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![illustrates the SEM image of diffusion reaction layer in AZ31/4047 Al composite extruded sheet. The results indicate that there are no voids and cracks between these two dissimilar metals adjacent to the transition layer. In addition, the thickness of the transition layer is approximately 3.6 μm. Yahiro et al. [19] stated that the bonding strength is not reduced in the case where the thickness of a diffusion layer is 3-5 μm, but it is deteriorated where the thickness increases to 10 μm or more and then making the clad sheet ineffective. Therefore, a sound interfacial bonded Mg/Al laminate is successfully fabricated by the proposed composite extrusion directly from the as-cast alloys. The EDS line analysis across the Mg/Al interface is plotted in . It reflects that, in the transition layer, the concentration of Al is decreased gradually from Al matrix to Mg matrix, while the Mg concentration presents an opposite tendency. The above phenomenon is in concordance with the research of Chen et al. [20] , which implied that 6063 Al and AZ91 Mg alloys materials were miscible and the intermetallic was not formed in the interface of Mg/Al composite laminate fabricated by porthole die extrusion.](publication/337280264/figure/fig2/AS:870498997137412@1584554542419/llustrates-the-SEM-image-of-diffusion-reaction-layer-in-AZ31-4047-Al-composite-extruded.jpg)
illustrates the SEM image of diffusion reaction layer in AZ31/4047 Al composite extruded sheet. The results indicate that there are no voids and cracks between these two dissimilar metals adjacent to the transition layer. In addition, the thickness of the transition layer is approximately 3.6 μm. Yahiro et al. [19] stated that the bonding strength is not reduced in the case where the thickness of a diffusion layer is 3-5 μm, but it is deteriorated where the thickness increases to 10 μm or more and then making the clad sheet ineffective. Therefore, a sound interfacial bonded Mg/Al laminate is successfully fabricated by the proposed composite extrusion directly from the as-cast alloys. The EDS line analysis across the Mg/Al interface is plotted in . It reflects that, in the transition layer, the concentration of Al is decreased gradually from Al matrix to Mg matrix, while the Mg concentration presents an opposite tendency. The above phenomenon is in concordance with the research of Chen et al. [20] , which implied that 6063 Al and AZ91 Mg alloys materials were miscible and the intermetallic was not formed in the interface of Mg/Al composite laminate fabricated by porthole die extrusion.
Source publication
The microstructures and mechanical properties of the composite extruded AZ31/AZ31 and AZ31/4047 Al sheets were investigated and made a comparison to the conventional extruded AZ31 sheet. Owing to the introduced intense shear deformation at the interface during the composite extrusion, grain refinement and tilted texture were detected in AZ31 layers...
Context in source publication
Context 1
... layer is 3-5 μm, but it is deteriorated where the thickness increases to 10 μm or more and then making the clad sheet ineffective. Therefore, a sound interfacial bonded Mg/Al laminate is successfully fabricated by the proposed composite extrusion directly from the as-cast alloys. The EDS line analysis across the Mg/Al interface is plotted in Fig. 4 . It reflects that, in the transition layer, the concentration of Al is decreased gradually from Al matrix to Mg matrix, while the Mg concentration presents an opposite tendency. The above phenomenon is in concordance with the research of Chen et al. [20] , which implied that 6063 Al and AZ91 Mg alloys materials were miscible and the ...
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The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significa...
Citations
... This can increase additional shear strain, refine grain size, overcome the dead zone phenomenon, and improve the smoothness of metal flow and flow property of the metal extrusion process. The flow rate gradient and strain gradient formed during this process cause the c-axis orientation of the sheet grains to tilt along the extrusion direction, weakening the basal texture of the sheet and improving overall mechanical properties [52][53][54]. ...
