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In this study, forming limit diagrams (FLDs), fracture toughness (FT), mechanical, magnetic, and electro-physical properties of Al/Fe2O3 composites have been investigated experimentally. Accumulative-roll-bonding (ARB) process was used to manufacture composite samples. Then, Al/Fe2O3 composites have been produced at 300∘C up to eight ARB passes. Also, magnetic composites have been fabricated with 0, 5% and 10wt.% of particles. The interlayer bonding quality was improved at higher passes. By studying the SEM rapture morphology, it was shown that the rapture mode changed to shear ductile for samples with more passes. For composite samples fabricated at higher passes and in comparison with the annealed sample, elongated dimples were turned to shallow dimples. FLDs area as the main forming criterion dropped severely after pass one and then began to improve at higher passes. Fracture test results showed that after the 8th pass, the value of FT improved gradually to the maximum value of 34.3MPam1∕2. [ABSTRACT FROM AUTHOR]

In this research, Al/18Cu/3WC/3MoS 2 (wt.%) multilayered hybrid composites were fabricated by accumulative roll bonding (ARB), and their electrical and mechanical properties were investigated. After seven ARB cycles, an Al-matrix multilayered hybrid composite with a uniform distribution of WC-MoS 2 particles and Cu islands was achieved. The presence of the WC-MoS 2 particles and Cu islands significantly affected the electrical and mechanical properties of the fabricated composites. The composite obtained after seven ARB cycles showed an enhanced strength of 259 MPa. Also, it was found that the electrical conductivity of the Al matrix decreased by applied strain (about 19 % IACS) and the presence of the WC-MoS 2 particles. By annealing the fabricated composite obtained from final cycles, the electrical conductivity increased from 54 % IACS to 71 % IACS. [ABSTRACT FROM AUTHOR]

In this study, the accumulative roll bonding (ARB) method, a severe plastic deformation (SPD) process, was used to fabricate copper-2 wt% silicon carbide composite strips. The ARB process was successfully conducted for up to nine cycles on pure copper strips with silicon carbide particles distributed between them, as well as on monolithic copper. Equiaxed tensile and Vickers hardness tests were conducted to evaluate the mechanical properties of the samples. SEM was utilized to study the fracture surfaces and to determine the fracture mechanism of ARB processed monolithic copper and composite samples after the tensile test. Texture parameters were calculated through X-ray analysis. The Rietveld method using MAUD software were employed to assess the crystallite size of the samples. Results indicated that average amount of porosity decreased and interface bonding between copper strip layers improved with increasing the number of ARB cycles. Moreover, an increased number of cycles led to homogeneous distribution of SiC particles within the copper matrix. The tensile strength of the fabricated composites improved with an increase in the number of cycles, ultimately reaching 483 MPa after nine cycles, compared to 388 MPa for the composite processed with a single cycle of ARB and 194 MPa for annealed copper strips. Initially, the elongation of the composite samples decreased dramatically to about 6% after applying five cycle of ARB process from the 46% observed for annealed pure copper strip. However, it improved as the process continued, reaching 8.9% after the ninth cycle. Investigation of fracture surfaces after the tensile test using SEM revealed that the dominant failure mode was shear ductile fracture. Analysis of sample textures demonstrated that the dominant texture was (100). Crystallite sizes for pure copper and nine cyclesrolled composites, as determined by Reitveld method, reached 111 nm and 89 nm, respectively. [ABSTRACT FROM AUTHOR]

In the present study, accumulative roll bonding is used to fabricate Al base composites with the thickness of 1 mm. then, fracture toughness, mechanical properties and forming limit diagrams (FLD) of them have been investigated versus ARB parameters experimentally. Boron nitride (BN) particles are used as reinforcements and Al/BN composites have been manufactured up to 10 accumulative rolling passes at 300°C. after the 10th pass, the strength of composite samples reached to 168 MPa registering 248% improvement than the initial AA1100 sample. Also, the bonding quality among the composite layers improved by increasing the number of passes. A uniform scattering of Boron nitride particles and bonding strength and quality was improved at higher number of passes. Moreover, the fracture mode at higher passes was observed as shear ductile that had been changed from deep dimples (for low number of passes). The area under the FLDs, dropped sharply after the first pass and then improved at higher passes, as the criterion of formability. Finally, fracture toughness enhanced to the maximum value of 30 MPam1/2 for the composite samples fabricated with 10 passes. [ABSTRACT FROM AUTHOR]

