Search Results (43)

Al/TiB₂ aluminum alloy laminates were fabricated using a combination of accumulative roll bonding (ARB) and cold rolling processes. The Al/TiB₂ interface and microstructure were meticulously characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties of the laminates were assessed through tensile testing. The experimental results demonstrate that with an increasing cold rolling reduction, a laminated composite sheet with a nanocrystalline structure was successfully produced. The critical strain for the onset of plastic instability was also investigated. The findings indicate that as the cold rolling reduction increases, severe necking occurs in the Al12Zn2.2Mg1.7Cu3TiB₂ layer. At a reduction of 80%, the necking region approaches fracture. Tensile results reveal that this pronounced necking has a detrimental effect on the strength of the laminate. It is proposed that the plastic instability originates from shear bands, and the mechanical property mismatch between the constituent layers is identified as the primary reason for the localized preferential deformation. Full article

Accumulative rolling bonding (ARB) Cu/Nb nanolaminates have been widely observed to exhibit unique and large numbers of interface-based plasticity mechanisms, and these have been associated with the many extraordinary properties of the material system, especially resistances in extreme engineering environments (mechanical/pressure, thermal, irradiation, etc.) and ability to self-heal defects (microstructural, as well as radiation-induced). Recently, anisotropy in the interface shearing mechanisms in the material system has been observed and much discussed. The Cu/Nb nanolaminates appear to shear on the interface planes to a much larger extent in the transverse direction (TD) than in the rolling direction (RD). Related to that, in this present study we observe interface rotation in Cu/Nb ARB nanolaminates under constrained and unconstrained loading conditions. Although the primary driving force for interface shearing was expected only in the RD, additional shearing in the TD was observed. This is significant as it represents an interface rotation, while there was no external rotational driving force. First, we observed interface rotation in in situ rectangular micropillar compression experiments, where the interface is simply sheared in one particular direction only, i.e., in the RD. This is rather unexpected as, in rectangular micropillar compression, there is no possibility of extra shearing or driving force in the perpendicular direction due to the loading conditions. This motivated us to subsequently perform in situ microbeam bending experiments (microbeam with a pre-made notch) to verify if similar interface rotation could also be observed in other loading modes. In the beam bending mode, the notch area was primarily under tensile stress in the direction of the beam longitudinal axis, with interfacial shear also in the same direction. Hence, we expect interface shearing only in that direction. We then found that interface rotation was also evident and repeatable under certain circumstances, such as under an offset loading. As this behaviour was consistently observed under two distinct loading modes, we propose that it is an intrinsic characteristic of Cu/Nb interfaces (or FCC/BCC interfaces with specific orientation relationships). This interface rotation represents another interface-based or interface-mediated plasticity mechanism at the nanoscale with important potential implications especially for design of metallic thin films with extreme stretchability and other emerging applications. Full article

Accumulative Roll Bonding (ARB) is a severe plastic deformation process typically used to produce ultra-fine-grained structures. This study investigates the feasibility of using the ARB process to recycle aluminum chips from an Al-Mg-Si alloy (AA6063). The chips were first compacted under a 200 kN hydraulic press and then directly hot-rolled at 550 °C without prior heat treatment to a final sheet thickness of 1.5 mm. Subsequent ARB cycles were then applied to achieve full consolidation. Mechanical properties were evaluated through tensile testing and microhardness measurements, while microstructure was characterized using Optical Microscopy and SEM-EBSD. These analyses revealed significant grain refinement and improved homogeneity with increasing ARB cycles. Mechanical testing showed that the ARB process substantially enhanced both tensile strength and hardness of the recycled AA6063 chips while maintaining good ductility. The best results were obtained after two ARB cycles, yielding an ultimate tensile strength (UTS) of 170 MPa and an elongation at rupture of 15.7%. The study conclusively demonstrates that the ARB process represents a viable and effective method for recycling aluminum chips. This approach not only significantly improves mechanical properties and microstructural characteristics but also offers environmental benefits by eliminating the energy-intensive melting stage. Full article

