Hot compression tests of A5083 aluminum alloys with extruded and homogenized initial microstructures were carried out at varying temperatures (350 to 450 °C) and strain rates (0.1 to 10/s). The ...effects owing to nonuniform temperature and strain distributions caused by deformation were compensated by inverse analysis to determine the flow curves. The obtained flow curves with a homogenized initial microstructure were lower than those with an extruded initial microstructure. Constitutive descriptions were obtained to study the dynamic kinetics during compression, and comparisons between the predicted results from constitutive equations and the experimental results from associate microstructures verified their accuracy. Electron backscatter diffraction (EBSD) was utilized for observing microstructures. The characteristics of continuous dynamic recrystallization, particle-stimulated dynamic recrystallization and conventional dynamic recrystallization were confirmed. The dynamic recrystallization process with a homogenized initial microstructure is slower than that with an extruded initial microstructure, owing to the different amounts of subgrain structures during the initial deformation stage, which can affect the speed of the continuous dynamic recrystallization process. Microhardness tests were conducted to study the connection between microstructure and mechanical property. The microhardness after deformation with an extruded initial microstructure are higher than those with a homogenized initial microstructure.
•A tribocorrosion mechanism of aluminum alloy in the deep ocean is first proposed.•The tribocorrosion mechanism relies on interaction of mechanics, chemistry and electrochemistry.•The tribocorrosion ...mechanism is different under different hydrostatic pressure.•The corrosion accelerates wear is the main failure factor of materials during rubbing.•The rise of hydrostatic pressure will inhibit the formation of OH−.
To understand the tribocorrosion behavior and mechanism in the deep ocean, the wear behavior of 7075-T6 aluminum alloy in 3.5 wt. % NaCl solution under the hydrostatic pressure of 0.1 MPa-30 MPa was investigated. The wear and corrosion mechanism of the aluminum alloy under different hydrostatic pressure were discussed, and its tribocorroison model was presented. Results show that mechanics, chemistry and electrochemistry interact with each other and accelerate the tribocorrosion process under the effect of high hydrostatic pressure. And the corrosion accelerates wear is the main failure factor of the aluminum alloy under a high hydrostatic pressure.
The morphology, size, and distribution of grains and secondary phases in 6063 aluminum alloy significantly influence the comprehensive mechanical properties of alloys. In this study, the rare-earth Y ...and Al–Ti–B master alloys were added to 6063 aluminum alloy, which is used to compare grain-refining effects, investigate the manner of existence of rare-earth Y, determine the influence and mechanism on the secondary phase, and analyze the influence of rare-earth Y on hardness, tensile property, and fracture morphology. Results revealed that adding the rare-earth Y combined with Al–Ti–B master alloy decreased the grain sizes of 6063 aluminum alloy. Rare earth Y is mainly distributed around TiB2 particles in the form of AlTiY particles, and part of it exists in α-Al grains in the form of Al3Y. Moreover, adding rare-earth Y decreased the Mg2Si size, contributed to turn β-AlFeSi phase into α-AlFeSi phase, formed various complex compounds (e.g., AlSiY, AlFeSi, and AlFeSiYMg), and reduced the impurity of Fe-rich phase at the grain boundary. Furthermore, the rare-earth Y combined with Al–Ti–B master alloy added to 6063 aluminum alloy can improve the tensile strength and elongation by 5% and 75% respectively. However, the value of hardness did not significantly change. Meanwhile, the rough and irregular dimples that formed in the fracture morphology became small dimples, and the form of fracture was ductile regardless of rare-earth Y or rare-earth Y combined with Al–Ti–B master alloy added to 6063 aluminum alloy.
•The addition of Y and Al-Ti-B master alloy has a good effect on grain refinement of 6063 alloy.•Adding Y decreased the Mg2Si size, contributed to turn β-AlFeSi into α-AlFeSi, formed various complex compounds.•The mechanical properties and fracture morphology of 6063 alloy were improved by adding Y and Al-Ti-B master alloy.