In this study, the accumulative roll bonding (ARB) method, a severe plastic deformation (SPD) process, was used to fabricate copper-2 wt% silicon carbide composite strips. The ARB process was successfully conducted for up to nine cycles on pure copper strips with silicon carbide particles distributed between them, as well as on monolithic copper. Equiaxed tensile and Vickers hardness tests were conducted to evaluate the mechanical properties of the samples. SEM was utilized to study the fracture surfaces and to determine the fracture mechanism of ARB processed monolithic copper and composite samples after the tensile test. Texture parameters were calculated through X-ray analysis. The Rietveld method using MAUD software were employed to assess the crystallite size of the samples. Results indicated that average amount of porosity decreased and interface bonding between copper strip layers improved with increasing the number of ARB cycles. Moreover, an increased number of cycles led to homogeneous distribution of SiC particles within the copper matrix. The tensile strength of the fabricated composites improved with an increase in the number of cycles, ultimately reaching 483 MPa after nine cycles, compared to 388 MPa for the composite processed with a single cycle of ARB and 194 MPa for annealed copper strips. Initially, the elongation of the composite samples decreased dramatically to about 6% after applying five cycle of ARB process from the 46% observed for annealed pure copper strip. However, it improved as the process continued, reaching 8.9% after the ninth cycle. Investigation of fracture surfaces after the tensile test using SEM revealed that the dominant failure mode was shear ductile fracture. Analysis of sample textures demonstrated that the dominant texture was (100). Crystallite sizes for pure copper and nine cycles-rolled composites, as determined by Reitveld method, reached 111 nm and 89 nm, respectively.

Abstract We created AA2024–AA1050 and AA2024–AA1050/0.005 vol.% Al2O3 nanocomposites by six accumulative roll bonding (ARB) process cycles. We used AA2024 and AA1050 sheets with a thickness of 0.7 mm and plate-shaped alumina nanoparticles to create a composite. The two AA1050 and one AA2024 sheets (among the two AA1050 sheets) were ARB-ed up to six cycles with and without adding alumina nanoparticles. Also, a sample of the AA1050 without composite making was ARB-ed up to six cycles. We aged some composites after the ARB process in the furnace at 110, 150, and 190 °C. This project performed SEM, TEM, and EDS-MAP analyses, tensile strength, microhardness, and Pin-on-Disc tests to study the ARB-ed sheets. The results of the tensile tests showed that the tensile strength of AA2024–AA1050 created by the six cycles ARB process was two times more than primary AA1050. Also, the wear resistance of this composite was 74% more than six cycles ARB-ed the AA1050. Using 0.005 vol.% alumina nanoparticles in AA2024–AA1050 composite improved its wear resistance by 30%. In the following, the aging process caused an improvement in tensile strength and total elongation of AA2024–AA1050/Al2O3 nanocomposites.

In this study, electrophysical, electromagnetic and mechanical properties, fracture toughness and forming limit diagram (FLD) of Al base composite samples have been studied experimentally. All samples have been fabricated via accumulative roll bonding (ARB) process. To this purpose, AA1060/ Fe2O3 composite strips with thickness of 1 mm have been fabricated with up to eight ARB passes at 3 0 0 ∘ C. In this study, magnetic Al/Fe2O3 composites reinforced with 0, 5% and 10 wt.% of Fe2O3 particles have been manufactured via ARB. The microstructure was studied by optical microscopy (OM). Also, by decreasing the thickness of layers at higher number of passes (increasing the plastic strain), the bonding quality among the layers was improved. Scanning electron microscopy (SEM) fracture surface morphology of samples after the tensile test showed that by increasing the passes, the fracture style (mode) converted to shear ductile at higher ARB passes. So, deep dimples shrink slowly and their number and depth decreased relative to the annealed sample. As the criterion of formability, the area under the FLDs dropped sharply after the first pass and then improved by increasing the passes. Results of fracture test have shown that the value of fracture toughness has been enhanced continually to the maximum value of 34.3 MPam 1 / 2 at the 8th pass. [ABSTRACT FROM AUTHOR]

