Cross Accumulative Roll Bonding Process Research Articles

Comparison of copper-based composites fabricated by cross-accumulative roll bonding method for packaging design

Copper-based composites have interesting properties and they are widely used in electronics, packaging, and automotive applications. In the present work, the cross-accumulative roll bonding (CARB) process was used to fabricate Cu-based composites with Zn and Brass reinforcing layers. The experimental observations revealed a clear relationship between rolling strain and plastic instabilities including the necking and rupture of reinforcement. However, the grain refinement was observed on Cu, Zn, and Brass layers after seven CARB cycles, indicating the positive impact of rolling rotation on obtaining the ultrafine grains. Better ductility of Brass also resulted in finer grains. This also led to more significant improvement in mechanical properties. During the CARB process, the hardness of Zn and Brass increased from 59 HV and 250 HV to 89 HV and 310 HV, respectively.

Microstructure, Mechanical and Thermal Properties of Al/Cu/SiC Laminated Composites, Fabricated by the ARB and CARB Processes

The aim of the current work is to investigate the effect of SiC particle weight percent and rolling passes on Al/Cu/SiC laminated composites, fabricated by accumulative roll-bonding (ARB) and cross-accumulative roll-bonding (CARB) processes. The optical microscopy (OM) images of composites revealed that despite the good bonding of the layers, they underwent plastic instabilities as a consequence of strain hardening of the layers. However, these instabilities occurred more in ARBed composites than in composites fabricated by the CARB process. This is because in the latter process, the composites are rolled in two directions, which leads to better strain distribution. Furthermore, with an increase in passes, SiC particles were well distributed in the matrix and interfaces. The mechanical findings showed that, by increasing passes, there was a growth in the values of strengths and elongation. This behavior is believed to be related to increased work-hardening of layers, better distribution of reinforcing particles, and an enhanced bonding of interfaces at higher rolling passes. In addition, the results of thermal conductivities showed a downward trend with an increase in passes; in fact, the increased number of Al/Cu interfaces declined the heat conduction of composites.

Consideration on zinc content on the microstructure, mechanical, and corrosion evolution of aluminum/zinc composites fabricated by CARB process

Aluminum/zinc laminated composites with different zinc contents (20 and 50 wt%) were fabricated in the form of sheets by using cross-accumulative roll bonding (CARB) process. Microstructural investigations by scanning electron microscopy showed the properly uniform distribution of thin zinc layers in the aluminum matrix in both laminated composites. The mechanical properties of the specimens were investigated by tensile, wear, and micro-hardness tests. Tensile results revealed that by increasing the zinc content, tensile strength is improved from about 275 MPa for 20 wt% zinc to about 350 MPa for 50 wt% zinc after the 8th cycle of CARB. Wear tests in the different zinc contents showed that the variation of the wear rate versus the number of rolling cycles has a similar behavior in both zinc contents. However, wear resistance was improved by increasing the zinc content in the laminated composites. Electrochemical corrosion tests were also carried out on both composites at different cycles. The results reflected that the composite samples containing 20 wt% zinc have better corrosion properties in comparison to that with 50 wt% zinc content at different cycles. In conclusion, this study pointed out the potential of aluminum/zinc laminated composites fabricated by CARB for further development.

RETRACTED: Investigating the solid-state diffusion at the interface of Ni/Ti laminated composite

The fabrication of Ni/Ti laminated composite via cross accumulative roll bonding (CARB) and subsequent annealing treatment has been studied. The relationships between annealing conditions and microstructure at interfaces of Ni/Ti have been investigated by SEM, XRD, and EDS analyses. The results show that the layers were well-bonded by the CARB process, and by increasing the temperature and time of annealing treatment, the interfacial layers grew as a result of the interdiffusion of Ni and Ti atoms. The main intermetallic phases were NiTi and NiTi 2 , both of which obeyed linear kinetics of growth. However, the calculated activation energy of NiTi was lower than that of NiTi 2 , indicating the comparable growth of NiTi. Further, based upon the results of tensile tests, the ultimate strength of samples decreased as the intermetallic layers grew; the detachment of layers and the intergranular fraction of intermetallic compounds were the main fracture mechanisms. • Ni/Ti laminated composite was produced by using the CARB process and post-annealing. • The following sequence of phases was detected: Ti/NiTi 2 /NiTi/Ni 3 Ti/Ni • The thickness of NiTi 2 and NiTi layers rose as the temperature and time of annealing treatment increased. • As the intermetallic layers grew, the values of ultimate tensile strength and elongation decreased and fluctuated, respectively.

