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Roll-bonded steel–aluminum composite plates exhibit poor plasticity due to work hardening induced by severe plastic deformation. In this study, the mechanisms for improving the plasticity of steel–aluminum composite plates were investigated through liquid-nitrogen quenching from both material science and mechanical perspectives. From a materials science perspective, rapid cryogenic quenching forms numerous dislocation walls and cells within the Al matrix. These dislocation configurations effectively limit dislocation movement during tensile deformation. Additionally, the difference in thermal expansion properties between the steel and aluminum matrices generate significant microstrain near the interface, enhancing the back stress-induced strengthening effect. From a mechanical perspective, rapid cryogenic quenching increases the hardness and tensile strength of the aluminum matrix. A stronger aluminum matrix restricts the deformation of the steel matrix during tensile loading, delaying the onset of necking in the steel matrix. Additionally, the significant hardening of the aluminum matrix can cause the tensile specimen to bend, creating two potential necking points that divide the tensile strain, thereby significantly increasing the pre-necking deformation of the composite plate. Compared with untreated specimens, the tensile elongation and tensile strength of the specimens treated with rapid cryogenic quenching increased by 49.1% and 10.8%, respectively. This study provides a novel approach to simultaneously enhance the strength and plasticity of composite plates.

In this work, the AZ31/1060 laminated metal composites with Zn interlayer were successfully prepared by hot pressing with a strain of 47% in the atmospheric environment at 350 °C. The effects of the hot-pressing rate (from 3.3 × 10−4 to 1.0 × 10−2 s−1) on the interfacial structure and shear strength were examined. The quality of interface bonding and phase compositions at the interface are significantly affected by hot-pressing rate. With the decrease in strain rate, voids and cracks at the interfaces can be eliminated, and the phase compositions of the Mg/Al interface were changed from the Al-Zn solid solution, Zn and MgZn2 to Mg-Zn-Al ternary compounds. The hot-pressing time plays a decisive role in the compositions of diffusion zone. The maximum shear strength can be obtained in the sample hot-pressed at a strain rate of 1.0 × 10−3 s−1 due to that fracture occurred mainly in the MgZn2 layer. When the ternary Mg-Zn-Al phase exists at the interface, the bonding strength will be largely deteriorated. [ABSTRACT FROM AUTHOR]

Accumulative roll bonding (ARB) is a repeated cladding process in which two or more sheets of material are joined together by rolling at temperatures below recrystallization. The present review is focused on ARB of high‐alloy steels, which, among other laminated metal composites (LMCs), deliver the highest mechanical properties. After a brief description of high‐strength steels, history, and state of the art of LMCs, the principal roll bonding mechanism is explained. Further, the methodology of ARB of steels and variable parameters (stacking, temperature, etc.) are discussed. Known examples of steel–steel laminates are summarized with respect to their rolling temperature and mechanical properties. Further, the main toughening mechanisms of steel‐based LMCs are listed. The most promising candidates of high‐alloy steel laminates are presented in more detail. The important deformation mechanisms of twinning‐ and transformation‐induced plasticity (TWIP and TRIP) high‐alloy steels are explained. Microstructural changes and layer bonding as well as mechanical properties and damage behavior of two‐ and four‐layered TRIP/TWIP steel laminates are illustrated, including some specific phenomena, such as deformation lenses. Finally, by summarizing the analyzed data on steel laminates, conclusions and outlook are formulated. [ABSTRACT FROM AUTHOR]

In this study, a constitutive model applied to predict the tensile properties and fracture behavior of well‐bonded multilayered metal composites is extended. The equivalent single‐layer model, as a convenient method, is introduced into finite‐element simulations by combining it with an improved Xue–Wierzbicki damage plasticity model that considers material anisotropy. The steel use stainless (SUS) 430/Al1050/SUS430 laminated sheet fabricated by cold rolling is selected as the research material. The quasistatic uniaxial tests and Nakazima tests are operated to verify the accuracy of the proposed method. The mean errors in tensile stress and fracture forming limit strains are 2% and 3%, respectively. A load‐sharing mixture rule is proposed to assess the effects of the volume fraction, strength coefficient, and hardening exponent of the constituent materials on the mechanical properties of the laminates. In the results, it is indicated that the laminate exhibits sufficient elongation and remains markedly enhanced in tensile strength, reaching 470 Mpa when the ductile Al layer is combined with the higher strength and hardenability steel layer. In this research, it is aimed to clarify the formability characteristics in laminated composites for optimal sheet configuration design and development. [ABSTRACT FROM AUTHOR]

