scandium resulted in (Al3Sc, Zr) particles that greatly refmed grains and promoted the formation of homogeneous discontinuous distribution of β-phase in the alloy base, which much contributed to good corrosion resistance of the Al-6Mg-Sc-Zr alloy.

  17. Deposition of duplex Al 2O 3/aluminum coatings on steel using a combined technique of arc spraying and plasma electrolytic oxidation

    Gu, Weichao; Shen, Dejiu; Wang, Yulin; Chen, Guangliang; Feng, Wenran; Zhang, Guling; Fan, Songhua; Liu, Chizi; Yang, Size


    Plasma electrolytic oxidation (PEO) is a cost-effective technique that can be used to prepare ceramic coatings on metals such as Ti, Al, Mg, Nb, etc., and their alloys, but this promising technique cannot be used to modify the surface properties of steels, which are the most widely used materials in engineering. In order to prepare metallurgically bonded ceramic coatings on steels, a combined technique of arc spraying and plasma electrolytic oxidation (PEO) was adopted. In this work, metallurgically bonded ceramic coatings on steels were obtained using this method. We firstly prepared aluminum coatings on steels by arc spraying, and then obtained the metallurgically bonded ceramic coatings on aluminum coatings by PEO. The characteristics of duplex coatings were analyzed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The corrosion and wear resistance of the ceramic coatings were also studied. The results show that, duplex Al 2O 3/aluminum coatings have been deposited on steel substrate after the combined treatment. The ceramic coatings are mainly composed of α-Al 2O 3, γ-Al 2O 3, θ-Al 2O 3 and some amorphous phase. The duplex coatings show favorable corrosion and wear resistance properties. The investigations indicate that the combination of arc spraying and plasma electrolytic oxidation proves a promising technique for surface modification of steels for protective purposes.

  18. Interfacial reaction between the oxidized SiC particles and Al-Mg alloys


    The interfacial reactions of oxidized SiC particles reinforced Al-Mg matrix composites were investigated by the field emission-scanning electron microscopy (FE- SEM), TEM and X-ray diffraction. It was found that the nanoscale MgO forms initially due to the interfacial reaction, then whether it reacts with molten Al continuously or not depends on the content of Mg in the matrix and its covering densification at the surface of particles. When there is not enough Mg in the matrix for the formation of dense MgO layer, MgO will transform into MgAl2O4 crystal owing to the continuous reaction with SiO2 and molten Al. When dense MgO layer forms at the surface of the particles due to the affluence of Mg for the initial reaction, it will protect the inner SiC from the attack of molten Al. However, the reaction products of both MgO and MgAl2O4 are thermo-stable phases at the surface of the particles under high temperature. The results clarify the interfacial reaction route and they are of great value to the control of the interfacial reactions and their interfacial design of the composites.

  19. Modification Performance of WC Nanoparticles in Aluminum and an Al-Si Casting Alloy

    Borodianskiy, Konstantin; Zinigrad, Michael


    The influence of a modifier based on tungsten carbide (WC) nanoparticles is investigated first using 1 kg of bulk aluminum and then in a real industrial process using a commercial Al-Si casting alloy. The modifier is prepared by two different approaches, and its influence is investigated in pure aluminum and in commercial aluminum alloy A356. Microstructural studies show that the mean grain size in pure aluminum is reduced by 11.5 pct. Such a change usually causes an improvement in the mechanical properties of metals. Accordingly, the mechanical properties of the A356 alloy modified with WC nanoparticles are determined after T6 heat treatment and compared with unmodified specimens of the same alloy. The results obtained in the modified A356 alloy reveal unusual behavior of the mechanical properties, where the elongation of the alloys improved by 32 to 64 pct, while the tensile strength and yield strength remained unchanged. This behavior is attributable to a grain-size strengthening mechanism, where strengthening occurs due to the high concentration of grain boundaries, which act as obstacles to the motion of dislocations in the lattice.

  20. New scheme for cation distribution and electrical characterization of nanocrystalline aluminum doped magnesium ferrite MgAlxFe2-xO4

    Zaki, H. M.; Al-Heniti, S.; Al Shehri, N.


    MgAlxFe2-xO4 (x=0.0 up to 1 step 0.2) was prepared using co-precipitation method. The value of lattice constant is found to decrease with increasing Al3+ concentration. The particle size of the samples calculated using the Sherrer formula was obtained in the range of 15-28 nm. The two main bands corresponding to tetrahedral and octahedral sites were observed to be around 600 cm-1 and 450 cm-1, respectively. These bands are shifted to high frequencies with more doping of Al3+ ions which may be attributed to the decrease in the mean radius of the tetrahedral and octahedral sites. The threshold frequency (νth) for the electronic transition decreases with increasing the Al3+content. The tetrahedral force constant (KT) increases continuously with Al3+ concentration.The bandwidth of the tetrahedral site is found to increase gradually with the Al3+ content. The validity of the proposed cation distribution is confirmed by considering the X-ray intensity ratios of diffraction lines sensitive to the tetrahedral and octahedral sites. DC conductivity measurements exhibited metallic and semiconductor-like behavior with temperature for all compositions. The decrease of Curie temperature with the increase of non-magnetic ions of aluminum indicates their preference to the octahedral sites as well and confirms the validity of the cation distribution.

  1. The Interface of TiB2 and Al3Ti in Molten Aluminum

    Wang, Xiaoming; Song, Jie; Vian, Wei; Ma, Haibin; Han, Qingyou


    In the grain refinement of aluminum, Al3Ti and TiB2 particles are introduced to reduce the casting grain size down to 200 micrometer level, which makes cold working possible. The particles are brought in by the addition of Al-Ti-B-type master alloys. It is generally believed that TiB2 particles are stable and nucleate α-Al grains in solidification in the presence of titanium in solution from the dissolution of Al3Ti particles in the master alloys. The titanium in solution either forms Al3Ti layers on the surface of TiB2 particles to promote the nucleation of α-Al grains or remains as solute to restrict the growth of α-Al grains in solidification. However, a consensus on a grain refinement mechanism is still to be reached due to the lack of direct observation of the three phases in castings. This paper presents finding of the TiB2/Al3Ti interfaces in an Al-Ti-B master alloy. It demonstrates a strong epitaxial growth of Al3Ti on the surface of TiB2 particles, a sign of the formation of an Al3Ti layer on the surface of TiB2 particles in grain refinement practice. The Al3Ti layer has a crystal coherency with α-Al and hence offers a substrate for heterogeneous nucleation of α-Al grains. However, the layer must be dynamic to avoid the formation of compounded Al3Ti and TiB2 particles leading to the loss of efficiency in grain refinement.

  2. Atomic bonding and mechanical properties of Al-Mg-Zr-Sc alloy

    高英俊; 班冬梅; 韩永剑; 钟夏平; 刘慧


    The valence electron structures of Al-Mg alloy with minor Sc and Zr were calculated according to the empirical electron theory(EET) in solid. The results show that because of the strong interaction of Al atom with Zr and Sc atom in melting during solidification, the Al3 Sc and Al3 (Sc1-xZrx) particles which act as heterogeneous nuclear are firstly crystallized in alloy to make grains refine. In progress of solidification, the Al-Sc, Al-Zr-Sc segregation regions are formed in solid solution matrix of Al-Mg alloy owing to the strong interaction of Al atom with Zr, Scatoms in bulk of alloy, so in the following homogenization treatment, the finer dispersed Al3 Sc and Al3 (Sc1-x Zrx) second-particles which are coherence with the matrix are precipitated in the segregation region. These finer second particles with the strong Al-Zr, Al-Sc covalent bonds can strengthen the covalent bonds in matrix of the alloy, and also enhance the hardness and strength of Al-Mg alloy. Those finer second-particles precipitated in interface of sub-grains can also strengthen the covalence bonds there, and effectively hinder the interface of sub-grains from migrating and restrain the sub-grains from growing, and cause better thermal stability of Al-Mg alloy.

  3. Formally Goes online to Create “Internet+Aluminum Product” New Model


    On the afternoon of May 18,the inauguration announcement meeting for""under the Shanghai Aluminum Trade Association was held ceremoniously at the Songjiang New Century Grand Hotel,Shanghai.Liu Fusheng,Director of the Shanghai Songjiang District Commission of Economy and information Technology,Xu Guotao,President of Shanghai Aluminum Trade Association,and Zhang Rong,Chairman and founder of"WWW.Buy",General

  4. The Formation of γ—AlON Spinel in the Reaction of Al2O3—AlN—MgO System

    LIYawei; YUANRunzhang; 等


    The stabilization of γ-aluminium oxyni-tride spinel(γ-AlON) has been investigated by addition of MgO,MgAl2O4,etc.,in reaction process.The results indicated that there are wider solid solution areas near ,Al2O3-rich side in AlN-Al2O3-MgO ternary systems,The content of stabilized AlON phase in samples is related to heating temperatures,additives,etc.The lattice parameters of their AlON phases could be well describedby the equation: a0=0.7900+0.0375[MgO]+0.015[AlN](nm)

  5. TL and OSL studies of carbon doped magnesium aluminate (MgAl2O4:C)

    Raj, Sanu S.; Mishra, D. R.; Soni, Anuj; Grover, V.; Polymeris, G. S.; Muthe, K. P.; Jha, S. K.; Tyagi, A. K.


    The MgAl2O4:C has been synthesized by using two different methods by electron gun and vacuum assisted melting of MgAl2O4 in presence of graphite. The MgAl2O4:C phosphor thus developed by these two different methods have similar types of the TL/OSL defects with multiple overlapping TL glow peaks from 100 °C to 400 °C. The Computerized Curve De-convolution Analysis (CCDA) has been used to measure TL parameters such as thermal trap depth, frequency factor and order of kinetic associated with charge transfer process in TL phenomenon. The investigated TL/OSL results show that these two methods of incorporating carbon in MgAl2O4 have generated closely resemble the defects of similar types in MgAl2O4:C lattice. However, the MgAl2O4:C synthesized by electron gun shows relatively larger concentration of the TL/OSL defects as compared to MgAl2O4:C synthesized using vacuum assisted melting method. The photo-ionization cross-section (PIC) associated with fastest OSL component of MgAl2O4: C is found to be ∼ 0.5 times than that of fastest OSL component of commercially available dosimetric grade α-Al2O3:C. The MgAl2O4:C thus developed shows good dynamic OSL dose linearity from few mGy to 1 Gy. This work reveals that MgAl2O4:C could be developed as potential tissue equivalent OSL / TL material.

  6. Ab initio study of Mg(AlH4)2

    van Setten, M.J.; de Wijs, G.A.; Popa, V.A.; Popa, V.A.; Brocks, G.


    Magnesium alanate Mg(AlH4)2 has recently raised interest as a potential material for hydrogen storage. We apply ab initio calculations to characterize structural, electronic and energetic properties of Mg(AlH4)2. Density functional theory calculations within the generalized gradient approximation

  7. Preliminary Study on MgAl2O3 Spinel Fiber

    YANG Daoyuan; GUO Xinrong; ZHONG Xiangchong


    MgAl2O3 spinel fibers may be obtained by thermal treatment of pressed specimens composed of Mg-Al-O materials with appropriate oxide-metal ratio at high temperature under controlled atmosphere. Their phase composition and microstructure have been examined.

  8. Ab initio study of Mg(AlH4)2

    Setten, van M.J.; Wijs, de G.A.; Popa, V.A.; Brocks, G.


    Magnesium alanate Mg(AlH4)2 has recently raised interest as a potential material for hydrogen storage. We apply ab initio calculations to characterize structural, electronic and energetic properties of Mg(AlH4)2. Density functional theory calculations within the generalized gradient approximation (G

  9. Pengaruh Milling Time Terhadap Pembentukan Fasa γ-MgAl Hasil Mechanical Alloying

    Ganive Pangesthiaji


    Full Text Available Paduan berbasis magnesium (Mg merupakan salah satu paduan yang banyak sekali manfaatnya dalam dunia industri. Salah satu manfaatnya dapat digunakan sebagai Hydrogen Storage Material. Baru-baru ini peneliti mengembangkan paduan berbasis magnesium sebagai metal hydride, salah satunya adalah paduan magnesium dengan aluminium (Mg-Al. Dalam penelitian ini metode yang digunakan adalah mechanical alloying. Alat yang digunakan adalah Modification Horizontal Ball Mill. Alat ini dibuat dengan menggunakan prinsip rotasi secara horizontal untuk proses milling-nya. Paduan Mg-Al dengan komposisi Mg-42 at.% Al disintesa melalui proses milling dengan variasi waktu 2, 5, 10, dan 20 jam. Serbuk hasil milling disintering dengan temperatur 600oC dengan holding time selama 2 jam. Pengujian dilakukan dengan menggunakan BET, XRD, SEM-EDX, dan DSC/TGA. Hasil penelitian menunjukan bahwa paduan γ-Mg17Al12 telah terbentuk pada pemanasan dengan temperatur 600oC. Hasil XRD juga menunjukan bahwa paduan membentuk solid solution Mg-Al, dimana hal ini diperlihatkan oleh puncak Al yang mengalami pelebaran akibat terlarutnya unsur Mg ke dalam Al begitu juga sebaliknya. Hasil DSC/TGA  memperlihatkan reaksi pembentukan paduan γ-Mg17Al12 terjadi pada temperatur 475,33oC.

  10. (26)Al-(26)Mg dating of asteroidal magmatism in the young Solar System

    Schiller, Martin; Baker, Joel; Bizzarro, Martin


    meteorites have (26)Mg excesses (delta(26)Mg* = +0.0135 to +0.0392 parts per thousand). The (26)Mg excesses cannot be explained by analytical artefacts, cosmogenic effects or heterogeneity of initial (26)Al/(27)Al, Al/Mg ratios or Mg isotopes in asteroidal parent bodies as compared to Earth or chondrites....... The (26)Mg excesses record asteroidal melting and formation of basaltic magmas with super-chondritic Al/Mg and confirm that radioactive decay of short-lived (26)Al was the primary heat source that melted plane-testimals. Model (26)Al-(26)Mg ages for magmatism on the eucrite/mesosiderite, angrite and NWA...... 29 (7) over bar6 parent bodies are 2.6-3.2, 3.9-4.1 and 3.5 Myr, respectively, after formation of calcium aluminium-rich inclusions (CAIs). However, the validity of these model ages depends on whether the elevated Al/Mg ratios of basaltic meteorites result from magma ocean evolution on asteroids...

  11. 26Al-26Mg dating of asteroidal magmatism in the young Solar System

    Schiller, Martin; Baker, Joel A.; Bizzarro, Martin


    meteorites have (26)Mg excesses (delta(26)Mg* = +0.0135 to +0.0392 parts per thousand). The (26)Mg excesses cannot be explained by analytical artefacts, cosmogenic effects or heterogeneity of initial (26)Al/(27)Al, Al/Mg ratios or Mg isotopes in asteroidal parent bodies as compared to Earth or chondrites....... The (26)Mg excesses record asteroidal melting and formation of basaltic magmas with super-chondritic Al/Mg and confirm that radioactive decay of short-lived (26)Al was the primary heat source that melted plane-testimals. Model (26)Al-(26)Mg ages for magmatism on the eucrite/mesosiderite, angrite and NWA...... 29 (7) over bar6 parent bodies are 2.6-3.2, 3.9-4.1 and 3.5 Myr, respectively, after formation of calcium aluminium-rich inclusions (CAIs). However, the validity of these model ages depends on whether the elevated Al/Mg ratios of basaltic meteorites result from magma ocean evolution on asteroids...

  12. 微波辅助溶液燃烧法制备 MgAl2 O4粉体%Synthesis of MgAl2 O4 powders by microwave-assisted combustion

    王朔; 余俊; 赵惠忠; 李超; 王斌斌; 段连威


    High purity,low agglomeration MgAl2O4 powders were synthesized by the microwave-assisted low temperature combustion method using magnesium nitrate,aluminum nitrate and urea (mass ratio of 1 2 6.66) as starting materials,mixing in water forming a transparent precursor liquid.The effects of the microwave out-put power (200,400,600,and 700 W)on the microstructure,morphology and specific surface area of MgAl2O4 powders were analyzed.The results show that the microwave-assisted combustion method can accelerate combusti on reacti on to produce l arge vol umes of gas i nstantl y,formi ng ul tra-fi ne MgAl 2 O4 parti cl es.Moreo-ver,the increasing microwave output power accelerates the oxidation of urea,which is beneficial to the growth of MgAl2O4 grains.Under the conditions of microwave power 700 W for 2 min,the high crystallinity MgAl 2 O4 powder wi th a uni form parti cl e si ze di stri buti on (average grai n si ze of 56.03 nm)can be prepared.%将硝酸镁、硝酸铝、尿素按物质的量比为126.66制得透明混合前驱液,用低温燃烧技术与微波加热技术相结合的方法制备了高纯度、低团聚的镁铝尖晶石(MgAl2 O4)粉体。研究了燃烧反应过程中,微波输出功率(200、400、600、700 W)对MgAl2 O4粉体晶体结构、形貌及比表面积的影响。结果表明:微波高效加热方式导致燃烧反应瞬间产生大量气体,促进了MgAl2 O4超细颗粒的形成。同时,随着微波输出功率的增加,尿素氧化加速,利于MgAl2 O4晶粒的生长发育。在微波功率700 W,微波时间2 min的条件下,可制备结晶完整,粒度分布均匀(平均晶粒尺寸为56.03 nm)的MgAl2O4粉体。

  13. Thermoelectric properties of Al-doped Mg2Si thin films deposited by magnetron sputtering

    Chen, Zhi-jian; Zhou, Bai-yang; Li, Jian-xin; Wen, Cui-lian


    The Al-doped Mg2Si thin films were fabricated by two-target alternative magnetron sputtering technique, and the influences of different Al doping contents on the thermoelectric properties of Al-doped Mg2Si thin films were investigated. The compositions, crystal structures, electronic transport properties and thermoelectric properties of the thin films were examined using energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Hall coefficient measurement and Seebeck coefficient measurement system, respectively. The EDS results show that the thin films doped with Al target sputtering power of 30 W, 60 W and 90 W have the Al content of 0.68 at.%, 1.56 at.% and 2.85 at.%, respectively. XRD results indicate that the diffraction peaks of Mg2Si become stronger with increasing Al dopant. The results of Hall coefficient measurement and Seebeck coefficient measurement system reveal that all the samples are n-type. The conductivities of Al-doped Mg2Si thin films are significantly greater than that of undoped Mg2Si thin film, and increase with increasing Al doping content. With the increase of temperature, the absolute value of the Seebeck coefficients of Mg2Si base thin films increase firstly and then decrease. The maximum power factor obtained is 3.8 mW m-1 k-2 for 1.56 at.% Al-doped Mg2Si thin film at 573 K.

  14. Mechanism of pore formation and structural characterization for mesoporous Mg-Al composite oxides


    Mg-Al layered double hydroxides(LDH) with different particle sizes were prepared using different aging times at high supersaturation by a new method developed in our laboratory. The key features of this method are a very rapid mixing and nucleation process followed by a separate aging process. By calcination of LDH at 500℃, mesoporous Mg-Al composite oxides with an ex-tremely narrow pore size distribution were produced. The crystal structure of the Mg-Al composite oxides was a multiphasic one consisting of MgO-like crystals and a layered material.

  15. Thermodynamically destabilized hydride formation in "bulk" Mg-AlTi multilayers for hydrogen storage.

    Kalisvaart, Peter; Shalchi-Amirkhiz, Babak; Zahiri, Ramin; Zahiri, Beniamin; Tan, XueHai; Danaie, Mohsen; Botton, Gianluigi; Mitlin, David


    Thermodynamic destabilization of MgH2 formation through interfacial interactions in free-standing Mg-AlTi multilayers of overall "bulk" (0.5 μm) dimensions with a hydrogen capacity of up to 5.5 wt% is demonstrated. The interfacial energies of Mg-AlTi and Mg-Ti (examined as a baseline) are calculated to be 0.81 and 0.44 J m(-2). The enhanced interfacial energy of AlTi opens the possibility of creating ultrathin alloy interlayers that provide further thermodynamic improvements in metal hydrides.

  16. Multinuclear solid-state high-resolution and C-13 -{Al-27} double-resonance magic-angle spinning NMR studies on aluminum alkoxides

    Abraham, A.; Prins, R.; Bokhoven, J.A. van; Eck, E.R.H. van; Kentgens, A.P.M.


    A combination of Al-27 magic-angle spinning (MAS)/multiple quantum (MQ)-MAS, C-13-H-1 CPMAS, and C-13-{Al-27} transfer of population in double-resonance (TRAPDOR) nuclear magnetic resonance (NMR) were used for the structural elucidation of the aluminum alkoxides aluminum ethoxide, aluminum

  17. Molecular Characterization of Atlas 66-Derived Wheat Near-Isogenic Lines Contrasting in Aluminum (Al) Tolerance

    GUO Pei-guo; BAI Gui-hua; LI Rong-hua; Brett Carver; Michael Baum


    Aluminum (Al) toxicity is the major limiting factor for wheat growth in acidic soils. Genetic improvement of Al tolerance is one of the most cost-effective solutions to improve wheat productivity. The objective of this study was to characterize near isogenic lines (NILs) contrasting in Al tolerance derived from Atlas 66 in the backgrounds of Al-sensitive cultivars Chisholm and Century using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR). A total of 200 AFLP and 88 SSR primer pairs were screened and 12 markers (11 AFLPs and one SSR) were associated with Altolerance in NILs of at least one recurrent parental background. Among them, nine were linked to Al tolerance in the Chisholm-derived NILs, seven were associated with Al-tolerance in the Century-derived NILs, and three AFLPs derived from the primer combinations of pAG/mGCAG, pCAG/mAGC and pGTG/mGCG, and one SSR, Xwmc331 on chromosome4D, associated with Al tolerance in NILs of both recurrent parental backgrounds. Those common markers across two backgrounds may be the major marker loci associated with Al-tolerance in Atlas 66 and could be useful for marker-assisted breeding to improve Al tolerance in wheat. In addition, evaluation of Al tolerance among different genotypes using hematoxylin stain and relative root growth revealed that Atlas 66 was more tolerant to Al stress than the NILs, therefore suggested that the Al-tolerant NILs might not carry all Al-tolerance loci from Atlas 66 and inheritance of Al tolerance in Atlas 66 is more likely multigenic.

  18. Analysis of EET on Ca increasing the melting point of Mg17Al12 phase


    The present investigation showed that the additions of Ca to the alloy AZ91 were mainly dissolved into the Mg17Al12 phase and increased its melting point and thermal stability, which would have great effects on the high- temperature properties of AZ91 alloy. The empirical electron theory (EET) of solid and molecules was used to calculate the valence electron structures (VES) of Mg17Al12 intermetallic compound with and without Ca addition. The results showed that Ca dissolving in Mg17Al12 phase increased the strength of bonds that control the thermal stability of Mg17Al12 phase. Additions of Ca also made the distribution of the valence electrons on the dominant bond network more uniform in the whole unit cell of Mg17Al12. The theoretical conclusions well account for the experimental results.

  19. Fabrication of Spherical AlSi10Mg Powders by Radio Frequency Plasma Spheroidization

    Wang, Linzhi; Liu, Ying; Chang, Sen


    Spherical AlSi10Mg powders were prepared by radio frequency plasma spheroidization from commercial AlSi10Mg powders. The fabrication process parameters and powder characteristics were investigated. Field emission scanning electron microscope, X-ray diffraction, laser particle size analyzer, powder rheometer, and UV/visible/infrared spectrophotometer were used for analyses and measurements of micrographs, phases, granulometric parameters, flowability, and laser absorption properties of the powders, respectively. The results show that the obtained spherical powders exhibit good sphericity, smooth surfaces, favorable dispersity, and excellent fluidity under appropriate feeding rate and flow rate of carrier gas. Further, acicular microstructures of the spherical AlSi10Mg powders are composed of α-Al, Si, and a small amount of Mg2Si phase. In addition, laser absorption values of the spherical AlSi10Mg powders increase obviously compared with raw material, and different spectra have obvious absorption peaks at a wavelength of about 826 nm.

  20. Influence of electron irradiation on Al-Mg-Sc alloy decomposition

    Repnikova, E.A.; Malinenko, I.A.; Chudinova, S.A.; Toropova, L.S.; Ustinovshchikov, V.M. (Petrozavodskij Gosudarstvennyj Univ. (USSR); AN SSSR, Moscow. Inst. Metallurgii)


    Methods of X-ray diffraction analysis have been used to investigate thermal and radiation structural and phase stability of Al-2.5% Mg-0.4%Sc alloy, irradiated with 2.3 MeV electrons (fluence - 2x10/sup 18/ cm/sup -1/). It is established that thermal treatment of alloys even without following irradiation stimulates the beginning of decomposition, which is the most clearly defined at 350 deg C. Presence of Mg/sub 2/Al/sub 3/, Mg/sub 3/Al/sub 4/ and Mg/sub 5/Al/sub 8/ is sufficiently positively revealed by the method of phase analysis. Electron irradiation results in developing of decomposition process in Al-Mg-Sc solid solutions that the most clearly manifests intself in the alloys, preliminary annealed at 350 deg C.

  1. Reactive wetting of amorphous silica by molten Al-Mg alloys and their interfacial structures

    Shi, Laixin; Shen, Ping; Zhang, Dan; Jiang, Qichuan


    The reactive wetting of amorphous silica substrates by molten Al-Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO2 surface was 115° while that for pure Mg was 35° at 1073 K. For the Al-Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al-Mg alloy on the SiO2 surface was mainly attributed to the formation of Mg2Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  2. Efficient KF loaded on MgCaAl hydrotalcite-like compounds in the transesterification of Jatropha curcas oil

    Guzmán-Vargas, Ariel, E-mail: [ESIQIE-IPN, Departamento de Ingeniería Química, Laboratorio de Investigación en Materiales Porosos, Catálisis Ambiental y Química Fina, UPALM Edif.7 P.B. Zacatenco, México D.F. 07738 (Mexico); Santos-Gutiérrez, Teresa [ESIQIE-IPN, Departamento de Ingeniería Química, Laboratorio de Investigación en Materiales Porosos, Catálisis Ambiental y Química Fina, UPALM Edif.7 P.B. Zacatenco, México D.F. 07738 (Mexico); Lima, Enrique [IIM-Universidad Nacional Autónoma de México, Circuito exterior s/n, Cd. Universitaria, 04510 México DF (Mexico); Flores-Moreno, Jorge L. [UAM-Azcapotzalco, Área de Química de Materiales, Av. San Pablo 180, Col. Reynosa Tamaulipas, 02200 México DF (Mexico); Oliver-Tolentino, Miguel A.; Martínez-Ortiz, María de J. [ESIQIE-IPN, Departamento de Ingeniería Química, Laboratorio de Investigación en Materiales Porosos, Catálisis Ambiental y Química Fina, UPALM Edif.7 P.B. Zacatenco, México D.F. 07738 (Mexico)


    Highlights: • MgCaAl hydrotalcite-like compounds were synthetized. • After KF impregnation and calcination fluorinated species were detected. • Fluorinated species were stables and actives. • LDH composition and KF load effect were evaluated in biodiesel production. - Abstract: In this work a series of MgCaAl hydrotalcite-like compounds were synthetized by coprecipitation method at constant pH. In order to obtain the catalysts, the samples were modified with KF by incipient wetness impregnation at different wt%, after that, they were dried and calcined to obtain the mixed oxides. The effect of divalent cations ratio and KF load were studied in the transesterification reaction of Jatropha curcas oil to obtain biodiesel employing an inedible oil. XRD analysis showed typical diffraction patterns of LDH, by nitrogen physisorption the LDH mesoporous structure was also confirmed, {sup 27}Al NMR spectra showed bands at 10 and 88 ppm attributed to the Al coordination before and after thermal treatment. While for the impregnated samples after calcination the profiles exhibited the mixed oxide formation, in addition, another peaks appeared associated to the formation of various fluorinated species as shown by XRD, additionally, {sup 19}F NMR showed a main signal at −180 ppm indicating the presence of active tetrahedral aluminum fluoride species. The reaction evolution was monitoring calculating the oil conversion to biodiesel by integration of the signal spectra using {sup 1}H NMR spectroscopy. The results of catalytic tests in transesterification reaction showed a direct correlation between Mg/Ca ratio and KF content in the oil conversion to biodiesel, the higher conversion was achieved (90%) when Mg/Ca = 1 and KF load was 30 wt%.

  3. Geometric and Chemical Composition Effects on Healing Kinetics of Voids in Mg-bearing Al Alloys

    Song, Miao; Du, Kui; Wang, Chunyang; Wen, Shengping; Huang, Hui; Nie, Zuoren; Ye, Hengqiang


    The healing kinetics of nanometer-scale voids in Al-Mg-Er and Al-Mg-Zn-Er alloy systems were investigated with a combination of in situ transmission electron microscopy and electron tomography at different temperatures. Mg was observed completely healing the voids, which were then rejuvenated to the alloy composition with further aging, in the Al-Mg-Er alloy. On the contrary, Mg51Zn20 intermetallic compound was formed in voids in the Al-Mg-Zn-Er alloy, which leads to complete filling of the voids but not rejuvenation for the material. For voids with different geometrical aspects, different evolution processes were observed, which are related to the competition between bulk and surface diffusion of the alloys. For voids with a large size difference in their two ends, a viscous flow of surface atoms can be directly observed with in situ electron microscopy, when the size of one end becomes less than tens of nanometers.

  4. Liquidus Temperatures of System Na3AlF6-K3AlF6-AlF3 for Aluminum Electrolysis at Lower Temperature

    WEI Chen-juan; LAI Yan-qing; LI Jie; TIAN Zhong-liang; WANG Jia-wei; ZOU Zhong; LIU Ye-xiang


    Liquidus temperatures in the molten salt system Na3AlF6-K3AlF6-AlF3 of interest for aluminum electrolysis were determined by thermal analysis method.The results were presented and an empirical equation describing liquidus temperatures for primary crystallization was derived t=1003.5-0.081 ×A2.3159-5.87×B0.657-0.024×A2.22×B1.14+0.035×A2.17×B1.084,where t is the liquidus temperature in degree Celsius,A denotes the mass fraction of AlF3 in system Na3AlF6-K3AlF6-AlF3,and B denotes K3A1F6/(Na3AlF6+K3AlF6)in mass(%,the value was defined as KR in this paper).The composition limitations are 0<w(AlF3)<30%,and 0<KR<50%.The isothermal diagram of molten salt system Na3AlF6-K3A1F6-AlF3 was obtained in this composition limitation.

  5. Analysis and Evaluation of Novel Al-Mg-Sc-Zr Aerospace Alloy Strip Produced Using the Horizontal Single Belt Casting (HSBC) Process

    Ge, Sa; Celikin, Mert; Isac, Mihaiela; Guthrie, Roderick I. L.


    Horizontal single belt casting (HSBC) is a near net shape casting process in which molten metal is directly cast into thin strips, at high cooling rates (order of several 100 °C/s), with the potential for high volume, friction free, continuous production of metal strips. This casting process was used in the present work to produce strips of Al-Mg alloys in the AA5000 series, with additions of Sc and Zr. Such aluminum alloys show exceptional potential as a structural material for transportation/aerospace applications. To demonstrate the suitability of the HSBC process to manufacture competitive strip products of Al-Mg-Sc-Zr, the mechanical properties and microstructures of the strips produced using the HSBC process were compared with conventionally cast products. The effects of annealing on the mechanical properties of the strip-cast Al-Mg-Sc-Zr alloys were also investigated.

  6. Microstructure and Mechanical Behaviour of Stir-Cast Al-Mg-Sl Alloy Matrix Hybrid Composite Reinforced with Corn Cob Ash and Silicon Carbide

    Oluwagbenga Babajide Fatile


    Full Text Available In this present study, the microstructural and mechanical behaviour of Al-Mg-Si alloy matrix composites reinforced with silicon carbide (SiC and Corn cob ash (An agro‑waste was investigated. This research work was aimed at assessing the suitability of developing low cost- high performance Al-Mg-Si hybrid composite. Silicon carbide (SiC particulates added with 0,1,2,3 and 4 wt% Corn cob ash (CCA were utilized to prepare 10 wt% of the reinforcing phase with Al-Mg-Si alloy as matrix using two-step stir casting method. Microstructural characterization, density measurement, estimated percent porosity, tensile testing, and micro‑hardness measurement were used to characterize the composites produced. From the results obtained, CCA has great potential to serve as a complementing reinforcement for the development of low cost‑high performance aluminum hybrid composites.

  7. Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

    Naeem, Haider T. [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia); College of Engineering, Al-Muthanna University, South Baghdad (Iraq); Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia)


    In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg{sub 2}Zn{sub 11}) phases during matrix of aluminum-alloy.

  8. Microstructure and mechanical properties of Mg-6Al magnesium alloy with yttrium and neodymium

    Chen Jun


    Full Text Available The effects of rare earth (RE elements Y and Nd on the microstructure and mechanical properties of Mg-6Al magnesium alloy were investigated. The results show that a proper level of RE elements can obviously refi ne the microstructure of Mg-6Al magnesium alloys, reduce the quantity of β-Mg17Al12 phase and form Al2Y and Al2Nd phases. The combined addition of Y and Nd dramatically enhances the tensile strength of the alloys in the temperature range of 20-175℃. When the content of RE elements is up to 1.8%, the values of tensile strength at room temperature and at 150℃ simultaneously reach their maximum of 253 MPa and 196 MPa, respectively. The main mechanisms of enhancement in the mechanical properties of Mg-6Al alloy with Y and Nd are the grain refi ning strengthening and the dispersion strengthening.

  9. Obtention of Al-Mg alloys of porous morphology; Obtencion de aleaciones Al-Mg de morfologia porosa

    Barragan V, J.; Zamora R, L.; Sandoval J, A.R.; Iturbe G, J.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)


    With the objective of using it as fuel cell, a Mg{sub 25}AI alloy of porous morphology was obtained. The material it was hydrogenates at 200 C by different time. It was analyzed by Scanning Electron Microscopy SEM and X-ray diffion, XRD. Those XRD diffractographs present peaks run toward the origin, that which indicates a volume increase of the unitary cell by effect of the hydrogen absorption. (Author)

  10. Eu{sup 3+} luminescence properties of Eu- and Mg-codoped AlGaN

    Kanemoto, Masayoshi [Department of Electrical and Electronics Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Sekiguchi, Hiroto, E-mail: [Department of Electrical and Electronics Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Yamane, Keisuke [Department of Electrical and Electronics Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Okada, Hiroshi [Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Department of Electrical and Electronics Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Wakahara, Akihiro [Department of Electrical and Electronics Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan); Electronics-Inspired Interdisciplinary Research Institute (EIIRIS), Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi 441-8580, Aichi (Japan)


    We investigated the effect of Mg codoping on luminescence properties of AlGaN:Eu to improve emission through synergy effect between an increase in bandgap by AlGaN and the Mg codoping technique. The luminescence properties of AlGaN:(Eu, Mg) are strongly influenced by the Mg concentration and Al composition. Mg codoping in AlGaN was observed to contribute to increasing photoluminescence (PL) integrated intensity and to improve thermal quenching from 7.3% to 60% while the dominant optical site remained site B (622.3-nm peak) with low excitation cross section. The total concentration of optically activated Eu at 25 K was a constant at for either optical site, indicating that Mg codoping did not affect the formation of optical sites. The PL decay times at room temperature (RT) increased with Mg concentration because of suppression of the back-transfer process. For optimized Mg concentration, an increase in the Al composition contributed to the total activated Eu concentration and changed the dominant optical site from A (620.3-nm peak) to B. The activation energy E{sub a}, which is the difference in energy between the {sup 5}D{sub 0} energy level and the trap level in the host material, was estimated from temperature dependence of PL decay time. The E{sub a} for site A was larger than that for site B, suggesting that the back-transfer rate for site A was less than that for site B. - Highlights: • Eu and Mg codoped AlGaN was grown on GaN template by NH{sub 3}-MBE. • The effect of Mg codoping on optical properties of Eu doped AlGaN was investigated. • Mg codoping contributed to increase PL intensity at RT and improve thermal quenching. • An increase in the Al content affected total activated N{sub Eu} and dominant optical site.