Fracture toughness, wear, and microstructure properties of aluminum/titanium/steel multi-laminated composites produced by cross-accumulative roll-bonding process

Fracture toughness, wear, and microstructure properties of aluminum/titanium/steel multi-laminated composites produced by cross-accumulative roll-bonding process

Mechanical properties and strength prediction of Al/E-glass fiber composites fabricated by cross accumulative roll bonding process

In this work, Al/E-glass fiber composites were fabricated by the cross accumulative roll bonding (CARB) process, and their structure and mechanical behaviors were investigated. The structural characterization by X-ray diffraction and scanning electron microscopy indicates that the continuous fibers are fragmented during the CARB process, leading to the production of an ultrafine-grained short fibers reinforced composite at the final cycle. A combined model was used to predict the yield strength of the fabricated Al/E-glass fiber composites. Also, the yield strength of the samples was measured by tensile tests. The agreement of the calculated and measured yield strength showed the model used for the strength prediction is dependable. The investigation of the micro-hardness and wear properties of the composites depicted that by increasing the CARB cycles, despite the increase in micro-hardness, the wear resistance is decreased, which was attributed to the layered structure. • Long fibers were crushed during the CARB process and changed to short fibers. • The final product of the process was an ultrafine-grained short fibers composite. • The predicted yield strength was in agreement with the measured value. • The main wear mechanism of the composite samples was delamination.

Structural, mechanical and corrosion evaluations of Cu/Zn/Al multilayered composites subjected to CARB process

In this research, the structure, tensile, wear, fracture toughness, and corrosion characteristics of Cu/Zn/Al multilayered composites fabricated by cross accumulative roll bonding (CARB) were determined. X-ray diffraction and scanning electron microscopy were used for structural analyses. Results showed that the crystallite size of the Cu matrix is reduced to about 50 nm at the ninth cycle of CARB, while the plastic instability and shear bands appeared in the layers after the third cycle. The tensile strength of the composites increased up to the third CARB cycle and then decreased to the ninth CARB cycle gradually. Typically, the maximum strength of about 330 MPa and elongation of almost 31.5% were obtained at the third and first cycles, respectively. A similar trend was found for the fracture toughness of the samples, so that the maximum fracture toughness of about 31 MPa.m1/2 was obtained at the third cycle. It was also shown that the wear mechanism of the composite samples changes by increasing the cycles, a compromise of abrasion and delamination wear. The accommodation of Al and Zn layers toward the surface of the composites by increasing the CARB cycles was also recognized to be responsible for the decrease of the corrosion resistance determined by polarization experiments.

Influence of Intermediate Heating in Cross Accumulative Roll-Bonding Process on Planar Isotropy of the Mechanical Properties of Commercial Purity Aluminium Sheet

In this study, the cross accumulative roll-bonding (CARB) process, as an improved technique of the conventional accumulative roll-bonding (ARB), was conducted on the AA1050 sheet up to 10 passes in two processing modes. The specimens were either preheated before the rolling step of CARB passes and promptly roll bonded (warm CARB) or were processed at room temperature (cold CARB). The microstructure of samples was characterized using a scanning electron microscope. The effect of intermediate heat treatment on the planar homogeneity of the mechanical properties in the CARB (and even ARB) deformed sheets has not been examined yet. Hence, the present research focuses on the comparison of the planar isotropy of tensile properties between warm and cold CARB products. Also, the uniformity of microhardness distribution throughout the thickness of samples was evaluated. The warm CARB presented higher elongation, lower tensile strength and microhardness with more uniformity of the microhardness distribution, and also premier planar isotropy of the mechanical properties than the cold CARB.

Graded microstructure and texture in ultrafine grained multi-layered immiscible bimetallic system

In this investigation we report the formation of a graded microstructure in copper/tantalum ultrafine grained (UFG) multi-layered composite fabricated by cross accumulative roll bonding (CARB) process at high temperatures. The microstructure, micro-texture and bulk texture evolution in the copper/tantalum composite was established. A gradient microstructure develops along the thickness of the specimen during the CARB process. The fragmentation of tantalum in between copper layers and the grain refinement with evolving passes has been explained. The deformed copper layers show rotated cube texture and deformed tantalum layers show cube texture with γ-fibre. The overall texture of copper/tantalum composite weakens after the process of ARB; copper undergoing texture randomization post annealing. The crucial role of interfaces on the evolution of texture is demonstrated. The microstructural gradient in the specimen possess equiaxed, lamellar as well as large deformed grains with tantalum's grain size being in the scale of 200 nm. The correlation of microstructural gradient with orientation relationship (OR) between copper and tantalum layers was studied, confirming higher misorientation in OR at regions under high strain. Dynamic recrystallization taking place at the copper/tantalum interface has been elaborated with the aid of microtexture analysis.