•LDH films are electrodeposited on an aluminum alloy substrate for the first time.•Electrodeposition overcomes the shortcomings of the traditional hydrothermal method, i.e., time consumption and high ...operation temperatures.•The electrodeposited LDH films exhibit satisfactory corrosion protection capacity.•The LDH films protect aluminum alloys via a physical barrier mechanism and the inhibiting effect of vanadates.
This work provides a simple strategy to enhance the corrosion resistance of layered double hydroxide (Zn-Al LDH) films on AA2024 aluminum alloys by an electrodeposition method. Inhibitor anion vanadates are further intercalated into the interlayer galleries of LDHs through an ion-exchange process to improve their corrosion performance. Vanadates enhance the barrier property of the LDH films and are enriched in the corrosion sites to actively protect aluminum alloys. A literature survey shows that the electrodeposited LDH films exhibit comparable corrosion protection capacity to those prepared by the traditional hydrothermal method, although the former have the smallest thickness.
The compatibility of the wrought Al-Ca alloy with the element Fe was investigated in the present study. In this work, both the Al-Ca alloy and Al-Ca-Fe alloy were synthesized through melting, ...casting, heat treatment, and rolling. A new ternary Al-Ca-Fe eutectic phase, identified as Alsub.10CaFesub.2 with an orthorhombic structure, demonstrated enhanced performance, as revealed by nanoindentation tests. Combining the results of the nanoindentation and EBSD, it can be inferred that during the rolling and heat treatment process, the divorced eutectic phases were broken and spheroidized, and the structure of the Fe-rich alloy became finer, which promotes the formation of fine grains during the process of dynamic recrystallization and effectively hindered the grain growth during thermal treatment. Consequently, the strength of the as-rolled Al-Ca alloy was improved with the addition of 1 wt.% Fe while the ductility of the alloy was maintained. Therefore, adding Ca into the high-Fe content recycled aluminum altered the form of the Fe-containing phases in the alloy, effectively expanding the application scope of recycled aluminum alloy manufacturing. This approach also offered a method for strengthening the Al-Ca aluminum alloys. Compared to the traditional approach of reducing Fe content in alloys through metallurgical means, this study opened a new avenue for designing novel, renewable aluminum alloys highly compatible with impurity iron in scrap.
•The fatigue resistance of milled AlSi10Mg samples surpasses conventional Al6061.•Producing samples without contour shows to be beneficial for the fatigue properties.•Vibratory polishing induces a ...compressive stress, improving fatigue resistance.•The effect of vibratory polishing seems to depend on the presence of a contour.
Additive Manufacturing (AM) is in general seen as a game changing technology. In particular for the space industry, it seems a promising tool for the constant strive towards increasing performance and reducing the cost of space missions. The layer-wise approach allows an increased design freedom and optimisation. Current space applications are designed with a large safety margin since the AM process generates imperfections in the material, which can lower the mechanical properties. A profound understanding on the one hand of the link between process parameters and final properties, and on the other hand of the influence of possible imperfections on mechanical properties still requires more research and can result in a further design and performance optimisation. With this aim, this study characterised the fatigue behaviour of AlSi10Mg processed via AM and the influence of the process parameters, and possible resulting imperfections, on fatigue behaviour. First of all, the influence of building direction, platform temperature, powder layer thickness, surface finish and heat treatment on the fatigue properties was verified. Results showed that there is a direct correlation between the process parameters and the fatigue properties of AlSi10Mg parts, having received the same post processing. Observations indicate that changing the parameters influences the defect population characteristics, determining the fatigue life. In addition, the different surface finishing methods have, as expected, a strong impact on the fatigue behaviour of AM AlSi10Mg materials. Interestingly, vibratory polished specimens produced without contour parameter endured on average a larger amount of cycles to failure than specimens produced with contour parameter. Therefore, the dimensions, roughness, hardness, microstructure, defect population and residual stresses were verified for these two different scanning strategies to look for an explanation for this behaviour. The samples without contour showed lower surface roughness and higher compressive residual stresses in the load direction, potentially explaining the higher number of sustained cycles to failure. Overall, this study showed that an optimised combination of process parameters and surface finish can improve fatigue performance, without the need for machining of the AM parts.