  11. Effect of homogenizing heatings on the properties of Al-Sc and Al-Mg-Sc alloy systems

    Drits, M.E.; Toropova, L.S.; Anastas' eva, G.K.; Nagornichnykh, G.L.

    Effect of annealing on hardness and electric conductivity of cast alloys of Al-Mg-Sc and Al-Sc systems has been studied. Magnesium content in studied alloys was changed in the range of 0-6.5%, scandium content was chosen to be constant -0.4%. It has been revealed that homogenizing heatings of Al-Sc alloys lead to a decomposition of abnormally saturated solid solution during crystallization at temperatures >250 deg C. Maximum hardness values are achieved after annealing at 300 deg C during 1h. Homogenizing of Al-Mg--- Sc alloys at 350 deg C during 24h leads to practically full solubility of a nonequilibrium ..beta..-phase (Mg/sub 2/Al/sub 3/) and also to a decomposition of a solid solution abnormally saturated with scandium. Maximum values of hardness are achieved after annealing at 35O deg C during 0.5-1h.

  12. Removal of borate by coprecipitation with Mg/Al layered double hydroxide

    Kurashina, Masashi; Inoue, Tatsuki; Tajima, Chihiro; Kanezaki, Eiji


    Borate has been used for various industrial products and excessive dose of boron is harmful to humans. We investigated the removal of borate by direct coprecipitation with Mg/Al layered double hydroxide. In this study, the maximum removal of boron was 90% when Mg 30 mmol and Al 15 mmol at pH = 10 were used for 498 mg/l as B. The boron adsorption isotherms could be fitted to Langmuir model. The calculated constant Ws, saturation limit of boron adsorption, is 25 ± 2 mg/g and it is larger than that of ion exchange reaction (Ws = 15±1 mg/g).

  13. Microstructure and Mechanical Properties of Mg-Al-Ca-Nd Alloys Fabricated by Gravity Casting


    The aims of this study are to investigate the effects of Nd addition in the Mg-Al-Ca alloys on microstructure and mechanical properties. Microstructure of as-cast Mg-5Al-3Ca alloy containing Nd consists of α-Mg matrix,eutectic phase and Al-Nd rich intermetallic compound. As Nd addition was increased, α-Mg matrix morphology was changed from dendritic to equiaxed grains and average value of grain size was decreased. Nd addition to Mg-5Al-3Ca based alloys resulted in the formation of Al-Nd rich intermetallic compounds at grain boundary and α-Mg matrix grains. And these Al-Nd rich intermetallic compounds were dispersed homogeneously. In these alloys, two kinds of eutectic phases were observed, i.e. coarse irregular-shape structure at grain boundary and fine needle-shape structure in the α-Mg matrix grain. It is found that the ultimate strength showed the maximum value of 271 MPa at Mg-5Al-3Ca-2Nd alloy and elongation was decreased as the addition of Nd was increased.

  14. Laser surface cladding of ZM5 Mg-base alloy with Al+Y powder

    陈长军; 王东生; 王茂才


    The surface properties of ZM5 Mg-base alloy were modified by laser cladding with Al+ Y powder. Laser cladding was carried out with a 5 kW continuous wave CO2 laser by melting the preplaced powder mixture of Al and Y. Following laser cladding, the cladding zone was characterized by a detailed microstructural observation and phase analysis. Moreover, the microhardness and element distribution were evaluated in detail. The surface modified layer consists of Mg17 Al12 and Al4 MgY phases, while a-Mg and Mg17 Al12 in the substrate. The microhardness of the cladding zone was significantly enhanced as high as HV122 - 180 as compared to HV60 - 80 of the substrate region. The maximal hardness about HV224 is in the interface due to the formation of intermetallic Mg17 Al12 phase. The microstructure is refined and Mg diffuses into the cladding material which leads to the formation of Mg17 Al12.

  15. Study on in-situ Mg2Si/Al-Si composites with different compositions

    Jing Qingxiu; Zhang Caixia; Huang Xiaodong


    Effects of chemical composition and heat treatment on microstructures and mechanical properties of in-situ Mg2Si/Al-Si composites were investigated. It was found that, in the microstructure of an Al-5.7wt% Mg2Si composite with 8.2wt% extra Si, the binary eutectic Mg2Si locates at the grain boundaries with an undeveloped Chinese script-like morphology, and the primary α-Al is formed into a cell structure due to the selective modification effect of the modifiers of mischmetal and Strontium salt; whereas in the composite with a near Al-Mg2Si eutectic composition and little extra Si content, the intercrescence eutectic Mg2Si formed with the binary eutectic a-Al grows into integrated Chinese script-like shape. As Si content increases, the eutectic Mg2Si dendrite becomes coarser in morphology but less in volum e fraction. Hardness and tensile strength of the cast Mg2Si/Al-Si composites do not increase with increasing of Mg content, but they are related to the size and morphology of the eutectic and primary Mg2Si phases. Heat treatment with optimal parameters is an effective way to improve the properties of the in-situ composites.

  16. Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process

    Saikawa S.


    Full Text Available High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC and Y-block shaped metal mold(Permanent mold Casting; PC C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of the two-step aged SC alloys were 353-387 MPa and about 0.4% respectively. This low tensile properties of the SC alloys might be caused by remaining of undissolved crystallized phase such as Al2CuM, MgZn2 and Al-Fe-Cu system compounds. However, good tensile properties were obtained from PC alloys, tensile strength and 0.2% proof stress and elongation were 503-537 MPa, 474-519 MPa and 1.3-3.3%.

  17. Wear and Friction Characteristics of AlN/Diamond-Like Carbon Hybrid Coatings on Aluminum Alloy

    Nakamura, Masashi; Kubota, Sadayuki; Suzuki, Hideto; Haraguchi, Tadao


    The use of diamond-like carbon (DLC) coatings has the potential to greatly improve the wear resistance and friction of aluminum alloys, but practical application has so far been limited by poor adhesion due to large difference in hardness and elasticity between the two materials. This study investigates the deposition of DLC onto an Al-alloy using an intermediate AlN layer with a graded hardness to create a hybrid coating. By controlling the hardness of the AlN film, it was found that the wear life of the DLC film could be improved 80-fold compared to a DLC film deposited directly onto Al-alloy. Furthermore, it was demonstrated through finite element simulation that creating a hardness gradient in the AlN intermediate layer reduces the distribution of stress in the DLC film, while also increasing the force of adhesion between the DLC and AlN layers. Given that both the DLC and AlN films were deposited using the same unbalanced magnetron sputtering method, this process is considered to represent a simple and effective means of improving the wear resistance of Al-alloy components commonly used within the aerospace and automotive industries.

  18. An aluminum - ionic liquid interface sustaining a durable Al-air battery

    Gelman, Danny; Shvartsev, Boris; Wallwater, Itamar; Kozokaro, Shahaf; Fidelsky, Vicky; Sagy, Adi; Oz, Alon; Baltianski, Sioma; Tsur, Yoed; Ein-Eli, Yair


    A thorough study of a unique aluminum (Al)-air battery utilizing a pure Al anode, an air cathode, and hydrophilic room temperature ionic liquid electrolyte 1-ethyl-3-methylimidazolium oligofluorohydrogenate [EMIm(HF)2.3F] is reported. The effects of various operation conditions, both at open circuit potential and under discharge modes, on the battery components were discussed. A variety of techniques were utilized to investigate and study the interfaces and processes involved, including electrochemical studies, electron microscopy, spectroscopy and diffraction. As a result of this intensive study, the upon-operation voltage drop (;dip;) obstacle, occurring in the initial stages of the Al-air battery discharge, has been resolved. In addition, the interaction of the Al anode with oligofluorohydrogenate electrolyte forms an Al-O-F layer on the Al surface, which allows both activation and low corrosion rates of the Al anode. The evolution of this layer has been studied via impedance spectroscopy genetic programming enabling a unique model of the Al-air battery.

  19. 常压及高压凝固Al-Mg及Al-Mg-Zn合金中Al相的固溶体结构%Solid solution structure of Al phase in Al-Mg and Al-Mg-Zn alloys solidifying under normal pressure and high pressure

    王振玲; 张涛; 李莉; 周月波; 王宏伟; 魏尊杰


    采用X射线衍射仪、能谱仪和透射电镜分别对Al-9.6%Mg合金、Al- 11Mg-4.5Zn合金和Al- 17Zn- 1.5Mg合金常压及6 GPa高压凝固后Al相的固溶体结构进行研究.结果表明:6GPa高压凝固后,Al-9.6%Mg合金中Mg在Al相中的固溶度显著增大:在Al-11Mg-4.5Zn合金和Al- 17Zn- 1.5Mg合金中,Mg、Zn溶质在Al相中的固溶度均增大,但Zn比Mg固溶的比例要大得多.在常压凝固条件下,与纯铝相比,3种合金中Al相的晶格常数均增大.与常压凝固相比,高压凝固Al-9.6Mg合金和Al-11Mg-4.5Zn中Al相晶格常数分别增大了1.178%和0.220%;在Al- 17Zn- 1.5Mg合金中,Al相晶格常数变化很小.此外,在Al-Mg-Zn合金中,原子半径较大的Mg固溶到Al相中,导致其晶格常数增大,原子半径较小的Zn固溶到Al相中,导致其晶格常数减小,且高压凝固后,溶质的原子半径越小,在Al相中固溶的比例越大.%The solid solution structures of Al phases in Al-9.6%Mg, Al-llMg-4.5Zn andAl-17Zn-1.5Mg alloys solidified under normal pressure and high pressure were investigated using XRD, EDS and TEM. The results show that the solid solubility of Mg in Al phase in Al-9.6%Mg alloy increases remarkably, and those of Mg and Zn in Al phase in Al-llMg-4.5Zn and Al-17Zn-1.5Mg alloys increase, however, the proportion of Zn saturating in Al phase is much more than that of Mg. Under the condition of normal pressure solidification, the lattice constants of Al phases in three alloys have an increment comparing with that of pure Al. In contrast to normal pressure solidification, the lattice constants of Al phases in Al-9.6Mg alloy and AI-llMg-4.5Zn alloy solidifying at 6 GPa high pressure increase up to 1.178% and 0.220%, respectively. And the lattice constant of Al phase in AI-17Zn-1.5Mg alloy changes little. Furthermore, Mg with larger atomic radius saturating in Al phase leads to the increment of the lattice constant in Al-Mg-Zn alloy, and that of Zn with smaller atomic radium causes

  20. Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin


    The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.

  1. Study of the structure and properties of laser-welded joints of the Al-Mg-Li alloy

    Pugacheva, N. B.; Antenorova, N. P.; Senaeva, E. I.


    The macro- and microstructures, the distribution of chemical elements and of the values of the microhardness over the width of the zones of remelting and heat-affected zone have been studied after the laser welding of sheets of an Al-Mg-Li alloy. It has been shown that the material of the zone of remelting (1.2 mm thick) represents in itself finely dispersed misoriented dendrites, in the primary branches of which particles of the strengthening δ' phase (Al3Li) with dimensions of no more than 10 nm and in the interdendrite spaces, dispersed particles of the S phase (Al2MgLi and FeAl2) have been revealed. The hardness of the material of the zone of remelting was 108-123 HV 0.05; the hardness of the basic alloy, 150-162 HV 0.05. In the heat-affected zones of thickness 2 mm, the primary recrystallization occurred only in a narrow zone directly at the boundary with the weld. The strength of the welded junction was 470-490 MPa, which corresponds to the regulated degree of strength of the aluminum alloys of this class. The relative elongation of the material of the weld proved to be considerably less than that in the alloy matrix because of the microporosity of the weld material. It is shown that the convective stirring of the melt in the welding pool upon the laser welding made it possible to avoid the appearance of macroscopic defects, but on the microlevel there are observed micropores in the form of spheres with dimensions of 5-50 μm. The solidification of the alloy occurred in such a way that the dendrites had time to grow around the gas bubbles prior to their collapse, forming a sufficiently strong carcass. Inside the dendritic carcass, there have been revealed coarse inclusions (to 200 μm) that consist of oxides (Al2O3, Fe2O3, MgO, SiO2, CaO), of an iron-based alloy, and of the host aluminum alloy.

  2. Sequestration of uranium on fabricated aluminum co-precipitated with goethite (Al-FeOOH)

    Sun, Yubing; Yang, Shubin; Wang, Qi; Wang, Xiangke [Chinese Academy of Science, Hefei (China). Key Laboratory of Novel Thin Film Solar Cells; Alsaedi, Ahmad [King Abdulaziz Univ., Jeddah (Saudi Arabia). Nonlinear Analysis and Applied Mathematics (NAAM) Research Group


    Aluminum co-precipitated with goethites (Al-FeOOHs) are ubiquitous within (sub)-surface environments, which are considered one of the most important sinks for radionuclide pollution management. Accordingly, various mole ratios Al-FeOOH were synthesized and characterized by XRD, FT-IR, TEM, specific surface area and potentiometric acid-base titration. According to XRD and TEM images, the morphology of Al-FeOOH was transformed from acicular-like goethite to cotton-like gibbsite with increasing Al content. The adsorption and sequential desorption of U(VI) on Al-FeOOHs were conducted by batch techniques under N{sub 2} conditions. The batch adsorption results showed that the adsorption of U(VI) on Al-FeOOHs slightly increased at pH < 4.0, then the significant increase of U(VI) adsorption was observed at pH from 4.0 to 7.0, whereas the suppressed adsorption at pH > 8.0 was due to the electrostatic repulsion between negative charge surface and negative carbonato-complexes. The adsorption of U(VI) on Al-FeOOHs was independent of ionic strength at pH > 5.0, indicating that the inner-sphere surface complexation predominated their adsorption behaviors, whereas U(VI) adsorption on Al-FeOOH could be the outer-sphere surface/cation exchange reaction. The sequential extraction texts showed that the desorption of U(VI) from Al-FeOOHs decreased with increasing Al content. These findings highlighted the effect of Al content on the sequestration and immobilization of U(VI) onto Al-FeOOHs from (sub)-surface environments in pollution management.

  3. Formation of nanocrystalline h-AlN during mechanochemical decomposition of melamine in the presence of metallic aluminum

    Rounaghi, S.A., E-mail: [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Kiani Rashid, A.R. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of); Eshghi, H., E-mail: [Department of Chemistry, Ferdowsi University of Mashhad, P.O. Box No. 91775-1436, Mashhad (Iran, Islamic Republic of); Vahdati Khaki, J. [Department of Materials Engineering, Ferdowsi University of Mashhad, P.O. Box No. 91775-1111, Mashhad (Iran, Islamic Republic of)


    Decomposition of melamine was studied by solid state reaction of melamine and aluminum powders during high energy ball-milling. The milling procedure performed for both pure melamine and melamine/Al mixed powders as the starting materials for various times up to 48 h under ambient atmosphere. The products were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The results revealed that Al causes melamine deammoniation at the first stages of milling and further milling process leads to the s-triazine ring degradation while nano-crystallite hexagonal aluminum nitride (h-AlN) was the main solid product. Comparison to milling process, the possibility of the reaction of melamine with Al was also investigated by thermal treatment method using differential scanning calorimeter (DSC) and thermo gravimetric analyzer (TGA). Melamine decomposition occurred by thermal treatment in the range of 270-370 Degree-Sign C, but no reaction between melamine and aluminum was observed. - Graphical Abstract: Mechanochemical reaction of melamine with Al resulted in the formation of nanocrystalline AlN after 7 h milling time Highlights: Black-Right-Pointing-Pointer High energy ball milling of melamine and aluminum results decomposition of melamine with elimination of ammonia. Black-Right-Pointing-Pointer Nano-crystalline AlN was synthesized by the mechanochemical route. Black-Right-Pointing-Pointer Milling process has no conspicuous effect on pure melamine degradation. Black-Right-Pointing-Pointer No reaction takes place by heating melamine and aluminum powder mixture in argon.

  4. Effect of heat treatment on the distribution and volume fraction of Mg2Si in structural aluminum alloy 6063

    Al-Marahleh, G.


    The structure and properties of an aluminum alloy after extrusion in cast and homogenized states are studied. Commercial billets are melted in a horizontal continuous casting installation. After homogenizing the billets are used for fabricating shapes of specified form in an extrusion press. The shapes are subjected to final aging. The volume fraction and the distribution of the second Mg2Si phase are determined after different kinds of treatment. The structure and mechanical properties of shapes obtained from cast and homogenized billets are compared after aging and without aging. The effect of homogenizing on the properties of the alloy after extrusion is analyzed.

  5. Al-Si-Mn Alloy Coating on Aluminum Substrate Using Cold Metal Transfer (CMT) Welding Technique

    Rajeev, G. P.; Kamaraj, M.; Bakshi, S. R.


    The cold metal transfer (CMT) process was explored as a weld overlay technique for synthesizing Al-Si-Mn alloy coating on a commercially pure Al plate. The effect of welding speed on the bead geometry, deposition rate, and the dilution were studied and the best parameter was used to synthesize the coatings. The CMT process can be used to produce thick coatings (>2.5 mm) without porosity and with low dilution levels. The Vickers hardness number of the Al substrate increased from 28 in the bulk to 57 in the coating. It is suggested that the CMT process can be an effective and energy-efficient technique for depositing thick coatings and is useful in weld repair of aluminum alloy components.

  6. Laser assembly nanostructured Al2O3/TiO2 coating on cast aluminum surface

    ZHANG Guang-jun; DAI Jian-qiang; WANG Hui-ping; YAN Min-jie; XI Wen-long; ZOU Chang-gu; GE Da-fang


    CO2 laser quick assembly technology is adopted on the surface of cast aluminum ZL104 to form a dense ceramic coating containing a great deal of nanometer Al2O3/TiO2 particles which eliminate cracks and porosities.The major phases of the coating are α-Al2O3 andβ-TiO2. The micro-hardness distribution of the coating is 1 813,1 504, 1 485 and 1 232 (HV0.05). The bonding strength of the coating LC1 is 11.4 N, which is 7.26 times higher than that of the conventional hot-spraying Al2O3/TiO2 coating. It has been proved by analysis that the bonding strength is achieved because of the effects of both super-quick laser consolidation and the nanometer effect of nanometer ceramic material.

  7. Microstructural characteristics of in situ Mg2Si/Al-Si composite by low superheat pouring

    Wu Xiaofeng


    Full Text Available To control the morphology and size of the primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si composite and achieve a feasible and reliable technique to produce appropriate feedstock for the thixo-casting and rheo-casting of this type of material, three Al-Si matrix composites reinforced by 5wt.%, 9wt.% and 17wt.% Mg2Si with hypoeutectic, eutectic and hypereutectic compositions were prepared by the low superheat pouring (LSP process. The effects of the pouring temperature (superheat on the morphology and size distribution of primary phases (primary α-Al and Mg2Si, binary (α-Al + Mg2Si eutectic cell and eutectic Mg2Si were investigated. The experimental results show that low pouring temperature (superheat not only refines the grain structure of the primary α-Al and binary (α-Al + Mg2Si eutectic cell in three composites and promotes the formation of more non-dendritic structural semi-solid metal (SSM slurry of these phases; but also refines the primary and eutectic Mg2Si phases, which seems to be attributed to the creation of an ideal condition for the nucleation and the acquisition of a high survival of nuclei caused by the LSP process.

  8. Microstructure Properties of Rapidly Solidified Al-Zn-Mg-Cu Alloys

    Emad M. Ahmed


    Full Text Available The Rietveld X-ray diffraction analysis was applied to analyze the weight fraction of precipitation phases and microstructure characterizations of rapidly solidified Al-8Zn-4Mg-xCu, x = 1, 4, 8, and 10 alloys (in wt.%, prepared by melt spun technique. A good agreement between observed and calculated diffraction pattern was obtained and the conventional Rietveld factors (Rp, Rwp, and GOF converged to satisfactory values. Solid solubilities of Zn, Mg, and Cu in α-Al were extended to high values. Besides, metastable Al0.71Zn0.29, intermetallic Al2CuMg, Al2Cu, and CuMgZn phases have been observed for x = 4, 8, and 10 Cu alloys. The crystal structure and microstructure characterizations exhibit strong Cu content dependence.

  9. Study of rare earth element effect on microstructures and mechanical properties of an Al-Cu-Mg-Si cast alloy

    WAN Weiwei; HAN Jianmin; LI Weijing; WANG Jinhua


    The improvements of microstructures and properties of a high strength aluminum cast alloy were studied.The effects of rare earth elements on the microstructures and mechanical properties of the high strength cast alloy Al-Cu-Mg-Si were investigated.The result shows that the addition of rare earth elements can change the microstructures in refining the grain size of the alloy and making the needle-like and laminar eutectic Si to a granular Si.With the increase of the rare earth, the tensile strength and elongation of the alloy increase first and then fall down.The mechanical properties of the alloy will reach the highest value when the content of rare earth elements is about 0.7%.

  10. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.


    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  11. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles

    Dutkiewicz, Jan; Rogal, Łukasz; Wajda, Wojciech; Kukuła-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas


    The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 μm, so the powder was sieved to obtain maximum size of 60 μm. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 °C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.

  12. The relation between the content of Al in Mg- Al alloy and the burning point of Mg - Al alloy%Mg-Al合金中Al含量对Mg-Al合金燃点影响的实验研究

    王世俊; 王泉; 汪岘


    研究了 Mg-Al合金中Al含量对Mg-Al合金燃点的影响,实验证明了保护熔剂能够有效的防止Mg-Al合金在熔炼中Mg和Al的氧化与燃烧,且在Al含量在10%~90%的Mg-Al合金中,Al含量40%的燃点最高,而在Al含量超过80%以后Mg-Al合金不发生燃烧现象.

  13. Synthesis of Al-doped Mg{sub 2}Si{sub 1−x}Sn{sub x} compound using magnesium alloy for thermoelectric application

    Hu, Xiaokai, E-mail: [Institute for Frontier Materials, Deakin University, Geelong, VIC 3217 (Australia); Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Barnett, Matthew R. [Institute for Frontier Materials, Deakin University, Geelong, VIC 3217 (Australia); Yamamoto, Atsushi [Research Institute for Energy Conservation, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)


    Mg{sub 2}Si{sub 1−x}Sn{sub x} thermoelectric compounds were synthesized through a solid-state reaction at 700 °C between chips of Mg{sub 2}Sn–Mg eutectic alloy and silicon fine powders. The Al dopants were introduced by employing AZ31 magnesium alloy that contains aluminum. The as-synthesized Mg{sub 2}Si{sub 1−x}Sn{sub x} powders were consolidated by spark plasma sintering at 650–700 °C. X-ray diffraction and scanning electron microscopy revealed that the Mg{sub 2}Si{sub 1−x}Sn{sub x} bulk materials were comprised of Si-rich and Sn-rich phases. Due to the complex microstructures, the electrical conductivities of Mg{sub 2}Si{sub 1−x}Sn{sub x} are lower than Mg{sub 2}Si. As a result, the average power factor of Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} is about 1.5 × 10{sup −3} W/mK{sup 2} from room temperature to 850 K, being less than 2.5 × 10{sup −3} W/mK{sup 2} for Al{sub 0.05}Mg{sub 2}Si. However, the thermal conductivity of Mg{sub 2}Si{sub 1−x}Sn{sub x} was reduced significantly as compared to Al{sub 0.05}Mg{sub 2}Si, which enabled the ZT of Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} to be superior to Al{sub 0.05}Mg{sub 2}Si. Lastly, the electric power generation from one leg of Al{sub 0.05}Mg{sub 2}Si and Al{sub 0.05}Mg{sub 2}Si{sub 0.73}Sn{sub 0.27} were evaluated on a newly developed instrument, with the peak output power of 15–20 mW at 300 °C hot-side temperature. - Highlights: • Aluminium is used as dopant in n-type Mg{sub 2}(Si,Sn) thermoelectric compounds. • Scrap magnesium alloy is used instead of pure raw material, and ball milling is avoided. • Dual phases of solid solution lower thermal conductivity. • Thermoelectric conversion of one-leg material is demonstrated.

  14. Influence of the heat treatment condition of alloy AlCu4Mg1 on the microstructure and properties of anodic oxide layers

    Morgenstern, R.; Dietrich, D.; Sieber, M.; Lampke, T.


    Due to their outstanding specific mechanical properties, high-strength, age-hardenable aluminum alloys offer a high potential for lightweight security-related applications. However, the use of copper-alloyed aluminum is limited because of their susceptibility to selective corrosion and their low wear resistance. These restrictions can be overcome and new applications can be opened up by the generation of protective anodic aluminum oxide layers. In contrast to the anodic oxidation of unalloyed aluminum, oxide layers produced on copper-rich alloys exhibit a significantly more complex pore structure. It is the aim of the investigation to identify the influence of microstructural parameters such as size and distribution of the strengthening precipitations on the coating microstructure. The aluminum alloy EN AW-2024 (AlCu4Mg1) in different heat treatment conditions serves as substrate material. The influence of the strengthening precipitations’ size and distribution on the development of the pore structure is investigated by the use of high-resolution scanning electron microscopy. Integral coating properties are characterized by non-destructive and light-microscopic thickness measurements and instrumented indentation tests.

  15. Experimental Study of the Al-Mg-Sr Phase Diagram at 400°C

    D. Kevorkov


    Full Text Available The Al-Mg-Sr system is experimentally studied at 400°C using EPMA and XRD techniques. It was determined that the intermetallic phases in the Al-Mg-Sr system have a tendency to form extended substitutional solid solutions. Two ternary phases were found in this system. Solubility limits of binary and ternary phases were determined and the phase equilibria among phases were established. The isothermal section of the Al-Mg-Sr system at 400°C has been constructed using results of the phase analysis and experimental literature data.

  16. High speed twin roll casting of Al-3Si-0.6Mg strip

    Haga, T.; Ikawa, M; H.Watari; S. Kumai


    Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast Al-3%Si-0.6%Mg strip was purpose, too.Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed.Findings: Findings are that Al-3%Si-0.6%Mg was could be cast at ...

  17. 高耐用性轻质Al_2O_3-MgO-C砖

    王振良; 吕冰; 王守权





    The ageing behavior and microstructures of the Al-Mg-Li alloys containing small amounts of silver have been studied. The results showed that small quantities of silver could modify the ageing characteristics of Al-Mg-Li alloys, enhance the peak hardness and strength, and delay the ageing peaks. X-Ray diffraction analysis showed that T phase was present in the Al-Mg-Li alloy containing 0.52 % (mass fraction, % )Ag, and TEM observations showed that silver prevented the growth of δ' phase during ageing.

  19. Effects of Additives on Properties of Unburned MgO—Al2O3 Refractory

    LIFang; TANLihua


    The influences of four kinds of additives added into the matrix of MgO-Al2O3 unbuned products were investigated,The results show that samples with proper MgO/Al2O3 ration and proper addition of Cr2O3(2%- 4%) have good thermal shock resistance and slag corrosion resistance as well,XRD and SEM determination results indicate that a kind of compound spinel(Mg,Al, Cr) O4 was formed and the microstucture of the samples are denser.

  20. Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered Composites Produced by Accumulative Roll Bonding

    H.S.Liu; B.Zhang; G.P.Zhang


    Al/Mg alloy multilayered composites were produced successfully at the lower temperature (280℃) by accumulative roll bonding (ARB) processing technique. The microstructures of Al and Mg alloy layers were characterized by scanning electron microscopy and transmission electron microscopy. Vickers hardness and three-point bending tests were conducted to investigate mechanical properties of the composites. It is found that Vickers hardness, bending strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARB pass. Delamination and crack propagation along the interface are the two main failure modes of the multilayered composite subjected to bending load. Strengthening and fracture mechanisms of the composite are analyzed.

  1. Preparation of Mg/Al-NO3--LDHs Intercalated with Dodecanoic Acid and Investigation of Its Tribological Characteristics%月桂酸插层Mg/Al-NO3--LDHs及其摩擦性能评价

    赵栋; 白志民


    采用液相共沉淀法制备了Mg/Al-NO3--LDHs;以月桂酸为插层剂,采用离子交换法对合成产物进行了插层改性;采用X射线衍射(XRD)、热重及差热分析(TG-DTA)、红外光谱(FT-IR)、扫描电镜(SEM)、比表面积分析仪、四球摩擦实验机和齿轮实验机等对合成产物的结构和性能进行了评价.结果表明,插层前,晶体呈六方片状,晶片大小在50~70 nm,比表面较大(137.66m2/g).月桂酸插层后,产物的通道高度增加,但比表面积显著降低;Mg/Al-NO3--LDHs及其月桂酸插层产物可明显降低金属摩擦副的摩擦系数、磨斑直径、润滑介质温度以及驱动电机功耗,是具有良好应用前景的润滑-减摩-节能材料.%Dodecanoic acids were intercalated into magnesium aluminum layered double hydroxides ( Mg/ Al-NO3-LDHs) prepared by coprecipitation by the method of anion exchange. The obtained compounds were characterized by X-ray diffraction, fourier transform infra-red, ghermo-gravimetric/differential thermal analyzer, scanning electron microscope and surface area analyzer. The tribological performances of LDHs in base oil were studied by four-ball wear machine and gear testing machine. These results indicated that the crystal shape is hexagonal flake with crystal size of 50-70 nm and larger specific surface area of 137.66 mVg before intercalation. After intercalation, the channel height of Mg/Al-NOj-LDHs increases, but the specific surface area decreases significantly. Mg/Al-NO3-LDHs and its products intercalated with dodecanoic acid can significantly reduce the friction coefficient, wear scar diameter, lubrication medium temperature and drive motor power, and are with good prospect of application in lubrication-antifriction-energy saving materials.

  2. Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by MgGa δ doping in (AlN)m/(GaN)n superlattice

    Wang, Xiao; Wang, Wei; Wang, Jingli; Wu, Hao; Liu, Chang


    P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)5/(GaN)1 superlattice (SL) in Al0.83Ga0.17N disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as MgGa δ doped AlGaN SLs. Mg acceptor activation energy was significantly reduced from 0.378 to 0.331 eV by using MgGa δ doping in SLs instead of traditional doping in alloys. This new process was confirmed to be able to realize high p-type doping in high Al-content AlGaN. PMID:28290480

  3. Atomic Layer Deposition of MgO Nanofilms on BaMgAl10O17:Eu2+ Blue Phosphors

    Hyug Jong Kim


    Full Text Available This paper reports the growth of MgO nanofilms on BaMgAl10O17:Eu2+ blue phosphors by using the atomic layer deposition method. MgO films were prepared at 120°C by using Mg(CpEt2 and H2O as the precursor and reactant gas, respectively. X-ray photoelectron spectroscopy (XPS analysis showed that the Mg peak of the coated powders was higher than that of the uncoated powders. This confirmed that the surface of the coated phosphor powder comprised MgO nanoscale film. Through TEM and FE-SEM analysis, it was observed that the growth rate was about 0.33 Å/cycle and that the surface morphology of the coated phosphors was smoother and clearer than that of uncoated phosphor. The photoluminescence (PL intensity for the coated phosphors was 5%–19% higher than that of uncoated phosphor. This means that the reactive surface is uniformly grown with stable magnesium oxide to reduce the dead surface layer without change of bulk properties.

  4. Effect of Cu, Zn, and Mg Concentration on Heat Treating Behavior of Squeeze Cast Al-(10 to 12Zn-(3.0 to 3.4Mg-(0.8 to 1Cu

    J.B. Ferguson


    Full Text Available Aluminum Alloy AA-7034 is a high strength wrought alloy with reasonable ductility containing 10–12 wt% Zn, 2–3 wt% Mg, and 0.8–1.2 wt% Cu. This work investigates the effect of varying the concentration of Zn (10–12 wt% and Cu (0.8–1 wt% on the solutionizing and aging behavior of squeeze cast AA-7034 samples. The same behaviors were investigated when Mg content was increased beyond 3 wt%. The solutionizing heat treatment dissolved much of the macroscopic second phases present in the as-cast AA-7034 alloys, but a significant amount of second phases remain after solutionizing in alloys with >3 wt% Mg. The behaviors of the various Al-Zn-Mg-Cu alloys are compared to squeeze cast Al-A206 casting alloy heat-treated to the T7 condition. All Al-Zn-Mg-Cu alloys obtained higher hardness values than those obtained by Al-A206-T7.

  5. Structural Characterization of Mg/Al hydrotalcite-like Compounds and their Thermal Stability

    Zhang, Shuhua; Yang, Siyuan; Wang, Cheng; Liu, Weijun; Gu, Xiaodan; Gan, Wenjun; Xue, Xiaoyu


    Hydrotalcite-like compounds, repersented by the formula [M1-x 2 + Mx3+ (OH)2]Xx/n n - . nH2O (M2+ = Ni2+, Mg2+, Cu2+,etc; M3+ = Al3+, Fe3+, etc; Xn- = CO32- , NO3-,etc) possess the brucite-like layers [Mg(OH)2] with positive charge and anionic compounds in the interlayer to form neutral materials. Catalytic effects to decompose NOx from automobile exhaust were highly related with the difference of M2+ and thermal stability because the catylists locate are about 200 ~ 500°. In this paper, Mg-Al-Cu and Mg-Al-Ni hydrotalcite-like compounds were characterized by XRD and FT-IR spectra and the thermal stability were analyzed by TGA and DTA. Even though they both have the typical diffraction peaks of hydrotalcites, but their interlayer spaces are different. Some weak chemical bonds were observed to be formed in Mg-Al-Ni hydrotalcites by FT-IR. Mg-Al-Ni hydrotalcite-like compound degraded at lower temperature, by contrast, Mg-Al-Cu hydrotalcite has the better structural stablilty and thermal stability.


    S Harris; Noble, B.; Dinsdale, K.


    Within the UK, research has concentrated on alloys of composition Al-2.5%Li-1.2%Cu-0.7%Mg-0.12%Zr (8090) which is a medium strength replacement for 2014. Ageing this lithium-containing alloy at an elevated temperature produces a mixture of phases which are, in order of importance, δ'(Al3Li), S(Al2CuMg) and T1(Al2CuLi). Changing the magnesium content of the alloy changes the relative proportions of the latter two phases, and also influences the volume fraction of δ' that is produced. A systema...

  7. Structure and photoluminescence of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides

    Chen, Yufeng; Li, Fei; Zhou, Songhua; Wei, Junchao; Dai, Yanfeng; Chen, Yiwang


    A series of Mg-Al-Eu ternary hydrotalcite-like layered double hydroxides (LDHs), with Eu/Al atomic ratios of ˜0.06 and Mg/(Al+Eu) atomic ratios ranging from 1.3 to 4.0, were synthesized by a coprecipitation method. The Mg-Al-Eu ternary LDHs were investigated by various techniques. X-ray diffraction (XRD) results indicated that the crystallinity of the ternary LDHs was gradually improved with the increase of Mg 2+/(Al 3++Eu 3+) molar ratio from 1.3/1 to 4/1, and all the samples were a single phase corresponding to LDH. The photoluminescent (PL) spectra of the ternary Mg-Al-Eu LDHs were described by the well-known 5D0- 7FJ transition ( J=1, 2, 3, 4) of Eu 3+ ions with the strongest emission for J=2, suggesting that the host LDH was favorable to the emissions of Eu 3+ ions. The asymmetry parameter ( R) relevant to 5D0- 7FJ transition ( J=1, 2) dependant of the atomic ratios of Mg 2+/(Al 3++Eu 3+) was discussed, and was consistent with the result of XRD.