Magnesium (Mg) alloy is a widely used lightweight metal structural material due to its high specific strength and stiffness, excellent damping performance, and recyclability. Wrought Mg alloys are widely favored in fields such as aerospace, transportation, and biomedical stents. However, most wrought Mg alloys with a hexagonal close-packed (HCP) crystal structure lack sufficient independent slip systems to meet the von Mises criterion for uniform plastic deformation at room temperature. This can result in the formation of strong basal texture during plastic deformation and poor room temperature plastic forming ability. Improving the room temperature forming performance is a crucial challenge that must be addressed to broaden the application of Mg alloy sheets. Our research group has comprehensively summarized significant work and latest research progress in improving the room temperature forming of Mg alloy sheets via extrusion technology in recent years. Specifically, we have developed a new type of asymmetric extrusion technology that combines material structure evolution, mechanical property, and forming behavior analysis. We have elucidated the extrusion process characteristics, texture control mechanism, and forming properties of Mg alloy sheets through plastic deformation mechanisms, mold design, and finite element numerical simulation. Our findings provide a novel extrusion technology for the fabrication of highly formable Mg alloy sheets, which can be utilized in various applications.
... The process of polymer composite reinforcements by using fibers, fabrics particles or whiskers to increase mechanical capacities of new composites can be numerically analyzed in order to increase the efficiency in the process [81]. The orientation as well as volumes of the fiber in the polymer matrixes reinforcements process can be analytically analyzed in order to increase the strength and flexibility of new generated composites. ...
Composite materials are used to produce multi-objective structures such as fluid reservoirs, transmission pipes, heat exchangers, pressure vessels due to high strength and stiffness to density ratios and improved corrosion resistance. The mathematical concepts can be used to simulate and analyze the generated mechanical and thermal properties of composite materials regarding to the desired performances in actual working conditions. To solve and obtain the exact solution of the developed nonlinear differential equations in the composite materials, analytical methods can be applied. Mechanical and thermal analysis of complex composite structures can be numerically analyzed using the Finite Element Method (FEM) to increase performances of composite structures in different working conditions. To decrease failure rate and increase performances of composite structures under complex loading system, thermal stress and effects of static and dynamic loads on the designed shapes of composite structures can be analytically investigated. The stresses and deformation of the composite materials under the complex applied loads can be calculated by using the FEM method in order to be used in terms of safety enhancement of composite structures. To increase the safety level as well as performances of the composite structures in different working conditions, crack development in elastic composites can be simulated and analyzed. To develop and optimize the process of composite deigning in terms of mechanical as well as thermal properties under different mechanical and thermal loading conditions, the advanced machine learning systems can be applied. A review in recent development of composite materials and structures is presented in the study and future research works are also suggested. Thus, to increase performances of composite materials and structures under complex loading systems, advanced methodology of composite designing and modification procedures can be provided by reviewing and assessing recent achievements in the published papers.
... Magnesium alloys are widely used, due to their low density and high strength, in transportation, electronic industry, military, and other fields [1][2][3][4]. Especially in aerospace, rail transit, electronic products, biomedical, architectural decoration and other fields, they have broad application prospects and have become one of the future new material development directions. Since magnesium is hexagonal close-packed (HCP), the symmetry is low, and its independent slip system is lessened at room temperature [5]. ...
The deformation mechanism and texture evolution of AZ31 Mg alloy compressed in three different directions at room temperature were studied, and the relationship between the two was compared through experiments and viscoplastic self-consistent (VPSC) modeling. Setting up only one specific deformation mode was the predominant mechanism by changing the CRSS ratio for the different deformation modes. The following conclusions were drawn: (1) It was demonstrated that basal slip causes a slow and continuous deflection of the grain toward the transverse direction (TD). When the sample is compressed in the extruded direction (ED), prismatic slip leads to grains being deflected toward the ED in the initial stages of compression, and when the sample is compressed 45° to the extrusion direction (45ED) and perpendicular to the extrusion direction (PED), prismatic slip contributes little to the texture evolution. (2) When the sample is compressed along three different directions, pyramidal <c+a> slip leads to the grain being deflected toward the normal direction (ND), and the {10-12} extension twin deflects the grain at a large angle. (3) When only the {10-11} compression twin is activated, the grain will be deflected in the ND while the sample is compressed along the ED and 45ED, but when the sample is compressed in the PED, the grains are concentrated from both sides of the ED to the center.