We created AA2024–AA1050 and AA2024–AA1050/0.005 vol.% Al2O3 nanocomposites by six accumulative roll bonding (ARB) process cycles. We used AA2024 and AA1050 sheets with a thickness of 0.7 mm and plate-shaped alumina nanoparticles to create a composite. The two AA1050 and one AA2024 sheets (among the two AA1050 sheets) were ARB-ed up to six cycles with and without adding alumina nanoparticles. Also, a sample of the AA1050 without composite making was ARB-ed up to six cycles. We aged some composites after the ARB process in the furnace at 110, 150, and 190 °C. This project performed SEM, TEM, and EDS-MAP analyses, tensile strength, microhardness, and Pin-on-Disc tests to study the ARB-ed sheets. The results of the tensile tests showed that the tensile strength of AA2024–AA1050 created by the six cycles ARB process was two times more than primary AA1050. Also, the wear resistance of this composite was 74% more than six cycles ARB-ed the AA1050. Using 0.005 vol.% alumina nanoparticles in AA2024–AA1050 composite improved its wear resistance by 30%. In the following, the aging process caused an improvement in tensile strength and total elongation of AA2024–AA1050/Al2O3 nanocomposites. [ABSTRACT FROM AUTHOR]

In this research, forming limit diagram (FLD) of aluminum alloy 1050 (AA 1050) sheet produced by Accumulative Roll Bonding (ARB) is investigated numerically and experimentally. The Gurson-Tvergaard-Needleman (GTN) ductile damage model is used to predict sheet failure and obtain its FLD using numerical simulation in Abaqus/Explicit. Nucleation and growth of voids in the material during the deformation is the basic concept of the GTN damage model. This damage model has nine basic parameters that obtaining through experimental tests is time-consuming and costly, and in some cases, impossible. Thus, the present study tries to obtain the above parameters for fine-grained aluminum 1050 fabricated by ARB using the finite element method. Therefore, after considering each parameter's interval, numerical simulation and the anti-inference method are used in the uniaxial tensile test to identify GTN parameters for the AA 1050 sheet using FEM. The optimum parameters of the GTN model are used in the FEM of the Nakazima test for FLD prediction. Also, The FLD of the fine-grained aluminum sheet is obtained experimentally using the Nakazima test. Finally, the numerical and experimental FLDs are compared for validation. [ABSTRACT FROM AUTHOR]

Six cycles of ARB at three elevated temperatures (400, 450, and 500 °C) were applied on Al/Mg laminated metallic composites. Samples were studied by microscopy, spectroscopy, and x-ray diffraction to investigate the effect of temperature on microstructures, second phases, and preferred crystallographic orientations. Stoichiometry analysis indicated the formation of non-equilibrium intermetallic phases at the Al/Mg interface. The thickness of the intermetallic layer increased in consecutive passes and by increasing process temperature. Annealing moved the composition toward predicted thermodynamically stable phases by absorbing Al and rejecting excess Mg. EDS examination showed the formation of Al2Mg and Al30Mg23 phases in addition to the previously reported Al12Mg17 and Al3Mg2. XRD results indicated that the preferred crystallographic orientation of the Al layer deviates from the expected plain-strain rolling texture. At the same time, for the Mg layer, the hexagonal c-axis remained parallel to the applied rolling force direction. The most uniform crack-free structure has been formed at 450 °C. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, microstructure, recrystallization texture, and mechanical properties of Al/WO3/SiC hybrid nanocomposite was investigated by electron backscatter diffraction (EBSD), analysis of orientation distribution function (ODF), and uniaxial tensile test during accumulative roll bonding (ARB) process. Microstructural observations show that the recrystallized grains are elongated in the rolling direction (RD) due to the Zener-pinning of nanoparticles at high angle grain boundaries and therefore growth is inhibited in the normal direction (ND) during the ARB process. The ODF investigation confirmed that after 5 cycles of ARB process, recrystallization is associated with nucleation of Goss, Q, and P components. When the number of ARB cycle was increased, Goss and Q recrystallization textures were eliminated, but on the other hand, the P, B and B* texture components were strongly developed. The ND-Cube and RT-Goss recrystallization texture is also formed with low intensity at the last stages. Also, the A and A* shear textures which formed in the fifth cycle, shifted towards the Dillamor and Cu textures with increasing the number of ARB cycles. Furthermore, the samples were heated using DSC under Argon atmosphere with four different heating rates. The Kissinger, Ozawa, Boswell, and Starink methods were used to determine the recrystallization kinetics. It can be seen that recrystallization temperature and thereby activation energy (Ea) decreases with increasing the number of ARB cycles. Furthermore, the tensile strengths and elongation of the hybrid nanocomposite increased and decreased by increasing the number of ARB cycle and reached to a maximum value of 204.5Mpa and 6.1% at the end of 9th cycle, respectively. [ABSTRACT FROM AUTHOR]