  8. "Intelligent" reforming catalysts: Trace noble metal-doped Ni/Mg(Al)O derived from hydrotalcites

    Katsuomi Takehira


    Trace amounts of noble metal-doped Ni/Mg(Al)O catalysts were pre-pared starting from Mg-Al hydrotalcites (HTs) and tested in daily start-up and shut-down (DSS) operation of steam reforming (SR) of methane or partial oxidation (PO) of propane. Although Ni/Mg(Al)O catalysts prepared from Mg(Ni)-Al HT exhibited high and stable activity in stationary SR,PO and dry reforming of methane and propane,the Ni/Mg(Al)O catalysts were drastically deactivated due to Ni oxidation by steam as purge gas when they were applied in DSS SR of methane. Such deactivation was effectively suppressed by dop-ing trace amounts of noble metal on the catalysts by using a "memory effect" of HTs. Moreover,the noble metal-doped Ni/Mg(Al)O cat-alysts exhibited "intelligent" catalytic behaviors,i.e.,self-activation and self-regenerative activity,leading to high and sustainable activity during DSS operation. Pt was the most effective among noble met-als tested. The self-activation occurred by the reduction of Ni2+ in Mg(Ni,Al)O periclase to Ni~0 assisted by hydrogen spillover from Pt (or Pt-Ni alloy). The self-regenerative activity was accomplished by self-redispersion of active Ni~0 particles due to a reversible reduction-oxidation movement of Ni between the outside and the inside of the Mg(Al)O periclase crystal;surface Ni~0 was oxidized to Ni~(2+) by steam and incorporated into Mg(Ni~(2+),Al)O periclase,whereas the Ni~(2+) in the periclase was reduced to Ni~0 by the hydrogen spillover and appeared as the fine Ni~0 particles on the catalyst surface. Fur-ther a "green" preparation of the Pt/Ni/[Mg3.5Al]O catalysts was ac-complished starting from commercial Mg3.5-Al HT by calcination,followed by sequential impregnation of Ni and Pt.

  9. Electrochemical behavior of Mg-Al-Pb alloy in 3.5% NaCl solution

    文利; 余琨; 房洪杰; 熊汉青; 尹翔; 朱化龙; 马家骥; 姜大越


    An investigation on electrochemical behavior of Mg-5%Pb alloy, Mg-6%Al alloy and Mg-6%Al-5%Pb alloy (mass fraction) in 3.5% NaCl (mass fraction) solution was conducted using electrochemical measurements and corroded morphology observation, in which solid solution and the as-aged state of each alloy were compared to discuss the influence mechanism of lead and aluminium on the electrochemical properties of alloys. The X-ray diffraction (XRD) analysis was performed to make microstructure characterization. The electrochemical results indicate that the corrosion of Mg-5%Pb alloy is predominated by homogeneous pitting and dissolution of PbCl2film due to Clions attack, while corrosion crevice propagates along grain boundaries in solid solution of Mg-6%Al alloy and the micro galvanic corrosion also plays vital role in Mg17Al12phase containing experimental alloys.The co-existence of lead and aluminium in magnesium alloy increases corrosion current density and electrochemical activity as well. The comparison between solid solution and the as-aged state demonstrates that Mg2Pb and Mg17Al12somewhat increase corrosion resistance but lighten anodic polarization by facilitating corrosion product flaking off.

  10. The Improvement of the Slag Resistance of Corundum—Spinel Castable with Addition of Aluminum Oxynitride (AlON)

    LIYawei; LINan; 等


    The slag corrosion resisance of corundum-spinel castable has been increased by adding aluminum oxynitride spinel (AlON) powder ,Its results show that corrosion resistance of this castable is remarkably imroved when 3 wt% of the AlON powder added ,It was assumed that solid solution between aluminum oxynitride and magnesium aluminate spinel occurred to prevent the slag penetration into castable and increase the corrosion resistance of the corundum-spinel castable However,the experimental resultsd suggest such castable containing AlON powder be much more appropriate to be used in non-oxidation condition rather than in oxidation atmosphere.

  11. Preparation and Properties of a Novel Al-Si-Ge-Zn Filler Metal for Brazing Aluminum

    Niu, Zhiwei; Huang, Jihua; Yang, Hao; Chen, Shuhai; Zhao, Xingke


    The study is concerned with developing a filler metal with low melting temperature and good processability for brazing aluminum and its alloys. For this purpose, a novel Al-Si-Ge-Zn alloy was prepared according to Al-Si-Ge and Al-Si-Zn ternary phase diagrams. The melting characteristics, microstructures, wettability, and processing property of the alloy were investigated. The results showed that the melting temperature range of the novel filler metal was 505.2-545.1 °C, and the temperature interval between the solidus and the liquidus was 39.9 °C. Compared with a common Al-Si-Ge alloy, it had smaller and better dispersed β-GeSi solid solution precipitates, and the Zn-rich phases distributed on the boundary of the β-GeSi precipitates. The novel filler metal has good processability and good wettability with Al. There was one obvious transition layer with a thin α-Al solid solution between the filler metal and base metal, which is favorable to improve the strength of brazing joint.

  12. Structural stability of intermetallic compounds of Mg-Al-Ca alloy

    ZHOU Dian-wu; LIU Jin-shui; ZHANG Jian; PENG Ping


    A first-principles plane-wave pseudopotential method based on the density functional theory was used to investigate the energetic and electronic structures of intermetallic compounds of Mg-Al-Ca alloy, such as Al2Ca, Al4Ca and Mg2Ca. The negative formation heat, the cohesive energies and Gibbs energies of these compounds were estimated from the electronic structure calculations, and their structural stability was also analyzed. The results show that Al2Ca phase has the strongest alloying ability as well as the highest structural stability, next Al4Ca, finally Mg2Ca. After comparing the density of states of Al2Ca, Al4Ca and Mg2Ca phases, it is found that the highest structural stability of Al2Ca is attributed to an increase in the bonding electron numbers in lower energy range below Fermi level, which mainly originates from the contribution of valence electron numbers of Ca(s) and Ca(p) orbits, while the lowest structural stability of Mg2Ca is resulted from the least bonding electron numbers near Fermi level.

  13. Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

    HUANG Kaijin; LIN Xin; XIE Changsheng; T M Yue


    Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hard a-Al2O3 and γ-Al2O,3phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.

  14. Temperature variation of the size effect in dilute AlMg and AlCa alloys: Measurement and theory

    Gilder, H. M.; Asty, M.; Audit, Ph.


    Optical-interferometric-differential-length and x-ray lattice-parameter measurements performed at low temperatures in dilute AlMg and AlCa alloys indicate that the temperature variation of the size effect corresponds to a relatively large difference between the intrinsic coefficient of thermal expansion βi of the solute atom structure and that, β, of the solvent. This result is another example of the surprising expansive properties of point defects previously described by Gilder and co-workers (high-temperature vacancy diffusion) and more recently by Ganne (low-temperature dilatometry on irradiated specimens). Specifically, in the temperature range 0.2AlCa. The calculated values of Δβ(Mg)Ci, Ci being the solute concentration, and βi(Mg) fall between the measured values in the two AlMg alloys studied. The calculation of Δβ(Ca)Ci and βi(Ca) is not possible due to a lack of elastic-constants data for pure, metallic calcium. Inasmuch as, in the case of Mg, solute-solute interactions are apparent in the measured values of the size effect, ΔβCi and βi, even at Ci(Mg)~0.2 at.%, extreme care must be exercised when comparing experimental data for dilute alloys with calculations of infinitely dilute alloy properties.

  15. Effect of Addition of Al and Mg on properties of Periclase-Spinel-Carbon Brick


    Periclase-spinel-carbon brick was made from sintered spinel,fused magnesia and flake graphite as principal raw materials,the influence of Mg/Al(w/w) ratio and the addition of Al,Mg in the matrix of periclas-spinel-carbon brikc on the carbonization and thermal expansion coeffi-cient and the weight los of the brick after heating at 1500℃ in a flowing stream of dry N2for 1.5 h have been studied.The results show that to control Mg/Al(w/w) ration and to add both Al and Mg appropriately can obvi-ously improve the properties of the bricks.

  16. Effect of precipitation on elastic modulus of Al-Zn-Mg-Cu-Li alloys

    ZHAO Zhong-kui; ZHOU Tie-tao; LIU Pei-ying; LI Huan-xi; CHEN Chang-qi


    Al-5.6Zn-3.0Mg-1.6Cu-1.1Li-0.24Cr alloys and Al-8.0Zn-2.4Mg-2.4Cu-1.1Li-0.18Zr alloys (mass fraction, %) were aged by different processes. The microstructure and mechanical properties were determined by transmission electron microscopy(TEM),tensile test and Vicker's hardness test. The experimental results show that the most signified hardening is obtained by double-ageing or multi-ageing for the Al-Zn-Mg-Cu-Li alloys. The yield strength and the elastic modulus of the Li-containing alloys have relationships with ageing processes. The elastic modulus of Li-containing alloys decreases with the increment of precipitates though it is higher than that of Al-Zn-Mg-Cu alloy.

  17. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    Zhang, Yu; Zhou, Ting-dong


    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  18. Effect of bariun on the refinement of primary aluminum and eutectics in a hypoeutectic Al-Si alloy

    LI Wei; FAN Hongyuan; ZHANG Xianju; SHEN Baoluo


    The effect of barium on the refinement of primary aluminum and on the modification of eutectics in a hypoeutectic aluminm-silicon alloy was investigated. The results indicate that barium not only modifies the eutectic silicon but also refines the primary aluminum and there is a relationship between the retained barium and the second spacing of primary aluminum. Experiments of barium-treated commercial Al-Si hypoeutectic alloy show that barium is a better modifier than sodium when there is a longer holding time.

  19. Friction Stir Welding of Zr_(55)Al_(10)Ni_5Cu_(30) Bulk Metallic Glass to Crystalline Aluminum

    Zuoxiang Qin; Cuihong Li; Haifeng Zhang; Zhongguang Wang; Zhuangqi Hu; Zhiqiang Liu


    The Zr_(55)Al_(10)Ni_5Cu_(30) bulk metallic glass plate were successfully welded to crystalline aluminum plates by using a friction stir welding (FSW) method. The welded zone was examined. No defects, cracks or pores were observed and no other crystalline phases except for aluminum were found in the welded joint. The strength of the joint is higher than that of aluminum. The glassy phase in the stir zone keeps the amorphous state, showing a successful welding. The storage modulus softens over the glass transition. And the weldability was discussed according to this phenomena.

  20. Effect of Aluminum Addition on the Microstructure, Tensile Properties, and Fractography of Cast Mg-Based Alloys

    M. H. Abdelaziz


    Full Text Available The present study was performed on Mg-based alloys containing Zn and Mn. The alloys were cast in a permanent metallic mold preheated to 200°C and with a protective atmosphere of dry air, CO2, and SF6. Two main phases are observed in the as-cast condition: Mg-Al-Zn and Mn-Al intermetallics. The size and morphology of the Mg-Al-Zn phase are significantly affected by the concentration of Al. Tensile properties, using standard ASTM B-108 samples, are directly related to the size, morphology, and density of the existing phase particles. The alloy ductility is reduced with increase in the Al concentration, whereas the ultimate tensile strength and the yield strength are more or less stable. The fracture surface of the tested tensile bars is mostly ductile for low Al-containing alloys and tends to be brittle with the increase in Al content as evidenced by an increase in the density of cleavage ruptured areas.

  1. On the Selective Laser Melting (SLM of the AlSi10Mg Alloy: Process, Microstructure, and Mechanical Properties

    Francesco Trevisan


    Full Text Available The aim of this review is to analyze and to summarize the state of the art of the processing of aluminum alloys, and in particular of the AlSi10Mg alloy, obtained by means of the Additive Manufacturing (AM technique known as Selective Laser Melting (SLM. This process is gaining interest worldwide, thanks to the possibility of obtaining a freeform fabrication coupled with high mechanical properties related to a very fine microstructure. However, SLM is very complex, from a physical point of view, due to the interaction between a concentrated laser source and metallic powders, and to the extremely rapid melting and the subsequent fast solidification. The effects of the main process variables on the properties of the final parts are analyzed in this review: from the starting powder properties, such as shape and powder size distribution, to the main process parameters, such as laser power and speed, layer thickness, and scanning strategy. Furthermore, a detailed overview on the microstructure of the AlSi10Mg material, with the related tensile and fatigue properties of the final SLM parts, in some cases after different heat treatments, is presented.

  2. Development of ultrafine-grained microstructure in Al-Cu-Mg alloy through equal-channel angular pressing

    Sai Anuhya, Danam; Gupta, Ashutosh; Nayan, Niraj; Narayana Murty, S. V. S.; Manna, R.; Sastry, G. V. S.


    Al-Cu-Mg alloys are extensively used for riveting applications in aerospace industries due to their relatively high shear strength coupled with high plasticity. The significant advantage of using V65 aluminum alloy ((Al-4Cu-0.2Mg) for rivet application also stems from its significantly slower natural aging kinetics, which gives operational flexibility to carryout riveting operation even after 4 days of solution heat treatment, in contrast to its equivalent alloy AA2024.Rivets are usually made by cold heading of wire rods. In order to form a defect free rivet head, grain size control in wire rods is essential at each and every stage of processing right from casting onwards upto the final wire drawing stage. Wire drawing is carried out at room temperature to reduce diameter as well as impart good surface finish. In the present study, different microstructures in V65 alloy bars were produced by rolling at different temperatures (room temperature to 523K) and subsequently deformed by equal channel angular pressing (ECAP) at 423K upto an equivalent strain of 7. ECAP was carried out to study the effect of initial microstructure on grain refinement and degree of deformation on the evolution of ultrafine grain structure. The refinement of V65 alloy by ECAP is significantly influenced by Initial microstructure but amount of deformation strongly affects the evolution processes as revealed by optical microscopy and transmission electron microscopy.

  3. Microstructure evolution and texture development in thermomechanically processed Mg-Li-Al based alloys

    Kumar, Vinod [Department of Materials Science and Engineering, IIT Kanpur (India); Govind [Vikram Sarabhai Space Center, Trivandrum (India); Shekhar, Rajiv; Balasubramaniam, R. [Department of Materials Science and Engineering, IIT Kanpur (India); Balani, Kantesh, E-mail: [Department of Materials Science and Engineering, IIT Kanpur (India)


    Highlights: Black-Right-Pointing-Pointer Thermomechanical processing of novel LAT 971 and LATZ 9531 Mg-Al-Li based alloys. Black-Right-Pointing-Pointer Microstructural deviation from the equilibrium phase diagram. Black-Right-Pointing-Pointer Disparity in texture of these alloys after hot-rolling (recrystallization and grain growth). Black-Right-Pointing-Pointer Role of alloying and phase distribution in affecting the texture/interplaner spacing. - Abstract: In the present study, the influence of alloying and thermomechanical processing on the microstructure and texture evolution on the two Mg-Li-Al based alloys, namely Mg-9 wt% Li-7 wt% Al-1 wt% Sn (LAT971) and Mg-9 wt% Li-5 wt% Al-3 wt% Sn-1 wt% Zn (LATZ9531) has been elicited. Novel Mg-Li-Al based alloys were cast (induction melting under protective atmosphere) followed by hot rolling at {approx}573 K with a cumulative reduction of five. A contrary dual phase dendritic microstructure rich in {alpha}-Mg, instead of {beta}-Li phase predicted by equilibrium phase diagram of Mg-Li binary alloy was observed. Preferential presence of Mg-Li-Sn primary precipitates (size 4-10 {mu}m) within {alpha}-Mg phase and Mg-Li-Al secondary precipitates (<3 {mu}m) interspersed in {beta}-Li indicated their degree of dissolution during hot-rolling and homogenization in the dual phase matrix. Presence of Al, Sn and Zn alloying elements in the Mg-Li based alloy has resulted an unusual dual-phase microstructure, change in the lattice parameter, and intriguing texture evolution after hot-rolling of cast LAT 971 and LATZ9531 alloy. Strong texture was absent in the as-cast samples whereas texture development after hot-rolling revealed an increased activity of the non-basal (101{sup Macron }0) slip planes. The quantification of the grain average misorientation (less than 2 Degree-Sign ) using electron backscattered diffraction confirmed the presence of strain free grains in majority of the grains (fraction >0.75) after hot-rolling of Mg-Li-Al

  4. Two-electron rearrangement K x-ray transitions in Na, Mg, and Al metals

    Aberg, T.; Reinikainen, K.; Keski-Rahkonen, O.


    One-photon KL/sup n//sub 2,3/ (n=1,2) radiative electron rearrangement (KL/sup n/ RER) x-ray transitions have been observed in sodium, magnesium, and aluminum metals following electron-impact excitation. The structure of the KL/sup n/ RER transitions has been separated from the KLL and KL/sub 1/V radiative Auger (RA) structure and their intensity relative to the KL/sup n//sub 2,3/-L/sup n/+1/sub 2,3/ transitions has been determined. No significant discrepancy between the experimental and calulated KL/sup 1/ RER branching ratios has been found in contrast to recent ion-impact results of Jamison et al. for aluminum and silicon. Our KL/sup 2/ RER results also agree with theoretical predictions.


    Eddy Heraldy


    Full Text Available Attempts to synthesis of Mg/Al HTlc using magnesium from several raw material resources are widely investigated. One of raw material would purpose as source of magnesium to synthesis of Mg/Al HTlc is brine water which is well known as the desalination process wastewater. Mg/Al HTlc are widely investigated for their potential applications in research and industrial processes as adsorbents, anionic exchange, catalysts and /or catalyst precursors for the preparation of inorganic materials and pharmaceutical industry excipients. As adsorbents, Mg/Al HTlc are receiving greater interests in the environmental community due to their high adsorption capacity. However, there is no literature available on the synthesis of Mg/Al HTlc from brine water except from artificial seawater. The objective of this research is to synthesis of Mg/Al HTlc from brine water and its ability tested for eosin yellow (EY removal. Characterization of the Mg/Al HTlc synthesized was confirmed through X-ray Diffraction and FT-IR Spectroscopy. The effect of various experimental parameters was investigated using a batch adsorption technique. In this manner, the adsorption isotherms, adsorption kinetics, and pH effects upon EY adsorption on Mg/Al HTlc were examined. The result showed that EY data fit well with the pseudo-second order kinetic model. The isothermal data could be well described by the Freundlich equation. The adsorption capacity was 2.41 × 10-1 mol g-1, and adsorption energy of EY was 24.89 kJ mol-1.

  6. Evaluation of corrosion behavior of Al-Mg-Li alloys in seawater

    Ahmad, Z.; Abdul Aleem, B.J. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia)


    Weldalite 050, a high-strength Al-Mg-Li alloy, was evaluated for its corrosion resistance in deaerated and air saturated Arabian Gulf water to determine its suitability for marine applications. Weight loss and electrochemical studies showed that the alloy had minimum corrosion rates of 1.82 and 4.82 mpy (mils per year), respectively, in deaerated and air saturated Arabian Gulf water with very high total dissolved solids (TDS) content. Weldalite 050 exhibited good resistance to corrosion at velocities up to 3.9 m/s. The formation of Al{sub 2}MgLi, Al-Li, Al{sub 12}Mg{sub 17}, and Al-Li precipitates has a pronounced effect on its corrosion resistance. The corrosion resistance of Weldalite 050 compares favorably with that of alloys 5052 and 5054, wrought alloys 6061 and 6013, and silicon carbide (SiC) reinforced alloys 6061 and 6013.

  7. Thermodynamics-Based Computational Design of Al-Mg-Sc-Zr Alloys

    Haidemenopoulos, G. N.; Katsamas, A. I.; Kamoutsi, H.


    Alloying additions of Sc and Zr raise the yield strength of Al-Mg alloys significantly. We have studied the effects of Sc and Zr on the grain refinement and recrystallization resistance of Al-Mg alloys with the aid of computational alloy thermodynamics. The grain refinement potential has been assessed by Scheil-Gulliver simulations of solidification paths, while the recrystallization resistance (Zener drag) has been assessed by calculation of the precipitation driving forces of the Al3Sc and Al3Zr intermetallics. Microstructural performance indices have been derived, used to rank several alloy composition variants, and finally select the variant with the best combination of grain refinement and recrystallization resistance. The method can be used, with certain limitations, for a thermodynamics-based design of Al-Mg and other alloy compositions.

  8. Formation of particulate Fe-Al films by selective oxidation of aluminum

    Jang, Pyungwoo; Shin, Seung Chan


    Fe-5wt%Al films were RF-sputtered and annealed in an atmosphere of hydrogen and water vapor mixture at 1173 K for up to 200 min in order to selectively oxidize aluminum. As the annealing time increased, the morphology of the films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. Thermodynamics simulation was performed to determine the ideal conditions for this process. Temperatures exceeding 1073 K are necessary to prevent iron from oxidation confirmed by both the depth profile in XPS and magnetic moment increment in VSM. Annealing the films in an atmosphere with a very low dew point of 77 K did not make the films become particulate. New findings are expected to be applied to the thin film inductors for GHz application as well as to manufacturing process of nanoparticles.

  9. Precipitate stability and recrystallisation in the weld nuggets of friction stir welded Al-Mg-Si and Al-Mg-Sc alloys

    Sauvage, X. [University of Rouen, Groupe de Physique des Materiaux, CNRS (UMR 6634), Avenue de l' Universite-BP 12, 76801 Saint-Etienne du Rouvray (France)], E-mail:; Dede, A. [University of Rouen, Groupe de Physique des Materiaux, CNRS (UMR 6634), Avenue de l' Universite-BP 12, 76801 Saint-Etienne du Rouvray (France); Munoz, A. Cabello; Huneau, B. [Institut de Recherche en Genie Civil et Mecanique, Ecole Centrale de Nantes, Universite de Nantes, CNRS (UMR 6183), 1 rue de la Noe-BP 92101, 44321 Nantes (France)


    Two different precipitate hardening aluminium alloys processed by friction stir welding were investigated. The microstructure and the hardness of the as delivered materials were compared to that of the weld nugget. Transmission electron microscopy observations combined with three-dimensional atom probe analyses clearly show that {beta}'' precipitates dissolved in the nugget of the Al-Mg-Si giving rise to some supersaturated solid solution. It is shown that the dramatic softening of the weld could be partly recovered by post-welding ageing treatments. In the Al-Mg-Sc alloy, Al{sub 3}Sc precipitate size and density are unchanged in the nugget comparing to the base metal. These precipitates strongly reduce the boundary mobility of recrystallised grains, leading to a grain size in the nugget much smaller than in the Al-Mg-Si alloy. Both coherent and incoherent precipitates were detected. This feature may indicate that a combination of continuous and discontinuous recrystallisation occurred in the weld nugget.

  10. Nanostructured Mg-Al hydrotalcite as catalyst for fine chemical synthesis.

    Basahel, Sulaiman N; Al-Thabaiti, Shaeel A; Narasimharao, Katabathini; Ahmed, Nesreen S; Mokhtar, Mohamed


    This paper reviews the recent research of nanostructured Mg-Al hydrotalcite (Mg-Al HT) and its application as an efficient solid base catalyst for the synthesis of fine chemicals. Mg-Al HT has many beneficial features, such as low cost, selectivity, catalytic properties, and wide range of preparation and modification methods. They hold promise for providing sought-after, environmentally friendly technologies for the 21st century. Replacement of currently used homogeneous alkaline bases for the synthesis of fine chemicals by a solid catalyst can result in catalyst re-use and waste stream reduction. We introduce briefly the structure, properties and characterization of the nanostructured Mg-Al HT. The efficacy and benign applications of Mg-Al HT as an alternative solid base to homogenous catalysts in the synthesis of fine chemicals are then reviewed. The challenges for the future applications of Mg-Al HT in the synthesis of fine chemicals in terms of green protocol processes are discussed.

  11. [Surface properties of ZuMgAl hydrotalcite-like compounds by inverse gas chromatography].

    Zhou, Liangqin; Fu, Dayou; Yuan, Dong; Fan, Jinlong; Tan, Wenyuan


    The structure of ZnMgAl hydrotalcite-like compounds (ZnMgAl-HTLC) prepared by hydrothermal synthesis was studied by X-ray diffraction (XRD). With a series of polar and nonpolar molecules as probes, inverse gas chromatography (IGC) was used to measure the surface properties of ZnMgAl-HTLC. It was found that the XRD pattern of ZnMgAl-HTLC was narrow, sharp and high. The results showed that ZnMgAl-HTLC with a higher purity was obtained by hydrothermal synthesis. The surface adsorption free energy was less than zero. The surface dispersive free energy was 6.02 mJ/m2. The acid-base interaction free energy was 5.33 kJ/mol. The adsorption enthalpy was 43.6 kJ/mol, and the adsorption entropy was 0.15 kJ/mol. The IGC method is significant in the study of the surface properties of ZnMgAl-HTLC.

  12. The Mechanism of Mg2Al3 Formation by Mechanical Alloying

    H. Suwarno


    Full Text Available Synthetic and characterization of the Mg2Al3 formation by mechanical alloying have been carried out using a high energy ball milling process. Mechanical alloying is a technique of solid state reactions among two or more metals to form a new alloy through the deformation properties of the metals. The Mg2Al3 alloy was formed by milling the individual constituents using a high energy ball milling under the varied milling time of 10, 20 and 30 h. The refinement results on the x-ray diffraction analysis show that the observation and calculation are fit to each other. After milling for 10, 20 and 30 h the mixed Mg and Al metals are converted into Mg2Al3 at the composition of 71.82, 90.73 and 96.19 wt%. It is concluded that the Mg2Al3 alloy can be performed by high energy mechanical alloying after 30 h of milling. The mechanism of the Mg2Al3 formation is discussed

  13. Sputter-deposited Mg-Al-O thin films: linking molecular dynamics simulations to experiments

    Georgieva, V; Bogaerts, A [PLASMANT Research Group, Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Antwerp (Belgium); Saraiva, M; Depla, D [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, B-9000 Gent (Belgium); Jehanathan, N; Lebelev, O I, E-mail: [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B2020 Antwerpen (Belgium)


    Using a molecular dynamics model the crystallinity of Mg{sub x}Al{sub y}O{sub z} thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al{sub 2}O{sub 3} film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the Mg-Al-O film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline Mg-Al-O films have a MgO structure with Al atoms in between.

  14. Enhancement of MgAl2O4 spinel formation from coprecipitated precursor by powder processing

    Soumen Pal; A K Bandyopadhyay; S Mukherjee; B N Samaddar; P G Pal


    Although low temperature fast coprecipitation technique has been used to synthesize stoichiometric (MgO–nAl2O3, = 1) MgAl2O4 spinel forming precursor, delayed spinellization has always been the concern in this process. In this article, the precursor of this ‘fast technique’ has been used for bulk production by further processing by high speed mixing with solvents and mechanical activation by attrition milling in terms of superior spinellization. At 1000°C, MgAl2O4 – -Al2O3 solid solution and MgO phases are formed (spinel formed by 1000°C is regarded as primary spinel). At higher temperatures, due to large agglomerate size, MgO can not properly interact with the exsolved -Al2O3 from spinel solid solution to form secondary spinel; and consequently spinellization gets affected. Solvent treatment and attrition milling of the coprecipitated precursor disintegrate the larger agglomerates into smaller size (effect is more in attrition). Then MgO comes in proper contact with exsolved alumina, and therefore total spinel formation (primary + secondary) is enhanced. Extent of spinellization, for processed calcined samples where some alumina exists as solid solution with spinel, can be determined from the percentage conversion of MgO. Analysis of the processed powders suggests that the 4 h attrited precursor is most effective in terms of nano size (< 25 nm) stoichiometric spinel crystallite formation at ≤ 1100°C.

  15. Sacrificial anode stability and polarization potential variation in a ternary Al-xZn-xMg alloy in a seawater-marine environment

    Muazu, Abubakar; Aliyu, Yaro Shehu; Abdulwahab, Malik; Idowu Popoola, Abimbola Patricia


    In this paper, the effects of zinc (Zn) and magnesium (Mg) addition on the performance of an aluminum-based sacrificial anode in seawater were investigated using a potential measurement method. Anodic efficiency, protection efficiency, and polarized potential were the parameters used. The percentages of Zn and Mg in the anodes were varied from 2% to 8% Zn and 1% to 4% Mg. The alloys produced were tested as sacrificial anodes for the protection of mild steel in seawater at room temperature. Current efficiency as high as 88.36% was obtained in alloys containing 6% Zn and 1% Mg. The polarized potentials obtained for the coupled (steel/Al-based alloys) are as given in the Pourbaix diagrams, with steel lying within the immunity region/cathodic region and the sacrificial anodes within the anodic region. The protection offered by the sacrificial anodes to the steel after the 7th and 8th week was measured and protection efficiency values as high as 99.66% and 99.47% were achieved for the Al-6%Zn-1%Mg cast anode. The microstructures of the cast anodes comprise of intermetallic structures of hexagonal Mg3Zn2 and body-centered cubic Al2Mg3Zn3. These are probably responsible for the breakdown of the passive alumina film, thus enhancing the anode efficiency.

  16. Preparation and optimization of a drug delivery system based on berberine chloride-immobilized MgAl hydrotalcite.

    Djebbi, Mohamed Amine; Bouaziz, Zaineb; Elabed, Alae; Sadiki, Moulay; Elabed, Soumya; Namour, Philippe; Jaffrezic-Renault, Nicole; Amara, Abdesslem Ben Haj


    Hydrotalcite (HT), also known as a layered double hydroxide (LDH) compound, has been widely used in past years in the formulation of drugs due to its specific properties including good biocompatibility, null toxicity, high chemical stability and pH-dependent solubility which aid in drug controlled release. In this work, berberine chloride (BBC) class antibacterial agent was immobilized into magnesium-aluminum LDH in order to improve the drug efficiency as well as to achieve the controlled release property. BBC molecules were immobilized into MgAl LDH through a conventional ion exchange reaction and co-precipitation method. The ion-exchange experiments of BBC on MgAl LDH were investigated with particular attention paid to the influence of the layer charge, the nature of the intercalated anion and the morphology. The immobilization efficiency was dependent upon the LDH properties and the immobilization process. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurements revealed that the interaction of BBC with MgAl LDH occurs by adsorption rather than intercalation of BBC within LDH layers. In vitro anti-bacterial tests were carried out using disc diffusion assay to prove the effectiveness of these novel biohybrid beads as a controlled drug delivery method. Consequently, the BBC-LDH co-precipitated formulation revealed an enhanced anti-bacterial activity compared to the ion-exchanged formulation not only due to an improvement of chemical stability and retained amount of BBC molecules but also due to the release property.

  17. Hot-Tearing Susceptibility of Ternary Mg-Al-Sr Alloy Castings

    Cao, G.; Zhang, C.; Cao, H.; Chang, Y. A.; Kou, S.


    The susceptibility of Mg-Al-Sr alloys to hot tearing during permanent mold casting was investigated using constrained rod casting (CRC) in a steel mold. The alloys included Mg- xAl-1.5Sr and Mg- xAl-3Sr, where x = 4, 6, or 8 wt pct. The hot-tearing susceptibility (HTS) was determined based on the widths and locations of the cracks in the rods. With the Mg- xAl-1.5 Sr alloys, the HTS decreased significantly with increasing Al content. With the Mg- xAl-3Sr alloys, the trend was similar but not as significant. At the same Al content, the HTS was significantly lower at 3 wt pct Sr than at 1.5 wt pct Sr. To help understand the HTS of these alloys, the solidification path and phase fractions were calculated for each alloy. The HTS was found to increase with increasing fraction solid at the end of primary solidification.

  18. New pattern Zn-Al-Mg-RE coating technics for steel structure sustainable design

    LIU Yan; XU Bin-shi; ZHU Zi-xin; LI Zhuo-xin; MA Jie


    Based on the advanced integrated technology of materials preparation and formation, a new pattern ZnAl-Mg-RE anti-corrosion coating for steel structure sustainable design was manufactured by cored wires and high velocity arc spraying (HVAS) technologies. The developments of thermally sprayed coatings for steel structure protection were described. Based on Al, Zn, Zn-Al and Zn-Al-Mg coatings, the anti-corrosion properties of new-pattern Zn-Al-Mg-RE coating were evaluated through electrochemical methods including electrochemical polarization and electrochemical impedance spectroscopy (EIS) coupled with SEM and XRD. The models of Zn-Al-Mg-RE coating undergoing corrosion with the initial pinhole defect and the latter with accelerated products were also discussed. The results show that Zn-Al-Mg-RE coating exhibites excellent corrosion resistance for long-term immersion, which is helpful for the sustainable design of steel structure in aggressive corrosion conditions. And the corrosion products seem to possess certain self-sealing function.

  19. Solute-Vacancy Clustering In Al-Mg-Si Alloys Studied By Muon Spin Relaxation Technique

    Nishimura K.


    Full Text Available Zero-field muon spin relaxation experiments were carried out with Al-1.6%Mg2Si, Al-0.5%Mg, and Al-0.5%Si alloys. Observed relaxation spectra were compared with the calculated relaxation functions based on the Monte Carlo simulation to extract the dipolar width (Δ, trapping (νt, and detrapping rates (νd, with the initially trapped muon fraction (P0. The fitting analysis has elucidated that the muon trapping rates depended on the heat treatment and solute concentrations. The dissolved Mg in Al dominated the νt at lower temperatures below 120 K, therefore the similar temperature variations of νt were observed with the samples mixed with Mg. The νt around 200 K remarkably reflected the heat treatment effect on the samples, and the largest νt value was found with the sample annealed at 100°C among Al-1.6%Mg2Si alloys. The as-quenched Al-0.5%Si sample showed significant νt values between 80 and 280 K relating with Si-vacancy clusters, but such clusters disappeared with the natural aged Al-0.5%Si sample.

  20. A study on quantification of homogenizing treatment for Al-Mg-Si alloy AA 6063

    Kelesoglu, Erguen [Yildiz Technical University, Istanbul (Turkey). Department of Metallurgical and Materials Engineering; Yildiz Technical University, Istanbul (Turkey). Research Development Center for Industrial Cooperation


    Homogenization of aluminum extrusion billets facilitates extrusion and improves product quality. In this work, a parameter has been developed that defines the homogenization level of AA6063 extrusion billets. The insoluble {alpha}-AlFeSi and {beta}-AlFeSi phases have been experimentally determined by evaluating the length/width ratio of the AlFeSi intermetallic in the microstructure. Using this identification, the area fraction of each phase has been measured. The area fraction of the {beta}-AlFeSi phase in the cast structure is over 65%. In the well-homogenized sample, the {beta}-AlFeSi area fraction decreases to values lower than 20%, while the {alpha}-AlFeSi phase ratio increases to over 80%. As the {alpha}-AlFeSi percentage in the structure increases, the elongation of the samples steadily increases, from 1% to 24%. Based on the ratio of {alpha}-AlFeSi to the entire intermetallic phase, we propose six different homogenization levels. The proposed indexing can be used to define the homogenization state of the billet, regardless of the homogenization temperature and time. The index numbers exhibit a good correlation with the deformation potential of the samples. (orig.)

  1. Phase relations of Al-4Mg-Sc-Zr quaternary system in Al-rich range at 430 ℃

    夏长清; 曾凡浩; 古一


    The 430 ℃ isothermal section of the Al-4Mg-Sc-Zr quaternary system in the Al-rich range was determined by means of equilibrium alloys with the use of microstructure, X-ray diffraction analysis and electron probe microanalysis. There coexist three single-phase fields, two two-phase fields and one three-phase field. It is established that the phase Al3Sc1-0.5Zr0-0.5 with L12 structure and Al3Zr1-0.8Sc0-0.2 with DO23 structure are in equilibrium with the α solid solution, Zr being dissolved in Al3Sc, further substituting for about 50% Sc(mole fraction) whilst Sc is present in the phase Al3Zr and the maximum substitution for Zr is about 20%.