-The precipitation of Omega-phase {111}.sub.alpha plates in the Al-Cu-Mg alloy has been investigated at a Cu/Mg ratio > 10 and low Si content. Unlike Al-Cu-Mg alloys containing Ag, nanoscale plates ...with an {111}.sub.alpha habit plane has been found for the first time to precipitate in the alloy according to a heterogeneous mechanism, namely, along low-angle boundaries, dislocation lines, and at the theta'-phase/Al-matrix interphase boundary.
Aluminum alloy is the main structural material of aircraft, launch vehicle, spaceship, and space station and is processed by milling. However, tool wear and vibration are the bottlenecks in the ...milling process of aviation aluminum alloy. The machining accuracy and surface quality of aluminum alloy milling depend on the cutting parameters, material mechanical properties, machine tools, and other parameters. In particular, milling force is the crucial factor to determine material removal and workpiece surface integrity. However, establishing the prediction model of milling force is important and difficult because milling force is the result of multiparameter coupling of process system. The research progress of cutting force model is reviewed from three modeling methods: empirical model, finite element simulation, and instantaneous milling force model. The problems of cutting force modeling are also determined. In view of these problems, the future work direction is proposed in the following four aspects: (1) high-speed milling is adopted for the thin-walled structure of large aviation with large cutting depth, which easily produces high residual stress. The residual stress should be analyzed under this particular condition. (2) Multiple factors (e.g., eccentric swing milling parameters, lubrication conditions, tools, tool and workpiece deformation, and size effect) should be considered comprehensively when modeling instantaneous milling forces, especially for micro milling and complex surface machining. (3) The database of milling force model, including the corresponding workpiece materials, working condition, cutting tools (geometric figures and coatings), and other parameters, should be established. (4) The effect of chatter on the prediction accuracy of milling force cannot be ignored in thin-walled workpiece milling. (5) The cutting force of aviation aluminum alloy milling under the condition of minimum quantity lubrication (mql) and nanofluid mql should be predicted.
Process parameters and their effects on thermal-mechanical properties of aluminum alloys are vitally important for the successful manufacture of aluminum alloy panel components under hot forming ...condition. In this study, firstly, thermal-mechanical properties of 7075 aluminum alloy sheets under hot forming conditions were comprehensively investigated using a series of isothermal uniaxial tensile tests at different temperatures and strain rates on a Gleeble 3500 thermal mechanical simulator. Based on the experimental results, the temperature rise ΔT generated from plastic deformation was further calculated considering the fraction of plastic work converted into heat, β, and the fraction of deformation heat appearing as a temperature rise, δ. ΔT increases with an increase in strain rate and a decrease in deformation temperature, with a maximum temperature rise ΔTmax reaching 33.5 K. Furthermore, taking ΔT into consideration, the relationship model between the work hardening rate, temperature and strain rate was constructed according to the Zener-Hollmon parameter. The variation of the work hardening rate with strain rate and temperature can be interpreted using this model. Finally, to determine the optimal processing parameters, the processing maps of 7075 aluminum alloy were established subsequently under the experimental conditions. The optimal processing parameters for 7075 aluminum alloy are located within the windows: (1) temperature, 573–680 K and strain rate, 0.368–8.1 s−1; (2) temperature, 695–723 K and strain rate, 0.05–1 s−1. According to the microstructure observations, it can be concluded that the main softening mechanism of “safe” domains is dynamic recovery (DRV) and the continuous dynamic recrystallization (DRX) can be effectively retarded due to the presence of precipitated particles. The work performed in this research, for the first time, provides quantitative evaluations of process parameters on the hot deformation of aluminum alloy sheet forming using processing maps considering corresponding microstructural evolutions, which enables to provide useful guides for process designers of sheet metal forming.
•Temperature rise of AA7075 generated from plastic deformation was calculated.•Work hardening rate of the alloys was analyzed with the constructed model.•The processing maps were used to optimize the hot stamping process.•The main softening mechanism of the “safe” domain is DRV.
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