The forming limit diagram (FLD), mechanical properties and fracture toughness of aluminum foil composites fabricated via accumulative roll bonding (ARB) process have been investigated as its novelty for the first time. To do this, AA1050/TiC composite foils with thickness of 0.2 mm have been fabricated from one up to twelve ARB passes at 320 °C. Also, optical microscopy (OM) was used to investigate the effect of cumulative forming process on the grain structure. The strength of samples improved to 168. 6 MPa after the 12th cumulative rolling pass, registering 248% improvement in comparison with initial AA1050 sample. Also, by cumulating the plastic strain at higher passes, the bonding quality among composite layers enhanced. SEM fracture surface morphology of samples showed the conversion of fracture mode to shear mode for composites fabricated at high number of passes. So, in comparison with the annealed sample, deep dimples are shrinking slowly and their number and depth were reduced. As the criterion of formability and at higher passes, the area under the FLDs, dropped sharply for one pass processed sample and then improved. Results of fracture test revealed that the value of fracture toughness enhanced continually and got to the 30 MPa.m1/2 at the 12th pass. Grain refinement and ARB process nature are two main mechanisms which are responsible for all ductility changes and mechanical properties. [ABSTRACT FROM AUTHOR]

In this study, graphene reinforced Inconel 718 composites were produced using a novel hybrid accumulative roll bonding (ARB)–gas tungsten arc welding (GTAW) and the mechanical and wear resistance of the composite were assessed. The microstructure characterization was studied by XRD, SEM, TEM and Raman spectroscopy. The results display that GTAW approach was a sustainable way to produce Inconel 718 based composite while addition of graphene nanoplatelets (GNPs) leads to a substantial improvement in strength of superalloy matrix, as well as the wear performance enhancement. Both yield strength and tensile strength of composite specimen with 1.0 wt% GNPs was 35% and 45% higher than those of base Inconel material, and the friction coefficient and wear rate were 204% and 52% lower than those of non-reinforced Inconel 718. Such enhancement of tribological properties can be ascribed to the hardness increase of GNPs–containing specimens and the formation of GNPs protecting film on the worn exteriors.

This study investigated the microstructure, texture, and mechanical properties of 1050 aluminum alloy sheets that underwent the accumulative roll bonding (ARB) method. The ARB proceeded up to eight passes in three ways: conventional process, preheat between rolling passes (preheating) or anneal between rolling passes (annealing). Heat treatment was done between the ARB passes for 5 min at 150 °C. The mean grain width of the 1050 Al sheet that was 11 μm before ARB, decreased to 295.73 nm, 317.33 nm, or 339.23 nm after six ARB passes in the conventional process, annealed or preheated conditions, respectively. Concurrent heat treatments cause a decrease in the strength of the texture components of Al sheets that were elaborated by the ARB method. Even though conventional and annealed processes successfully enhanced the microhardness by ∼80% and tripled the tensile strength, these improvements were weaker in the preheated condition than the other conditions due to dynamic recovery.

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.

A multiple processing technique that combines cold spraying (CS) and accumulative roll bonding (ARB) was designed to prepare multilayered 1060Al/Al–Al2O3 composites with improved ductility. Microstructural evolution during processing was characterized using scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The deposited Al–Al2O3 complex layer was well bonded to the 1060Al matrix, and during ARB processing, the deposited layers were highly squeezed to eliminate voids, Al2O3 particles were split to reduced size and dispersed to a homogeneous distribution within the deposited layers. The tensile test results revealed that the best combination of strength and ductility was achieved in the sample with optimized 3-pass ARB processing, with an increase of ∼41.66% in ultimate tensile strength (153 MPa) and an increase of ∼95.73% in tensile elongation (7.34%) compared to the initial As-Annealed sample. Fracture behavior of the prepared composite was also analyzed. The analysis of microstructural features provided insight into the underlying mechanisms explaining the high strength and great ductility.

Cu/Ti laminated sheets with heterogeneous Ti layers are successfully fabricated by accumulative roll bonding (ARB). The microstructure during processing is characterized by scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). During the deformation of the constituent metals, the hard Ti layers neck preferentially but with a continuous layered structure. Upon four ARB cycles, there are five Ti layers with different microstructure states and grain sizes (from 1.3 to 0.5 μm) in the ARB4 sample. Tensile test of ARB4 sample indicates excellent comprehensive mechanical properties, compared with pure Cu and pure Ti, it has higher ultimate tensile strength (508 MPa), and the elongation (9.2%). In the result of loading–unloading–reloading test, there is a strain gradient during the tensile process due to heterogeneous existence of Ti layers, which produces a multilevel hetero‐deformation‐induced (HDI) stress strengthening and improves the coordinated deformation ability of the sample. Second, layered structure and interface with alternate strong and weak bonding can effectively hinder the propagation of cracks to outline higher strength with improved ductility. This structural design helps to prepare laminated materials sheet with excellent comprehensive mechanical properties through the ARB process. [ABSTRACT FROM AUTHOR]