  2. Materiales de Al2O3 - MgAl2O4 - CaAl12O19 - Ca2Mg2Al28O46 obtenidos mediante un proceso de sinterización reactiva entre Al2O3 y CaMg(CO32

    Pena, P.


    Full Text Available Taking into account the system Al2O3-MgO-CaO, refractory materials containing Al2O3-MgAl2O4-CaAl12O19-Ca2Mg2Al28O46 has been obtained by reaction-sintering of appropriate mixtures of Al2O3 and CaMg(CO32. The study of the mechanism of reaction was carried out by differential thermal analysis (DTA and thermogravimetry (TG, followed by dilatometric and xray diffraction (XRD studies. A static study of the reaction was performed at different temperatures. After each thermal treatment a XRD analysis of the phases present was made, as well as a microestructural study by scanning electron microscopy (SEM coupled with energy-dispersive spectroscopy (EDS. From the results obtained, and taking into account the free energy of formation of the different compounds, the mechanism of reaction was established.Utilizado la información suministrada por el diagrama de equilibrio de fases Al2O3-MgO-CaO se ha diseñado y obtenido un material de Al2O3-MgAl2O4-CaAl12O19-Ca2Mg2Al28O46 mediante sinterización reactiva de una mezcla de Al2O3 y CaMg(CO32. Las reacciones que tienen lugar en la mezcla durante el proceso se han estudiado usando técnicas de análisis térmico diferencial, termogravimetrico y dilatometría. Muestras reaccionadas a temperaturas seleccionadas se han estudiado por difracción de rayos X y microscopía electrónica de barrido con microanálisis mediante dispersión de energías. Los resultados obtenidos revelan que la reacción entre las materias primas tiene lugar en varias etapas con formación de fases transitorias, dando lugar a una microestructura final con granos aciculares de CaAl12O19 y partículas de la fase ternaria Ca2Mg2Al28O46 formadas en aquellos puntos en los que entran en contacto las fases de MgAl2O4 y CaAl12O19.

  3. Deformation and reconstruction mechanisms in coarse-grained superplastic Al-Mg alloys

    Soer, W. A.; Chezan, A. R.; De Hosson, J. Th. M.


    This paper concentrates on the superplastic response of fine-grained and coarse-grained Al-Mg alloys under uniaxial tension. To identify the main characteristics of superplastic deformation and to determine the optimum deformation parameters, the microstructure and dislocation substructure of the al

  4. Study on the thermal storage properties of Al-Si-Cu-Mg alloy

    XIE, Yi; WAN, Ke-yang; XIE, Guo-sheng; HU, Jia-rui; YIN, Fu-cheng; GONG, Jing


    Based on thermodynamic calculation technology, the thermodynamic data of six alloys (inc. Al-Si and Al-Si-Cu-Mg systems) was calculated. The microstructure, phase transformation temperature and latent heat of the Al-4%Cu-12%Mg-7%Si alloy and Al-13%Si alloy were also verified by X-ray diffraction(XRD), scanning electron microscopy/Energy-dispersive system (SEM/EDS) and Differential scanning calorimetry (DSC). The results show that The enthalpy change value of Al-Si-Cu-Mg alloy is larger than that of Al-Si alloy from 800 °C to 400 °C, while its phase transformation temperature is lower. In particular, the enthalpy value of Al-4%Cu-12%Mg-7%Si alloy is 85% higher than that of Al-13%Si near eutectic alloy, and its initial temperature of phase transformation is about 74 °C lower. The former has relatively low phase transformation temperature and over-dimensioned latent heat of phase transformation, displaying the excellent thermal storage property. Therefore, the alloy is a good potential solar energy thermal storage material. The results in the paper also indicated that thermodynamic calculation is of value in seeking new potential solar energy thermal storage materials for solar thermal power generation system.

  5. Evolution of Intermetallics, Dispersoids, and Elevated Temperature Properties at Various Fe Contents in Al-Mn-Mg 3004 Alloys

    Liu, K.; Chen, X.-G.


    Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight, and low-cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys have been found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high-temperature properties of 3004 alloys has been investigated. Results show that the dominant intermetallic changes from α-Al(MnFe)Si at 0.1 wt pct Fe to Al6(MnFe) at both 0.3 and 0.6 wt pct Fe. In the Fe range of 0.1-0.6 wt pct studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of yield strength and creep resistance at 573 K (300 °C) is obtained in the 0.3 wt pct Fe alloy with the finest size and highest volume fraction of dispersoids. The superior properties obtained at 573 K (300 °C) make 3004 alloys more promising for high-temperature applications. The relationship between the Fe content and the dispersoid precipitation as well as the materials properties has been discussed.

  6. Influence of Steam Activation on Pore Structure and Acidity of Zeolite Beta: An Al K Edge XANES Study of Aluminum Coordination

    Koningsberger, D.C.; Bokhoven, J.A. van; Kunkeler, P.J.; Bekkum, H. van


    The effect of steam activation on the aluminum coordination in zeolite NH{4}-beta was investigated by means of quantitative analysis of Al K edge XANES spectra. Framework tetrahedral aluminum is converted to octahedral aluminum after calcination and steaming, a process that, at the same time,

  7. Cetyltrimethyl ammonium bromide-Mg/Al hydrotalcite for removal phenol in water

    Kurniawati, Puji; Wiyantoko, Bayu; Purbaningtias, Tri Esti; Muzdalifah


    Hydrotalcite materials was synthesized by using Cetyltrimethyl Ammonium Bromide (CTAB) and Mg/Al layered double hydroxide with ratio molar 3:1. Synthesis of CTAB-Mg/Al hydrotalcite was carried out using ex situ co-precipitation method at pH 10±0.5. Removal of phenol was optimum at medium pH 6 and it had optimum contact time in 300 min. It followed pseudo second order with adsorption rate constant was 1.15.10-4 mM-1.min-1. The maximum adsorption capacities obtained from the Langmuir model was 35.71 mg.g-1 at room temperature.

  8. High speed twin roll casting of recycled Al-3Si-0.6Mg strip

    S. Kumai; H.Watari; Ikawa, M; Haga, T.


    Purpose: Purpose of this paper is to clear the possibility of high speed roll casting of thin strip of recycled Al-3%Si-0.6%Mg alloy. Investigation of the mechanical properties of the roll cast recycled Al-3%Si-0.6%Mg strip was purpose, too.Design/methodology/approach: Method used in the present study was high speed twin roll caster and low temperature casting. These methods were used to realize rapid solidification, and increase of casting speed.Findings: Findings are that recycled Al-3%Si-0...

  9. Thermoelectric properties of Al doped Mg{sub 2}Si material

    Kaur, Kulwinder, E-mail:; Kumar, Ranjan [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Rani, Anita [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India); Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab (India)


    In the present paper we have calculated thermoelectric properties of Al doped Mg{sub 2}Si material (Mg{sub 2−x}Al{sub x}Si, x=0.06) using Pseudo potential plane wave method based on DFT and Semi classical Boltzmann theory. The calculations showed n-type conduction, indicating that the electrical conduction are due to electron. The electrical conductivity increasing with increasing temperature and the negative value of Seebeck Coefficient also show that the conduction is due to electron. The thermal conductivity was increased slightly by Al doping with increasing temperature due to the much larger contribution of lattice thermal conductivity over electronic thermal conductivity.


    Z.D. Zhao; W.M. Mao


    In this article, semi-solid AlSi7Mg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring. The effects of pouring temperature and stirring power on the microstructure of the AlSi7Mg alloy slurry were studied. The results showed that the semi-solid AlSi7Mg alloy slurry, 127 mm in diameter, could be prepared by using the low superheat pouring and weak electromagnetic stirring technology and this new technology could save energy and make the pouring process convenient. When the liquid AlSi7Mg alloy was poured at 650°C or 630°C, the solidified microstructure of the AlSi7Mg alloy slurry, prepared by weak electromagnetic stirring, was remarkably improved when compared with that of the slurry prepared without stirring. The primary α-Al grains appeared rosette-like or spherical. When the pouring temperature was decreased, the shape of the primary α-Al grains gradually changed from dendritic-like grains to spherical grains. When the pouring temperature was appropriately increased, that is, raised to a certain superheat, the pouring processbecame easier and an ideal spherical microstructure of the AlSiTMg alloy slurry, prepared by weak electromagnetic stirring, could also be obtained. In this experiment,when the stirring power was 0.36 kW, the optimized pouring temperature parameter was 630°C. When the AISiTMg alloy slurry was prepared by low superheat pouring and weak electromagnetic stirring, the pouring temperature was 630°C. Increasing the stirring power appropriately could gain better spherical primary α-Al grains, but if the stirring power was increased to a certain value, the shape of the primary α-Al grains did not improve further. In this experiment, the optimized stirring power parameter was 0.36 kW.

  11. Photoluminescence of Tb-doped MgAl-LDHs depending on phase transition caused by annealing

    陈玉凤; 鲍垚; 余志鹏; 杨广超; 王肖庆


    This paper presented the photoluminescence of Tb-doped Mg-Al layered double hydroxides (Tb-doped MgAl-LDHs) de-pending on phase transition caused by annealing. Tb-doped MgAl-LDHs structure transformed from hexagonal LDHs, cubic MgO to spinel MgAl2O4 phase as temperature varied from 200 to 1000 °C. Emission and excitation spectra of Tb-doped MgAl-LDHs obvi-ously changed with phase transformation. The emissions of Tb3+ ions attributed to5D4→7FJ transitions (J=3, 4, 5, 6) were observed in the emission spectra of all the Tb-doped samples. The ratio of (5D4→7F5)/(5D4→7F6) emission intensity, which was sensitive to sur-roundings of Tb3+ ion, markedly enhanced with temperature rising to 600 from 400 °C. Over 600 °C, the ratio of (5D4→7F5)/ (5D4→7F6) intensity tended to decreasing up to 1000 °C. The change concerning the ratio of the (5D4→7F5)/(5D4→7F6) emission in-tensity might be due to various surroundings of Tb3+ induced by phase transformation.

  12. 铸造Al-Mg-Mn合金的显微组织及力学性能%Microstructure and Tensile Properties of Al-Mg-Mn Alloy

    孙景旺; 王渠东; 丁文江


    研究了Mg含量、冷却速度、固溶处理对A1-6.8Mg-0.3Mn、Al-3.8Mg-0.3Mn两种合金力学性能的影响.结果表明,随着Mg含量提高,晶界相增多.当Mg含量提高到6.8%时,晶界出现网状组织;随着Mg含量升高,合金强度提高,塑性下降;通过砂型铸造空冷、金属型铸造空冷、金属型铸造淬火来实现不同的冷却速度,发现金属型淬火试样的金相组织中,在晶界附近没有析出网絮状或颗粒状第二相,而强度和伸长率要高于其他两种工艺.两种合金经过430℃×60 h固溶处理后,合金的综合力学性能得到大幅度提高.Al-6.8Mg-0.3Mn金属型铸造空冷试样固溶后抗拉强度由280 MPa提高到335 MPa,伸长率由10.4%提高到20%.%Effects of Mg content, cooling rate and solution treatment on the tensile properties of Al-6. 8Mg-0. 3Mn, Al-3. 8Mg-0. 3Mn alloy were investigated. The results show that the amount of grain boundary phases is increased with increasing in Mg content, and with 6. 8% Mg content, network structure occurs in grain boundary. In addition, strength is improved and the plasticity of the magnesium alloy is decreased with the Mg content increases. Mg alloy samples were fabricated in sand casting with air-cooled, metal mold casting with air-cooled, metal mold casting quenched in water to achieve different cooling rates, respectively. The results reveal that absence of flocculent or granular precipitation in the grain boundary of microstructure in quenched sample can be observed, and the strength and elongation are higher than those of the samples fabricated in the other two cooling rates. After 430℃ for 60 h solution treatment, comprehensive properties of the two alloys have been substantially improved. Tensile strength and elongation of Al-6. 8Mg-0. 3Mn alloy in permanent mold casting with air cooled are improved from 280 Mpa to 335 Mpa and from 10. 4% to 20%; respectively, after solid solution treatment.

  13. Corrosion Resistance of the Superhydrophobic Mg(OH2/Mg-Al Layered Double Hydroxide Coatings on Magnesium Alloys

    Fen Zhang


    Full Text Available Coatings of the Mg(OH2/Mg-Al layered double hydroxide (LDH composite were formed by a combined co-precipitation method and hydrothermal process on the AZ31 alloy substrate in alkaline condition. Subsequently, a superhydrophobic surface was successfully constructed to modify the composite coatings on the AZ31 alloy substrate using stearic acid. The characteristics of the composite coatings were investigated by means of X-ray diffractometer (XRD, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, scanning electronic microscope (SEM and contact angle (CA. The corrosion resistance of the coatings was assessed by potentiodynamic polarization, the electrochemical impedance spectrum (EIS, the test of hydrogen evolution and the immersion test. The results showed that the superhydrophobic coatings considerably improved the corrosion resistant performance of the LDH coatings on the AZ31 alloy substrate.

  14. TEM Nanostructural Study of Al-6Si-3Cu-Mg Melt-Spun Ribbons

    Ismeli Alfonso López


    Full Text Available Three quaternary Al-6Si-3Cu-xMg (x = 0.59, 3.80, and 6.78 wt.% alloys were produced by melt-spun and characterized using X-ray diffractometry (XRD, transmission electron microscopy (TEM, and microhardness techniques. Obtained second phases were Al2Cu( for the alloy with 0.59% Mg and Al5Cu2Mg8Si6 (Q for the alloys with 3.80 and 6.78% Mg. These phases are present as 30–50 nm or as 5–10 nm nanoparticles. Alloying elements content in solid solution increased, mainly for Si and Mg. The high alloying elements content in solid solution and the small -Al cell size for melt-spun alloys leads to microhardness values about 2 times higher than those of ingot counterparts. The microhardness increase for melt-spun alloys with 3.80 and 6.78% Mg depends on Mg content in solid solution.

  15. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    Balasamy, Rabindran J.


    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  16. Results and Outlook of The Aluminum Capture Experiment (AlCap)

    Quirk, John R.; Miller, James; ALCap Collaboration Collaboration


    Observation of neutrinoless muon-to-electron conversion in the presence of a nucleus would be unambiguous evidence of physics Beyond the Standard Model. Two experiments, COMET at J-PARC and Mu2e at Fermilab, will search for this process in the coming decade. Barring discovery, these experiments will provide upper-limits on this branching ratio up to 10,000 times better than previously published. COMET/Mu2e developed a joint venture, the AlCap Experiment, to measure particle emission spectra from muonic interactions in a number of materials. As a major source of background hits in COMET/Mu2e detectors, AlCap sought to measure the charged particle and neutron spectra following nuclear capture on the candidate target materials aluminum and titanium. Additionally, COMET/Mu2e are exploring normalization schemes via AlCap's measurement of the photon spectra following both atomic and nuclear capture. Over the course of 2013 and 2015, AlCap performed three runs at the Paul Scherrer Institut in Switzerland. The first acquired preliminary data for all spectra, the second run collected only neutron and photon data, and the third primarily charged particle data. Preliminary analyses of the first two runs, already impactful for COMET/Mu2e, is presented along with a summary of the third.

  17. Dual-scale phase-field simulation of Mg-Al alloy solidification

    Monas, A.; Shchyglo, O.; Höche, D.; Tegeler, M.; Steinbach, I.


    Phase-field simulations of the nucleation and growth of primary α-Mg phase as well as secondary, β-phase of a Mg-Al alloy are presented. The nucleation model for α- and β-Mg phases is based on the “free growth model” by Greer et al.. After the α-Mg phase solidification we study a divorced eutectic growth of α- and β-Mg phases in a zoomed in melt channel between α-phase dendrites. The simulated cooling curves and final microstructures of α-grains are compared with experiments. In order to further enhance the resolution of the interdendritic region a high-performance computing approach has been used allowing significant simulation speed gain when using supercomputing facilities.

  18. Aminobenzoate modified MgAl hydrotalcites as a novel smart additive of reinforced concrete for anticorrosion applications

    Yang, Z.; Fischer, H.R.; Cerezo, J.; Mol, J.M.C.; Polder, R.B.


    A carbonate form of MgAl hydrotalcite, Mg(2)Al-CO3 and its p-aminobenzoate (pAB) modified derivative, Mg(2)Al-pAB, were synthesized and characterized by means of XRD, FT-IR and TG/DSC. The anticorrosion behavior of Mg(2)Al-pAB was evaluated based on open circuit potential (OCP) of carbon steel in si

  19. Evolution of eutectic structures in Al-Zn-Mg-Cu alloys during heat treatment

    FAN Xi-gang; JIANG Da-ming; MENG Qing-chang; ZHANG Bao-you; WANG Tao


    The evolution of the eutectic structures in the alloys with different copper contents during heat treatment was studied by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and differential scanning calorimetry(DSC). The as cast microstructures involve α(Al), eutectic(α(Al) + Mg(Al, Cu, Zn)2) and Al7Cu2Fe. The Al2CuMg particles form during heat treatment. The volume of coarse phases decreases quickly in the initial 12 h during heat treatment. The volume of coarse phases change a little at 400 and 420 ℃. Copper content has a great influence on the evolution of the eutectic. The coarse phases dissolve slowly in alloy with higher copper content.

  20. Effect of Mg as sintering additive on the consolidation of mechanically alloyed Al powder

    Fuentes, J.J. [UNET, Dept. de Ingenieria Mecanica, San Cristobal (Venezuela); Rodriguez, J.A.; Herrera, E.J. [Grupo de Metalurgia e Ingenieria de los Materiales, Escuela Superior de Ingenieros, Univ. de Sevilla, Camino de los Descubrimientos, Sevilla (Spain)


    Mechanically alloyed aluminium, MA Al, powder particles are hard and covered by surface oxide layers. This gives problems in consolidation processing. Consolidation is often carried out by hot extrusion, as the main processing step. An alternative consolidation method consisting in a press-and-sinter process has been developed at the University of Seville. MA Al powder was prepared by attrition milling. To improve the sinterability of MA Al powder, small amounts of magnesium, ranging from 0.0 to 1.2 wt% Mg, were added after milling. The mixed powder was consolidated by cold pressing (1120 MPa) and vacuum sintering (650 C, 1 h). Different mechanical and structural studies have been carried out. It has been observed that the addition of magnesium improves the mechanical properties of sintered MA Al. This is attributed to the reducing action of Mg on the Al sesquioxide layer and to the formation of liquid phases during sintering. (orig.)

  1. Postperovskite phase equilibria in the MgSiO3-Al2O3 system.

    Tsuchiya, Jun; Tsuchiya, Taku


    We investigate high-P,T phase equilibria of the MgSiO(3)-Al(2)O(3) system by means of the density functional ab initio computation methods with multiconfiguration sampling. Being different from earlier studies based on the static substitution properties with no consideration of Rh(2)O(3)(II) phase, present calculations demonstrate that (i) dissolving Al(2)O(3) tends to decrease the postperovskite transition pressure of MgSiO(3) but the effect is not significant ( approximately -0.2 GPa/mol% Al(2)O(3)); (ii) Al(2)O(3) produces the narrow perovskite+postperovskite coexisting P,T area (approximately 1 GPa) for the pyrolitic concentration (x(Al2O3) approximately 6 mol%), which is sufficiently responsible to the deep-mantle D'' seismic discontinuity; (iii) the transition would be smeared (approximately 4 GPa) for the basaltic Al-rich composition (x(Al2O3) approximately 20 mol%), which is still seismically visible unless iron has significant effects; and last (iv) the perovskite structure spontaneously changes to the Rh(2)O(3)(II) with increasing the Al concentration involving small displacements of the Mg-site cations.

  2. Microstructure and Mechanical Properties of Al-10Zn-4.5Mg-xCu Turbine Impeller Produced by Investment Casting

    Muhammad Syahid


    Full Text Available Aluminium alloy can be applied for a turbine impeller of Organic Rankine Cycle power plant that operates at temperatures below 150 oC. Aluminum turbine impeller can enhance efficiency of turbine due to light weight material. Al alloys was used for impeller due to good mechanical properties. Turbine impeller commonly produced by machining but which is time-consuming and less efficient because of material removal. . It can be replace by Investment casting to produce impeller turbine due to their complex geometry and precision. This study identifies effect Cu content of Al-9Zn-4Mg-xCu on the microstructure and mechanical properties of turbine impeller produce by investment casting. The study also identifies casting defect of turbine impeller. The structures consisted of α-Al, MgZn2, CuMgAl2 and CuAl2. Higher Cu content is the higher hardness value due to CuAl2 phase. Visual examination showed that the turbine impeller was free of macro defects and misruns

  3. Growth and Annealing Study of Mg-Doped AlGaN and GaN/AlGaN Superlattices

    WANG Bao-Zhu; LI Jin-Min; WANG Zhan-Guo; WANG Xiao-Liang; HU Guo-Xin; RAN Jun-Xue; WANG Xin-Hua; GUO Lun-Chun; XIAO Hong-Ling; LI Jian-Ping; ZENG Yi-Ping


    @@ Mg-doped AlGaN and GaN/AlGaN superlattices are grown by metalorganic chemical vapour deposition (MOCVD).Rapid thermal annealing (RTA) treatments are carried out on the samples. Hall and high resolution x-ray diffraction measurements are used to characterize the electrical and structural prosperities of the as-grown and annealed samples, respectively. The results of hall measurements show that after annealing, the Mg-doped AlGaN sample can not obtain the distinct hole concentration and can acquire a resistivity of 1.4×103 Ωcm. However, with the same annealing treatment, the GaN/AlGaN superlattice sample has a hole concentration of 1.7×1017 cm-3 and a resistivity of 5.6Ωcm. The piezoelectric field in the GaN/AlGaN superlattices improves the activation efficiency of Mg acceptors, which leads to higher hole concentration and lower p-type resistivity.

  4. Structural considerations in friction welding of hybrid Al2O3-reinforced aluminum composites

    In-Duck PARK; Choon-Tae LEE; Hyur-Soo KIM; Woo-Jin CHOI; Myung-Chang KANG


    Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al2O3-reinforced aluminum composites were conducted. Metal matrix composites (MMCs) with 37% (volume fraction)aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interface. a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently,it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very good joint.

  5. Performance comparison of AlTiC and AlTiB master alloys in grain refinement of commercial and high purity aluminum

    LI Jian-guo; HUANG Min; MA Mo; YE Wei; LIU Dong-yu; SONG Dong-ming; BAI Bing-zhe; FANG Hong-sheng


    For further knowledge about the refining performance of AlTiC master alloys, Al5.5Ti0.25C and Al6.5Ti0.5C master alloys containing high Ti and C content were prepared and used in grain refining experiments of 99.8% commercial pure aluminum(CPAl). Their performance was compared with two types of Al5TilB refiners whose performance was nowadays considered to be the best. These two types of master alloys show similar refining efficiency at the addition level of 0.2%. However, at the addition level of 0.5%, there still exists great performance difference between AlTiC and Al5TiB alloys in grain refinement of 99.98% and 99.995% high purity aluminum(HPAl). The growth of columnar grains is fully suppressed due to the refinement of AlTiC at the addition level of 0.5%. Also, at the same addition level, the grain refining experiments of Al3Ti0.15C and Al5Ti0.2C master alloys which have found initial commercial applications are conducted in the above-mentioned three types of pure aluminum.According to the experimental results, these two refiners of different compositions are both nonideal. The second phase particles extracted from each refiner were observed through TEM, while the nuclei of grains after grain refinement were observed through SEM. The results were analyzed through computation and comparison of the constitutional-supercooling parameter and the growth-restriction parameter whose values were determined by solute element in aluminum melt with different purity. Apparently,AlTiC master alloys with high content of Ti and C element have great refining potential.

  6. Bonding strength of Al/Mg/Al alloy tri-metallic laminates fabricated by hot rolling

    X P Zhang; M J Tan; T H Yang; X J Xu; J T Wang


    One of major drawbacks of magnesium alloy is its low corrosion resistance, which can be improved by using an aluminized coating. In this paper, 7075 Al/Mg–12Gd–3Y–0.5Zr/7075 Al laminated composites were produced by a hot roll bonding method. The rolling temperature was determined based on the flow stresses of Mg–12Gd–3Y–0.5Zr magnesium alloy and 7075 Al alloy at elevated temperature. The bonding strength of the laminate composites and their mechanism were studied. The effects of the reduction ratio (single pass), the rolling temperature, and the subsequent annealing on the bonding strength were also investigated. It was observed that the bonding strength increased rapidly with the reduction ratio and slightly with the rolling temperature. The bonding strength increases with the annealing time until the annealing time reaches 2 h and then decreases. The mechanical bond plays a major role in the bonding strength.

  7. Effect of Calcination at Synthesis of Mg-Al Hydrotalcite Using co-Precipitation Method

    Niar Kurnia Julianti


    Full Text Available The use of hydrotalcite in catalysis has wide attention in academic research and industrial parties. Based on its utilization, hydrotalcite can be active catalyst or support. This research is focused on the investigation of characteristic like spesific surface area of Mg-Al hydrotalcite which is prepared with different temperature of calcination. Synthesis of Mg-Al hydrotalcites with Mg/Al molar ratio 3:1 were prepared by co-precipitation method. Mg(NO33.6H2O and Al(NO33.9H2O as precursors of Mg-Al hydrotalcite. Na2CO3 was used as precipitant agent and NaOH was used as buffer solution. The solution was mixed and aging for 5 hours at 650oC. The dried precipitate was calcined at 2500oC, 3500oC, 4500oC, 5500oC and 6500oC. The characterization of functional group was determined by Fourier Transform Infra Red (FT-IR. The Identical peaks diffractogram were analyzed by X-Ray Diffraction (XRD. The spesific surface area was determined by adsorption-desorption of nitrogen. The largest surface area that obtained from the calcination temperature of 650oC is 156.252 m2/g.

  8. Tuning Acid-Base Properties Using Mg-Al Oxide Atomic Layer Deposition.

    Jackson, David H K; O'Neill, Brandon J; Lee, Jechan; Huber, George W; Dumesic, James A; Kuech, Thomas F


    Atomic layer deposition (ALD) was used to coat γ-Al2O3 particles with oxide films of varying Mg/Al atomic ratios, which resulted in systematic variation of the acid and base site areal densities. Variation of Mg/Al also affected morphological features such as crystalline phase, pore size distribution, and base site proximity. Areal base site density increased with increasing Mg content, while acid site density went through a maximum with a similar number of Mg and Al atoms in the coating. This behavior leads to nonlinearity in the relationship between Mg/Al and acid/base site ratio. The physical and chemical properties were elucidated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 physisorption, and CO2 and NH3 temperature-programmed desorption (TPD). Fluorescence emission spectroscopy of samples grafted with 1-pyrenebutyric acid (PBA) was used for analysis of base site proximity. The degree of base site clustering was correlated to acid site density. Catalytic activity in the self-condensation of acetone was dependent on sample base site density and independent of acid site density.

  9. Fatigue characteristics and microcosmic mechanism of Al-Si-Mg alloys under multiaxial proportional loadings

    Jiang, Xiao-Song; He, Guo-Qiu; Liu, Bing; Zhu, Zheng-Yu; Zhang, Wei-Hua


    With the increasing use of Al-Si-Mg alloys in the automotive industry, the fatigue performance of Al-Si-Mg alloy has become a major concern with regard to their reliability. The fatigue characteristics and microcosmic mechanism of an Al-Si-Mg alloy under multiaxial proportional loadings were investigated in this research. As low cycle fatigue life and material strengthening behavior are closely related, the effect of equivalent strain amplitude on the multiaxial fatigue properties was analyzed. Fatigue tests were conducted to determine the influence of equivalent strain amplitude on the multiaxial proportional fatigue properties. The fatigue life exhibits a stable behavior under multiaxial proportional loadings. The dislocation structures of the Al-Si-Mg alloy were observed by transmission electron microscopy (TEM). The dislocation structure evolution of the Al-Si-Mg alloy under multiaxial proportional loadings during low cycle fatigue develops step by step by increasing fatigue cycles. Simultaneously, the dislocation structure changes with the change in equivalent strain amplitude under multiaxial proportional loadings. The experimental evidence indicates that the multiaxial fatigue behavior and life are strongly dependent on the microstructure of the material, which is caused by multiaxial proportional loadings.

  10. Nonstoichiometry and phase stability of Al and Cr substituted Mg ferrite nanoparticles synthesized by citrate method

    Ateia, Ebtesam. E.; Mohamed, Amira. T.


    The spinel ferrite Mg0.7Cr0.3Fe2O4, and Mg0.7Al0.3Fe2O4 were prepared by the citrate technique. All samples were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Micrographs (HRTEM), Energy Dispersive X ray Spectroscopy (EDAX) and Atomic Force Microscope (AFM). XRD confirmed the formation of cubic spinel structure of the investigated samples. The average crystallite sizes were found to be between 24.7 and 27.5 nm for Al3+ and Mg2+ respectively. The substitution of Cr3+/Al3+ in place of Mg2+ ion initiates a crystalline anisotropy due to large size mismatch between Cr /Al and Mg2+, which creates strain inside the crystal volume. According to VSM results, by adding Al3+ or Cr3+ ions at the expense of Mg2+, the saturation magnetization increased. The narrow hysteresis loop of the samples indicates that the amount of dissipated energy is small, which is desirable for soft magnetic applications. Magnetic dynamics of the samples were studied by measuring magnetic susceptibility versus temperature at different magnetic fields. The band gap energy, which was calculated from near infrared (NIR) and visible (VIS) reflectance spectra using the Kubelka-Munk function, decreases with increasing the particle size. Furthermore, the band gaps were quite narrow (1.5-1.7 eV), hence the investigated samples could act as visible light driven photo catalysts. To sum up the addition of trivalent Al3+, and Cr3+ ions enhanced the optical, magnetic and structure properties of the samples. Mg0.7 Cr0.3Fe2O4 sample will be a better candidate for the optical applications and will also be a guaranteeing hopeful for technological applications.

  11. Microstructure and mechanical properties of cast Mg-15Al-xNd alloy by permanent mold

    Zhou Kangkang


    Full Text Available To improve the comprehensive mechanical properties of Mg-15Al magnesium alloy, different amounts (from 0 to 4.0wt.% of Nd were added to the alloy and six Mg-15Al-xNd alloys were prepared by metal mould casting. The effect of Nd content on microstructure of the alloys was investigated by means of OM, SEM, EDS, TEM, and XRD. The tensile properties were tested at room temperature (RT and high temperature (473 K. The results indicate that the primary α-Mg dendrite is significantly refined with the addition of Nd. The best refinement is reached at 1.0wt.% Nd content and the average dendrite arm spacing decreases from 80-100 μm (without Nd addition to ~20 μm. A further increase in Nd content leads to the coarsening of the primary α-Mg dendrite. The addition of Nd improves the tensile properties of Mg-15Al both at RT and 473 K. The Mg-15Al alloy containing 1.0wt.% Nd exhibits the best tensile properties. Compared with the alloy without Nd, the yield and ultimate tensile strength of the Mg-15Al-1.0Nd alloy at RT increase from 132.3 to 148.6 MPa and 152.3 to 189.6 MPa, increase by 12.3% and 24.5%, respectively; and the elongation at RT increases from 0.05 % to 1.24%. The yield and tensile strength of the alloy at 473 K increase from 97.9 to 115.3 MPa and 121.6 to 140.1 MPa, increase by 15.2% and 20%, respectively. Further increment of Nd content to 1.5wt.% degrades the tensile properties, which is ascribed to grain coarsening and growth of the Al-Nd phase.

  12. Conduction electron spin resonance in Mg 1 - x Al x B2

    Likodimos, V.; Koutandos, S.; Pissas, M.; Papavassiliou, G.; Prassides, K.


    Conduction electron spin resonance is employed to study the interplay of the electronic and structural properties in the normal state of Mg 1 - x Al x B2 alloys as a function of Al-doping for 0 <= x <= 1. The x-dependence of the spin susceptibility reveals considerable reduction of the total density of states N(EF) with increasing Al concentration, complying with theoretical predictions for a predominant filling effect of the hole σ bands by electron doping. The CESR linewidth exhibits significant broadening, especially prominent in the high-Al-content region, indicative of the presence of enhanced structural disorder, consistent with the presence of compositional fluctuations.

  13. Transparent Al+3 doped MgO thin films for functional applications

    Maiti, Payel; Sekhar Das, Pradip; Bhattacharya, Manjima; Mukherjee, Smita; Saha, Biswajit; Mullick, Awadesh Kumar; Mukhopadhyay, Anoop Kumar


    The present work reports the utilization of a relatively simple, cost effective sol-gel technique based route to synthesize highly transparent, spin coated 4.1 at% Al+3 doped MgO thin films on quartz substrates. The films were characterized by XRD, XPS, Raman spectroscopy, and SIMS techniques. The microstructures were characterized by FESEM and TEM while the nanomechanical properties were assessed by the nanoindentation technique. Finally the optical transmittance was measured by UV-vis technique. The x-ray diffraction (XRD) study suggests the crystal facet (2 0 0) of MgO lattice to be distorted after incorporation of Al+3 into MgO lattice. From FESEM the doped films were found to have a dense microstructure with a crystallite size of about 20 nm as revealed by the TEM studies. Nanoindentation measurements indicated drastic increase of elastic modulus for the Al+3 doped MgO thin films by ~73% compared to that of the pristine MgO thin films along with retaining the nanohardness at ~8 GPa. The transmittance of Al+3 doped MgO thin films in the visible range was significantly higher (~99%) than that of pristine MgO (~90%) thin films. The films also had a relatively higher refractive index of about 1.45 as evaluated from the optical properties. The enhanced transmittance as well as the improved elastic modulus of Al+3 doped MgO thin films suggest its promising candidature in magnetic memory devices and as buffer layers of solar cells.

  14. Spectroscopic factor strengths in $^{27}$Al(d,$^{3}$He)$^{26}$Mg and $^{27}$Al(d,$t$)$^{26}$Al reactions

    Srivastava, P C


    In the present work we calculated spectroscopic factor strengths for recently measured experimental data for $1p$ and $1n$ pick-up reactions $^{27}$Al(d,$^{3}$He)$^{26}$Mg [Phys. Rev. C {\\bf 93}, 044601 (2016)] and $^{27}$Al( d,$t$)$^{26}$Al [Phys. Rev. C {\\bf 91}, 054611 (2015)] within the framework of the shell-model. We performed calculations with USDA and USDB effective interactions, results are in a good agreement with the experimental data.

  15. Superplasticity of the aluminum alloys containing the Al{sub 3}Ni eutectic particles

    Portnoy, V.K. [Department of Physical Metallurgy Non-Ferrous Metals, National University of Science and Technology ' ' MISIS' ' , Moscow (Russian Federation); Mikhaylovskaya, A.V.


    The structures and parameters of superplasticity of aluminum alloys containing fine and coarse eutectic Al{sub 3}Ni particles were investigated. Traditional hot and cold rolling were used for sheet producing. The research alloys have low- or high - alloying solid solution. Superplasticity characterization of the alloy with high-alloying solid solution is much better beside alloys with low-alloying solid solution. Alloying by zirconium improves superplasticity in some investigated alloys. Some alloys with partially recrystallized structure show d = 500-700% at T = 0.95 Tm with the constant strain rates to the range of (1.10{sup -3}-1.10{sup -2}) s{sup -1}. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Role of Laser Cladding Parameters in Composite Coating (Al-SiC) on Aluminum Alloy

    Riquelme, Ainhoa; Escalera-Rodriguez, María Dolores; Rodrigo, Pilar; Rams, Joaquin


    The effect of the different control parameters on the laser cladding fabrication of Al/SiCp composite coatings on AA6082 aluminum alloy was analyzed. A high-power diode laser was used, and the laser control parameters were optimized to maximize the size (height and width) of the coating and the substrate-coating interface quality, as well as to minimize the melted zone depth. The Taguchi DOE method was applied using a L18 to reduce the number of experiments from 81 to only 18 experiments. Main effects, signal-noise ratio and analysis of variance were used to evaluate the effect of these parameters in the characteristics of the coating and to determine their optimum values. The influence of four control parameters was evaluated: (1) laser power, (2) scanning speed, (3) focal condition, and (4) powder feed ratio. Confirmation test with the optimal control parameters was carried out to evaluate the Taguchi method's effectivity.