The preparation of Al/Mg/Al laminated metal composites (LMCs) by lamination technique can well combine the good corrosion resistance of Al alloy and the lightweight characteristics of Mg alloy. In this paper, the atmospheric corrosion behavior and underlying mechanism of 6082/AZ31/6082 LMCs with and without side exposure for one year of filed exposure to the tropical marine atmospheric environment were investigated. The results showed that the corrosion rates of AZ31 and 6082 and LMC-C were 55.967, 1.167, and 0.925 g m−2·a−1, respectively. The microstructure of the Al layer on the surface of LMCs underwent a significant transformation, characterized by a noticeable grain refinement and a concomitant increase in dislocation density. Moreover, the potential disparity between the second phase (AlMnFeSi and Mg2Si) and the matrix was diminished. These findings collectively contribute to the enhanced resistance of 6082/AZ31/6082 LMCs to intergranular corrosion and pitting corrosion. However, the accelerated dissolution of the intermediate Mg layer, facilitated by the galvanic corrosion effect during field exposure of the LMCs, resulted in a 4.5-fold increase in corrosion-induced mass loss. Notably, the ultimate tensile strength of the LMCs exhibited insensitivity to field exposure duration, while their plasticity underwent a gradual decline. This comprehensive study elucidates the corrosion behavior and underlying mechanisms of 6082/AZ31/6082 LMCs subjected to a tropical marine atmospheric environment, providing valuable insights for the rational design and development of LMCs with enhanced comprehensive performance.

The deformation behavior of hot-roll-bonded Mg/Al laminated metal composites (LMCs) is investigated, focusing on the crack formation around the interface. The material demonstrates a positive strain rate sensitivity mainly arising from the Mg matrix. A diffusion layer was formed at the Mg/Al interface with a serrated morphology during the two-pass rolling process, which consists of the Al3Mg2 and Mg17Al12 phases. The mechanical responses of the LMCs are evaluated using uniaxial tension, interfacial debonding tests (in normal and shear modes), and microstructure characterization techniques, which clarify the interfacial heterogeneity. The fracture constants of the interface were calibrated and incorporated in the finite element models to predict the failure modes of heterogeneous Mg/Al interface under three-point bending. With the increased thickness ratio of the Mg layer, the damage accumulation rate decreases at the interface and increases in the Mg matrix. As a result, the failure mode transferred from interface failure to matrix fracture. The findings of the present work provide new insight into the failure mechanism in laminated metal composites under bending conditions and can provide theoretical guidance for the plastic forming of such materials.

In this work, Mg/Al composite plates were prepared by direct hot pressing under atmospheric conditions. The impacts of the strain rate (from 3.3 × 10−4 s−1 to 1.0 × 10−2 s−1) on the interface and bonding strength were investigated. Results showed that Mg/Al composite plates can be successfully fabricated by hot pressing with a 40% strain at 350 °C. The strain rate will largely affect the interfacial bonding quality and the structure of the interface. As the strain rate decreases, the thickness of the diffusion layer at the interface becomes thicker, and the composition of the interface gradually changes from a mixed zone of Mg17Al12 and Mg2Al3 to two single-phase zones. In all samples, the Mg2Al3 phase layer at the interface tends to exhibit brittle fracture during shear. When the strain rate of the hot pressing reduces to 3.3 × 10−4 s−1, the single-phase zone of Mg2Al3 at the interface breaks up. In the present work, the Mg/Al plate hot pressed at a strain rate of 1.0 × 10−3 s−1 demonstrates the highest shear strength. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Laminated metal composites (LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft, and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 µm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters. The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality. In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed.