The high production efficiency, energy-saving characteristics, and universal applicability of accumulative roll bonding (ARB) in the field of commercial aluminum sheets fabrication are well recognized. However, microstructure characterization driven by processing parameters still needs optimization. The purpose of this study is to investigate the effect of cyclic preheating parameters on the microstructure of commercial purity aluminum sheets processed by six cycles of ARB. Specifically, a series of cyclic preheating conditions set as A: 523 K-1200 s, B: 573 K-300 s, and C: 573 K-1200 s was repeatedly applied, and differences among these three sample groups in microstructure and mechanical properties were discussed by comparing their scanning electron microscopic (SEM) pictures, orientation image maps (OIMs), Vickers hardness, and tensile strength. It was found that B: 573 K-300 s was the critical condition for sheets with both stable bonding state and ultrafine grains (UFGs). This study provides a reference for selecting cyclic preheating and reveals microstructural characteristics of ARB processed commercial-purity aluminum sheets. [ABSTRACT FROM AUTHOR]

Ultrafine-grained Cu/Al/Ag composites were processed by an accumulative roll bonding (ARB) technique from pure copper and aluminum sheets and a silver powder. The Al content was fixed to 11 wt.% while the silver concentration was 1, 2, or 3 in wt.%. The ARB-processed samples were heat treated at different temperatures between 750 and 1050 °C for 60 min and then quenched to room temperature (RT) for producing Cu–Al–Ag alloys. The effect of the addition of different Ag contents and various heat treatment temperatures on the structural evolution was investigated. The ARB-processed samples were composed of Cu and Al layers with high dislocation density and fine grain size (a few microns). During heat treatment of the ARB-processed samples, new intermetallic phases formed. For the lowest Ag content (1 wt.%), the main phase was a brittle simple cubic Al4Cu9, while for higher Ag concentrations (2 and 3 wt.%), the quenched samples contain mainly an orthorhombic β1-AlCu3 martensite phase. The martensite phase consisted of very fine lamellas with a thickness of one micron or less. The heat treatment increased the microhardness and the strength of the samples at RT due to the formation of a fine-grained hard martensite phase. For 2 and 3% Ag, the highest martensite phase content was achieved at 850 and 950 °C, respectively. The annealed and quenched samples exhibited good shape memory behavior at RT. [ABSTRACT FROM AUTHOR]

This article concerns the effect of strain accumulation during low-cycle fatigue on the post-fatigue tensile behavior of metal matrix composites (MMCs) with identical layers of aluminum reinforced by Fe 3 O 4 nanoparticles produced via the accumulative roll bonding (ARB) technique. Work-hardening behavior, deduced from ratcheting curves, was evaluated by the post-fatigue tensile test. The key finding in the mechanical properties of homogeneous nanocomposite in terms of reinforcement distribution, evolving due to microstructural evolution during the ARB process, is that accumulation of ratcheting strain decreases, and fatigue and post-fatigue tensile behavior significantly increases. The rupture mechanism, analyzed by scanning electron microscope, revealed that deep hemispherical-shaped dimples, a well-known feature of ductile rupture, were changed to elongated shallow shear dimples by the impact of microstructural evolution due to imposed 1000 cycles of ratcheting test. [ABSTRACT FROM AUTHOR]

The study examined how various annealing methods affect the structure and characteristics of Al/Zn layered composite plates. Four distinct composite plates underwent annealing at temperatures of 160 °C, 200 °C, and 240 °C for durations ranging from 0.5 h, 1 h, 1.5 h, and 2 h. Changes in grain structure, interface appearance, and thickness of the interface diffusion layer were analyzed using metallographic microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Tensile and microhardness tests were performed under different annealing conditions and cycling durations. Results showed that as annealing time increased, tensile strength initially rose before declining, while elongation remained consistently high. The optimal balance between strength and ductility was observed at 200 °C for 1.5 h of annealing across all plate types. Before annealing, Al displayed a fractured ultrafine crystalline structure, while Zn's texture underwent changes. [ABSTRACT FROM AUTHOR]