Structure, wear and corrosion characterizations of Al/20wt.% Zn multilayered composites fabricated by cross-accumulative roll bonding

In this study, Al/20 wt.% Zn laminated composites are produced by the cross-accumulative roll bonding (CARB) process. The microstructural, mechanical and corrosion characteristics of the composites are investigated at different passes of the CARB process. Using scanning electron microscopy, it is observed that during the CARB process, the Zn layers are necked, ruptured and gradually distributed in the Al matrix. Tensile testing results reveal that the incremental trend of strength stops unexpectedly at the sixth pass and then continues again at the higher passes, reaching 275 MPa at the eighth pass. The wear resistance of the samples increases up to the fourth pass, whereas it decreases gradually at the higher passes contrary to expectations. A mixed mode of abrasion, adhesion and delamination mechanisms is found to control the wear damage of the samples. The corrosion current density of the samples fabricated at the first pass is 3 times higher than the eighth pass, indicating the improvement of the corrosion resistance. Also, Nyquist plots show a single capacitance loop attributed to the formation of a passive film.

Graded Microstructure and Texture in Ultrafine Grained Multi-Layered Immiscible Bimetallic System

In this investigation we report the formation of a graded microstructure in copper/tantalum ultrafine grained (UFG) multi-layered composite fabricated by cross accumulative roll bonding (CARB) process at high temperatures. The gradient microstructure develops as a consequence of the strain gradient present along the thickness of the specimen during the CARB process. The correlation of strain gradient with the microstructure, micro-texture and bulk texture in copper/tantalum composite was established. The fragmentation of tantalum in between copper layers and the grain refinement with evolving passes has been explained. The deformed copper layers show rotated cube texture and deformed tantalum layers show cube texture with γ- fibre. The overall texture of copper/tantalum composite weakens after the process of ARB; copper undergoing texture randomization. The crucial role of interfaces on the evolution of texture is demonstrated. The effect of strain on orientation relationship (OR) between copper and tantalum layers was studied, confirming higher misorientation in OR at regions under high strain. Dynamic recrystallization taking place at the copper/tantalum interface has been elaborated with the aid of microtexture analysis.

Comparative Study of the Planar Uniformity of the Mechanical Properties of the AA1050 Strips Processed by Conventional and Cross Accumulative Roll-Bonding Techniques

In this research, a modified method of the conventional accumulative roll-bonding (ARB) process, named cross accumulative roll-bonding (CARB), was applied on an AA1050 strip for up to 13 cycles. The planar uniformity of the mechanical properties in the products of ARB and CARB processes has not been investigated yet. This article aims to compare the planar inhomogeneity of the tensile properties in different directions of the rolling plane of the ARB- and CARB-processed specimens. For this purpose, uniaxial tensile tests were performed in the rolling, transverse, and diagonal directions of the products. Furthermore, Vickers microhardness was used to investigate the hardness distribution throughout the thickness of specimens. The results revealed that the CARB process exhibited higher tensile strength, elongation, and hardness with more homogeneous distribution of the hardness and particularly better planar uniformity of the tensile properties compared with the conventional ARB process.

Microstructure and mechanical properties of Mg-5Li-1Al sheets processed by cross accumulative roll bonding

Mg-5Li-1Al alloy was processed by cross accumulative roll bonding (CARB). The processed Mg-5Li-1Al sheet possesses ultra-fine grains, and its strength increases both in the rolling direction (RD) and transverse direction (TD) with the elongation remaining 16˜18%. The proper CARB processing is helpful to improve the isotropy of mechanical properties of Mg-5Li-1Al sheet. At the same time, the CARB process has a beneficial effect on improving the plasticity of Mg-5Li-1Al sheet. With the change of the direction between the CARB passes, the basal texture of Mg-5Li-1Al sheet is weakened, and the non-basal texture is strengthened. Both prismatic slip and pyramidal slip are initiated. The dominant deformation mechanism changes from twin deformation to slip deformation, and finally shear deformation. The grain refinement mechanism changes from twin dynamic recrystallization to continuous dynamic recrystallization, and finally rotational dynamic recrystallization.

Aluminum-matrix composites reinforced with E-glass fibers by cross accumulative roll bonding process

In this research, the structure and mechanical properties of 1050 aluminum strips reinforced with E-glass fibers, processed by the cross accumulative roll bonding (CARB) process, were investigated from microscopic, hardness, tensile and peeling viewpoints. The results indicated that the incorporation of the glass fibers in the Al matrix increases strength and micro-hardness but decreases elongation. In addition, it was realized that some of these fibers are broken and changed to short fibers during the CARB process. The presence of the glass fibers strongly also reduces the bond efficiency of the Al strips, typically from 50% to 5%. To compensate this deleterious effect, it was found that at least 25% should be increased to the normal thickness reduction used in CRAB.