Cu/Nb multilayer composites with a continuous layered structure were fabricated using accumulative roll bonding (ARB). The effects of Joule heating on the mechanical properties and fracture behavior of these composites under electrically assisted tension (EAT) at different current densities were investigated. It is observed that the ultimate tensile strength (UTS) exhibits a progressive decline with the increasing current density. When the current density reaches 120 A/mm², the UTS decreases by 68.9 MPa, and this decline tends to saturate at high current densities. Furthermore, the elongation (EL) displays significant enhancement at current densities of 40 A/mm² and 80 A/mm², particularly reaching a maximum improvement of 42.1% at 80 A/mm² when compared with room temperature (RT). The fracture mode observed during the EAT process is consistent with that at RT, which remains a ductile fracture. Full article

AA 1060 aluminum alloy underwent roll bonding with reductions of 25% and 35%, followed by accumulative roll bonding (ARB) for up to seven cycles at ambient temperature. The evolution of surface layer texture throughout the ARB process was analyzed using X-ray diffraction. Initially, the cube texture at the surface progressively transitioned to the r-cube texture throughout ARB, and the r-cube orientation intensity increases from 0 to 9.2 as the true strain accumulates. The shear texture evolution at the surface layer was quantified through mathematical formulations of texture volume fractions and accumulated true strain. The rate (dM_i/dε) of cube texture reduction and r-cube texture formation are initially 15% and 20%, respectively, and they decrease rapidly with increasing cumulative true strain and then slow down to 0.6% and 0.8%. The quantitative analysis of the texture evolution used the JMAK equation, which is rarely applied in ARB studies. Full article

Accumulative roll bonding was employed on 1060 aluminum alloy along the transverse direction without lubrication. The texture evolution and lattice rotation of an ARB-processed aluminum sheet, which initially exhibited a rotated β fiber texture, were examined using X-ray diffraction. Successful interlayer bonding was achieved during the ARB process, and the grains in the sheets were refined and stretched along the rolling direction. The rotated β fiber was unstable during shear deformation, gradually transitioning to a stable r-cube orientation along different rotation paths. Variations in ODFs with accumulated true strain were utilized to determine the rotation paths from the initial rotated β fiber to the end r-cube orientation. The rotated β fiber disappearance rate initially decreased rapidly as the accumulated true strain increased, followed by a slower decline. The B’ {0 1 1}<1 1 1> orientation moved to the S’ {1 2 3}<17 22 9> orientation along the skeleton of the initial rotated β fiber, while the C’ {1 1 2}<1 1 0> orientation moved to the r-cube orientation along the transverse direction axis. A slight deviation from the C’ orientation was revealed in the rotation path from the S’ orientation to the r-cube orientation. Texture evolution was clarified quantitatively through establishing a mathematical relation between texture component volume fractions and accumulated true strain utilizing the JMAK equation. The relatively high r values indicated that the JMAK equation could quantify texture evolution during shear deformation. Full article

In order to meet the demand for structural/functional integrated materials in the field of electromagnetic shielding, a graphene nanosheets (GNSs) reinforced magnesium matrix composite was fabricated using an electrophoretic deposition and subsequent accumulative roll bonding process (ARB). The microstructure, mechanical properties, and electromagnetic interference (EMI) shielding effectiveness (SE) of the GNSs/Mg composites were characterized systematically. The results showed that synergistic strengthening of the mechanical properties and EMI shielding performance of the composites was realized. The strengthening mechanisms for the mechanical and EMI shielding performance of the GNSs/Mg composites were analyzed thoroughly. After five passes of ARB, the ultimate tensile strength and elongation were 271.79 MPa and 12.9%, respectively. For the laminated structure, the strengthening is related to the thickness of the graphene layer, the dispersion, and the interfacial bonding with the metal matrix. In electromagnetic shielding aspects, after ARB-5, the SE is 93.36–105.15 dB. The introduction of well-organized multivariate multi-scale macro–micro interfaces increased the electromagnetic wave propagation paths and multiple reflection loss absorption in the internal propagation paths. Moreover, the addition of carbon nanomaterials led to an increase in the number of interfaces, which was conducive to the expansion of the internal reflection paths; carbon nanomaterials at the interfaces also improved the electromagnetic wave absorption. Full article