... When the sheet metal is bending, the outer layer of fiber is stretched, and the inner layer is shortened. There exists a layer between the elongation layer and the shortening layer (Chai et al., 2019). ...
Purpose
“V-bending” is the most commonly used bending process in which the sheet metal is pressed into a “V-shaped” die using a “V-shaped” punch to form a required angular bend. When the punch is removed after the operation, because of elastic recovery, the bent angle varies. This shape discrepancy is known as spring back which causes problems in the assembly of the component in the modern aerospace industry. Regarding the optimization of spring-back accuracy, this research will illustrate the laws of the transition area (TA) of the nondeformation area (NDA) during the 90° “V-shape” bending process.
Design/methodology/approach
According to the traditional “V-bending” process to optimize the spring-back accuracy, the bent sheets are divided into deformation area (DA) and NDA. For this reason, the traditional “V-bending” process may prolong error to optimize the spring-back accuracy because NDA has a certain amount of deformation, which the researcher always avoids. Firstly, bent sheets are divided into three parts in this research: DA, TA and NDA to avoid the distortion error in TA that are not considered in the NDA in traditional theory. Then, the stress and strain in the DA and TA were discussed during theoretical derivation and some hypotheses were proposed. In this research, the interval, position and distortion degree of the TA of the bending sheet are used by finite element analysis. Finally, V-shape bending tests for aluminum alloy at room temperature are used and labeled all the work pieces' TAs to realize the deformation amount in the TA.
Findings
The bending radius does not affect the range of the TA, it only changes the position of TA in the bending sheet. It is evident that the laws of TA were explored in the width direction and gradually changed from the inner layer to the outer layer based on the ratio of width and thickness of the bending plate/sheet.
Originality/value
In the modern aerospace industry, aircraft manufacturing technology must maintain high accuracy. This research has practical value in the 90° “V-shape” bending of metal sheets and the development of its spring-back accuracy.
... In recent years, magnesium alloys have been extensively used in industrial fields (e.g., aerospace, automotive manufacturing, electronic communications, military affairs, nuclear power) due to their unique mechanical properties, such as low density, high specific stiffness and high specific strength and easy recovery. However, the poor plasticity and formability of magnesium alloy sheets are exhibited at room temperature due to their special crystal structure (the hexagonal closed-packed crystal structure, with few slip systems and a strong basal plane texture) [8]. Through the research of William J. Joost [9], the results showed that magnesium alloy exhibits tremendous potential in the industrial field, but some technical barriers limit its development. ...
Magnesium alloys play an important role in lightweight structures, which are extensively used in different industries due to their excellent mechanical and physical properties. In this paper, the formability of the AZ31B magnesium alloy sheet was studied by using tensile tests at different temperatures (from 25 to 250 °C) and strain rates (from 0.017 s−1 to 0.34 s−1). The results showed that the material behaves with positive temperature sensitivity when forming at a temperature lower than 200 °C. The effect of the strain rates on the formability of AZ31B was larger at high temperatures. The metallography of AZ31B at different temperatures and strain rates was observed by OM. The results showed that the partially recrystallized structure was exhibited at a temperature of 150 °C. With the increase in temperature, the approximate complete recrystallization was exhibited at a temperature of 250 °C. The fracture morphology of AZ31B was observed at different strain rates and temperatures by SEM. Additionally, the main fracture pattern was quasi-cleavage at room temperature. However, with the increase in temperature, the fracture pattern was transited from a quasi-cleavage pattern to a ductile fracture pattern. The ductile fracture pattern was the main fracture pattern at a temperature of 250 °C.