  17. Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents

    Guo, M.X., E-mail:; Zhang, Y.; Zhang, X.K.; Zhang, J.S.; Zhuang, L.Z.


    The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

  18. Effect of the composition of Al-Li alloys on the quantitative relation between the δ'(Al3Li), S1(Al2MgLi), and T1(Al2CuLi) phases

    Betsofen, S. Ya.; Antipov, V. V.; Grushin, I. A.; Knyazev, M. I.; Khokhlatova, L. B.; Alekseev, A. A.


    Al-Li alloys are considered. A quantitative approach to the determination of the ratio of the fractions of the binary and ternary intermetallic phases in Al-Mg(Cu)-Li alloys is developed on the basis of chemical and phase composition balance equations and the experimentally measured lattice parameter of the α solid solution. The ratio of the fractions of the δ'(Al3Li) and S1(T1) phases in Al-Mg(Cu)-Li alloys is shown to be determined by the ratio of the mole fractions of Li and Mg(Cu). Equations are proposed for calculating the weight fractions of the S1(Al2MgLi), T1(Al2CuLi) and δ'(Al3Li) phases in domestic and foreign Al-Mg-Li alloys 1420, 1424, 5090 and Al-Cu-Li alloys 1440, 1460, 1461, 1441, 1469, 2090, 2095, 8090, and Weldalite 049.

  19. From Powders to Dense Metal Parts: Characterization of a Commercial AlSiMg Alloy Processed through Direct Metal Laser Sintering

    Eleonora Atzeni


    Full Text Available In this paper, a characterization of an AlSiMg alloy processed by direct metal laser sintering (DMLS is presented, from the analysis of the starting powders, in terms of size, morphology and chemical composition, through to the evaluation of mechanical and microstructural properties of specimens built along different orientations parallel and perpendicular to the powder deposition plane. With respect to a similar aluminum alloy as-fabricated, a higher yield strength of about 40% due to the very fine microstructure, closely related to the mechanisms involved in this additive process is observed.

  20. ACO-zeotype iron aluminum phosphates with variable Al/Fe ratios controlled by F⁻ ions.

    Wang, Yanyan; Li, Yi; Wang, Lei; Zhang, Jingzhe; Yan, Yan; Li, Jiyang; Yu, Jihong; Wang, Jincheng; Xu, Ruren


    Three new iron aluminum phosphates |(C(2)H(10)N(2))(4)|[Fe(8 - x)Al(x)F(x)(H(2)O)(2 - x)(PO(4))(8)]·2H(2)O (χ = 1.64, 1.33, 0.80) with ACO-zeotype structures denoted as FeAPO-CJ66(a), FeAPO-CJ66(b), and FeAPO-CJ66(c), respectively, have been synthesized in the fluoride ion system. Their framework structures are made of double 4-ring (D4R) building units formed by the alternating connection of Fe(Al)O(4)F(O) trigonal bipyramids and PO(4) tetrahedra, which possess 3D intersecting 8-ring channels running along the [001], [010], and [100] directions. Fluoride ions or water molecules reside in the center of D4Rs, and diprotonated ethylenediamine cations and water molecules are occluded in the free space of channels to stabilize the whole structure. Notably, the Al/Fe ratios in the frameworks can be effectively controlled from 1/3.9 to 1/5.0 to 1/9.0 by adjusting the amounts of phosphoric acid and hydrofluoric acid added to the initial reaction mixture. Mössbauer and magnetic measurements show that the Fe ions in the compounds are bivalent and undergo antiferromagnetic ordering at room temperature.

  1. Effect of Preparation Parameter on Microstructure and Grain Refining Behavior of In Situ AlN-TiN-TiB2/Al Composite Inoculants on Pure Aluminum

    Qian Wang


    Full Text Available The formation of in situ AlN-TiN-TiB2/Al composite inoculants, which contain multi-phase refiner particles including AlN, TiN, TiB2, Al3Ti, and α-Al, was investigated using nitrogen gas injection. The effects of the main preparation parameters such as nitriding temperature, nitriding time, Ti content in melts, on the microstructure and grain refinement of in situ AlN-TiN-TiB2/Al composite inoculants were studied. The shape, content and size of different ceramic particles in the inoculants can be tuned by controlling the nitriding temperature and time, inducing excellent refining and reinforcing effects on pure aluminum. As a result, the average grain size of pure aluminum can be reduced to about 122 ± 22 μm from original 1010 ± 80 μm by adding 0.3 wt % inoculants. The mechanical properties including the tensile strength, yield strength and microhardness of the refined as-cast pure aluminum are also improved.

  2. Preparation and characterization of Mn/MgAlFe as transfer catalyst for SOx abatement

    Ruiyu Jiang; Honghong Shan; Chunyi Li; Chaohe Yang


    A series of manganese-promoted MgAlFe mixed oxides,used as sulfur transfer catalysts,were prepared by acid-processed gelatin method and characterized by TGA-DTA,XRD,N2 adsorption-desorption and FT-IR techniques.It was found that the sulfur transfer catalysts with 0.5-3.0 wt% manganese showed its good dispersion in the precursor.The novel Mn/MgAlFe catalysts with 0.5-5.0 wt% manganese oxide showed a high oxidative adsorption rate and sulfur adsorption capacity,and 5.0 wt% Mn/MgAlFe sample was superior to the others for SO2 removal.Moreover,the presence of CO had no obvious effect on the adsorption activity of sulfur transfer catalysts for SO2 uptake.

  3. Homogenization and Recrystallization of Al-6Mg Alloys with and without Sc and Zr

    姜锋; 尹志民; 黄伯云; 贺跃辉; 陈苏里


    Plates of Al-6Mg alloys with and without scandium were prepared by semi-continuous cast, homogenization, hot-rolled, cold-rolled and annealing. Based on studying of effects of temperature and time on hardness and conductivity during homogenization, it was found that homogenization of ingot with Sc and Zr can result in dispersion strengthening. Recrystallization temperature of alloys was studied by hardness method and optical metallographic method. Staring recrystallization temperature of Al-6Mg alloys with Sc and Zr is 375 ℃, increasing by 150 ℃ than Al-6Mg alloys without Sc and Zr. Mechanical properties (σb, σ0.2, δ) of hot-rolled alloy with Sc and Zr are 400 MPa, 280 MPa and 18%; cold-rolled and anneal alloy with Sc and Zr are 420 MPa, 310 MPa and 12% respectively.

  4. Grain growth of Al-4Cu-Mg alloy during isothermal heat treatment


    The microstructure of an Al-4Cu-Mg alloy during isothermal heat treatment in the Strain Induced Melt Activation (SIMA)process was investigated and the kinetics of grain growth was analyzed. The grain growth during isothermal heat treatment of the Al4Cu-Mg alloy coincided with the Ostwald ripening theory. During isothermal heat treatment, both grain shape and the high volume fraction of solid phase have significant effects on grain growth. Therefore, a new grain growth model based on the Ostwald ripening theory was proposed taking into consideration the grain shape and the volume fraction of solid phase. By comparing the calculated results with the experimental results, it was confirmed that the present model could be applied to grain growth during isothermal heat treatment of the Al-4Cu-Mg alloy in the SIMA process.

  5. Directional growth of Al-Mg2Si eutectic alloy in the SZ2 unmanned spaceship

    PAN; Mingxiang(潘明祥); LI; Shunpu(李顺朴); ZHAO; Deqian(赵德乾); WANG; Weihua(汪卫华); WEN; Ping(闻平); YU; Yude(俞育德); NIE; Yuxin(聂玉昕); ZHAO; Shengxue(赵生旭); ZHUANG; Yanxin(庄艳歆); CHEN; Xichen(陈熙琛)


    This paper reports the investigation results on directional growth of Al-Mg2Si eutectic alloy in the SZ2 unmanned spaceship. The analysis shows that microgravity has influence on the directional growth of Al-Mg2Si eutectic alloy. The eutectic colony in space-grown sample is larger than that in ground-grown sample, and the directional effect is not so good as that of terrestrial sample. But there is no obvious difference in the lamellar thickness between these samples, and lamellar interspacing in space sample is smaller than that grown on the ground. A simple discussion is done on the gravity effect on the directional growth of Al-Mg2Si eutectic alloy.

  6. Spin-orbit torque in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO epitaxial magnetic heterostructures

    Zhenchao Wen


    Full Text Available We study the spin-orbit torque (SOT effective fields in Cr/CoFeAl/MgO and Ru/CoFeAl/MgO magnetic heterostructures using the adiabatic harmonic Hall measurement. High-quality perpendicular-magnetic-anisotropy CoFeAl layers were grown on Cr and Ru layers. The magnitudes of the SOT effective fields were found to significantly depend on the underlayer material (Cr or Ru as well as their thicknesses. The damping-like longitudinal effective field (ΔHL increases with increasing underlayer thickness for all heterostructures. In contrast, the field-like transverse effective field (ΔHT increases with increasing Ru thickness while it is almost constant or slightly decreases with increasing Cr thickness. The sign of ΔHL observed in the Cr-underlayer devices is opposite from that in the Ru-underlayer devices while ΔHT shows the same sign with a small magnitude. The opposite directions of ΔHL indicate that the signs of spin Hall angle in Cr and Ru are opposite, which are in good agreement with theoretical predictions. These results show sizable contribution from SOT even for elements with small spin orbit coupling such as 3d Cr and 4d Ru.

  7. Microstructural Evolution in AlMgSi Alloys during Solidification under Electromagnetic Stirring

    Piotr Mikolajczak


    Full Text Available Equiaxed solidification of AlMgSi alloys with Fe and Mn was studied by electromagnetic stirring to understand the effect of forced flow. The specimens solidified with a low cooling rate, low temperature gradient, and forced convection. Stirring induced by a coil system around the specimens caused a transformation from equiaxed dendritic to rosette morphology with minor dendrites and, occasionally, spheroids. This evolution was quantitatively observed with specific surface Sv. The precipitation sequence of the phases was calculated using the CALPHAD (Computer Coupling of Phase Diagrams and Thermochemistry technique. Melt flow decreased secondary dendrite arm spacing λ2 in the AlSi5Fe1.0 alloy, while λ2 increased slightly in Mg-containing alloys. The length of detrimental β-Al5FeSi phases decreased only in AlSi5Fe1.0 alloy under stirring, whereas in Mg-containing alloys, changes to the β-Al5FeSi phase were negligible; however, in all specimens, the number density increased. The modification of Mn-rich phases, spacing of eutectics, and Mg2Si phases was analyzed. It was found that the occurrence of Mg2Si phase regions reduced fluid flow in the late stages of solidification and, consequentially, reduced shortening of β-Al5FeSi, diminished secondary arm-ripening caused by forced convection, and supported diffusive ripening. However, the Mg2Si phase was found to have not disturbed stirring in the early stage of solidification, and transformation from dendrites to rosettes was unaffected.

  8. Introductory lecture on corrosion chemistry: a focus on anodic hydrogen evolution on Al and Mg.

    Frankel, G S; Fajardo, S; Lynch, B M


    The increase in the rate of hydrogen evolution (HE) on dissolving Mg surfaces with increasing anodic current density or potential, which is sometimes called the negative difference effect, has been the topic of much discussion in recent years. A review of the very recent contributions to this subject is given in this paper. Increased catalytic activity of the corrosion product layer, either from the accumulated impurities or from the Mg oxy-hydroxide itself, is shown to have a minor influence on the anodic HE observed on dissolving Mg at high anodic current densities and potentials. Al exhibits similar characteristics during anodic polarization in concentrated HCl, although the anodic HE rate on Al is less than on Mg. Possible mechanisms for the anodic hydrogen are provided and implications in the area of intergranular corrosion and environmental cracking are discussed.

  9. An Al@Al2O3@SiO2/polyimide composite with multilayer coating structure fillers based on self-passivated aluminum cores

    Zhou, Yongcun; Wang, Hong


    We demonstrate a capability in combining two kinds of nanosize and microsize particles of core-shell Al@Al2O3@SiO2 with aluminum cores to form multilayer coating structures as fillers in polyimide matrix for electronic applications. The core-shell Al@Al2O3@SiO2 structure can effectively adjust the relative permittivity (about 12 @1 MHz) of the composite while keeping lower dielectric loss (0.015 @1 MHz) compared to that uncoated aluminum particles. The combination of "macro" and "micro" coating can significantly improve the dielectric properties of the composites. This work provides a useful method to modify the fillers for polymer matrix nanocomposite materials.

  10. Braze Welding TIG of Titanium and Aluminium Alloy Type AlMg

    Winiowski A.


    Full Text Available The article presents the course and the results of technological tests related to TIG-based arc braze welding of titanium and AW-5754 (AlMg3 aluminium alloy. The tests involved the use of an aluminium filler metal (Al99.5 and two filler metals based on Al-Si alloys (AlSi5 and AlSi12. Braze welded joints underwent tensile tests, metallographic examinations using a light microscope as well as structural examinations involving the use of a scanning electron microscope and an X-ray energy dispersive spectrometer (EDS. The highest strength and quality of welds was obtained when the Al99.5 filler metal was used in a braze welding process. The tests enabled the development of the most convenient braze welding conditions and parameters.

  11. Vanadium-doped MgAl{sub 2}O{sub 4} crystals as white light source

    Fujimoto, Yutaka [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose 066-8655 (Japan)], E-mail:; Tanno, Hiroaki; Izumi, Kazuhiro; Yoshida, Shigetomo; Miyazaki, Shiori [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose 066-8655 (Japan); Shirai, Masanobu; Tanaka, Kouichirou [Japan Science and Technology Corporation, 758-65 Bibi, Chitose 066-8655 (Japan); Department of Physics, Kyoto University, Kyoto 606-8224 (Japan); Kawabe, Yutaka; Hanamura, Eiichi [Chitose Institute of Science and Technology, 758-65 Bibi, Chitose 066-8655 (Japan); Japan Science and Technology Corporation, 758-65 Bibi, Chitose 066-8655 (Japan)


    Spinel MgAl{sub 2}O{sub 4} crystals doped with transition metals show charge-transfer transitions for Ti:MgAl{sub 2}O{sub 4} on one hand and multiplet transitions of (3d)-electrons for Mn:, Fe:, and Co:MgAl{sub 2}O{sub 4} on the other hand. We will show that optical responses of V:MgAl{sub 2}O{sub 4} are closer to those of Ti:MgAl{sub 2}O{sub 4} and also that white emission spectrum is observed. The microscopic process of the white emission is also proposed.

  12. Measurement of 25Mg(p; gamma)26Al resonance strengths via gamma spectrometry

    Formicola, A; Imbriani, G; Junker, M; Bemmerer, D; Bonetti, R; Broggini, C; Caciolli, A; Confortola, F; Corvisiero, P; Costantini, H; Elekes, Z; Fülöp, Z; Gervino, G; Guglielmetti, A; Gyurky, Gy; Gustavino, C; Lemut, A; Limata, B; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P


    The COMPTEL instrument performed the first mapping of the 1.809 MeV photons in the Galaxy, triggering considerable interest in determing the sources of interstellar 26Al. The predicted 26Al is too low compared to the observation, for a better understanding more accurate rates for the 25Mg(p; gamma)26Al reaction are required. The 25Mg(p;gamma)26Al reaction has been investigated at the resonances at Er= 745; 418; 374; 304 keV at Ruhr-Universitat-Bochum using a Tandem accelerator and a 4piNaI detector. In addition the resonance at Er = 189 keV has been measured deep underground laboratory at Laboratori Nazionali del Gran Sasso, exploiting the strong suppression of cosmic background. This low resonance has been studied with the 400 kV LUNA accelerator and a HPGe detector. The preliminary results of the resonance strengths will be reported.

  13. Comparison of Efficiencies and Mechanisms of Catalytic Ozonation of Recalcitrant Petroleum Refinery Wastewater by Ce, Mg, and Ce-Mg Oxides Loaded Al2O3

    Chunmao Chen


    Full Text Available The use of catalytic ozonation processes (COPs for the advanced treatment of recalcitrant petroleum refinery wastewater (RPRW is rapidly expanding. In this study, magnesium (Mg, cerium (Ce, and Mg-Ce oxide-loaded alumina (Al2O3 were developed as cost efficient catalysts for ozonation treatment of RPRW, having performance metrics that meet new discharge standards. Interactions between the metal oxides and the Al2O3 support influence the catalytic properties, as well as the efficiency and mechanism. Mg-Ce/Al2O3 (Mg-Ce/Al2O3-COP reduced the chemical oxygen demand by 4.7%, 4.1%, 6.0%, and 17.5% relative to Mg/Al2O3-COP, Ce/Al2O3-COP, Al2O3-COP, and single ozonation, respectively. The loaded composite metal oxides significantly increased the hydroxyl radical-mediated oxidation. Surface hydroxyl groups (–OHs are the dominant catalytic active sites on Al2O3. These active surface –OHs along with the deposited metal oxides (Mg2+ and/or Ce4+ increased the catalytic activity. The Mg-Ce/Al2O3 catalyst can be economically produced, has high efficiency, and is stable under acidic and alkaline conditions.

  14. Evaluation of an Al, La Modified MgZn2Y2 Alloy


    electrochemical (corrosion) performance, new Mg alloys are routinely evaluated in order to determine their potential for use in the Army systems and...or platforms. As a result, the purpose of this study was to evaluate the mechanical and electrochemical performance of a MgZn2Y2 alloy with minor Al...subjected to coarse and fine grinding followed by subsequently finer polishing steps starting at 3-µm diamond suspension and finishing with 0.05-µm

  15. Mg++-Stoffwechselkorrelationen als Diagnose und Prognose beim Sport und bei Hypertonikern


    Anhand eines Vergleichs der Daten dreier verschiedener Untersuchungen konnten wir demonstrieren, dass Veränderungen von ionisiertem Magnesium im Blut sowohl mit metabolischen Veränderungen als auch mit diastolischen und systolischen Blutdruckveränderungen korrelieren. Zuerst gelang es darzulegen, dass man imstande ist, durch die Bestimmung von Mg++ zusammen mit pH, Laktat und Leistungspunkten bei einem sportlichen Wettbewerb schon vor dem Bewerb anhand einer Mg++/pH-Korrelation di...

  16. Preparation, microstructure and properties of Al-Zn-Mg-Sc alloy tubes

    何振波; 尹志民; 林森; 邓英; 商宝川; 周向


    The Al-6.0Zn-2.0Mg-0.2Sc-0.10Zr hollow tube ingots, prepared by semi-continuous casting technology, were subjected to ho- mogenization treatment, hot extrusion, intermediate annealing, tension, solution and aging treatment. The microstructures and properties of as-cast Al-Zn-Mg-Sc alloy at different homogenization treatment conditions were studied using hardness measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The results showed th...

  17. Synthesis and structural analysis of a regular Cu-Mg-Al hydrotalcite-like compound

    WU, Jian-Song; XIAO, Ying-Kai; Liu, Yu-ping; XU, Wan-Bang


    A fine-quality, regular Cu-Mg-Al hydrotalcite-like compound was synthesized via the glycothermal method using CuCl2 \\cdot 2H2O, MgCl2 \\cdot 6H2O, AlCl3 \\cdot 6H2O, and Na2CO3 as raw materials and sodium hydroxide as the precipitant. Hydrotalcite samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric-differential thermal analysis, and Brunauer-Emmett-Teller N2 surface ar...

  18. Testing LaMgAl11O19 crystal for X-ray spectroscopy

    Chen, H; Beiersdorfer, P; Baronova, E; Kalashnikova, I; Stepanenko, M


    We investigated the properties of the rare earth crystal LaMgAl{sub 11}O{sub 19} and its application to soft X-ray spectroscopy. Its relative reflectivity and half width rocking curve were measured to up to the reflection order of 28. In addition, a comparative measurement of the iron L-shell soft X-ray line emission was made on the EBIT-I Livermore electron beam ion trap by fielding the LaMgAl{sub 11}O{sub 19} crystal side by side with a rubidium hydrogen phthalate crystal in a flat crystal spectrometer. From these measurements, reflectivity and spectral resolving power were determined.

  19. Li-substituted MgAl2O4 barriers for spin-dependent coherent tunneling

    Scheike, Thomas; Sukegawa, Hiroaki; Mitani, Seiji


    Epitaxial magnetic tunnel junctions (MTJs) with a Li-substituted spinel MgAl2O4 barrier were prepared by sputtering and plasma oxidation of an Mg/LiAl bilayer. The formed MTJ with Fe(001) electrodes showed a relatively large tunnel magnetoresistance (TMR) ratio of 120% (174%) at room temperature (3 K) and two local minima in the tunneling conductance spectra (parallel magnetization), revealing the occurrence of the coherent tunneling effect through the Li-substituted spinel barrier. The results are likely to pave the way for a variety of quaternary spinel oxide barriers in which structural and transport properties of MTJs can be engineered in the coherent tunneling regime.

  20. Electrical transport characterization of Al and Sn doped Mg 2 Si thin films

    Zhang, Bo


    Thin-film Mg2Si was deposited using radio frequency (RF) magnetron sputtering. Al and Sn were incorporated as n-type dopants using co-sputtering to tune the thin-film electrical properties. X-ray diffraction (XRD) analysis confirmed that the deposited films are polycrystalline Mg2Si. The Sn and Al doping concentrations were measured using Rutherford backscattering spectroscopy (RBS) and energy dispersive X-ray spectroscopy (EDS). The charge carrier concentration and the charge carrier type of the Mg2Si films were measured using a Hall bar structure. Hall measurements show that as the doping concentration increases, the carrier concentration of the Al-doped films increases, whereas the carrier concentration of the Sn-doped films decreases. Combined with the resistivity measurements, the mobility of the Al-doped Mg2Si films is found to decrease with increasing doping concentration, whereas the mobility of the Sn-doped Mg2Si films is found to increase.

  1. Self-learning kinetic Monte Carlo simulations of Al diffusion in Mg

    Nandipati, Giridhar; Govind, Niranjan; Andersen, Amity; Rohatgi, Aashish


    Atomistic on-lattice self-learning kinetic Monte Carlo (SLKMC) method was used to examine the vacancy-mediated diffusion of an Al atom in pure hcp Mg. Local atomic environment dependent activation barriers for vacancy-atom exchange processes were calculated on-the-fly using climbing image nudged-elastic band method (CI-NEB) and using a Mg-Al binary modified embedded-atom method (MEAM) interatomic potential. Diffusivities of vacancy and Al atom in pure Mg were obtained from SLKMC simulations and are compared with values available in the literature that are obtained from experiments and first-principle calculations. Al Diffusivities obtained from SLKMC simulations are lower, due to larger activation barriers and lower diffusivity prefactors, than those available in the literature but have same order of magnitude. We present all vacancy-Mg and vacancy-Al atom exchange processes and their activation barriers that were identified in SLKMC simulations. We will describe a simple mapping scheme to map a hcp lattice on to a simple cubic lattice that would enable hcp lattices to be simulated in an on-lattice KMC framework. We also present the pattern recognition scheme used in SLKMC simulations.

  2. Pengaruh Kecepatan Milling Terhadap Perubahan Struktur Mikro Komposit Mg/Al3Ti

    Budi Amin Simanjuntak


    Full Text Available Material yang ringan dan kuat menjadi syarat utama sebagai komponen-komponen otomotif, persenjataan, bahkan peralatan ruang angkasa. Oleh karena itu penelitian tentang material ringan terus-menerus di lakukan oleh masyarakat. Salah satu material yang menjanjikan adalah Metal Matrix composite (MMC yang berbasis magnesium (Mg dan di perkuat oleh partikulat Al3Ti. Pada penelitian kali ini  dilakukan mechanical alloying menggunakan mesin HEM E3D untuk mensintesis Al3Ti yang tersebar pada matriks Mg. Kemudian di kompaksi 4 ton selanjutnya disintering 700oC selama 1 jam untuk membentuk komposit Mg/Al3Ti dengan memvariasikan kecepatan milling mulai dari 700rpm, dan 933rpm dan dengan 20% Al3Ti untuk mencapai  fisik  terbaik dari komposit tersebut. Setelah proses pemaduan selesai, dihasilkan pelet yang kemudian  diuji struktur mikronya  menggunakan Mikroskop elektron, analisa fasa dengan diffraksi sinar-X  dan pengujian massa jenis serta porositas menggunakan prinsip Archimedes Kata Kunci—Mg/Al3Ti ,Komposisi berat, MMC, kecepatan milling

  3. The β Decay of 35Mg and the Structure of 35Al

    Carls, A. B.; Rajabali, M. M.; Ash, J. E.; Griffin Collaboration


    Far from the line of beta-stability, the well described shell structure of nuclei falls apart. Near the N = 20 shell closure lies the ``island of inversion'', an area in which the nuclei exhibit ground states deformed with an intruder configuration. The 35Al nucleus is near this region and whether it belongs to the island is a focus of this study. The experiment to study the β decay of 35Mg was performed at TRIUMF Laboratory. Studying the resulting data provides the information to obtain half-life measurements for 35Mg and 35Al, new level information for 35Al, and provides branching ratios for the feeding of the Si decay chain from Mg. Analyzing the data from the isotope implantation and decay cycles yielded spectra featuring the exponential decay of the nuclei. Fitting this curve will provide the desired half-lives for 35Mg and 35Al. The level scheme for 35Al will be pieced together through a methodical study of the γ - γ coincidences with in a β - γ time difference gate. A detailed description of the methods for eliminating erroneous and unnecessary data will be presented along with the results. This work is funded in part by the Office of Provost and Research Office of Tennessee Tech University.

  4. Effects of Mg and Si ions on the symmetry of δ-AlOOH

    Komatsu, K.; Sano-Furukawa, A.; Kagi, H.


    We conducted powder neutron diffraction for δ-AlOOH samples with and without Mg and Si ions under ambient conditions in order to investigate the long-standing problem of the symmetry of this phase. The observed reflection conditions clearly show that the space group of pure δ-AlOOH is P21 nm with ordered hydrogen bonds, whereas that of δ-(Al0.86Mg0.07Si0.07)OOH is Pnnm or Pnn2 with disordered hydrogen bonds. It is more likely that the space group of δ-(Al0.86Mg0.07Si0.07)OOH is Pnnm, because cation or hydrogen ordering that breaks the mirror plane perpendicular to c axis in the Pnnm structure would not occur. The previously reported inconsistency for the space group of this phase was caused by the substitution of Mg and Si ions to Al site, i.e., the disordered cations with different valences may fluctuate hydrogen positions, and the disordered hydrogen causes the symmetry change.

  5. Hydrolysis Studies and Quantitative Determination of Aluminum Ions Using [superscript 27]Al NMR: An Undergraduate Analytical Chemistry Experiment

    Curtin, Maria A.; Ingalls, Laura R.; Campbell, Andrew; James-Pederson, Magdalena


    This article describes a novel experiment focused on metal ion hydrolysis and the equilibria related to metal ions in aqueous systems. Using [superscript 27]Al NMR, the students become familiar with NMR spectroscopy as a quantitative analytical tool for the determination of aluminum by preparing a standard calibration curve using standard aluminum…

  6. The Microstructure and Compressive Properties of Aluminum Alloy (A356 Foams with Different Al-Ti-B Additions

    Zan ZHANG


    Full Text Available Closed-cell aluminum alloy (A356 foams with different percentages of Al-Ti-B are prepared by melt foaming method, using Ca and TiH2 as thickening agent and foaming agent, respectively. SEM and Quasi-static compression tests are performed to investigate the effect of Al-Ti-B on the microstructure and compressive properties of aluminum alloy (A356 foams. The results show that foams with Al-Ti-B percentage of 0.3 wt.% possess good combinations of micro hardness, yield strength, plateau strength, densification strain and energy absorption capacity under the present conditions. The reasons are mainly due to the foams with Al-Ti-B percentage of 0.3 wt.% possess optimal eutectic Si morphology (with eutectic Si existing in the forms of particles or short fiber.DOI:

  7. The β decay of 34,35Mg and the structure of 34Al

    Rajabali, Mustafa; Griffin Collaboration On Experiment S1367 Team


    Nuclei in the island of inversion, near the N = 20 shell closure, exhibit a fascinating behavior where the nuclear ground states show deformed configurations dominated by particle-hole excitations across the neutron shell gap. The 31-35Mg nuclei are in or at the border of this island displaying intruder ground-state configurations, while the 31-35Al isotopes are suggested to have mixed ground-state configurations of normal and intruder type and thus serve as a transition from intruder dominated Mg isotopes to the normal ground-state configuration in Si isotopes. An experiment was performed at the TRIUMF-ISAC-I facility with the goal of populating states in 33-35Al via the beta decay of 33-35Mg. Mg ions were produced, transported and implanted onto a moving Mylar tape at the center of the GRIFFIN spectrometer. Results obtained from the analysis of the 34,35Mg decay data from this experiment will be presented. This includes the half-lives of 34,35Mg and 34,35Al which clarify current conflicting information in the literature. This work is supported by Tennessee Technological University Research Office, the Canadian Founda- tion for Innovation, the National Research Council of Canada and the Natural Sciences and Engineering Research Council of Canada.

  8. The grain refinement of 6063 aluminum using Al-5Ti-1B and Al-3Ti-0.15C grain refiners

    Moldovan, P.; Popescu, Gabriela


    The Al-Ti-B grain refiners containing boride nucleant particles are used to promote a uniform microstructure throughout aluminum ingots and to suppress the growth of columnar grains. In addition, for the last eight years a new generation of Al-Ti-C grain refiners has been used commercially in a wide range of alloy systems. This paper will compare the potency of the commercially available Al-5Ti-1B grain refiner with that of the Al-3Ti-0.15C grain refiner for the 6063 cast alloy.

  9. Ionizing radiation effects in MgAl sub 2 O sub 4. Efecto de la radiacion ionizante en MgAl2 O4

    Ibarra, A.


    The effect of ionizing radiation in MgAl{sub 2}O{sub 4} has been studied, paying special interest to the influence of the high concentration of intrinsic defects of this material. Optical absorption, ESR, photoluminescence, radioluminescence, and thermoluminescence are the main techniques used. The ionizing radiation induces formation of V centres. During the work its characteristics (structure, thermal stability, absorption spectra, etc.) has been studied. The thermoluminescence spectra allowed the discovery of several charge release processes between 85 and 650 K, all of them associated to electron release. The V-centres and several impurities (Cr, Mn,...) appear as recombination centres. The obtained data show that the kinetic of these charge release processes is regulated by the presence of a point defect with a very high concentration. This defect is an electron trap and its structure is an Al ion in a lattice site of tetrahedral symmetry. (Author)

  10. The influence of heat treatment on properties of three-metal explosion joint: AlMg-Al-Steel

    I. Samardžić; Mateša, B.; I. Kladarić


    The procedure of welding by explosion is as technical optimal solution of ship-shell parts joining frequently used in shipbuilding industry at transition three-metal joint: AlMg4.5-Al-St.52-3 working out. The investigations of mechanical and metallographic properties of joints, exposed on heat treatment at different temperatures levels, are performed. The results of mechanical and metallographic examinations of transition joints at elevated temperatures, direct on its use below 300 °C. The ad...

  11. The influence of heat treatment on properties of three-metal explosion joint: AlMg-Al-Steel

    I. Samardžić


    Full Text Available The procedure of welding by explosion is as technical optimal solution of ship-shell parts joining frequently used in shipbuilding industry at transition three-metal joint: AlMg4.5-Al-St.52-3 working out. The investigations of mechanical and metallographic properties of joints, exposed on heat treatment at different temperatures levels, are performed. The results of mechanical and metallographic examinations of transition joints at elevated temperatures, direct on its use below 300 °C. The additional melting welding working out is in closeness of explosion- welded joint allowed.

  12. Effects of Al and Sn on electrochemical properties of Mg-6%Al-1%Sn (mass fraction) magnesium alloy as anode in 3.5%NaCl solution

    黄俏; 余琨; 杨士海; 文利; 戴翼龙; 乔雪岩


    Mg-6%Al-1%Sn (mass fraction) alloy is a newly developed anode material for seawater activated batteries. The electrochemical properties of Mg-1%Sn, Mg-6%Al and Mg-6%Al-1%Sn alloys are measured by galvanostatic and potentiodynamic tests. Scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) is used to characterize the microstructures of the experimental alloys. The results show that the Mg-6%Al-1%Sn alloy obtains more negative discharge potential (−1.38 V (vs SCE)) in hot-rolled condition. This is attributed to the fine dynamically recrystallized grains during the hot rolling process. After the experimental alloys are annealed at 473 K for 1 h, the discharge potentials of Mg-6%Al-1%Sn alloy are more negative than those of Mg-6%Al alloy under different current densities. After annealing at 673 K, the discharge potentials of Mg-6%Al-1%Sn alloy become more positive than those of Mg-6%Al alloy. Such phenomenon is due to the coarse grains and the second phase Mg2Sn. The discharge potentials of Mg-1%Sn shift positively obviously in the discharge process compared with Mg-6%Al-1%Sn alloy. This is due to the corrosion products pasting on the discharge surface, which leads to anode polarization.

  13. Synthesis of high-surface-area spinel-type MgAl$_2$O$_4$ nanoparticles by [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] and [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O: influence of inorganic precursor type


    Spinel-type MgAl$_2$O$_4$ nanoparticles with high surface area were synthesized by thermal decomposition of three different ion-pair complexes precursors, including [Mg(H$_2$O)$_6$][Al(dipic)$_2$]$_2$·6H$_2$O, [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] and [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O. Influence of the inorganic precursor was investigated on synthesis and textural properties of magnesium aluminate nanopowders. The precursors [Mg(H$_2$O)$_6$][Al(dipic)$_2$]$_2$·6H$_2$O and [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] displayed pure spinel-type MgAl$_2$O$_4$, while the sample synthesized by [Mg(H$_2$O)$_6$][Al(ox)$_2$(H$_2$O)$_2$]$_2$·5H$_2$O precursor consisted of MgAl$_2$O$_4$ and MgO. The MgAl$_2$O$_4$ synthesizedvia [Al(sal)$_2$(H$_2$O)$_2$]$_2$[Mg(dipic)$_2$] precursor exhibited higher BET specific surface area (226.7 m$^2$ g$^{−1}$) and smaller particle size than those of the samples obtained from the two other precursors.

  14. Influence of Aluminum on the Formation Behavior of Zn-Al-Fe Intermetallic Particles in a Zinc Bath

    Park, Joo Hyun; Park, Geun-Ho; Paik, Doo-Jin; Huh, Yoon; Hong, Moon-Hi


    The shape, size, and composition of dross particles as a function of aluminum content at a fixed temperature were investigated for aluminum added to the premelted Zn-Fe melt simulating the hot-dip galvanizing bath by a sampling methodology. In the early stage, less than 30 minutes after Al addition, local supersaturation and depletion of the aluminum concentration occurred simultaneously in the bath, resulting in the nucleation and growth of both Fe2Al5Zn x and FeZn13. However, the aluminum was homogenized continuously as the reaction proceeded, and fine and stable FeZn10Al x formed after 30 minutes. An Al-depleted zone (ADZ) mechanism was newly proposed for the "η→η+ζ→δ" phase transformations. The ζ phase bottom dross partly survived for a relatively long period, i.e., 2 hours in this work, whereas the η phase disappeared after 30 minutes. In the early stage of dross formation, both Al-free large particles as well as high-Al tiny particles were formed. The dross particle size decreased slightly with increased reaction time before reaching a plateau. The opposite tendency was observed when the Al content was 0.130 mass pct; with a relatively high Al content, the nucleation of tiny η phase dross was significantly enhanced because of the high degree of supersaturation. This unstable η phase dissolved continuously and underwent simple transformation to the stable δ phase. The relationship between nucleation potential and supersaturation ratio of species is discussed based on the thermodynamics of classical nucleation theory.