Fine Texture Enhancement of Al-Mg-SC alloy by Using Cross Accumulative Roll Bonding Technique

Aluminum alloys were as a rule used to fabricate in a few car and aviation parts. Al-Mg-Sc combination sheets were prepared a couple of cycles of Cross accumulative roll bonding (CARB) & similarly of accumulative roll bonding (ARB). In these two procedures Micro-structural advance have been occurring. It was clearly observed microstructure depicted by checking electron microscopy (SEM). In the midst of these both the system, Al-Mg-Sc alloys was adequately made with no disfigurement. In the midst of CARB process, Reinforcement (Mg, SC) particles reliably scattered inside Al system differentiated and similarly examined Al-Mg-Sc alloys in ARB process. In these two procedures, to incorporating of minor Sc in Al-Mg was extended hardness and besides it credited to the fine surface development. TEM imaging demonstrates development of fine hastens shaped inside grid in CARB contrast and ARB amid heat treatment. The Al-Mg-Sc alloy hardness was evaluated with using a Vickers hardness analyzer.

High strength and thermal stability of bulk Cu/Ta nanolamellar multilayers fabricated by cross accumulative roll bonding

Bulk Cu/Ta nanolamellar multilayers with an individual layer thickness from several micrometers down to 50 nm were successfully fabricated via a combination of cross accumulative roll bonding (CARB) and an intermediate annealing step. This fabrication technique allowed to effectively suppress the formation of plastic instabilities and edge cracks during the repeated rolling process. A transition of the layered morphology from non-planar interfaces at the submicron level to nearly planar interfaces at the nano-scale was observed with decreasing layer thickness. High resolution transmission electron microscopy, selected area electron diffraction and X-ray diffraction were performed, and the results indicate that the Cu/Ta nanolamellar multilayers with a layer thickness of 50 nm show a {100}Ta[110]∥{110}Cu[111] rolling texture relationship. Tensile tests revealed that the ultimate tensile strength of the composite was up to 950 MPa, which is approximately 5 times higher than that of the initial pure Cu and Ta. The hardness of the prepared multilayer maintained unchanged even after an annealing at 500 °C for 1 h. These unique properties are attributed to an atomically flat bimetal interface and the low amount of homophase grain boundaries resulted from the CARB process.

An alternative method for manufacturing Al/B4C/SiC hybrid composite strips by cross accumulative roll bonding (CARB) process

For the first time, the cross accumulative roll bonding (CARB) process was used as an effective alternative method for manufacturing Al/B4C/SiC hybrid composite strips and compared with the accumulative roll bonding (ARB) processed hybrid composite. The XRD results showed that nanostructured Al/B4C/SiC hybrid composites have successfully been fabricated by using CARB process without any additional phase. During CARB, the ceramic reinforcement particles (B4C and SiC) were more uniformly dispersed within the matrix compared with ARB process, due to changes in strain path. In addition, the tensile strength, elongation, and microhardness of CARB composites were measured to be higher than those in the ARB product. Finally, scanning electron microscopy (SEM) observations of fractured surfaces showed that fracture mode both hybrid composites was shear ductile rupture, dimples, and shear zones.

A comparative study on metal–matrix composites fabricated by conventional and cross accumulative roll-bonding processes

This paper focuses on some structural and mechanical characteristics of Al–Al2O3 composites produced by conventional accumulative roll-bonding (ARB) and cross accumulative roll-bonding (CARB). The obtained structures were studied by transmission electron microscopy, X-ray diffraction, and optical microscopy; typically, the reinforcement distribution on different orthogonal planes was quantitatively compared. Also, the composite samples were mechanically characterized by hardness, uniaxial tensile, and fractographic experiments. The results showed that the CARB process, compared with ARB, gives rise to somewhat more effective grain refinement. Concerning the particles dispersion, the lateral rolling planes of the CARB samples, contrary to those of the ARB composites, present a similar feature. It was also found that the hardness, yield stress, tensile strength, and elongation of the CRAB specimens are higher than those of the ARB composites.

Comparison between ARB and CARB processes on an AA5754/AA6061 composite

The present work aims to compare two processes: Accumulative Roll Bonding and Cross Accumulative Roll Bonding (CARB). Both processes consist in the repetition of rolling but the second technique adds a 90° rotation of the sheet around its normal direction between each rolling. Microstructure, mechanical properties and texture were compared for both processes on an AA5754/AA6061 composite. As a result a thinner and less elongated microstructure was obtained in the CARB process leading to an isotropy and an improvement of the mechanical properties. Besides, the texture was characterized by the rotated Cube component for both processes but for CARB it is of less strength.