... The shift of neutral axis leads to extra shear stress during bending process, and it is accepted that the reduction of neutral axis is beneficial for the bendability. It is previously reported the neutral axis shift can be achieved by introducing asymmetry structure [45][46][47][48]. Yilamu et al. reported the neural axis of stainless steel clad aluminum sheet was shifted towards the clad steel layer as it is a strong layer [45]. ...
... In Mg alloys, this shift was also reported in Mg-Al bimetallic sheet [47] and Mg/Al/Steel clad composites [48]. After USSP treatment, as the formed surface nanocrystalline is with higher strength, it can easily imply the shift of neutral axis should be activated after USSP treatment, especially for one side treatment. ...
... Therefore, the β value is calculated to represent the values of USSP-external was bigger than that of the as-received, which means the shift of the neutral towards external side is more obvious. The result is consistent with previous finding that the neutral axis is shifting towards the strong side in inhomogeneous materials [45][46][47][48]. During the bending process, the deformation of the neutral axis is pure bending while the external or internal region undergoes a nonuniform bending deformation to corporate the thinning or thickening of the sheet. ...
A surface nanocrystalline was fabricated by ultrasonic shot peening (USSP) treatment at AZ31 Mg alloy. The effect of nanocrystalline thickness and its placed side (external or internal) on the bendability was studied by a V-bending test. Three durations, 5min, 10min and 15min, were applied to form the surface nanocrystalline with thicknesses of 51μm, 79μm and 145μm, respectively. Two-side treatment led to a similar bendability as that of as-received. One-side (internal) treatment for 5 min resulted in an improved bendability while the improvement was limited and degenerated for longer treatment. The improvement was related to the drawing back of the neutral axis. The one-side (external) treatment also improved the bendability and the improvement was due to the redistribution of strain and stress during bending. It resulted in larger stress but smaller strain at the convex, which prevented the happening of crack during bending.
... Coextrusion is a process in which two or more materials are concurrently extruded into a single composite billet. This is a new method for manufacturing Mg-based composites with excellent ductility and high strength [80,83,84]. As shown in Figure 1, Zhao et al. [80] prepared a bimetal composite rod composed of a softer AZ31 sleeve and a harder WE43 core. ...
Magnesium-based composites are promising materials that can achieve higher strength, modulus, stiffness, and wear resistance by using metals, ceramics, and nanoscale carbon-based materials as reinforcements. In the last few decades, high-performance magnesium-based composites with excellent interfacial bonding and uniformly distributed reinforcements have been successfully synthesized using different techniques. The yield strength, Young’s modulus, and elongation of SiC nanoparticle-reinforced Mg composites reached ∼710 MPa, ∼86 GPa, and ∼50%, respectively, which are the highest reported values for Mg-based composites. The present work summarizes the commonly used reinforcements of magnesium composites, particularly nano-reinforcements. The fabrication processes, mechanical properties, reinforcement dispersion, strengthening mechanisms, and interface optimization of these composites are introduced, and the factors affecting these properties are explained. Finally, the scope of future research in this field is discussed.
... Recently, bimetal alloys are of the keen interest of researchers, the large-scale production of bimetal alloys can easily be produced through the extrusion process. The interface of the alloys after extrusion in AZ31/4047Al alloy was much stronger [75]. From mechanistic and engineering points of view, the lightweight material can produce ease for the military applications and save energy and cost, therefore a high strength Al 7075 Mg alloy [76e79] fabricated through spray forming and Mg alloy (rare-earth free) fabricated through semi-continuous casting can be subjected to the extrusion processing as shown in Fig. 8. ...