  15. The Designation Method of Bend Forming Dies for Aluminum Tube of PE-Al-PE Composite Pipe


    The PE-Al-PE composite pipe is a multiplayer pipe t hat is composed of PE (polyethylene) and Aluminum. Al is inlayed the inner PE la yer and the outer PE layer. In the producing technological process of this kind of pipe the bend forming of Al belt to tube is very important. It is the bend fo rming dies that are used in the process of producing PE-Al-PE pipe that is stu died in this article. To make a elaborate division, these dies can be classified as bending dies and forming dies here. In this paper, t...

  16. Mg/O2 Battery Based on the Magnesium-Aluminum Chloride Complex (MACC) Electrolyte

    Vardar, Galin; Smith, Jeffrey G.; Thomson, Travis


    rechargeability in these systems is severely limited. The Mg/O2-MACC/DME discharge product comprises a mixture of Mg(ClO4)2 and MgCl2, with the latter likely formed from slow decomposition of the former. The presence of Cl in these compounds suggests that the electrolyte participates in the cell reaction...... or reacts readily with the initial electrochemical products. A rate study suggests that O2 diffusion in the electrolyte limits discharge capacities at higher currents. Formation of an insulating product film on the positive electrodes of Mg/O2-MACC/DME cells following deep discharge increases cell impedance......Mg/O2 cells employing a MgCl2/AlCl3/DME (MACC/DME) electrolyte are cycled and compared to cells with modified Grignard electrolytes, showing that performance of magnesium/oxygen batteries depends strongly on electrolyte composition. Discharge capacity is far greater for MACC/DME-based cells, while...

  17. Coating of 6028 Aluminum Alloy Using Aluminum Piston Alloy and Al-Si Alloy-Based Nanocomposites Produced by the Addition of Al-Ti5-B1 to the Matrix Melt

    El-Labban, Hashem F.; Abdelaziz, M.; Mahmoud, Essam R. I.


    The Al-12 pctSi alloy and aluminum-based composites reinforced with TiB2 and Al3Ti intermetallics exhibit good wear resistance, strength-to-weight ratio, and strength-to-cost ratio when compared to equivalent other commercial Al alloys, which make them good candidates as coating materials. In this study, structural AA 6028 alloy is used as the base material. Four different coating materials were used. The first one is Al-Si alloy that has Si content near eutectic composition. The second, third, and fourth ones are Al-6 pctSi-based reinforced with TiB2 and Al3Ti nano-particles produced by addition of Al-Ti5-B1 master alloy with different weight percentages (1, 2, and 3 pct). The coating treatment was carried out with the aid of GTAW process. The microstructures of the base and coated materials were investigated using optical microscope and scanning electron microscope equipped with EDX analyzer. Microhardness of the base material and the coated layer were evaluated using a microhardness tester. GTAW process results in almost sound coated layer on 6028 aluminum alloy with the used four coating materials. The coating materials of Al-12 pct Si alloy resulted in very fine dendritic Al-Si eutectic structure. The interface between the coated layer and the base metal was very clean. The coated layer was almost free from porosities or other defects. The coating materials of Al-6 pct Si-based mixed with Al-Ti5-B1 master alloy with different percentages (1, 2, and 3 pct), results in coated layer consisted of matrix of fine dendrite eutectic morphology structure inside α-Al grains. Many fine in situ TiAl3 and TiB2 intermetallics were precipitated almost at the grain boundary of α-Al grains. The amounts of these precipitates are increased by increasing the addition of Al-Ti5-B1 master alloy. The surface hardness of the 6028 aluminum alloy base metal was improved with the entire four used surface coating materials. The improvement reached to about 85 pct by the first type of

  18. Thermodynamic properties and mixing thermodynamic parameters of Ba-Al, Mg-Al, Sr-Al and Cu-Al metallic melts



    Application of equations of mixing thermodynamic parameters formulated on the basis of the coexistence theory of metallic melts in Ba-Al, Mg-Al, Sr-A1 and Cu-Al melts leads to fruitful results that not only the evaluated mass action concentrations agree well with the measured activities, but also the calculated mixing thermodynamic parameters are quite coincident with the experimental values. Moreover, the calculated mass action concentrations strictly obey the mass action law. The evaluated mixing thermodynamic parameters have very fine regularity: the mixing free energy is composed of standard free formation energies of all compounds and chemical potentials of all structural units at equilibrium; the mixing enthalpy consists of standard formation enthalpies of all compounds; the mixing entropy is composed of standard entropies of all compounds and configuration entropies of all structural units at equilibrium. As the equations of mixing thermodynamic parameters formulated are widely applicable to metallic melts involving compound formation, they can be used as the second practical criterion to determine whether thermodynamic models of metallic melts are correctly formulated.

  19. Magnetoelectric effect in ytterbium aluminum borate YbAl3(BO3)4

    Ivanov, V. Yu.; Kuzmenko, A. M.; Mukhin, A. A.


    The anisotropic magnetoelectric properties of an ytterbium aluminum borate YbAl (BO single crystal having noncentrosymmetric crystal structure (space group R32) are studied, including the orientational, field, and temperature dependences of the polarization in magnetic fields up to 5 T in the temperature range of 2-300 K. It has been shown experimentally for the first time that the symmetry of the observed magnetoelectric effects exactly corresponds to the trigonal structure of the crystal and is characterized by two quadratic magnetoelectric constants. The polarization in the basal plane P a, b is a quadratic function of the field at low fields and reaches 250-300 μC/m2 in a field of 5 T at a temperature of 2 K, almost an order of magnitude exceeding the previously reported values. A theoretical model based on the spin Hamiltonian of the ground Kramers doublet of Yb3+ ions in the crystal field is proposed including magnetoelectric interactions allowed by the symmetry. This model makes it possible to quantitatively describe all observed magnetic and magnetoelectric properties of YbAl3(BO3)4.

  20. Analysis of hardness of nanocrystalline coatings of aluminum-rich Ti1−AlN

    J Hernández-Torres; L García-González; L Zamora-Peredo; T Hernández-Quiroz; A Sauceda-Carvajal; P J García-Ramírez; N Flores-Ramírez


    Titanium aluminum nitride coatings were fabricated by a d.c.magnetron sputtering system from a Ti–Al (60/40wt%) target. Coatings were deposited on steel substrates, at a substrate temperature of 250 °C and a bias voltage of –80 V. The nitrogen flow was varied from 1.5–6 sccm and the Ar flow was kept constant at 20 sccm. The morphology and microstructure of the coatings were analysed by X-ray diffraction and scanning electron microscopy. The results of X-ray diffraction showed the presence of two cubic crystalline phases, TiN and AlN, which were confirmed by X-ray photoelectron spectroscopy. The Vicker hardness was obtained by the effective model of indentation. It was observed that the hardness of the coatings decreases from 22.8–9.5 GPa with an increased nitrogen content from 1.5–4.5 sccm. Subsequently, the hardness increased to 22.1 GPa by increasing nitrogen to 6 sccm. The behavior of hardness with grain size variation is consistent with the Hall-Peth relationship. The high value in the hardness of the coatings is mainly attributed to small grain sizes and the compressive stress present.

  1. Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy


    The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

  2. Significantly enhanced hydrogen desorption properties of Mg(AlH42 nanoparticles synthesized using solvent free strategy

    Xuezhang Xiao


    Full Text Available Mg(AlH42 nanoparticles with a particle size less than 10 nm have been successfully synthesized by mechanochemical method using LiAlH4 and MgCl2 as raw materials together with LiCl buffering additive. In comparison to Mg(AlH42 microparticles, Mg(AlH42 nanoparticles exhibit a faster hydrogen desorption kinetics and lower desorption temperature. The hydrogen desorption temperatures of the first and second dehydrogenation steps are 80 and 220 °C for the Mg(AlH42 nanoparticles, which are about 65 and 60 °C, respectively, lower than those of Mg(AlH42 microparticles. The decomposition activation energy is reduced from 135 kJ/mol for Mg(AlH42 microparticles to 105.3 kJ/mol for Mg(AlH42 nanoparticles. It is proposed that the shortened diffusion distance and enhanced diffusivity of Mg(AlH42/MgH2 nanoparticles provide an energy destabilization for lowering the dehydrogenation temperature, and thus being the key factor for promoting the hydrogen desorption kinetics. More importantly, it is demonstrated that the dehydrided nano MgH2 hydride with a particle size below 10 nm can be formed after rehydrogenation process, resulting in the good cycling hydrogen desorption performance of nano MgH2.

  3. Bias voltage effects on tunneling magnetoresistance in Fe/MgAl2O4/Fe (001 ) junctions: Comparative study with Fe/MgO/Fe(001) junctions

    Masuda, Keisuke; Miura, Yoshio


    We investigate bias voltage effects on the spin-dependent transport properties of Fe/MgAl 2O 4 /Fe(001) magnetic tunneling junctions (MTJs) by comparing them with those of Fe/MgO/Fe(001) MTJs. By means of the nonequilibrium Green's function method and the density functional theory, we calculate bias voltage dependencies of magnetoresistance (MR) ratios in both the MTJs. We find that in both the MTJs, the MR ratio decreases as the bias voltage increases and finally vanishes at a critical bias voltage Vc. We also find that the critical bias voltage Vc of the MgAl 2O 4 -based MTJ is clearly larger than that of the MgO-based MTJ. Since the in-plane lattice constant of the Fe/MgAl 2O 4 /Fe(001) supercell is twice that of the Fe/MgO/Fe(001) one, the Fe electrodes in the MgAl 2O 4 -based MTJs have an identical band structure to that obtained by folding the Fe band structure of the MgO-based MTJs in the Brillouin zone of the in-plane wave vector. We show that such a difference in the Fe band structure is the origin of the difference in the critical bias voltage Vc between the MgAl 2O 4 - and MgO-based MTJs.

  4. Synthesis, structure and photocatalytic activity of calcined Mg-Al-Ti-layered double hydroxides

    Hosni, Khaled; Abdelkarim, Omar; Srasra, Ezzeddine [Centre National des Recherches en Sciences des Matériaux (CNRSM), Soliman (Turkey); Frini-Srasra, Najoua [Faculté des Sciences de Tunis (FST), Tunis (Turkey)


    Mg-Al-Ti layered double hydroxides (LDH), consisting of di-, tri- and tetra-valent cations with different Al{sup 3+}/Ti{sup 4+} ratio, have been synthesized by co-precipitation which was demonstrated as efficient visible-light photocatalysts. The structure and chemical composition of the compound were characterized by PXRD, FT-IR, SAA, N{sub 2} adsorption-desorption isotherms, and DSC techniques. It is found that no hydrotalcites structure were formed for Ti{sup 4+}/(Ti{sup 4+}+ Al{sup 3+})>0.5 and the substitution of Ti(IV) for Al(III) in the layer increases the thermal stability of the resulting LDH materials. The calcined sample containing titanium showed relatively high adsorption capacity for MB as compared to that without titanium. Results show that the pseudo-second-order kinetic model and the Langmuir were found to correlate the experimental data well. The photocatalytic activity was evaluated for the degradation of the methylene blue. The photocatalytic activity increased with the increase of the Al/Ti cationic ratio. 71% of the dye could be removed by the Mg/Al/Ti-LDH with the cationic ratio Al/Ti=0 : 1 and calcined at 500 .deg. C.

  5. Investigation on the Combustion Behavior of CMDB Propellant with Mg/Al Alloy%Mg/Al合金对CMDB推进剂燃烧性能的影响

    吴雄岗; 宋桂贤; 严启龙; 李笑江; 党永战; 张晓宏


    The particle size and distribution of particle size of Mg/Al were analyzed by Mastersizer. The thermal characterisitics of CDMB propellant were analyzed by TG-DSC. The flame structure was studied by using the burning device and the differences of the flame structure were compared amongst CMDB, Al-CMDB, Mg-CMDB and Mg/Al-CMDB propellants. The surface appearance of the propellant quenched and surface composition were researched by the SEM and EDS. The results show that the Mg/Al alloy has a peak 630.3℃ of the heat of CMDB propellant. The combustion condition of CMDB propellant with Mg/Al is changed. Meanwhile,the metallic Al fuel combustion efficiency is improved.%通过激光粒度仪分析了Mg/Al合金粉的粒径及粒度分布。利用TG-DSC热分析仪分析推进剂的热分解特性。用燃烧实验装置研究了推进剂的火焰结构,并对CMDB,Al-CMDB,Mg-CMDB和Mg/Al-CMDB推进剂四种火焰结构进行比较。用SEM和EDS研究了CMDB推进剂的熄火表面形貌和表面特征组成。结果表明:Mg/Al-CM-DB推进剂在DSC曲线上存在一放热峰660.3℃。Mg/Al合金粉改变了推进剂的燃烧状态,提高金属燃料Al粉的燃烧效率。

  6. Warm deep-drawing and post drawing analysis of two Al-Mg-Si alloys

    Ghosh, M.; Miroux, A.; Werkhoven, R.J.; Bolt, P.J.; Kestens, L.A.I.


    The increasing use of aluminium alloys in light weight structural applications is restricted mainly due to their lower room temperature formability compared to steels. Forming at higher temperature is seen as a promising solution to this problem. In the present investigation two Al-Mg-Si alloys (EN

  7. Mechanical properties and microstructure of laser treated Al-Cu-Mg alloys

    Hosson, J.Th.M. De; Noordhuis, J.


    The mechanical properties and microstructural features of Al-Cu-Mg alloys were investigated, as exposed to laser treatments at various scan velocities. As far as the mechanical property is concerned a striking observation is a minimum in the hardness value at a laser scan velocity of 1/2 cm/s. Usual

  8. Texture and grain structure of Al-Li-Mg-Zr-Sc alloy sheets

    Fridlyander, J.N.; Kolobnev, N.I.; Khokhlatova, L.B. [All-Russian Inst. of Aviation Mater., Moscow (Russian Federation); Berezina, A.L.; Katko, A.V.; Haszler, A.; Keidel, C.


    Change of a grain structure nature, of crystallographic texture and of a phase composition in dependence of thermal-mechanical parameters of sheets manufacture was shown with X-ray and electron-microscopic investigations of Al-Li-Mg-Zr-Sc sheets. (orig.)

  9. Effect of solution heat treatment time on a rheocast Al-Zn-Mg-Cu alloy

    Mazibuko, NE


    Full Text Available During rheo-high pressure die casting (R-HPDC) of Al-Zn-Mg-Cu alloys a coarse eutectic phase is formed. This eutectic phase is difficult to take into solution because of its size and it would require longer solution heat treatment times...

  10. Mechanical properties and microstructure of laser treated Al-Cu-Mg alloys

    Hosson, J.Th.M. De; Noordhuis, J.


    The mechanical properties and microstructural features of Al-Cu-Mg alloys were investigated, as exposed to laser treatments at various scan velocities. As far as the mechanical property is concerned a striking observation is a minimum in the hardness value at a laser scan velocity of 1/2 cm/s.

  11. The stabilities and electron structures of Al-Mg clusters with 18 and 20 valence electrons

    Yang, Huihui; Chen, Hongshan


    The spherical jellium model predicts that metal clusters having 18 and 20 valence electrons correspond to the magic numbers and will show specific stabilities. We explore in detail the geometric structures, stabilities and electronic structures of Al-Mg clusters containing 18 and 20 valence electrons by using genetic algorithm combined with density functional theories. The stabilities of the clusters are governed by the electronic configurations and Mg/Al ratios. The clusters with lower Mg/Al ratios are more stable. The molecular orbitals accord with the shell structures predicted by the jellium model but the 2S level interweaves with the 1D levels and the 2S and 1D orbitals form a subgroup. The clusters having 20 valence electrons form closed 1S21P61D102S2 shells and show enhanced stability. The Al-Mg clusters with a valence electron count of 18 do not form closed shells because one 1D orbital is unoccupied. The ionization potential and electron affinity are closely related to the electronic configurations; their values are determined by the subgroups the HOMO or LUMO belong to. Supplementary material in the form of one pdf file available from the Journal web page at http://

  12. Hydrothermal Synthesis and Characterization of 3R Polytypes of Mg-Al Layered Double Hydroxides

    Budhysutanto, W.N.


    Layered Double Hydroxides (LDH) is a unique group of clays that have an anionic exchange capability. This research explored the hydrothermal method as an alternative method to synthesize Mg-Al LDH. It is a simple and more environmentally friendly compared to the conventional method of co-precipitati

  13. Warm deep-drawing and post drawing analysis of two Al-Mg-Si alloys

    Ghosh, M.; Miroux, A.; Werkhoven, R.J.; Bolt, P.J.; Kestens, L.A.I.


    The increasing use of aluminium alloys in light weight structural applications is restricted mainly due to their lower room temperature formability compared to steels. Forming at higher temperature is seen as a promising solution to this problem. In the present investigation two Al-Mg-Si alloys (EN

  14. Studies on Synthesis and Properties of Mg-Al-nitrate Layered Double Hydroxides


    A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprccipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the positive nanoparticle were studied by SEM, XRD, FTIR,chemical analysis, spectroanalysis and measuring of electrophoretic mobilities. Preliminary results show the positive nanopartiele is a promising precursor ofpolymer/LDHs nanocomposite.

  15. Localized corrosion mechanism associated with precipitates containing Mg in Al alloys


    To clarify the localized corrosion mechanism associated with precipitates containing Mg in Al alloys, the simulated bulk precipitates of S and β were synthesized through melting and casting. Their electrochemical behaviors and coupling behaviors with α(Al) in NaCl solution were measured. Meanwhile, simulated Al alloys containing S and β particles were prepared and their corrosion morphologies were observed. It's found that there exist two kinds of corrosion mechanisms associated with precipitates containing Mg. The precipitate of β is anodic to the alloy base, resulting in its anodic dissolution and corrosion during the whole corrosion process. While, there exists a corrosion conversion mechanism associated with the S precipitate, which contains active element Mg and noble element Cu simultaneously. At an initial stage, S is anodic to the alloy matrix at its periphery and the corrosion occurs on its surface. However, during its corrosion process, Mg is preferentially dissolved and noble Cu is enriched in the remnants.This makes S become cathodic to α(Al) and leads to anodic dissolution and corrosion on the alloy base at its periphery at a later stage.

  16. Development of a Master Sintering Curve for Al-Mg Alloy

    Yong-Shin Lee


    Full Text Available A new master sintering curve (MSC is proposed for Al-Mg alloy in order to effectively design the pressure-assisted sintering process. In this work, hot pressing experiments of Al-Mg alloy powders are performed. The changes of relative density during hot pressing are measured for the various heating rates of 5°C/min, 10°C/min, and 20°C/min at the fixed pressure of 50 MPa. A work of sintering, designated as Θ, is introduced and defined as Θ(t,T=∫0t1/Texp-Q/RTdt. A work of sintering, Θ, could be interpreted as a measure for the amount of sintering work. The MSC in this work defines the relation between the apparent density and a work of sintering, Θ. Since the measurement of an apparent activation energy, Q, is very difficult, the correct value of Q is obtained numerically using a mean residual square method. Then, the master sintering curves for sintering of Al-Mg alloy powders are proposed for the sintering temperatures of 400°C and 500°C through scaling procedures. It is expected that the master sintering curves proposed in this work could help an engineer to design pressure-assisted sintering process for Al-Mg alloy.

  17. Aluminum nitrate (Al(NO3)3) as defluoridating agent in drinking water soil pots (vessels of earthenware).

    Yadav, R N; Yadav, Rajdeep


    Presence of fluoride in drinking water above (and sometimes even below) permissible limit (1.5 ppm according to WHO) leads to fluorosis. Aluminum salts are commonly used as coagulants in water treatments. Aluminum fluoride is less toxic than other fluorides. The concentration of fluoride was determined by the fluoride ion selective electrode method. In this study, Al (NO3)3 was incorporated in different amounts in soil and prepared soil pots by the mixture. It is observed that these soil pots remarkably decrease the concentration of fluoride in drinking water. Langmuir and Freundlich isotherm studies were also carried out.

  18. Dynamic Wetting of CaO-Al2O3-SiO2-MgO Liquid Oxide on MgAl2O4 Spinel

    Abdeyazdan, Hamed; Dogan, Neslihan; Rhamdhani, M. Akbar; Chapman, Michael W.; Monaghan, Brian J.


    Inclusion type and content in steel is critical in steelmaking, affecting both productivity through clogging, and downstream physical properties of the steel. They are normally removed from steel by reacting with a slag (liquid oxide) phase. For efficient inclusion removal, the inclusions must attach/bond with this liquid phase. The strength of the attachment can be in part characterized by the wettability of the liquid oxide on the inclusions. In this study, the dynamic wetting of liquid oxides of the CaO-Al2O3-SiO2-MgO system on a solid spinel (MgAl2O4) substrate with low porosity of 1.9 pct was measured at 1773 K (1500 °C) using a modified sessile drop technique. The dynamic contact angle between the liquid and solid spinel was determined for different CaO/Al2O3 mass percent ratios ranging from 0.98 to 1.55. Characteristic curves of wettability ( θ) vs time showed a rapid decrease in wetting in the first 10 seconds tending to a plateau value at extended times. A mathematical model for spreading behavior of liquid oxides by Choi and Lee was adopted and shown to provide a reasonable representation of the spreading behavior with time. The chemical interaction at the interface between spinel (MgAl2O4) and slag was analyzed by carrying out detailed thermodynamic evaluation and characterization using scanning electron microscopy/energy dispersive spectroscopy. There is evidence of liquid penetrating the substrate via pores and along grain boundaries, forming a penetration layer in the substrate. The depth of the penetration layer was found to be a function of substrate porosity and sample cooling rate. It decreased from ~350 µm for 6.7 pct-porous substrate to ~190 µm for substrate with porosity of 1.9 pct and from ~190 µm to ~50 µm for a slow-cooled liquid oxide-spinel substrate sample in the furnace to a rapidly cooled liquid cooled-spinel substrate sample, respectively.

  19. Mechanical behavior of Al-Mg-Si alloys reinforced with ceramic and intermetallic particles

    Costa, C.E. da [Dept. de Ingenieria Mecanica y de Materiales, Univ. Politecnica de Valencia (Spain); Martinez, N.; Amigo, V.; Salvador, M.D. [Univ. do Estado de Santa Catarina, Centro de Ciencias Tecnologicas, Dept. Ingenieria Mecanica, Joinville (Brazil)


    Aluminum matrix composites (AMCs) reinforced with ceramic and Ti-Al intermetallic particles were prepared in the laboratory by following a powder metallurgy route. Hot extrusion was used as consolidation processes. Different studies were carried out in the composites developed. The influence of production process was also estimated. To evaluate interfaces and possible reaction products between the matrix and reinforcement, heat treatments regarding time were carried out. Tests were developed in fabricated AMCs and in unreinforced aluminum matrix, to evaluate influence of reinforcement type. In this study, optical and scanning electron microscopy with X-ray microanalysis, were used to determine the possible reaction products in the matrix/reinforcement interface and its composition. Ultimate strength and strain to failure were studied. There were performed tests at room temperature and at high temperature of the material in different precipitation state. The type of damage was analyzed by scanning electron microscopy. Ultimate strength trends to grow with reinforcement addition in both T1 and T6 conditions for low temperature. Strain to failure remains the lowest on T6 state. The effect of reinforcement addition decrease for high temperature testing and matrix influence was demonstrated. (orig.)

  20. Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

    Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.


    Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial......-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher...... temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg(60)CU(30)Y(10) specimen was determined experimentally by a combination of DSC data and temperature vs, time...

  1. 26Al-26Mg systematics in chondrules from Kaba and Yamato 980145 CV3 carbonaceous chondrites

    Nagashima, Kazuhide; Krot, Alexander N.; Komatsu, Mutsumi


    We report the mineralogy, petrography, and in situ measured 26Al-26Mg systematics in chondrules from the least metamorphosed CV3 (Vigarano-type) chondrites, Kaba and Yamato (Y) 980145. Two Y 980145 chondrules measured show no resolvable excesses in 26Mg (26Mg∗), a decay product of a short-lived (t1/2 ∼0.7 Ma) radionuclide 26Al. Plagioclase in one of the chondrules is replaced by nepheline, indicative of thermal metamorphism. The lack of 26Mg∗ in the Y 980145 chondrules is most likely due to disturbance of their 26Al-26Mg systematics during the metamorphism. Although Kaba experienced extensive metasomatic alteration (core in this body suggested from the paleomagnetic records of Allende [Carporzen et al. (2011) Magnetic evidence for a partially differentiated carbonaceous chondrite parent body. Proc. Natl. Acad. Sci. USA108, 6386-6389] and Kaba [Gattacceca et al. (2013) More evidence for a partially differentiated CV parent body from the meteorite Kaba. Lunar Planet. Sci.44, abstract#1721].

  2. Corrosion Behavior of Mg-Al/TiC Composites in NaCl Solution

    L. A. Falcon


    Full Text Available The corrosion behavior of TiC particles reinforced Mg-Al alloy in 3.5% NaCl solution has been evaluated using electrochemical techniques. Tested alloys included an Mg-9Al (Mg AZ91E alloy with and without 56 wt. % TiC particles. Electrochemical techniques included potentiodynamic polarization curves, linear polarization resistance, electrochemical noise, and electrochemical impedance spectroscopy measurements. All techniques showed that the composite exhibited a lower corrosion rate than the base alloy. Evidence of galvanic effects that increased the composite corrosion rate was found between the matrix and the TiC particles. Additionally, the tendency to suffer from pitting corrosion was higher for the base alloy than that for the composite. Electrochemical impedance results showed the importance of adsorption/diffusion phenomena in both materials.

  3. Effect of Al content and pressing temperature on ECAP of cast Mg alloys

    Chang, S.Y. [Dept. of Materials Engineering, Hankuk Aviation Univ., Koyang, Kyunggi-do (Korea); Lee, K.S.; Shin, D.H. [Dept. of Metallurgy and Materials Science, Hanyang Univ., Ansan, Kyunggi-do (Korea); Lee, S.H. [Div. of Advanced Materials Science and Engineering, Mokpo National Univ. (Korea); Hong, S.K. [Dept. of Metallurgical Engineering, Chonnam National Univ., Kwangju (Korea); Park, K.T. [Div. of Advanced Materials Science and Engineering, Hanbat National Univ., Taejon (Korea)


    The difficult-to-work Mg alloys was subjected to equal channel angular pressing (ECAP) under a condition of various pressing temperatures. Pure Mg was susceptible to shear localization during ECAP; surface cracking occurred along to the direction of shear localization at lower temperatures than 573 K. Uniform flow occurred at 573 K, resulting in the successful 4 repetitive ECAP. The ECAP of Mg alloys containing Al (AZ series alloys) was unsuccessful at even higher temperature than 573 K. However, the ECAP temperature of AZ series alloys hot-rolled before ECAP became lowered, and the temperature for successful ECAP decreased with decreasing Al content. In particular, the hot-rolled AZ31 alloy could be ECAPed at 493 K. The ECAPed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10 {mu}m. The deformation during ECAP was analyzed by dislocation characteristics. (orig.)


    Z.M.Zhang; T.Lū; C.J.Xu; X.F.Guo


    Directionally solidified binary Mg-Al eutectic alloy wires of approximately 5 mm in diameter were produced by the Ohno continuous casting (OCC) process and the mi-crostructure was examined.It was found that the wires possess obvious unidirectional growth characteristic along its axial direction.The microstructure consists of parallel columnar grains that resulted from the competitive growth of equiaxed grains solidified on the head of dummy bar.Each columnar grain comprises regular eutectic α-Mg and β-Mg17 Al12 phases,which grew along the axial direction of the wires.The morphology of the eutectic is mainly lameUar,meanwhile rod eutectic exists.The formation of rod eutectic was attributed to the "bridging effect" caused by incidental elements in the alloy.

  5. Low Cycle Mechanical and Fatigue Properties of AlZnMgCu Alloy

    Pysz S.


    Full Text Available The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075 was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.

  6. Improvement of warm formability of Al-Mg sheet alloys containing coarse second-phase particles

    HanLiang ZHU; Arne K DAHLE; Amit K GHOSH


    Several alloying elements involving Zr, Cu, Zn and Sc were added to AI-Mg sheet alloys in order to obtain an excellent combination of high strength and good high-temperature formability. Microstruc-tural examination showed that coarse intermetallic particles were formed in the microstructure and their amounts changed with variations of the alloying elements. During warm rolling of thermome-chanical treatments prior to warm deformation, the coarse particles initiated cracks, decreasing the warm formability. For healing the crack damage and further improving the warm formability, a process of hot isothermal press was developed and optimized to the sheet alloys. With this process, the biaxial stretch formability at 350"(2 was improved by 22% for an aluminum alloy containing a large amount of coarse particles.

  7. Silicon reduces aluminum accumulation in rats: relevance to the aluminum hypothesis of Alzheimer disease.

    Bellés, M; Sánchez, D J; Gómez, M; Corbella, J; Domingo, J L


    In recent years, a possible relation between the aluminum and silicon levels in drinking water and the risk of Alzheimer disease (AD) has been established. It has been suggested that silicon may have a protective effect in limiting oral aluminum absorption. The present study was undertaken to examine the influence of supplementing silicon in the diet to prevent tissue aluminum retention in rats exposed to oral aluminum. Three groups of adult male rats were given by gavage 450 mg/kg/day of aluminum nitrate nonahydrate 5 days a week for 5 weeks. Concurrently, animals received silicon in the drinking water at 0 (positive control), 59, and 118 mg Si/L. A fourth group (-Al, - Si) was designated as a negative control group. At the end of the period of aluminum and silicon administration, urines were collected for 4 consecutive days, and the urinary aluminum levels were determined. The aluminum concentrations in the brain (various regions), liver, bone, spleen, and kidney were also measured. For all tissues, aluminum levels were significantly lower in the groups exposed to 59 and 118 mg Si/L than in the positive control group; significant reductions in the urinary aluminum levels of the same groups were also found. The current results corroborate that silicon effectively prevents gastrointestinal aluminum absorption, which may be of concern in protecting against the neurotoxic effects of aluminum.

  8. Laser Brazing of Aluminum with a New Filler Wire AlZn13Si10Cu4

    Tang, Z.; Seefeld, T.; Vollertsen, F.

    Laser brazing processes of aluminum with both single beam and double beam techniques were developed using a new AlZn13Si10Cu4 filler wire which has a lower solidification range comparing to normal AlSi12 filler wire and the base material. Brazing experiments on both bead on plate and flange joints showed that the new wire has a very good wettability on the aluminum samples. Comparing to the AlSi12 wire one needs a lower heat input (in some cases 73% less heat input) for joining the same samples with the new filler wire and reaches a high hardness value in the joint. In addition, brazing with double beam technique showed its potential to increase the joint quality.

  9. Low-energy resonances in sup 25 Mg(p,. gamma. ) sup 26 Al, sup 26 Mg(p,. gamma. ) sup 27 Al and sup 27 Al(p,. gamma. ) sup 28 Si

    Iliadis, C.; Schange, T.; Rolfs, C.; Schroeder, U.; Somorjai, E.; Trautvetter, H.P.; Wolke, K. (Muenster Univ. (Germany, F.R.). Inst. fuer Kernphysik); Endt, P.M.; Kikstra, S.W. (Rijksuniversiteit Utrecht (Netherlands). Robert van de Graaff Lab.); Champagne, A.E. (Princeton Univ., NJ (USA). Dept. of Physics); Arnould, M.; Paulus, G. (Universite Libre de Bruxelles (Belgium). Inst. d' Astronomie et d' Astrophysique)


    Gamma-ray decay schemes have been measured with bare and Compton-suppressed Ge detectors at low-energy resonances (E{sub p}<340 keV) in the (p, {gamma}) reactions on {sup 25}Mg, {sup 26}Mg and {sup 27}Al. Althogether 58 new decay branches have been observed and a new {sup 26}Mg(p, {gamma}){sup 27}Al resonance has been found at E{sub p}=154.5{plus minus}1.0 keV. The new branchings lead to J{sup {pi}}; T determinations (or limitations) for two states in {sup 26}Al and four states in {sup 28}Si. The absolute strengths of the {sup 25}Mg(p, {gamma}){sup 26}Al and {sup 26}Mg(p, {gamma}){sup 27}Al resonances have also been obtained, and the uncertainties of the stellar rates, deduced from the available data for both reactions, are significantly reduced. Some astrophysical consequences are discussed. (orig.).

  10. Microstructure Characteristics and Properties of Mg/Al Dissimilar Metals Made by Cold Metal Transfer Welding with ER4043 Filler Metal%ER4043焊丝Mg/Al异种金属冷金属过渡焊接接头组织及性能研究

    尚晶; 王克鸿; 周琦; 张德库; 黄俊; 李广乐


    AZ31B magnesium alloy and 6061 aluminum alloy were joined in stable welding process by cold metal transfer welding with ER4043 as filler metal.The microstructure,morphology and phase composition of the welded joints were studied by OM,SEM,EDX and XRD.The results show that weld metal and aluminum substrate are combined with a good interface,while weld metal and Mg substrate are combined with a epitaxial solidification area where the intermetallic compounds of Mg2Al3,Mg17Al12 and Mg2Si are generated.The micro-hardness distribution shows a decreasing trend from Mg side to Al side in the weld.The joint is brittle fractured in the fusion zone of Mg side,where plenty of Mg2Si,Mg2Al3 and Mg17Al12 are distributed continuously.%模板采用冷金属过渡(CMT)焊接工艺,以ER4043铝硅焊丝作为焊缝填充金属对AZ31镁合金和6061铝合金进行对接,焊接过程稳定,焊缝成型良好.利用光学显微镜、扫描电镜、能谱和X射线衍射等表征方法,对接头的组织、成分和相组成等进行了分析.结果表明:填充金属与铝母材界面结合良好,与镁母材联生结晶,晶粒长大形成均匀分布的柱状晶,为α镁基固溶体和γ(Mg17Al12)的共晶组织,镁侧熔合区生成了Mg17Al12、Mg2Al3、Mg2Si金属间化合物.力学性能测试表明:镁侧熔合区的显微硬度值较高,该处生成了脆硬的金属间化合物;断裂均发生在镁侧熔合区,属于脆性断裂.断裂的主要原因是镁侧熔合区生成了大量的Mg2Si、Mg17A112和Mg2Al3金属间化合物.

  11. U-Pb and Al-Mg systematics of the ungrouped achondrite Northwest Africa 7325

    Koefoed, Piers; Amelin, Yuri; Yin, Qing-Zhu; Wimpenny, Josh; Sanborn, Matthew E.; Iizuka, Tsuyoshi; Irving, Anthony J.