Ultrafine-grained Cu/Al/Ag composites were processed by an accumulative roll bonding (ARB) technique from pure copper and aluminum sheets and a silver powder. The Al content was fixed to 11 wt.% while the silver concentration was 1, 2, or 3 in wt.%. The ARB-processed samples were heat treated at different temperatures between 750 and 1050 °C for 60 min and then quenched to room temperature (RT) for producing Cu–Al–Ag alloys. The effect of the addition of different Ag contents and various heat treatment temperatures on the structural evolution was investigated. The ARB-processed samples were composed of Cu and Al layers with high dislocation density and fine grain size (a few microns). During heat treatment of the ARB-processed samples, new intermetallic phases formed. For the lowest Ag content (1 wt.%), the main phase was a brittle simple cubic Al4Cu9, while for higher Ag concentrations (2 and 3 wt.%), the quenched samples contain mainly an orthorhombic β1-AlCu3 martensite phase. The martensite phase consisted of very fine lamellas with a thickness of one micron or less. The heat treatment increased the microhardness and the strength of the samples at RT due to the formation of a fine-grained hard martensite phase. For 2 and 3% Ag, the highest martensite phase content was achieved at 850 and 950 °C, respectively. The annealed and quenched samples exhibited good shape memory behavior at RT.

Product miniaturisation and functional integration are currently global trends to save weight, space, materials and costs. This leads to an increasing demand for metallic micro components. Thus, the development of appropriate production technologies is in the focus of current research activities. Due to its efficiency, accuracy and short cycle times, microforming at room temperature offers the potential to meet the steadily increasing demand. During microforming, size effects occur which negatively affect the part quality, process stability, tool life and handling. Within this contribution, a multi-stage bulk microforming process from sheet metal is investigated for the materials Cu-OFE and AA6014 with regard to the basic feasibility and the occurrence of size effects. The results reveal that the process chain is basically suitable to produce metallic micro parts with a high repeatability. Size effects are identified during the process. Since several studies postulate that size effects can be minimised by scaling down the metallic grain structure, the grain size of the aluminium material AA6014-W is scaled down to less than one micrometre by using an accumulative roll bonding process (ARB). Subsequently, the effects of the ultrafine grain (UFG) structure on the forming process are analysed. It could be shown that a strengthened material state increases the material utilization. Furthermore, too soft materials can cause damage on the part during ejection. The occurring size effects cannot be eliminated by reducing the grain size.

In the present work, fatigue and cyclic deformation behavior of ultrafine-grained (UFG) pure aluminum AA1100 product by accumulative roll bonding (ARB) process under stress-controlled in the presence of mean stress were performed. After seven cycles of the ARB process, grain refinement due to severe strain imposed improves tensile properties. The fatigue life shows a substantial reliance on the ARB cycle, so that the fatigue life improves with the increasing ARB cycle. Fatigue-induced microstructural evolution was investigated by TEM microscopy. Cyclic deformation behavior in the presence of mean stress leads to strain accumulation in each cycle. The amount of strain accumulated increases by increasing mean stress and stress amplitude. TEM observations demonstrated that dense dislocation patterns such as dislocation tangle and LAGBs were recovered and turned into HAGBs during cyclic deformation. Low cycle fatigue-induced microstructural evolution. (a) after7 cycles of the ARB. process(initial specimen for fatigue test), (b) the formation of dislocation tangle and subgrain boundaries(after 60 cycles of fatigue test), (c) migration dislocations to grain. boundaries, and the formation of dislocation pile-up(during steady-state region after 300. cycles) (d) annihilation of dislocation within the grains and decreasing dislocation density. in grain interior(after failure). [Display omitted] • Fatigue and ratcheting behavior of nanostructured Al producted by the ARB process was investigated. • The amount of strain accumulation during cyclic deformation was investigated. • By increasing fatigue cycle, the amount of ratcheting strain was increased. • Microstructural evolution of Al-ARBed after 7 cycles was observed by TEM during cyclic deformation. • Mechanism of microstructural evolution during cyclic deformation was proposed. [ABSTRACT FROM AUTHOR]