The military and aerospace industries require lightweight and high stiffness materials, which can reduce the CO2 emission and total cost of the project. Magnesium alloys are one of the best replacements of heavy-weight materials and can be employed to withstand the high strain rate shock wave impact under stringent environments. The resistance against shock wave impact can be endured by the plastic deformation, therefore, understanding the complex deformation behavior of magnesium alloys and temperature rise under high strain rate impact is necessary, especially, adiabatic shear band development which leads to early failure. So, this article emphasizes the shapes of stress-strain curves (sigmoidal shape and concave down shape) and the deformation behaviors of high strain rate compressed magnesium alloys under different temperatures and further its correlation with the ballistic impact. The prediction of temperature rise and strain rate away from the crater is a big dilemma owing to the very short interval of ballistic impact. Here, based on Wright criterion and microstructure evolution of dynamically compressed alloys with the microstructure of ballistic impacted magnesium alloys, the temperature rise in adiabatic shear bands and away from the carter was evaluated. In the end, some suggestion has been proposed for increasing the efficiency of the magnesium alloys during high strain rate compression/ballistic impact.
... However, its strain hardening can be eliminated by an intermediate annealing process [2]. On the other hand, it improves the strength [3,4], hardness [5,6], and wear resistance [7,8] of metals, which is particularly important for pure metals and certain alloys that cannot be strengthened by heat treatment [9]. Therefore, strain hardening can hinder the continued development of plastic deformation and greatly improve the safety of the components. ...
In this work, in situ magnesium-based composite composed of nanoscale magnesium oxide (MgO), prepared by spark plasma sintering, shows significant plasticity and high strain hardening. During the strain-hardening stage, the incremental work-hardening exponent shows drastic fluctuations due to the pile-up and release of dislocations. The dislocation pile-up at the interface makes it possible to form dislocation cells. Mixed dislocations can be generated within the cells surrounding the MgO particles, which can interact with the stress field and effectively hinder the movement of dislocations, leading to an increase in dislocation density. What is more, grain boundaries have higher elastic modulus and hardness, which may lead to the appearance of microcracks and eventually intergranular fractures. Our results may shed some light on understanding the role of MgO particles in influencing the mechanical properties of Mg alloys and Mg-based composites, especially in work hardening.
... Recently, considerable attentions have been focused on magnesium alloys due to their low density and wide application prospects in aerospace, automotive and other fields [1][2][3][4][5][6] , which can be a good substitute to steels and aluminum alloys [7] . With ascending demands of commercial application, mechanical properties, manufacture performances and corrosion resistance of Mg alloys need to be further optimized [8][9][10] . ...
... (1) nucleus is treated as the sphere; (2) the melting, agglomeration, growth, and shrinkage of nucleus are not considered; (3) The force between nuclei is not taken into account; (4) Nuclei are uniformly released from the side wall of the mold, and it is assumed that the number of nuclei is the same under various magnetic fields. (5) Supposing that nuclei release at a certain time in the early stage of the solidification, and this moment is defined as the initial moment during the simulation of the nuclei movement. ...
For obtaining the finer grains of magnesium alloy, a novel combined pulsed magnetic field with different initial phases, also called out-of-phase pulsed magnetic field (OPPMF), was applied to study the solidification structure of AZ80 magnesium alloy. The numerical simulation was simultaneously conducted to investigate the refinement mechanisms. The experimental results showed that the macrostructure could be effectively refined by applying external magnetic field. Meanwhile, finer grains were obtained with the higher current intensity. However, the increase of current intensity could only refine the grains to about 0.5 mm. Furthermore, compared to a single pulsed magnetic field (PMF) and alternating series of OPPMF (Connection II), a finer structure was observed when the consecutive series of OPPMF (Connection I) was imposed. In contrast with a single PMF and Connection II, the numerical results showed that the greater axial Lorentz force was obtained under the Connection I, generating the stronger forced flow in the melt. It is believed that abundant nuclei could detach from the mold wall and move faster into the interior melt due to the stronger forced flow; besides, the lower superheat and greater temperature uniformity in bulk melt were realized, accounting for the finest structures under the Connection I.