    Northwest Africa (NWA) 7325 is a unique ungrouped gabbroic achondrite which has characteristics consistent with a possible link to the planet Mercury. In order to understand the origin of this meteorite and the nature of its parent body, we have determined its crystallisation age using the long-lived U-Pb and short-lived Al-Mg chronometers. An internal Pb-Pb isochron defined by six acid leached pyroxene fractions yields an age of 4563.4 ± 2.6 Ma, assuming that the 238U/235U ratio for NWA 7325 is identical to the bulk Earth and Solar System value of 137.794. The Al-Mg isotope analyses of seven fractions (four plagioclase, one pyroxene, one olivine and one whole rock) define a regression line corresponding to 26Al/27Al0 = (3.03 ± 0.14) × 10-7 and an initial δ26Mg∗ of 0.093 ± 0.004‰. When anchored to the D'Orbigny angrite, this initial 26Al/27Al yields an age of 4563.09 ± 0.26 Ma. The Pb-Pb age of 4563.4 ± 2.6 Ma and Al-Mg age of 4563.09 ± 0.26 Ma are in complete agreement, but the low U concentrations of NWA 7325 resulted in a relatively low precision Pb-Pb age. The observed excess in initial δ26Mg∗ can be explained by 27Al/24Mg fractionation and subsequent Mg isotopic evolution after planetary differentiation. Furthermore, the parental magma of NWA 7325 most likely formed within 1.72 Ma after calcium-aluminium rich inclusion (CAI) formation. NWA 7325 formed near simultaneously with quenched angrites and a number of ungrouped achondrites at ∼4563 Ma, suggesting that a multitude of planetary bodies had formed and differentiated by ∼4-5 Myr after CAI formation. This ancient age may be interpreted as an argument against NWA 7325 originating from Mercury, however it does not completely rule it out.

  12. Microstructures and properties of graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites

    YANG Xiao-hong; LIU Yong-bing; SONG Qi-fei; AN Jian


    Graphite and Al2O3 short fibers reinforced Mg-Al-Zn alloy hybrid composites were fabricated by perform squeeze-infiltration route. The effects of the volume of graphite particles on the microstructure, mechanical properties and tribological behavior were investigated under the conditions of constant size of graphite particle and volume of Al2O3 short fiber. The results reveal that the uniform distribution of the reinforced graphite particles and Al2O3 short fiber can be obtained by this technique, and they have strong bonding with the metal matrix. Increasing graphite volume results in decrease in hardness, the ultimate tensile strength whereas the Al2O3 short fiber makes contribution to the increase in hardness of the composite. The composite exhibits good wear resistance, small wear mass loss and low coefficient of friction as compared with the metal matrix. The wear mechanisms transit from oxidation wear, abrasion wear into delamination wear as the applied load is increased, and a film of lubricant covering almost entire surface of specimen, is found to be formed, which separates the wear surfaces from metal to metal contact and thus improves the tribological properties.

  13. The effect of metallic oxide deposition on the electrochemical behaviour of Al-Zn-Mg-Sn alloy in natural tropical seawater

    Din Yati, M. S.; Nazree Derman, Mohd; Isa, M. C.; Y Ahmad, M.; Yusoff, N. H. N.; Muhammad, M. M.; Nain, H.


    The potential of aluminium alloys as anode materials in cathodic protection system has been explored and a significant improvement has been achieved. However, for marine application, it is quite difficult to maintain continuous activation process due to passivation behavior of aluminum alloys. Therefore, to choose the best activation mechanism for aluminium alloy in marine environment, it has to be considered from various points such as alloy composition and surface treatment. This paper report the effect of metallic ruthenium oxide (RuO2) deposition on the surface of as-cast Al-Zn-Mg-Sn alloy and to study the effect of its presence on the electrochemical behavior using direct current (DC) electrochemical polarization and current capacity measurement. The morphology and topography of corroded surface were studied by the aid of scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) respectively. Results from this study showed that the presence of intermetallic compound (Mg2Sn) and also mixed metal oxide compound (Al2O3 and RuO2) on the alloy surface has been very useful in improving electrochemical reaction and charge transfer activities in chloride containing solution. This study also showed that RuO2 catalytic coating applied on the surface of Al-Zn-Mg-Sn alloy has slightly increased the corrosion current density compared to Al-Zn-Mg-Sn without RuO2. The corrosion morphology and topography of corroded surface of Al-Zn-Mg-Sn alloy deposited with RuO2 was found more uniform corrosion attack with the formation of porous and fibrous mud-like crack on outer layer. Based on surface morphology and 3D topographic studies, these features were believed to facilitate ionic species adsorption and diffusion through corrosion product layer at solution-alloy interface. Deposited RuO2 films also was found to increase of current efficiency by more than 10%.

  14. Electrochemical corrosion behaviour of Mg-Al alloys with thermal spray Al/SiCp composite coatings; Comportamiento a la corrosion electroquimica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyeccion termica

    Pardo, A.; Feliu Jr, S.; Merino, M. C.; Mohedano, M.; Casajus, P.; Arrabal, R.


    The corrosion protection of Mg-Al alloys by flame thermal spraying of Al/SiCp composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiC particles (SiCp) varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of micro-channels, largely in the vicinity of the SiC particles, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5-30 vol.% SiCp compared with the un reinforced thermal spray aluminium coatings. (Author) 31 refs.

  15. Synthesis and morphological modification of semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films

    Valente, Jaime S., E-mail: [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); López-Salinas, Esteban [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico); Prince, Julia [Universidad Anáhuac México Norte, Av. Universidad Anáhuac # 46, Huixquilucan, Edo. de México 52786 (Mexico); González, Ignacio; Acevedo-Peña, Prospero [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Apdo. Postal 55-534, 09340 México D.F. (Mexico); Ángel, Paz del [Instituto Mexicano del Petróleo, Eje Central # 152, 07730 México D.F. (Mexico)


    Layered double hydroxide (LDH) thin films with different chemical compositions (MgZnAl, MgZnGa, MgGaAl) and varying thicknesses were easily prepared by sol–gel method followed by dip-coating. Films were chemically uniform, transparent and well adhered to a conductive indium tin oxide (ITO) substrate. Structure, chemical composition and morphology of the thin films were characterized by XRD-GADDS, SEM-EDS and AFM. Additionally, the semiconducting properties of all the prepared films were studied through the Mott–Schottky relationship; such properties were closely related to the chemical compositions of the film. The films were characterized after electrochemical treatment and important modifications regarding surface morphology, particle and crystal sizes were observed. An in-depth study was conducted in order to investigate the effect of several different electrochemical treatments on the morphology, particle size distribution and crystal size of LDH thin films. Upon electrochemical treatment, the films' surface became smooth and the particles forming the films were transformed from flaky open LDH platelets to uniformly distributed close-packed LDH nanoparticles. - Highlights: • Semiconducting Mg(Zn)Al(Ga)–LDH/ITO thin films prepared by sol–gel. • LDH thin films show a turbostratic morphology made up of porous flakes. • Electrochemical treatments change the flaky structure into a nanoparticle array.

  16. Mitigation of Intergranular Stress Corrosion Cracking in Al-Mg by Electrochemical Potential Control

    McMahon, M. E.; Scully, J. R.; Burns, J. T.


    Intergranular stress corrosion cracking in the Al-Mg alloy AA5456-H116 is suppressed via cathodic polarization in 0.6 M NaCl, saturated (5.45 M) NaCl, 2 M MgCl2, and saturated (5 M) MgCl2. Three zones of intergranular stress corrosion cracking (IG-SCC) susceptibility correlate with pitting potentials of unsensitized AA5456-H116 and pure β phase (Al3Mg2) in each solution. These critical potentials reasonably describe the influence of α Al matrix and β phase dissolution rates on IG-SCC severity. Complete inhibition occurred at applied potentials of -1.0 V and -1.1 V versus saturated calomel electrode ( V SCE) in 0.6 M NaCl. Whereas only partial mitigation of IG-SCC was achieved at -0.9 V SCE in 0.6 M NaCl and at -0.9, -1.0, and -1.1 V SCE in the more aggressive environments. Correlation of pitting potentials in bulk environments with IG-SCC behavior suggests an effect of bulk environment [Cl-] and pH on the stabilized crack tip chemistry.

  17. Calculation Model of Mass Action Concentration for Mg-Al, Sr-Al and Ba-Al Melts and Determination of Their Thermodynamic Parameters


    Based on the phase diagrams and the mass action law in combination with the coexistence theory of metallic melts structure, the calculation model of mass action concentration for Mg-Al, Sr-Al and Ba-Al was built, and their thermodynamic parameters were determined. The agreement between calculated and measured results shows that the model and the determined thermodynamic parameters can reflect the structural characteristics of relevant melts. However, the fact that the thermodynamic parameters from literature don′t give the value agree with the measured result may be due to unconformity of these parameters to real chemical reactions in metallic melts.

  18. Synthesis and analysis of nanocrystalline β1-Cu3Al and β2-NiAl intermetallic-reinforced aluminum matrix composite by high energy ball milling

    Nguyen, Hong-Hai; Nguyen, Minh-Thuyet; Kim, Won Joo; Kim, Jin-Chun


    Nanocrystalline β1-Cu3Al and β2-NiAl intermetallic compounds were in-situ reinforced in the aluminum matrix with the atomic composition of Al67Cu20Ni13 by the mechanical alloying of elemental powders. Both β1-Cu3Al, β2-NiAl phases that can be only co-synthesized in Cu base alloys have been obtained after 15h milling in this study. The phase evolution during milling process was investigated by X-ray diffraction. The β1-Cu3Al, β2-NiAl phases were metastable with further milling time up to 40 h. Specially, unreacted Al matrix has been totally transformed to amorphous state in the final powder. A remarkable crystalline size of 6.5 nm was reached after 15 h milling time. Thermal stability of the milled powder was also studied by differential thermal analysis. It is shown that β1-Cu3Al, β2-NiAl phases were stable up to higher than 550 °C. Moreover, the inter-diffusion between Al matrix and Cu3Al within the temperature range of 620-740 °C led to the formation of superstructure ζ1-Al3Cu4 phase.

  19. Creep behaviour of a casting titanium carbide reinforced AlSi12CuNiMg piston alloy at elevated temperatures; Hochtemperaturkriechverhalten der schmelzmetallurgisch hergestellten dispersionsverstaerkten Kolbenlegierung AlSi12CuNiMg

    Michel, S.; Scholz, A. [Zentrum fuer Konstruktionswerkstoffe, TU Darmstadt (Germany); Tonn, B. [Institut fuer Metallurgie, TU Clausthal (Germany); Zak, H.


    This paper deals with the creep behaviour of the titanium carbide reinforced AlSi12CuNiMg piston alloy at 350 C and its comparison to the conventional AlSi12Cu4Ni2MgTiZr piston alloy. With only 0,02 vol-% TiC reinforcement the creep strength and creep rupture strength of the AlSi12CuNiMg piston alloy are significantly improved and reach the level of the expensive AlSi12Cu4Ni2MgTiZr alloy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Global Transcriptome Analysis Reveals Distinct Aluminum-Tolerance Pathways in the Al-Accumulating Species Hydrangea macrophylla and Marker Identification.

    Haixia Chen

    Full Text Available Hydrangea (Hydrangea macrophylla is a well known Al-accumulating plant, showing a high level of aluminum (Al tolerance and accumulation. Although the physiological mechanisms for detoxification of Al and the roles of Al in blue hydrangea sepals have been reported, the molecular mechanisms of Al tolerance and accumulation are poorly understood in hydrangea. In this study, we conducted a genome-wide transcriptome analysis of Al-response genes in the roots and leaves of hydrangea by RNA sequencing (RNA-seq. The assembly of hydrangea transcriptome provides a rich source for gene identification and mining molecular markers, including single nucleotide polymorphism (SNP and simple sequence repeat (SSR. A total of 401,215 transcripts with an average length of 810.77 bp were assembled, generating 256,127 unigenes. After annotation, 4,287 genes in the roots and 730 genes in the leaves were up-regulated by Al exposure, while 236 genes in the roots and 719 genes in the leaves were down-regulated, respectively. Many transporters, including MATE and ABC families, were involved in the process of Al-citrate complex transporting from the roots in hydrangea. A plasma membrane Al uptake transporter, Nramp aluminum transporter was up-regulated in roots and leaves under Al stress, indicating it may play an important role in Al tolerance by reducing the level of toxic Al. Although the exact roles of these candidate genes remain to be examined, these results provide a platform for further functional analysis of the process of detoxification of Al in hydrangea.

  1. Effect of neutron irradiation and postradiation annealing on the microstructure and properties of an Al-Mg-Si alloy

    Maksimkin, O. P.; Tsai, K. V.; Rofman, O. V.; Sil'nyagina, N. S.


    The effect of long-term neutron irradiation and postradiation thermal-induced aging on the microstructure and mechanical properties of an aluminum-based reactor Al-Mg-Si alloy grade SAV-1 has been studied. The material under study is the shell of an automatic fine-control rod used to control the reactivity of the core of a VVR-K research reactor. Successive 1-h annealings of specimens of the SAV-1 alloy irradiated to doses of 0.001 and 5 dpa in the temperature range of 100-550°C have been carried out. The evolution of the fine structure of the material and changes in its mechanical characteristics have been studied. The phenomenon of the acceleration of the aging of the SAV-1 alloy under the effect of a high neutron fluence at an irradiation temperature of 80°C has been observed, which involves the formation of numerous lineage (stitch) Guinier-Preston zones in the alloy. It has been shown that the strength characteristics of the SAV-1 alloy depend significantly on the degree of its radiation- and thermal-induced aging.

  2. An evaluation of the benefits of utilizing rapid solidification for development of 2XXX (Al-Cu-Mg) alloys

    Paris, H. G.; Chellman, D. J.


    The advantages of rapid solidification processing over ingot metallurgy processing in the development of 2XXX aluminum alloy compositions were evaluated using a similarly processed ingot metallurgy (IM) control alloy. The powder metallurgy (PM) alloy extrusions showed a reduced age-hardening response in comparison with similar IM compositions, with higher tensile properties for naturally aged extrusions but lower properties for artificially aged ones. However, the tensile properties of naturally and artificially aged PM alloy extrusions based on a version of IM 2034 alloy, but containing 0.6 weight percent zirconium, were comparable to those of the IM control extrusions and had significantly superior combinations of strength and toughness. The tensile properties of this PM alloy showed even greater advantage in 6.4-mm (0.25-in.) and 1.8-mm (0.070-in.) plate and sheet, the yield strength being about 68 MPa (10 ksi) greater than reported values for the IM 2034 alloy sheet. An artificially aged PM alloy based on 2219 alloy also showed a strength and strength-toughness combination comparable to those of the PM Al-Cu-Mg-Zr alloy, substantially outperforming the IM 2219 alloy. These results show that rapid solidification offers the flexibility needed to modify conventional IM compositions to produce new alloy compositions with superior mechanical properties.

  3. Synthesis and Quasi-Static Compressive Properties of Mg-AZ91D-Al2O3 Syntactic Foams

    David B. Newsome


    Full Text Available Magnesium alloys have considerably lower density than the aluminum alloy matrices that are typically used in syntactic foams, allowing for greater specific energy absorption. Despite the potential advantages, few studies have reported the properties of magnesium alloy matrix syntactic foams. In this work, Al2O3 hollow particles of three different size ranges, 0.106–0.212 mm, 0.212–0.425 mm, and 0.425–0.500 mm were encapsulated in Mg-AZ91D by a sub-atmospheric pressure infiltration technique. It is shown that the peak strength, plateau strength and toughness of the foam increases with increasing hollow sphere wall thickness to diameter (t/D ratio. Since t/D was found to increase with decreasing hollow sphere diameter, the foams produced with smaller spheres showed improved performance—specifically, higher energy absorption per unit weight. These foams show better performance than other metallic foams on a specific property basis.

  4. Synthesis of Renewable Energy Materials, Sodium Aluminum Hydride by Grignard Reagent of Al

    Jun-qin Wang


    Full Text Available The research on hydrogen generation and application has attracted widespread attention around the world. This paper is to demonstrate that sodium aluminum hydride can be synthesized under simple and mild reaction condition. Being activated through organics, aluminum powder reacts with hydrogen and sodium hydride to produce sodium aluminum hydride under atmospheric pressure. The properties and composition of the sample were characterized by FTIR, XRD, SEM, and so forth. The results showed that the product through this synthesis method is sodium aluminum hydride, and it has higher purity, perfect crystal character, better stability, and good hydrogen storage property. The reaction mechanism is also discussed in detail.

  5. Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

    J.B. Ferguson


    Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

  6. Effect of Aging Treatment on Microstructural and Mechanical Characteristics of PEO Coatings on Mg-Al Alloy


    Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation (PEO) method. The Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear resistance. After PEO coating, however, the microhardness and wear resistance of coatings on Mg-6 wt pct Al alloy showed a tendency to decrease with increasing aging time, which was in aggrement with the change of thickness with aging time. In addition, the coatings on solution-treated Mg-6 wt pct Al alloy had better microhardness and wear resistance than those on aged Mg-6 wt pct Al alloys. Consequently, it can be understood that the aging treatment has a deleterious influence on the mechanical properties of coatings on Mg-6 wt pct Al alloy.

  7. Direct Observation of Lattice Aluminum Environments in Li Ion Cathodes LiNi1-y-zCoyAlzO2 and Al-Doped LiNixMnyCozO2 via (27)Al MAS NMR Spectroscopy.

    Dogan, Fulya; Vaughey, John T; Iddir, Hakim; Key, Baris


    Direct observations of local lattice aluminum environments have been a major challenge for aluminum-bearing Li ion battery materials, such as LiNi1-y-zCoyAlzO2 (NCA) and aluminum-doped LiNixMnyCozO2 (NMC). (27)Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is the only structural probe currently available that can qualitatively and quantitatively characterize lattice and nonlattice (i.e., surface, coatings, segregation, secondary phase etc.) aluminum coordination and provide information that helps discern its effect in the lattice. In the present study, we use NMR to gain new insights into transition metal (TM)-O-Al coordination and evolution of lattice aluminum sites upon cycling. With the aid of first-principles DFT calculations, we show direct evidence of lattice Al sites, nonpreferential Ni/Co-O-Al ordering in NCA, and the lack of bulk lattice aluminum in aluminum-"doped" NMC. Aluminum coordination of the paramagnetic (lattice) and diamagnetic (nonlattice) nature is investigated for Al-doped NMC and NCA. For the latter, the evolution of the lattice site(s) upon cycling is also studied. A clear reordering of lattice aluminum environments due to nickel migration is observed in NCA upon extended cycling.

  8. Pulsed laser deposition of AlMgB14 thin films

    Britson, Jason Curtis [Iowa State Univ., Ames, IA (United States)


    Hard, wear-resistant coatings of thin film borides based on AlMgB14 have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising for industrial applications. Cutting tools coated with AlMgB14 used to mill titanium alloys have been shown to substantially reduce the wear on the cutting tool and extend its cutting life. However, little research into the thin film fabrication process using pulsed laser deposition to make AlMgB14 has been conducted. In this work, research was conducted into methods to optimize the deposition parameters for the AlMgB14 films. Processing methods to eliminate large particles on the surface of the AlMgB14 films, produce films that were at least 1m thick, reduce the surface roughness of the films, and improve the adhesion of the thin films were investigated. Use of a femtosecond laser source rather than a nanosecond laser source was found to be effective in eliminating large particles considered detrimental to wear reduction properties from the films. Films produced with the femtosecond laser were also found to be deposited at a rate 100 times faster than those produced with the nanosecond laser. However, films produced with the femtosecond laser developed a relatively high RMS surface roughness around 55nm. Attempts to decrease the surface roughness were largely unsuccessful. Neither increasing the surface temperature of the substrate during deposition nor using a double pulse to ablate the material was found to be extremely successful to reduce the surface roughness. Finally, the adhesion of the thin films to M2 tool steel

  9. Impurity Diffusion Coefficients of Al and Zn in Mg Determined from Solid-to-Solid Diffusion Couples

    Kammerer, Catherine [University of Central Florida, Orlando; Kulkarni, Nagraj S [ORNL; Warmack, Robert J Bruce [ORNL; Perry, Kelly A [ORNL; Belova, Irina [University of Newcastle, NSW, Australia; Murch, Prof. Graeme [University of Newcastle, NSW, Australia; Sohn, Yong Ho [University of Central Florida


    Increasing use and development of lightweight Mgalloys have led to the desire for more fundamental research in and understanding of Mg-based systems. As property enhancing components, Al and Zn are two of the most important and common alloying elements for Mg-alloys. We have investigated the concentration dependent interdiffusion of Al and Zn in Mg using diffusion couples of pure polycrystalline Mg mated to Mg solid solutions containing either <9 at.% Al or <3 at.% Zn. Concentration profiles were determined by electron micro-probe microanalysis of the diffusion zone. The interdiffusion coefficients were determined by the classical Boltzmann-Matano method within the Mg solid solution. As the concentration of Al or Zn approaches the dilute ends, we employ an analytical approach based on the Hall method to estimate the impurity diffusion coefficients. Results of Al and Zn impurity diffusion in Mg are reported and compared to published impurity diffusion coefficients typically determined by thin film techniques.

  10. Thermodynamic database of the phase diagrams in the Mg-Al-Zn-Y-Ce system

    LIU Xingjun; WANG Cuiping; WEN Mingzhong; CHEN Xing; PAN Fusheng


    The Mg-Al-Zn-Y-Ce system is one of the key systems for designing high-strength Mg alloys. The purpose of the present article is to develop a thermodynamic database for the Mg-Al-Zn-Y-Ce multicomponent system to design Mg alloys using the calculation of phase diagrams (CALPHAD) method, where the Gibbs energies of solution phases such as liquid,fcc, bcc, and hcp phases were described by the subregular solution model, whereas those of all the compounds were described by the sublattice model. The thermodynamic parameters describing Gibbs energies of the different phases in this database were evaluated by fitting the experimental data for phase equilibria and thermodynamic properties. On the basis of this database, a lot of information concerning stable and metastable phase equilibria of isothermal and vertical sections, mo lar fractions of constituent phases, the liquidus projection, etc., can be predicted. This database is expected to play an important role in the design of Mg alloys.

  11. Deteriorated superconductivity of MgB{sub 2} films due to Al diffusion from Al{sub 2}O{sub 3} substrates: Thermodynamic perspective

    Yamazaki, Keisuke; Naito, Michio, E-mail:


    Highlights: •The intrinsic problem of interdiffusion between MgB2 films and Al2O3 substrates was pointed out. •Mg is a stronger reductant than Al and takes out oxygen from Al{sub 2}O{sub 3}. •Thermodynamics predicts appropriate choice of substrate and barrier materials for MgB2 films. -- Abstract: Recently we reported the growth of MgB{sub 2} films by pyrolysis of decaborane (B{sub 10}H{sub 14}) in Mg vapor. In this article, we discuss the intrinsic problem at the MgB{sub 2}/Al{sub 2}O{sub 3} interface, which was encountered during our optimization of the growth temperature. Mg is a stronger reductant than Al, and takes out oxygen from Al{sub 2}O{sub 3}. Increasing the growth temperature, this reaction becomes noticeable and leads to the formation of MgO and Mg{sub 1−x}Al{sub x}B{sub 2}, which deteriorates the properties of resultant MgB{sub 2} films. Our observations present a general issue in the choice of substrate and barrier materials in thin film growth and/or junction fabrication of compounds containing reactive cations such as Mg.

  12. Kinetics of the β-AlFeSi to α-Al(FeMn)Si transformation in Al-Mg-Si alloys

    Kuijpers, N.C.W.


    Among all the process steps of the production of aluminium extrusion products, the homogenisation of Al-Mg-Si aluminium billets is a very important one, since it gives significant changes in the microstructure of the alloy, leading to an improved extrudability of the material and improved properties

  13. Structure and Mechanical Properties of AlMg4.5 And AlMg4.5Mn Wires Extruded by Kobo Method

    Jaskowski M.


    Full Text Available W pracy badano wpływ liczby operacji wyciskania metodą KoBo (z identycznym sumarycznym stopniem przerobu λ = 100 na strukturę, własności mechaniczne i charakterystyki umocnieniowe drutów ze stopów AlMg4.5 i AlMg4.5Mn (AA5083. Stwierdzono, że wyciskanie jednooperacyjne prowadzi w przypadku obu stopów do formowania struktury typowej dla materia- łów zrekrystalizowanych. podczas gdy zastosowanie dwuoperacyjnego wyciskania skutkuje utworzeniem struktury włóknistej o charakterze „mieszanym”, tzn. zawierającej zarówno obszary, w których dominowały procesy intensywnego zdrowienia, jak i rekrystalizacji. W konsekwencji własności wytrzymałościowe tych ostatnich są zdecydowanie wyższe zarówno po wyciskaniu, jak i po późniejszym walcowaniu na zimno. We wszystkich przypadkach na krzywych rozciągania drutów obserwowano sko- kowe oscylacje naprężenia, charakterystyczne dla efektu Portevin - LeChatelier (P-L. W nielicznych próbach rozciągania efekt P-L poprzedzała niestateczność płynięcia plastycznego typowa dla występowania pasma LUdersa. Charakterystyki umocnienia wywołane procesem walcowania wykazywały przebieg monotonicznie rosnący.

  14. Supercritical hydrothermal synthesis of polycrystalline gadolinium aluminum perovskite materials (GdAlO3, GAP

    HN Girish


    Full Text Available The orthorhombic perovskite, Gadolinium aluminum oxide (GdAlO3, GAP material was successfully prepared by hydrothermal supercritical fluid method using co-precipitated gel of GAP. All experiments were carried out in the pressure and temperature ranges of 100–150 MPa and 180–650 °C respectively. The as-prepared GAP samples were systematically characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, X-ray spectroscopy (EDS, thermo gravimetry (TGA and differential thermo gravimetry analysis (DTA. The XRD profile confirms fully crystalline and orthorhombic nature of as-prepared materials, which is well correlated to the reported results. The SEM studies reveal that the GAP materials synthesized at 650 °C/150 MPa for 92 hrs possesses polycrystalline nature with average particle size in the range of 5–20 µm. The DTA shows a crystallization peak at 361 °C at this temperature the agglomerated GAP gel starts to crystallize into polycrystalline GAP materials. When compared with other methods, like sol-gel and solid-state reactions our crystallization temperature is very much lower and feasible. This work not only demonstrates a simple way to fabricate GAP polycrystalline materials from co-precipitated gels but also shows a possible utilization of same technique for synthesis of other high temperature materials.

  15. Influence of Mg Addition on Crystallisation Kinetics and Structure of the Zn-Al-Cu Alloy

    Krupiński M.


    Full Text Available In this work the effect of Mg addition on structure as well as kinetics of crystallisation of Zn-Al-Cu cast alloy was presented. To the zinc alloy was added 0.1% mass of Mg. The alloy was cast into a metal mould. Thermo-derivative analysis was performed using the UMSA platform (Universal Metallurgical Simulator and Analyzer. The investigated alloys were freely cooled down with a rate of 0.1°C s-1. For the structure analysis were used results obtained using light microscopy, scanning and transmission electron microscopy.

  16. Partial oxidation of dimethyl ether using the structured catalyst Rh/Al2O3/Al prepared through the anodic oxidation of aluminum.

    Yu, B Y; Lee, K H; Kim, K; Byun, D J; Ha, H P; Byun, J Y


    The partial oxidation of dimethyl ether (DME) was investigated using the structured catalyst Rh/Al2O3/Al. The porous Al2O3 layer was synthesized on the aluminum plate through anodic oxidation in an oxalic-acid solution. It was observed that about 20 nm nanopores were well developed in the Al2O3 layer. The thickness of Al2O3 layer can be adjusted by controlling the anodizing time and current density. After pore-widening and hot-water treatment, the Al2O3/Al plate was calcined at 500 degrees C for 3 h. The obtained delta-Al2O3 had a specific surface area of 160 m2/g, making it fit to be used as a catalyst support. A microchannel reactor was designed and fabricated to evaluate the catalytic activity of Rh/Al2O3/Al in the partial oxidation of DME. The structured catalyst showed an 86% maximum hydrogen yield at 450 degrees C. On the other hand, the maximum syngas yield by a pack-bed-type catalyst could be attained by using a more than fivefold Rh amount compared to that used in the structured Rh/Al2O3/Al catalyst.

  17. High thermal stability and low Gilbert damping constant of CoFeB/MgO bilayer with perpendicular magnetic anisotropy by Al capping and rapid thermal annealing

    Wang, Ding-Shuo; Lai, Shu-Yu; Lin, Tzu-Ying; Wang, Liang-Wei; Liao, Jung-Wei; Lai, Chih-Huang, E-mail: [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Chien, Cheng-Wei; Wang, Yung-Hung [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Chutung, Taiwan (China); Ellsworth, David; Lu, Lei; Wu, Mingzhong [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)


    We demonstrate that the magnetic anisotropy of the CoFeB/MgO bilayer can be manipulated by adding an aluminum capping layer. After rapid thermal annealing, we can achieve large perpendicular magnetic anisotropy of CoFeB with a high thermal stability factor (Δ = 72) while the Gilbert damping constant can be reduced down to only 0.011 simultaneously. The boron and residual oxygen in the bulk CoFeB layer are properly absorbed by the Al capping layer during annealing, leading to the enhanced exchange stiffness and reduced damping. The interfacial Fe-O bonding can be optimized by tuning annealing temperature and thickness of Al, resulting in enhanced perpendicular anisotropy.

  18. The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

    Gilman, P. S.


    Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

  19. Synthesis of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of Congo Red from aqueous solution

    Zhigang Jia; Shengbiao Li; Jianhong Liu; Qi Qin; Rongsun Zhu


    MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres were prepared by urea-hydrolysed hydrothermal reaction and the subsequent calcinations. The morphology and structure of the products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscope and Fourier transformed infrared. The adsorption performance of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of an anionic dye (Congo Red, CR) from aqueous solution was investigated. The results showed that MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres are particularly efficient in removing CR. The adsorption follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model. The maximum adsorption capacities of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for CR were found to be 213.2 and 49.8 mg g−1, respectively. The both adsorption processes were found to be spontaneous and exothermic in nature.

  20. Wear Resistance of Aluminum Matrix Composites Reinforced with Al2O3 Particles After Multiple Remelting

    Klasik, Adam; Pietrzak, Krystyna; Makowska, Katarzyna; Sobczak, Jerzy; Rudnik, Dariusz; Wojciechowski, Andrzej


    Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple remelting method must be analyzed for any material separately.

  1. Dynamic strain aging precipitation of Mg17Al12 in AZ80 magnesium alloy during multi-directional forging process

    Zhu, Q. F.; Wang, G. S.; Wang, X. J.; Liu, F. Z.; Ban, C. Y.; Cui, J. Z.


    Dynamic aging precipitation of Mg17Al12 phases in AZ80 magnesium alloy was studied by multi-directional forging (MDF) with decreasing temperatures from 410 to 300 °C. The results show that the morphology of the dynamically precipitated β-Mg17Al12 phases (formed during forging process) exhibited granular shape. During the multi-directional forging process, the inhomogeneous dynamic precipitation of the β-Mg17Al12 phases result in the coexistence of the fine grains (with many granular Mg17Al12 phases) and coarse grains (without Mg17Al12 phases) in the samples. The fine grains (with many granular Mg17Al12 phases) area expands with the decreasing of final forging temperature. The inhomogenous Al content distribution in the Mg matrix leads to the non-uniform dynamic precipitation of the Mg17Al12 phase. These Mg17Al12 phase retards the growth of the DRX grains, which in turns results in the formation fine grains area during the during the MDF process with temperature decreasing.

  2. Theoretical Investigation of the Structural, Elastic, and Thermodynamic Properties of MgAl2O4 Spinel under High Pressure

    Mao, Xiao-Chun; Liu, Ke; Hou, Bao-Sen; Tan, Jiao; Zhou, Xiao-Lin


    The structural and elastic properties of MgAl2O4 spinel under high pressure are investigated through the first-principles calculations. The lattice parameters and elastic constants are in good agreement with the available experimental and theoretical results. The polycrystalline elastic moduli of MgAl2O4 spinel are calculated using the Voigt-Reuss-Hill approximation. By the elastic stability criteria, the MgAl2O4 spinel is mechanically stable within 80 GPa. MgAl2O4 possesses ductile nature, and the ductility is enhanced with the increase of pressure. The sound velocities over a wide range of pressures are also obtained. Furthermore, the elastic anisotropies of MgAl2O4 are investigated via the various anisotropic indexes and the 3D surface constructions. It is found that MgAl2O4 is isotropic for bulk modulus, while is anisotropic for shear modulus and Young's modulus, and the elastic anisotropy of MgAl2O4 increases due to the applying pressure. Besides, the directions with smaller values of shear modulus for MgAl2O4 will deform preferentially under high hydrostatic pressure. Through the quasi-harmonic Debye model, we also investigated the thermodynamic properties of MgAl2O4 spinel.

  3. Flow Stress Behavior and Processing Map of Al-Cu-Mg-Ag Alloy during Hot Compression

    YANG Sheng; YI Danqing; ZHANG Hong; YAO Sujuan


    The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.

  4. Study of $^{26}$Mg through 1p pick up reaction $^{27}$Al(d,$^{3}$He)

    Srivastava, Vishal; Rana, T K; Manna, S; Kundu, S; Bhattacharya, S; Banerjee, K; Roy, P; Pandey, R; Mukherjee, G; Ghosh, T K; Meena, J K; Roy, T; Chaudhuri, A; Sinha, M; Saha, A K; Asgar, Md A; Dey, A; Roy, Subinit; Shaikh, Md M


    The even-even nucleus $^{26}$Mg has been studied through the reaction $^{27}$Al(d,$^{3}$He) at 25 MeV beam energy. The spectroscopic factors have been extracted upto 7.50 MeV excitation energy using local, zero range distorted wave Born approximation. The comparison of the spectroscopic factors have been done with previously reported values using the same reaction probe. The extracted spectroscopic factors for different excited states were found to be in good agreement with the previously reported values for the same. The present results were also compared with the predictions from shell model as well as rotational model. The analog states of $^{26}$Al and $^{26}$Mg were found to be in good agreement.

  5. Dose Dependence of Mechanoluminescence Properties in MgAl2O4: Dy Phosphor

    Kabita K. Satapathy


    Full Text Available A reliable dosimetry is fundamental for quality assurance of the processes and irradiation products. All dosimetric systems for high doses have some limitation with regard to their use. Dosimetric system should be easy to use, fast to measure, and of low cost. Good phosphor which shows high luminescence properties may fulfil the above criteria in some way. MgAl2O4: Dy phosphor has been prepared by solution combustion technique and confirmed with the help of XRD. ML has been excited impulsively by dropping a load of mass 0.7 kg onto the phosphors from various heights; two distinct ML peaks are observed for all the samples. It is observed that MgAl2O4: Dy phosphor shows linear response to gamma-ray dose and low fading which can be used for dosimetric purpose.

  6. Optimization of Squeeze Parameters and Modification of AlSi7Mg Alloy

    A. Zyska


    Full Text Available The paper present the examination results concerning mechanical properties of castings made of AlSi7MG alloy in correlation both with the most significant squeeze casting parameters and with the modification treatment. Experiments were planned and held according to the 23 factorial design. The regression equations describing the influence of the squeeze pressure, the mould temperature, and the quantity of strontium modifier on the strength and elongation of the examined alloy were obtained. It was found that the main factor controlling the strength increase is the squeeze pressure, while the plasticity (A5 of the alloy is affected most advantageously by modification. The application of modification treatment in squeeze casting technology enables for production of the slab-type castings made of AlSi7Mg alloy exhibiting strength at the level of 230 MPa and elongation exceeding 14%.

  7. Rapid timescales for accretion and melting of differentiated planetesimals inferred from Al-Mg chronometry

    Bizzarro, Martin; Haack, H.; Baker, J.A.


    Constraining the timescales for the assembly and differentiation of planetary bodies in our young solar system is essential for a complete understanding of planet-forming processes. This is best achieved through the study of the daughter products of extinct radionuclides with short half-lives, as......Constraining the timescales for the assembly and differentiation of planetary bodies in our young solar system is essential for a complete understanding of planet-forming processes. This is best achieved through the study of the daughter products of extinct radionuclides with short half...... the eucrite and mesosiderite parent bodies (EPB and MPB) with suprachondritic Al/Mg ratios have resolvable Mg excesses compared to matrix-matched samples from the Earth, the Moon, Mars, and chondrites. Basaltic magmatism on the EPB and MPB thus occurred during the life span of the now-extinct Al nuclide...