Texture evolution during accumulative roll-bonding (ARB) is complicated because of the change in the through-thickness position that results from repeated cutting–stacking and roll-bonding. In this study, a macro–micro two-scale modeling was carried out to investigate the behaviors of texture evolution during ARB. The finite element method (FEM) was used to predict the strain history at a macro-scale, while a crystal plasticity FEM was used to reproduce the texture at a micro-scale. The texture evolution along three different cutting–stacking paths was traced and investigated. The patterns of texture transition between the rolling-type, shear-type, and random-type textures were studied by using area fractions of texture components, the distribution of textures, and the distribution of crystal rotation angles. Full article

Accumulative roll bonding (ARB) is a severe plastic deformation process that enables the production of materials with ultrafine microstructures and enhances the characteristics of the base material, particularly in metal matrix composites. The primary objective of this study is to experimentally investigate the bonding strength in AA3105 strips that underwent the roll bonding process, with a specific focus on examining the influence of temperature and reduction rate on bonding. Three temperature levels (200 °C, 300 °C, and 400 °C) and three thickness reduction levels (35%, 50%, and 65%) were considered. The T-peel test was carried out to assess the bonding quality. It was employed to determine the peak force required to separate the two bonded strips. Additionally, ANOVA analysis was performed to develop a regression equation for analyzing peak force. Optical microscopy was used to evaluate the interface bonding quality in the longitudinal section. The results indicate that the bonding strength increases with both temperature and percentage reduction. Full article

This study investigates the mechanical properties of titanium carbide/aluminum metal matrix composites (AMMCs) using both experimental and computational methods. Through accumulative roll bonding (ARB) and cryorolling (CR) processes, AA1050 alloy surfaces were reinforced with TiCp particles to create the Al–TiCp composite. The experimental analysis shows significant improvements in tensile strength, yield strength, elastic modulus, and hardness. The finite element analysis (FEA) simulations, particularly the microstructural modeling of RVE−1 (the experimental case model), align closely with the experimental results observed through scanning electron microscopy (SEM). This validation underscores the accuracy of the computational models in predicting the mechanical behavior under identical experimental conditions. The simulated elastic modulus deviates by 5.49% from the experimental value, while the tensile strength shows a 6.81% difference. Additionally, the simulated yield strength indicates a 2.85% deviation. The simulation data provide insights into the microstructural behavior, stress distribution, and particle–matrix interactions, facilitating the design optimization for enhanced performance. The study also explores the influence of particle shapes and sizes through Representative Volume Element (RVE) models, highlighting nuanced effects on stress–strain behavior. The microstructural evolution is examined via transmission electron microscopy (TEM), revealing insights regarding grain refinement. These findings demonstrate the potential of Al–TiCp composites for lightweight applications. Full article

In this study, AA1050/AA6061 laminated composites were prepared by three-cycle accumulative roll bonding (ARB) and subsequent rolling. The effects of the rolling process on the microstructure evolution and mechanical properties of AA1050/AA6061 laminated composites were systematically investigated. The results indicate that the mechanical properties of the laminated composites can be effectively improved by cryorolling compared with room-temperature rolling. The microstructure analysis reveals that cryorolling can suppress the necking of the hard layer to obtain a flat lamellar structure. Moreover, the microstructure characterized by transmission electron microscopy shows that cryorolling can inhibit the dynamic recovery and significantly refine the grain size of the constituent layers. Meanwhile, the tensile fracture surface illustrates that AA1050/AA6061 laminated composites have the optimal interfacial bonding quality after cryorolling. Therefore, the laminated composites obtain excellent mechanical properties with the contribution of these factors. Full article

The initial thickness ratio and number of layers of dissimilar metal components greatly influence the impact performance of laminated metal composites. In this paper, positive and lateral impact tests of 5-layer composite sheets with thickness ratios of 3:1, 1.35:1, and 1:2 and 80-layer composite sheets prepared by ARB (accumulative roll bonding) were conducted to study the influences of the thickness ratio and layer number on the impact fracture behavior of composite sheets. The results showed that the higher the proportion of AA7075, the higher the bending strength of the AA6061/AA7075 laminated composite sheet; compared with the 5-layer composite sheet, the side impact performance of the 80-layer composite sheet is obviously improved, and its side impact strength, energy absorbed in the crack initiation stage, and crack propagation stage are better than those of the 5-layer composite sheet. In addition, the toughening mechanism of the 80-layer composite sheet is mainly that the increase in the number of layers makes the cracks deflect more frequently. Under the rapid impact load, the impact energy absorbed by the sample increases with the increase in the number of layers. Full article