Cu-26Zn-5Al shape memory alloy (SMA) was produced by accumulative roll bonding (ARB) and subsequent heat treatment. In this regard, different austenitization cycles and cooling conditions, including furnace, air, cold-water, and boiling-water cooling were experimented. The heat-treated specimens were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The corrosion behavior of the specimens was also studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in a 3.5 wt% NaCl solution. The results revealed that only by cooling in the boiling- and ice-water environments, a fully martensitic microstructure showing the shape memory effect is obtained. In contrast, by using the other cooling conditions, different phases like α-phase (Cu-saturated solid solution) are formed as well as martensite. From the corrosion testing results, it was found that the SMA specimens with the fully martensitic microstructure have the highest corrosion resistance, where cooling in boiling water was recognized to be optimal. In conclusion, Cu-26Zn-5Al SMA with an improved corrosion resistance can be produced by ARB followed by controlled heat treatment. • Cu-26Zn-5Al shape memory alloy (SMA) was successfully fabricated by ARB and heat treatment. • Cooling in boiling water was optimal to obtain Cu-Zn-Al SMA with improved corrosion resistance. • The contribution of grain size and galvanic couples was critical to the corrosion behavior of Cu-Zn-Al SMA. [ABSTRACT FROM AUTHOR]

Accumulative roll bonding (ARB) was used to fabricate aluminum matrix composites (AMCs) with 2 vol% Al 2 O 3 particles. Monolithic sheets without Al 2 O 3 particles under the same conditions were also fabricated for comparison. For all produced sheets, different variables, such as average grain size, fraction of high angle grain boundaries and local number of 2-dimension at random points (LN2DR), were measured to better understand the evolution of matrix microstructure and particle spatial distribution. The role of Al 2 O 3 particles on strengthening in AMCs processed by ARB was finally revealed. It was found that during ARB, monolithic sheets exhibited deformed-micrometer grains. In comparison, composites also started with deformed-micrometer grains, however, evolved over ARB cycles to have significantly refined grains. Machine learning results showed that particle spatial uniformity improved with the increasing number of ARB cycles. After the 11 cycles of ARB, final composites were more strengthened (1.15 times higher Vickers hardness, 1.19 times higher tensile strength), however, had less elongation than the monolithic sheets. Therefore, comparing to monolithic sheets, the composites are more strengthened not only due to the matrix strain hardening and grain refinement caused by ARB, but also the presence of Al 2 O 3 particles with improved spatial uniformity. • Composite aluminum sheets were produced by accumulative roll bonding (ARB). • Aluminum matrix in composite sheets evolved during ARB to have ultrafine grains. • Particle uniformity improves with increasing ARB cycles, shown by machine learning. • Composites were more strengthened compared to monolithic sheets. • The composite rupture mode is brittle, but elongation slightly improved during ARB. [ABSTRACT FROM AUTHOR]

• First study using machine learning on accumulative roll bond (ARB) processed composites. • Repeated ARB cycles promote decohesion and uniformity of reinforcement particles and refine matrix grains. • Composite microstructure evolves and consequently, tensile properties improve. • All composite parameters saturate from 14 cycles, suggesting limitation of ARB in strengthening. The effects of repeated accumulative roll bonding (ARB) cycles on reinforcement phase features, matrix microstructure and composite tensile behavior evolution were investigated by microscopy, machine learning, tensile testing, and fracture surface observation. The results showed that with increasing ARB cycles, the reinforcement particles decohered and their distribution uniformity improved. Meanwhile, the matrix microstructure evolved and consequently, the mechanical properties of the composite were improved. However, all parameters saturated at higher ARB cycles suggesting the limitation of further cycles in strengthening composites. These findings are significant for enhancing the knowledge about the microstructure and mechanical properties of particle reinforced composite and optimizing the fabrication of composites by ARB. [ABSTRACT FROM AUTHOR]

Multilayer Zn–Al eutectoid alloy (ZA22) was fabricated via accumulative roll bonding (ARB) for the first time, and the microstructural evolution, damping and tensile mechanical properties of the resultant specimens were studied. In the early stage of ARB, Zn–Al alloy layers were firstly formed between Zn and Al layers. With increasing the cycles of ARB, the volume fraction of the alloy layers increased gradually. After 9 cycles of ARB, the ZA22 alloy with uniform composition was obtained. Property tests showed that after 6 cycles of ARB, the damping in a wide temperature range from room temperature to around 275 °C, the tensile strength and the elongation to failure began to be higher than those of the cast ZA22 alloy. In particular, the elongation to failure of the ARB-7 specimen was 10.7 times that of the cast ZA22 alloy. Solution treatment could further significantly improve the damping and the elongation to failure. The microstructural origins of the improved properties were discussed in detail. • Multilayer ZA22 alloy was successfully fabricated via ARB for the first time. • Resultant specimens have significantly improved damping and mechanical properties. • The elongation of the ARB-7 specimen is 10.7 times that of the cast ZA22 alloy. • Solution treatment can further dramatically improve the damping and elongation. • Microstructural origins of the improved properties were discussed in detail. [ABSTRACT FROM AUTHOR]