  8. Photostability enhancement of azoic dyes adsorbed and intercalated into Mg-Al-layered double hydroxide

    Liu, Pengfei; Liu, Pei; Zhao, Kongcao; Li, Lei


    Two azoic dyes 4-aminoazobenzene-4-sulfonic (AS) and ethyl orange (EO) were adsorbed on or intercalated into Mg-Al-CO3 layered double hydroxide (LDH) for photostability enhancement. Fluorescence analysis results showed that the photostability of two dyes could be greatly improved after being adsorbed on the surface of Mg-Al-CO3-LDH matrix. Furthermore, photostability of adsorbed dyes was superior to that of intercalated dyes. It was suggested that AS or EO was adsorbed on LDHs surface through a strong chemisorption interaction, resulting in the enhancement of photostability. After the UV irradiation under N2 atmosphere, the absorbed dyes not only show great increase of fluorescence intensity but also exhibited high stability against UV irradiation. This work provides a feasible approach to enhance the photostability of azoic dye confined in an inorganic two-dimensional (2D) matrix via changing the microenvironment, which may be considered to be a promising method of improving photostability of solid fluorescent materials.


    Katarína Miková


    Full Text Available This contribution deals with evaluation of the corrosion resistance of extruded Mg-2Al-1RE (AE21 magnesium alloy in the state before and after treatment of ground surface by selected phosphatizing procedure. Specimens were exposed to 0.1M NaCl solution for several time periods starting from 5 minutes up-to 168 hours at room temperature of 22 ± 1 °C. Afterwards electrochemical impedance spectroscopy was carried out on the exposed specimens. Based on the results obtained from the electrochemical tests and visual observation of corrosion attack progress, positive or negative impact of selected phosphating process on the corrosion resistance of Mg-2Al-1RE magnesium alloy under given conditions was assessed.

  10. Friction Stir Welding of a Thick Al-Zn-Mg Alloy Plate

    Buchibabu, V.; Reddy, G. M.; Kulkarni, D.; De, A.


    Al-Zn-Mg alloys are widely used as structural materials due to high strength-to-weight ratio and impact toughness. As fusion welds in these alloys commonly face hot cracking and macro porosity, friction stir welding is increasingly becoming the preferred recourse. We report here a detailed experimental study on friction stir welding of a specific Al-Zn-Mg alloy with its chemical compositions close to AA7039. The effect of tool rotational speed and welding speed on the weld profile, joint microstructure, and mechanical properties is studied extensively. The results show sound weld profiles and joint properties within the selected range of process conditions. Within the selected range of welding conditions, the welds made at a tool rotational speed of 350 rpm and welding speed of 3 mm/s have showed joint structure, tensile, and impact toughness properties fairly close to that of the base material.

  11. Comparison of microstructure and corrosion properties of Al-Zn-Mg-Cu alloys 7150 and 7010

    MENG Qing-chang; FAN Xi-gang; REN Shi-yu; ZHANG Xin-mei; ZHANG Bao-you


    The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa higher than that of 7010 alloy.The 7010 alloy exhibits higher resistance to stress corrosion cracking as compared with the 7150 alloy. The coarse Cu-bearing particles are detrimental to the resistance to stress corrosion cracking. The increase of size of matrix and subgrain boundary precipitates decreases the susceptibility of stress corrosion. The anodic dissolution and hydrogen embrittlement govern the cracking process. The severity of stress corrosion cracking is shown to be related to the coarse Cu-bearing particles, matrix and subgrain precipitates in Al-Zn-Mg-Cu alloys.

  12. Defects in electron-irradiated MgOxnAl/sub 2/O/sub 3/ crystals

    Gritsyna, V.T.; Gritsenko, N.V.; Kobyakov, V.A. (Khar' kovskij Gosudarstvennyj Univ. (Ukrainian SSR))


    Using the methods of optical and EPR spectroscopy point defects in crystals of magnesium-aluminium spinel of the MgOxAl/sub 2/O/sub 3/ and MgOx2.5Al/sub 2/O/sub 3/ composition after-irradiation with high-energy (14 MeV) electrons have been studied. Based an comparing the intensity of optical absorption bands versus the irradiation dose (from 3 x 10/sup 14/ to 9 x 10/sup 15/ el x cm/sup -2/) and EPR signals, and on angular dependences of the EPR spectram the spectroscopic characteristics and structure of monoelectron and monohole centres are determined.

  13. Kinetics of hydrogen desorption from MgH2 and AlH3 hydrides

    Terent'ev, P. B.; Gerasimov, E. G.; Mushnikov, N. V.; Uimin, M. A.; Maikov, V. V.; Gaviko, V. S.; Golovatenko, V. D.


    Kinetic parameters of the process of thermal decomposition of the MgH2 hydride (obtained by the method of the mechanoactivation of magnesium in a hydrogen atmosphere) and of the commercial AlH3 hydride have been studied upon the rapid heating in the range of temperatures of 150-510°C at hydrogen pressures of 0-2 atm. The time dependences of the amount of hydrogen released by the metal hydrides at different temperatures and pressures have been determined. It has been shown that the activation energies of the hydrogen desorption are 135 kJ/mol for MgH2 and 107 kJ/mol for AlH3. The maximum rates of hydrogen desorption from the investigated metal hydrides have been established, and the temperatures and initial pressures that ensure the maximum rate and maximum volume of the hydrogen release have been determined.

  14. PLA/MgAlCu-LDH复合材料的制备、表征及性能研究%Fabrication, Characterization and Properties of PLA/MgAlCu-LDH Composites Materials

    张红梅; 朱同贺


    用溶液插层法制备了PLA/MgAlCu-LDH共混溶液,通过涂膜法制备了不同MgAlCu-LDH含量的PLA/MgAlCu-LDH复合膜,采用扫描电镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)、力学性能测试仪器对制备的复合膜的形貌、结构及性能进行测试表征.结果表明:部分PLA分子链插入到MgAlCu-LDH片层间隙中,使得MgAlCu-LDH层间距变大,MgAlCu-LDH作为插层剂对整个共混聚合物的韧性和强度有明显的影响;PLA/MgAl-Cu-LDH复合材料的杨氏模量随MgAlCu-LDH含量的增加而增加,加入少量MgAlCu-LDH时PLA/MgAlCu-LDH复合材料的抗拉强度、屈服强度和断裂伸长率均增加,在室温下拉伸时,PLA/MgAlCu-LDH 3%(质量分数)复合材料的抗拉强度、屈服强度和断裂伸长率分别比PLA提高14.5%、11.5%和23.7%.

  15. Culturability of Bacillus spores on aerosol collection filters exposed to airborne combustion products of Al, Mg, and B·Ti.

    Adhikari, Atin; Yermakov, Michael; Indugula, Reshmi; Reponen, Tiina; Driks, Adam; Grinshpun, Sergey A


    Destruction of bioweapon facilities due to explosion or fire could aerosolize highly pathogenic microorganisms. The post-event air quality assessment is conducted through air sampling. A bioaerosol sample (often collected on a filter for further culture-based analysis) also contains combustion products, which may influence the microbial culturability and, thus, impact the outcome. We have examined the interaction between spores deposited on collection filters using two simulants of Bacillus anthracis [B. thuringiensis (Bt) and B. atrophaeus (referred to as BG)] and incoming combustion products of Al as well as Mg and B·Ti (common ingredient of metalized explosives). Spores extracted from Teflon, polycarbonate, mixed cellulose ester (MCE), and gelatin filters (most common filter media for bioaerosol sampling), which were exposed to combustion products during a short-term sampling, were analyzed by cultivation. Surprisingly, we observed that aluminum combustion products enhanced the culturability of Bt (but not BG) spores on Teflon filters increasing the culturable count by more than an order of magnitude. Testing polycarbonate and MCE filter materials also revealed a moderate increase of culturability although gelatin did not. No effect was observed with either of the two species interacting on either filter media with products originated by combustion of Mg and B·Ti. Sample contamination, spore agglomeration, effect of a filter material on the spore survival, changes in the spore wall ultrastructure and germination, as well as other factors were explored to interpret the findings. The study raises a question about the reliability of certain filter materials for collecting airborne bio-threat agents in combustion environments.

  16. Microstructures and tensile properties of hot-extruded Al matrix composites containing different amounts of Mg{sub 2}Si

    Emamy, M., E-mail: [School of Metallurgy and Materials, College of Engineering, University of Tehran, P.O. Box 14395-731, Tehran (Iran, Islamic Republic of); Vaziri Yeganeh, S.E.; Razaghian, A. [Imam Khomeini International University, Qazvin (Iran, Islamic Republic of); Tavighi, K. [School of Metallurgy and Materials, College of Engineering, University of Tehran, P.O. Box 14395-731, Tehran (Iran, Islamic Republic of)


    The effect of hot extrusion process on the microstructure and tensile properties of aluminum matrix composite containing 15, 20, 25 and 30 wt% Mg{sub 2}Si phase has been studied in this investigation. Microstructural examinations were assessed by the use of optical microscope and scanning electron microscopy. The results revealed that hot extrusion breaks primary Mg{sub 2}Si phase and changes its morphology from dendritic to regular shape. It was also found that hot extrusion reduces the size of primary particles as well as casting defects such as porosity. Further examination showed that hot extrusion has strong effect on breaking eutectic Mg{sub 2}Si network. Remarkable result of this study was concerned with significant improvement in ductility by hot extrusion. Fractographic examinations revealed that hot extrusion encourages ductile mode of fracture by introducing homogenous and fine dimples on the fracture surface of the aluminum matrix composites.

  17. Soluble molecular compounds with the Mg-O-Al structural motif: a model approach for the fixation of organometallics on a MgO surface.

    Nembenna, Sharanappa; Roesky, Herbert W; Mandal, Swadhin K; Oswald, Rainer B; Pal, Aritra; Herbst-Irmer, Regine; Noltemeyer, Mathias; Schmidt, Hans-Georg


    We report a facile route to the molecular compounds with the Mg-O-Al structural motif. The reaction of Mg[N(SiMe3)2]2 (1) with a stoichiometric amount of LAlOH(Me) (2) [L = CH{(CMe)(2,6-iPr2C6H3N)}2] in THF/n-hexane at 0 degrees C results in the formation of the heterobimetallic compound (Me3Si)2NMg(THF)2-O-Al(Me)L (3) in high yield. The similar reaction of 1 equiv of Mg[N(SiMe3)2]2 and 2 equiv of LAlOH(Me) results in the formation of trimetallic compound L(Me)Al-O-Mg(THF)2-O-Al(Me)L (4). Structural analyses of 3 and 4 have been carried out, revealing the presence of the Mg-O-Al motif. A tentative assignment of the Mg-O-Al vibrations has been made and was supported by calculations.

  18. High-Temperature CO2 Sorption on Hydrotalcite Having a High Mg/Al Molar Ratio.

    Kim, Suji; Jeon, Sang Goo; Lee, Ki Bong


    Hydrotalcites having a Mg/Al molar ratio between 3 and 30 have been synthesized as promising high-temperature CO2 sorbents. The existence of NaNO3 in the hydrotalcite structure, which originates from excess magnesium nitrate in the precursor, markedly increases CO2 sorption uptake by hydrotalcite up to the record high value of 9.27 mol kg(-1) at 240 °C and 1 atm CO2.

  19. Metallurgical Parameters Controlling the Eutectic Silicon Charateristics in Be-Treated Al-Si-Mg Alloys

    Mohamed F. Ibrahim


    Full Text Available The present work was carried out on Al-7%Si-0.4%Mg-X alloy (where X = Mg, Fe, Sr or Be, where the effect of solidification rate on the eutectic silicon characteristics was investigated. Two solidification rates corresponding to dendrite arm spacings (DAS of 24 and 65 μm were employed. Samples with 24 μm DAS were solution heat-treated at 540 °C for 5 and 12 h prior to quenching in warm water at 65 °C. Eutectic Si particle charateristics were measured using an image analyzer. The results show that the addition of 0.05% Be leads to partial modification of the Si particles. Full modification was only obtained when Sr was added in an amount of 150–200 ppm, depending on the applied solidification rate. Increasing the amount of Mg to 0.8% in Sr-modified alloys leads to a reduction in the effectiveness of Sr as the main modifier. Similar observations were made when the Fe content was increased in Be-treated alloys due to the Be-Fe interaction. Over-modification results in the precipitation of hard Sr-rich particles, mainly Al4SrSi2, whereas overheating causes incipient melting of the Al-Cu eutectic and hence the surrounding matrix. Both factors lead to a deterioration in the alloy mechanical properties. Furthermore, the presence of long, acicular Si particles accelerates the occurrence of fracture and, as a result, yields poor ductility. In low iron (less than 0.1 wt% Al-Si-Mg alloys, the mechanical properties in the as cast, as well as heat treated conditions, are mainly controlled by the eutectic Si charatersitics. Increasing the iron content and, hence, the volume fraction of Fe-based intermetallics leads to a complex fracture mode.


    D.T. Zhang; M. Suzuki; K. Maruyama


    Macro-texture of an Mg-Al-Ca alloy prepared by friction stir welding (FSW) was investigated through pole figure measurement and X-ray diffraction (XRD) pattern analysis. It was found that at the top and bottom surfaces of friction stir zone (FSZ), (0002) basal planes of magnesium tend to be arranged parallel to the plate surface. In the cross section of FSZ, no obvious texture had evolved and (0002) basal planes showed a random distribution.

  1. Magnetic behavior of Mg-Al-Zn-Fe mixed oxides from precursors layered double hydroxide

    Oliva, M.I., E-mail: [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); IFFAM AF (CONICET - FaMAF UNC), M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); Heredia, A. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Zandalazini, C.I. [Centro Laser de Ciencias Moleculares. INFIQC-FCQ-Grupo de Ciencia de Materiales-FaMAF-Universidad Nacional de Cordoba, Ciudad Universitaria, CP5000 Cordoba, Argentina CONICET (Argentina); Crivello, M. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Corchero, E. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina)


    Mixed oxides of Mg-Al-Zn-Fe were obtained by calcination of layered double hydroxides (LDH) prepared by coprecipitation reaction with hydrothermal treatment. The structural characterization of precursors and oxides was carried out by X rays diffraction, showing increases of ZnO phase with the increase of the zinc content. Magnetic behavior was studied by vibrating sample magnetometer (VSM) and by a superconducting quantum interference device (SQUID) showing both paramagnetic and super paramagnetic behavior depending on both particles size and composition.

  2. Combining (27)Al Solid-State NMR and First-Principles Simulations To Explore Crystal Structure in Disordered Aluminum Oxynitride.

    Tu, Bingtian; Liu, Xin; Wang, Hao; Wang, Weimin; Zhai, Pengcheng; Fu, Zhengyi


    The nuclear magnetic resonance (NMR) technique gives insight into the local information in a crystal structure, while Rietveld refinement of powder X-ray diffraction (PXRD) sketches out the framework of a crystal lattice. In this work, first-principles calculations were combined with the solid-state NMR technique and Rietveld refinement to explore the crystal structure of a disordered aluminum oxynitride (γ-alon). The theoretical NMR parameters (chemical shift, δiso, quadrupolar coupling constants, CQ, and asymmetry parameter, η) of Al22.5O28.5N3.5, predicted by the gauge-including projector augmented wave (GIPAW) algorithm, were used to facilitate the analytical investigation of the (27)Al magic-angle spinning (MAS) NMR spectra of the as-prepared sample, whose formula was confirmed to be Al2.811O3.565N0.435 by quantitative analysis. The experimental δiso, CQ, and η of (27)Al showed a small discrepancy compared with theoretical models. The ratio of aluminum located at the 8a to 16d sites was calculated to be 0.531 from the relative integration of peaks in the (27)Al NMR spectra. The occupancies of aluminum at the 8a and 16d positions were determined through NMR investigations to be 0.9755 and 0.9178, respectively, and were used in the Rietveld refinement to obtain the lattice parameter and anion parameter of Al2.811O3.565N0.435. The results from (27)Al NMR investigations and PXRD structural refinement complemented each other. This work provides a powerful and accessible strategy to precisely understand the crystal structure of novel oxynitride materials with multiple disorder.

  3. The Effects of Burnishing and Conventional Finishing Processes on Surface Roughness and Roundness of the Al 6061 Aluminum Parts

    Adnan AKKURT


    Full Text Available Burnishing is used increasingly as a finishing operation which gives additional advantages such as increased hardness and optimum surface roughness and becoming more popular in satisfying the increasing demands of machine component performance. It is very difficult getting rounded surfaces which are desired where hole machining process (turning, honing, reaming and burnishing. In this study, surface characterizations of getting surface with burnishing and other machining process was evaluated. Especially, inner surface of hole was examined and machining process compared. In the present work, Al 6061 aluminum alloy is selected as work piece material. The experimental results showed that burnishing process must be used where roundness is important. In addition, advantage of burnishing process for Al 6061 aluminum alloy material come out when comparing hardness of hole surface.

  4. Layered Double Hydroxides with Hydrotalcite—type Structure Containing Fe3+,Al3+ and Mg2+

    GUOXiong-hua; LIShu-ping; HOUWan-guo; HANShu-hua; HUJi-fan; LIDong-qing


    Layered double hydroxides(LDHs)with hydrotalcite-type structure containing Fe3+,Al3+ and Mg2+ were prepared by means of a coprecipitation method.The products were characterized by element analysis, X-ray powder diffraction and transmission electron microscopy.It was found that even if the molar ratio of n(Fe+Al)/n(Fe+Al+Mg)>0.33,yet a pure hydrotalcite-like compound(HTlc)phase was gained when n(Fe)/n(Al+Mg+Fe)≤0.30 and n(Al+Mg+Fe)≤0.30;the Al(OH)3 phase appeared in the products when n(Al)/n(Al+Mg+Fe)>0.30;and an amorphous phase emerged when n(Fe)/n(Al+Mg+Fe)>0.33.These results show that there is no concentration superposition effect between Fe3+ and Al3+ on the crystalline state of the produced samples.In our previous work,the concentration superposition effect between Zn2+ and Mg2+ in the synthesis of Zn-Mg-Al-LDHs was found.For the prepared Fe-Al-Mg-LDHs samples,the value of lattice parameter a is between 0.30-0.32nm;and the value of lattice parameter c is between 2.30-2.47nm,the bassl spacing is in the range of 0.76-0.83nm.When the ratio of n(Fe)/n(Al)is a constant,the values of a and c increase with the increase of the Mg2+ content of the produced samples.The mean particle size and the mean crystal grain were determined by virtue of a particle-size instrument,XRD-Scherrer formulsa and TEM method,respectively.

  5. Mechanisms controlling the artificial aging of Al-Mg-Si Alloys

    Pogatscher, S., E-mail: [Institute of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Antrekowitsch, H. [Institute of Nonferrous Metallurgy, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Leitner, H. [Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Franz-Josef-Strasse 18, 8700 Leoben (Austria); Ebner, T. [AMAG Rolling GmbH, Postfach 32, 5282 Ranshofen (Austria); Uggowitzer, P.J. [Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)


    Highlights: > Artificial aging of Al-Mg-Si alloys in the range of 150 and 250 deg. C. > We study precipitation kinetics caused by various thermal histories. > Natural pre-aging affects kinetics at low artificial aging temperatures. > Natural pre-aging promotes kinetics at high artificial aging temperatures. > A vacancy-prison mechanism explains the effect of natural pre-aging. - Abstract: In this study the artificial aging behavior of the Al-Mg-Si alloy AA 6061 was investigated in the temperature range 150-250 deg. C using atom probe tomography, hardness and resistivity measurements for various thermal histories. It was found that the precipitation kinetics and age-hardening response of artificial aging at temperatures below 210 deg. C are lowered by prior natural aging but enhanced above this temperature. An analysis of hardness data was used to evaluate the temperature dependence of precipitation kinetics and dissolution processes. Supported by theoretical considerations, it is assumed that artificial aging of Al-Mg-Si alloys is controlled via the concentration of mobile vacancies. The 'vacancy-prison mechanism' proposed determines the mobile vacancy concentration in the case of natural pre-aging by temperature-dependent dissolution of co-clusters and solute-vacancy interactions.

  6. Mechanism of electropulsing induced recrystallization in a cold-rolled Mg-9Al-1Zn alloy

    Jiang Yanbin, E-mail: [Key Laboratory for Advanced Materials Processing (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Tang Guoyi [Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Shek Chanhung [Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong (Hong Kong); Xie Jianxin [Key Laboratory for Advanced Materials Processing (MOE), University of Science and Technology Beijing, Beijing 100083 (China); Xu Zhuohui [Shenzhen Nonfemet Technology Co., Ltd, Shenzhen 518122 (China); Zhang Zhihao [Key Laboratory for Advanced Materials Processing (MOE), University of Science and Technology Beijing, Beijing 100083 (China)


    Highlights: Black-Right-Pointing-Pointer EPT tremendously accelerated recrystallization of cold-rolled AZ91 alloy. Black-Right-Pointing-Pointer Microstructure evolution of cold-rolled AZ91 alloy under EPT was studied. Black-Right-Pointing-Pointer Mechanism of EPT-induced recrystallization in cold-rolled AZ91 alloy is discussed. - Abstract: Electropulsing induced recrystallization of a cold-rolled Mg-9Al-1Zn alloy was studied using electron backscattering diffraction pattern (EBSD), transmission electron microscopy (TEM) and hardness test. The results indicated that compared with conventional heat treatment, electropulsing treatment (EPT) substantially accelerated recrystallization of the cold-rolled Mg-9Al-1Zn alloy within a short time of several seconds at relatively low temperature, as well as suppressed precipitation of {beta}-Mg{sub 17}Al{sub 12} phase. Based on the EPT enhanced atomic diffusion resulting from the coupling of the thermal and athermal effects with the direct electron-atom interactions, EPT accelerated recrystallization due to significantly increasing both the velocity of dislocation motion and subgrain growth rate.

  7. Microstructures and Mechanical Properties of Rapidly Solidified Mg-Al-Zn-MM Alloys


    Mg-Al-Zn-MM (misch metal) alloy powders were manufactured by inert gas atomization and the characteristics of alloy powders were investigated. In spite of the low fluidity and easy oxidation of the magnesium melt, the spherical powder was made successfully with the improved three piece nozzle systems of gas atomization unit.It was found that most of the solidified powders with particles size of less than 50 μm in diameter were single crystal and the solidification structure of rapidly solidified powders showed a typical dendritic morphology because of supercooling prior to nucleation. The spacing of secondary denrite arms was deceasing as the size of powders was decreasing. The rapidly solidified powders were consolidated by vacuum hot extrusion and the effects of misch metal addition to AZ91 on mechanical properties of extruded bars were also examined. During extrusion of the rapidly solidified powders, their dendritic structure was broken into fragments and remained as grains of about 3μm in size. The Mg-Al-Ce intermetallic compounds formed in the interdendritic regions of powders were finely broken, too. The tensile strength and ductility obtained in as-extruded Mg-9 wt pct Al-1 wt pct Zn-3 wt pct MM alloy were σT.S. =383 MPa and ε=10.6%, respectively. All of these improvements on mechanical properties were resulted from the refined microstructure and second-phase dispersions.

  8. Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics.

    Zhang, Jie; Lu, Tiecheng; Chang, Xianghui; Wei, Nian; Qi, Jianqi


    Nanoindentation tests were performed on nanostructured transparent magnesium aluminate (MgAl2O4) ceramics to determine their mechanical properties. These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN. The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data. The results reveal a remarkable enhancement in plastic deformation as the applied load increases from 300 to 9,000 μN. After the nanoindetation tests, scanning probe microscope images show no cracking in nanostructured transparent MgAl2O4 ceramics, which confirms the absence of any cracks and fractures around the indentation. Interestingly, the flow of the material along the edges of indent impressions is clearly presented, which is attributed to the dislocation introduced. High-resolution transmission electron microscopy observation indicates the presence of dislocations along the grain boundary, suggesting that the generation and interaction of dislocations play an important role in the plastic deformation of nanostructured transparent ceramics. Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

  9. Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles

    Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.


    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  10. Adsorption of methyl orange from aqueous solutions by calcined ZnMgAl hydrotalcite

    Yuan, Dong; Zhou, Liangqin; Fu, Dayou


    The calcined ZnMgAl hydrotalcite was used for degration of methyl orange (MO). The adsorbent was characterized by XRD, SEM, and FT-IR. The results reveal that the ZnMgAl layered structures were disappeared after calcining for 5 h at 500 °C, then were recovered to layer hydrotalcite structure after adsorbing MO anions. The several important affecting factors of adsorption behavior, including the initial pH value of solution, adsorbent dosage, and the initial concentration of solution, were also discussed. The adsorption kinetic processes were fitted with the equations of pseudo-first-order, pseudo-second-order, and intraparticle diffusion, respectively, in which the pseudo-second-order equation fitting results was the better. The equilibrium isotherm of MO was described by both Langmuir and Freundlich model, but better complys with the Langmuir model ( R 2 > 0.98). The possible adsorption mechanism has been presumed. The adsorption experiments indicated that the ZnMgAl hydrotalcite had good adsorption ability to methyl orange in wastewater.

  11. Deformation and microstructure characterization during semi-solid extrusion of Al-4Cu-Mg alloy

    LU Ya-lin; LI Miao-quan; LI Xing-cheng


    Effects of the process parameters, including deformation temperature, punch velocity and extrusion ratio, on the deformation and microstructure characterization during the semi-solid extrusion of Al-4Cu-Mg alloy, were investigated. The experimental results show that the load decreases with an increase of deformation temperature and/or a decrease of punch velocity.When the displacement is more than 4 mm, the load decreases significantly with an increase of the deformation temperature, which is related to the high liquid fraction. The microstructure varies with the process parameters and deformation regions. It can be found that the dynamic recovery occurs during the semi-solid extrusion of Al-4Cu-Mg alloy at lower deformation temperature.Subsequently, the microstructure elongated gradually polygonizes with an increase of deformation temperature. So, the higher deformation temperature should be chosen during the semi-solid extrusion of Al-4Cu-Mg alloy because the grains polygonized and high liquid fractions are beneficial to deformation.

  12. Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles

    Agrawal, Shraddha, E-mail:; Parveen, Azra; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg.& Technology, Aligarh Muslim University, Aligarh-202002 (India)


    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  13. From spent Mg/Al layered double hydroxide to porous carbon materials.

    Laipan, Minwang; Zhu, Runliang; Chen, Qingze; Zhu, Jianxi; Xi, Yunfei; Ayoko, Godwin A; He, Hongping


    Adsorption has been considered as an efficient method for the treatment of dye effluents, but proper disposal of the spent adsorbents is still a challenge. This work attempts to provide a facile method to reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II (OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washed with acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that the carbonization could be well achieved above 600°C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000°C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption-desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m(2)/g and 1.67 cm(3)/g for the sample carbonized at 800°C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH.

  14. Czochralski growth and characterization of MgAl2O4 single crystals

    Bajor, Andrzej L.; Chmielewski, Marcin; Diduszko, Ryszard; Kisielewski, Jaroslaw; Lukasiewicz, Tadeusz; Orlinski, Krzysztof; Romaniec, Magdalena; Szyrski, Wlodzimierz


    MgAl2O4 (MALO) single crystals were pulled by the Czochralski method in [111] direction. The crystals were doped with Co (0.06-0.6 at% (charge compositions)), because Co2+ ions in tetrahedral positions exhibit non-linear optical properties, and, currently, Co:MALO seems to be the best saturable absorber in the eye-safe region (ca. 1.5 μm). By XRD powder technique a stoichiometric MALO was evidenced without admixtures of higher order spinels (MgAl4O7 and MgAl6O10). Also no excessive residual stresses have been discovered by different optical methods, and irrespective of the doping level we did not face any problem of cracking when cutting the crystals into wafers and other structures. In this work we have concentrated our efforts on investigation of thermal properties of MALO. Due to the 2nd order phase transition ca. 650 °C they seem to be of crucial importance in future thermal bonding of this material to the lasing host (Yb,Er-glass) expected just about this temperature.

  15. MgAl alloy synthesis, characterization and its use in hydrogen storage

    Palma, Amelia Sampayo [Facultad de Estudios Superiores Zaragoza (UNAM), Batalla 5 de Mayo s/n, esq. Fuerte de Loreto Col. Ejercito de Oriente, C.P. 09230, Del. Iztapalapa Mexico D.F. (Mexico); Iturbe-Garcia, Jose Luis; Lopez-Munoz, Beatriz Eugenia [Departamento de Quimica (Mexico); Jimenez, Alberto Sandoval [Departamento del Acelerador, Instituto Nacional de Investigaciones Nucleares (Mexico)


    The synthesis and characterization of intermetallic MgAl in two stoichiometric relations, Mg25Al and Mg50Al, and their possible use in hydrogen storage are presented. The intermetallic was prepared by thermal induction in an argon atmosphere. The obtained ingot was submitted to a thermal homogenization treatment at 573 K for 72 h. The particle size diminished with a high energy mill type spex, for which the milling time was 30 and 60 min. The material was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Hydrogenation tests were carried out in a micro-reactor with varying pressure, temperature and reaction time. The material was analyzed with a thermogravimetric system before and after the hydrogenation process. The results indicate that the intermetallic phase range with the mill process did not change with the times used. Because of this, smaller particle sizes of less than a micron were obtained just as scanning electronic microscopy analyses demonstrated. X-ray diffraction showed that phase change does not exist in the intermetallic structure after one hour of milling time. The first results obtained by the thermogravimetric system of the hydrogen quantity absorbed in this material report 3% weight approximately under the experimental conditions of mainly pressure and temperature. (author)

  16. Structure and thermal evolution of Mg-Al layered double hydroxide containing interlayer organic glyphosate anions

    Li Feng; Zhang Lihong; Evans, David G.; Forano, Claude; Duan Xue


    Layered double hydroxide (LDH) with the Mg{sup 2+}/Al{sup 3+} molar ratio of 2.0 containing interlayer organic pesticide glyphosate anions (MgAl-Gly-LDH) has been synthesized by the use of anion exchange and coprecipitation routes. Intercalation experiments with glyphosate (Gly) reveal a correlation between the temperatures for thermal treatments and the types of reaction it undergoes with Gly. The grafting of the Gly anion onto hydroxylated sheets of LDH by moderate thermal treatments (hydrothermal treatments and calcinations) was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis (TGA-DTG), and {sup 31}P nuclear magnetic resonance (NMR). The thermal decomposition of MgAl-Gly-LDH results in the removal of loosely held interlayer water, grafting reaction between the interlayer anions and hydroxyl groups on the lattice of LDH, dehydroxylation of the lattice and decomposition of the interlayer species in succession, thus leading to a variety of crystallographic transitions.

  17. High strain rate tensile behavior of Al-4.8Cu-1.2Mg alloy

    Bobbili, Ravindranadh, E-mail:; Paman, Ashish; Madhu, V.


    The purpose of the current study is to perform quasi static and high strain rate tensile tests on Al-4.8Cu-1.2Mg alloy under different strain rates ranging from 0.01–3500/s and also at temperatures of 25,100, 200 and 300 °C. The combined effect of strain rate, temperature and stress triaxiality on the material behavior is studied by testing both smooth and notched specimens. Johnson–Cook (J–C) constitutive and fracture models are established based on high strain rate tensile data obtained from Split hopkinson tension bar (SHTB) and quasi-static tests. By modifying the strain hardening and strain rate hardening terms in the Johnson–Cook (J–C) constitutive model, a new J–C constitutive model of Al-4.8Cu-1.2Mg alloy was obtained. The improved Johnson–Cook constitutive model matched the experiment results very well. With the Johnson–Cook constitutive and fracture models, numerical simulations of tensile tests at different conditions for Al-4.8Cu-1.2Mg alloy were conducted. Numerical simulations are performed using a non-linear explicit finite element code autodyn. Good agreement is obtained between the numerical simulation results and the experiment results. The fracture surfaces of specimens tested under various strain rates and temperatures were studied under scanning electron microscopy (SEM).

  18. Formation of Aluminum Containing Solids in Drinking Water: Influence on Pb/Cu Corrosion, Al Solubility and Enhanced Softening

    Kvech, Steven Joseph


    Aluminum salts are used as the primary coagulants in the majority of United States drinking water treatment plants. Despite decades of practical experience, there are important knowledge gaps regarding the effects of residual Al on distribution system materials as well as specific types of solids formed. The first phase of this work examined the formation of aluminosilicate deposits in copper and lead pipes using water from Denver, Colorado. It was anticipated was that these de...

  19. Synthesis and characterization of nanocrystalline MgAl{sub 2}O{sub 4} spinel via modified sol–gel method

    Sanjabi, S., E-mail:; Obeydavi, A.


    Highlights: • Nanocrystallines of MgAl{sub 2}O{sub 4} were synthesis by the simple, short time and inexpensive sol–gel method. • The structure properties of MgAl{sub 2}O{sub 4} nanoparticles obtained was excellent including. • The average crystallite’s sizes spinel and specific surface area were estimated about 11.07 nm and 154 m{sup 2} g{sup −1}. • The nanoparticles sizes were about 12 nm and have mesoporous structure. • MgAl{sub 2}O{sub 4} nanopowders with these structure properties are suitable as catalyst supports. - Abstract: Nanocrystallines of magnesium aluminate spinel (MgAl{sub 2}O{sub 4}) were synthesis by modified sol–gel method using aluminum nitrate, magnesium nitrate, citric acid and diethylene glycol monoethyl ether were used as precursor materials with a molar ratio Al/Mg = 2. After obtained a dry powder, the precursor was heat-treated in air at desired temperatures (700–900 °C) for 2 h. The formation nanocrystallines of MgAl{sub 2}O{sub 4} spinel were characterization by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermal gravimetric and differential thermal analysis (TGA/DTA), Field emission scanning electron microcopy (FESEM) with the energy dispersive X-ray spectroscopy (EDX), High resolution transmission electron microscopy (HRTEM) and specific surface area of the synthesized powders was measured with a Brunauer–Emmett–Teller (BET) apparatus using N{sub 2} adsorption. According to obtained XRD patterns the formation of single phase MgAl{sub 2}O{sub 4} completed up 700 °C. The average crystallite’s sizes increased with increasing temperature of calcination, but the specific surface area spinels decreased. The average crystallite’s sizes spinel and specific surface area at 800 °C were estimated about 11.07 nm and 154 m{sup 2} g{sup −1}, respectively. The results of FESEM analysis show that the nanoparticles shape are as spherical shape, uniform and a little agglomerated. The dimension

  20. Corrosion behaviour of powder metallurgical and cast Al-Zn-Mg base alloys

    Sameljuk, A.V.; Neikov, O.D.; Krajnikov, A.V.; Milman, Yu.V.; Thompson, G.E


    The behaviour of Al-Zn-Mg base alloys produced by powder metallurgy and casting has been studied using potentiodynamic polarisation in 0.3% and 3% NaCl solutions. The influence of alloy production route on microstructure has been examined by scanning electron microscopy, Auger electron spectroscopy and secondary ion mass spectrometry. An improvement in performance of powder metallurgy (PM) materials, compared with the cast alloy, was evident in solutions of low chloride concentration; less striking differences were revealed in high chloride concentration. Both powder metallurgy and cast alloys show two main types of precipitates, which were identified as Zn-Mg and Zr-Sc base intermetallic phases. The microstructure of the PM alloys is refined compared with the cast material, which assists understanding of the corrosion performance. The corrosion process commences with dissolution of the Zn-Mg base phases, with the relatively coarse phases present in the cast alloy showing ready development of corrosion.