Copper and its alloys are structural materials used in industries and engineering applications due to their excellent thermal and electrical conductivity and chemical stability. Integrating graphene, known for its exceptional electrical conductivity, into the copper matrix is a promising strategy to enhance mechanical properties without sacrificing electrical conductivity. The Accumulative Roll Bonding (ARB) process can effectively and homogeneously introduce graphene into the metal matrix and is adaptable to an industrial scale. This study investigates the impact of varying graphene concentrations and two heat treatment protocols (without a controlled atmosphere) on the mechanical and electrical properties of ARBed copper/graphene composites. Optical microscopy revealed minimal voids and graphene clumps, and the energy dispersive spectroscopy analysis revealed the absence of copper oxide in some samples. The conductivity test showed little influence of the graphene content and stress relief heat treatment temperature on electrical conductivity (~86% of the International Annealed Copper Standard) within a limited number of ARB cycles. The tensile tests did not reveal a significant influence of the graphene content and stress relief heat treatment temperature on the ultimate tensile strength (220–420 MPa) and elongation (~2%). Full article

In this study, we successfully obtained a 2Mg-Fe mixture through mechanical alloying (MA) and processed it via accumulative roll bonding (ARB) (MA+ARB). Our primary focus was to analyze the impact of ambient air exposure while also evaluating the processing route. Some powder samples were exposed to air for 12 months (stored in a glass desiccator with an average yearly temperature and relative humidity of ~27 °C and 50.5%) before undergoing ARB processing. The Mg samples obtained after ARB processing exhibited a (002)-type texture. Our results demonstrate that all samples, including those processed via ARB, could rapidly absorb hydrogen within a matter of minutes despite considerable differences in surface area between powders and rolled samples. Grain size reduction by MA and ARB processing and texturing may have influenced this behavior. ARB-processed samples reached approximately 60% (~1.8 wt.%) of their maximum acquired capacity within just 24 min compared to powders (~2.2 wt.%) stored for a year, which took 36 min. In addition, the desorption temperatures (~300 °C) were lower than those of MgH₂ (~434 °C). The absorption and desorption kinetics remained fast, even after prolonged exposure to air. Although there were minor variations in capacities, our overall findings are promising since scalable techniques such as ARB have the potential to produce hydrogen storage materials that are both safe and cost-effective in a highly competitive market. Full article

In order to understand the strengthening and the failure mechanism of accumulative roll bonding (ARB)-processed AZ63 Mg alloy, the interfacial bonding and fracture behavior of an ARB-processed AZ63 sheet were studied through electron microscopic analysis. The correlation between the mechanical properties, the microstructure, and the ARB processing parameters of an AZ63 sheet were presented. The experimental results have demonstrated that the average grain size of AZ63 Mg alloy processed by ARB was remarkably refined from 12.8 μm to 5.7 μm when the ARB processing temperature was set to 623 K, indicating the occurrence and development of dynamic recrystallization (DRX) nucleation. With the increase in ARB passes, the microstructure obviously became uniform. However, after five passes of the ARB process at 623 K, grains with different crystallographic orientations at the interface can be rearranged to generate the coherent eutectic plane, which inhibits the further refinement of grain size. During the ARB process of the AZ63 Mg alloy, the grain refinement was controlled by twin-induced recrystallization and dynamic recrystallization. Microcracks at the bonded interface of the ARB₁ sample were eliminated during the following 3~5 rolling passes at 623 K. After three passes of the ARB process at 623 K, the strength and elongation of the AZ63 Mg alloy increased from 232 MPa and 18.5% to 282 MPa and 26.3%, respectively. The tensile fracture morphology of the sample processed by three passes of ARB exhibited numerous dimples, and the slip lines caused by the cooperative deformation of refined grains can produce a network-like dimple structure, indicating that excellent ductile fracture characteristics could be obtained. Full article