The heavy-ion irradiation behavior of bulk zirconium-niobium multilayered composites was investigated up to large doses. Multilayers with an average individual layer thicknesses ranging between 15 and 80 nm were synthesized by accumulative roll bonding technique. The irradiation was performed with a defocused 7 MeV Zr2+ ion beam at 500 °C. The maximum dose achieved was ∼145 dpa at the depth of ∼1.5 μm from the irradiated surface. Sub-surface microstructural damage and the chemical redistribution were characterized by transmission electron microscopy and energy dispersive spectroscopy, respectively. Irrespective of the layer thicknesses, the irradiation condition caused layer instability and the extent of damage varied with the dose levels. Doses lesser than ∼60 dpa caused layer fragmentation and greater than ∼60 dpa resulted in layer dissolution. The chemical mixing of layers occur to a depth of ∼1 μm, consuming multiple bi-layer periods. Despite the elevated irradiation temperature (500 °C) and a slightly positive heat of mixing (+6 kJ/mol), no phase separation was observed and single-phase was retained in the mixed region. The results demonstrate that chemical mixing was facilitated by the liquid phase miscibility of Zr and Nb, which propelled the interdiffusion within the thermal spikes towards mixing. [ABSTRACT FROM AUTHOR]

Product miniaturisation and functional integration are currently global trends to save weight, space, materials and costs. This leads to an increasing demand for metallic micro components. Thus, the development of appropriate production technologies is in the focus of current research activities. Due to its efficiency, accuracy and short cycle times, microforming at room temperature offers the potential to meet the steadily increasing demand. During microforming, size effects occur which negatively affect the part quality, process stability, tool life and handling. Within this contribution, a multi-stage bulk microforming process from sheet metal is investigated for the materials Cu-OFE and AA6014 with regard to the basic feasibility and the occurrence of size effects. The results reveal that the process chain is basically suitable to produce metallic micro parts with a high repeatability. Size effects are identified during the process. Since several studies postulate that size effects can be minimised by scaling down the metallic grain structure, the grain size of the aluminium material AA6014-W is scaled down to less than one micrometre by using an accumulative roll bonding process (ARB). Subsequently, the effects of the ultrafine grain (UFG) structure on the forming process are analysed. It could be shown that a strengthened material state increases the material utilization. Furthermore, too soft materials can cause damage on the part during ejection. The occurring size effects cannot be eliminated by reducing the grain size. [ABSTRACT FROM AUTHOR]

• In this study, ARB was used to produce a composite plate of Mg-Li and Al1050 sheets at room temperature. • Tensile strength, total elongation, and fracture behavior of the samples were evaluated. • Plastic instability was detected in the Al/MgLZ91 composite during the ARB process. • Mg-Li properly withstands high exerted strains during the ARB process. • Total elongation and the tensile strength experienced the same trend as continuous growth. [Display omitted] Adding Li to Mg, dual-phase Mg-Li with very low density and high formability at room temperature was produced and used as a reinforcement phase for fabricating a three-layered metal matrix Al-Mg composite through accumulative roll bonding (ARB) process. In this study, due to the inherent nature of the ARB process, which is associated with high strain, and low strength of the magnesium-lithium alloy, the fracture toughness test and energy absorption were used in addition to the tensile test to observe the interaction effect of the increasing strength and the reducing elongation, which were caused by the ARB. By preparing the compact tension (CT) specimens and conducting R-curve tests, the fracture behavior of the processed composite in various ARB cycles (primary sandwich and four ARB cycles) was investigated. Meanwhile, a Digital Image Correlation (DIC) system was also employed to measure the variation of crack growth, crack opening, and corresponding forces and increase the accuracy and quality of the results. The surrounded area under the force-displacement of crack opening curves was measured and calculated as the toughness and absorbed energy. Tensile strength and total elongation of the processed composite improved gradually, 275.7% and 38%, respectively, compared to the primary phase as the number of cycles increased and the thickness of the layers decreased. Plastic instability was more prominent in the last cycles because of the increasing trend of imposed strains and the reduction in thickness which reached their highest amounts at the final step. Although obtained results confirmed the general improvement in fracture toughness of the ARBed composite, its value varied slightly from one cycle to another. The highest values were achieved for total energy absorption and crack opening at maximum force after the second ARB cycle. In contrast, the maximum amount of fracture toughness, 29.08 MPa m1/2, was belonged to the last cycle of the process. Dimples and micro-cavities, seen in both SEM images of Al and Mg layers, resulted in a ductile failure. [ABSTRACT FROM AUTHOR]