A new strategy via a combination of rolling bonding and isolation method was developed to evaluate the mechanical behavior of Ti/Al/Cu laminated metal composite (LMC) under the rule of mixture (ROM) condition, with a great emphasis on the effect of interface structure. The results showed that the development of the microstructure through the thickness of the Al layer was inhomogeneous after rolling bonding, which was attributed to the formation of shearing action caused by the difference in flow properties between the constituent layers. Additionally, the evolution of the crystallographic texture of the Al layer at different positions indicated that the severe shearing effect resulted in the appearance of a typical shear texture r-Cube {001} component in the region near the Ti side, and the coexistence of deformation and recrystallization textures in the region near the Cu side was considered to be the result of dynamic recovery. The measured strengths of Ti/Al/Cu LMCs significantly deviated from the predicted strengths in the calculation scheme of Cu, Al and Ti single sheets by the ROM (about 22.2 MPa), while the Ti + Al/Cu and Cu + Al/Ti schemes exhibited a slight deviation for the predicted results (about 4.7 MPa and 9 MPa). It is found that the existence of the layer interface contributed to the development of mechanical properties as a result of crack nucleation and propagation during plastic deformation, resulting in a large deviation between the experimental results and the predicted values in the scheme of ignoring the interface effect.

In this work, Mg/Al composite plates were prepared by direct hot pressing under atmospheric conditions. The impacts of the strain rate (from 3.3 × 10−4 s−1 to 1.0 × 10−2 s−1) on the interface and bonding strength were investigated. Results showed that Mg/Al composite plates can be successfully fabricated by hot pressing with a 40% strain at 350 °C. The strain rate will largely affect the interfacial bonding quality and the structure of the interface. As the strain rate decreases, the thickness of the diffusion layer at the interface becomes thicker, and the composition of the interface gradually changes from a mixed zone of Mg17Al12 and Mg2Al3 to two single-phase zones. In all samples, the Mg2Al3 phase layer at the interface tends to exhibit brittle fracture during shear. When the strain rate of the hot pressing reduces to 3.3 × 10−4 s−1, the single-phase zone of Mg2Al3 at the interface breaks up. In the present work, the Mg/Al plate hot pressed at a strain rate of 1.0 × 10−3 s−1 demonstrates the highest shear strength.

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.

Accumulative roll bonding is an advanced manufacturing process, which is capable of simultaneously refining the grain size into the nanometer regime and bonding different metallic sheet materials. Herein, homogenous aluminum/aluminum as well as heterogeneous aluminum/steel laminated metal composite (LMCs) are fabricated. The residual stresses are experimentally determined by X‐ray diffraction and the hole‐drilling method. Generally, a complex residual stress profile is found in all LMCs. The level of residual stress strongly depends on the bonded materials. Compressive residual stresses are induced in all sheets in the near surface area. These stresses range from −5 MPa in aluminum to −240 MPa in steel. In the homogenous aluminum/aluminum LMCs, compressive stresses up to −26 MPa in the softer layers and tensile stresses up to 30 MPa in the stronger layers are built up. This is different to heterogeneous aluminum/steel LMCs, where tensile stresses up to 40 MPa in the softer aluminum layers and compressive stresses up to −72 MPa in the inner harder steel layers are present. Based on the results obtained it is possible to directly design the material combination or stacking architecture of ultrafine‐grained LMCs to tailor the residual stress profile. [ABSTRACT FROM AUTHOR]

Laminated metal composites (LMCs) are a unique composite material and have great application prospects in automobiles, ships, aircraft, and other manufacturing industries. As lightweight materials, the Mg/Al LMCs are expected to combine the advantages of both Mg and Al alloys to broaden their application prospects. Roll-bonding is the most popular process for the fabrication of Mg/Al LMCs due to high production efficiency and good product quality stability. The roll-bonding process involves the deformation of the substrates and the formation of the interfacial diffusion layer. The latter will directly determine the interface bonding strength of Mg/Al LMCs. Bonding strength is very sensitive to the thickness of the reaction layer in the diffusion layer. When the thickness of the reaction layer exceeds 5 µm, the bonding strength decreases sharply. Therefore, controlling the thickness of the reaction layer is very important for the design of rolling parameters. The latest research also showed that the addition of intermediate layer metal and the construction of three-dimensional interfaces can further improve the interface bonding strength. How to apply these methods to roll-bonding is the focus of future research. Recently, a new rolling technique, corrugated roll/plat roll rolling+flat roll/flat roll rolling has been developed to fabricate Mg/Al LMCs. It can effectively promote the deformation of the hard layer and generate a wavy interface, resulting in the enhancement of the bonding quality and rolling quality. In the current review, the effects of rolling parameters and subsequent annealing on the interface structure of Mg/Al LMCs were elaborated in detail. The application of some special rolling techniques in the preparation of Mg/Al LMCs was also summarized. The latest research results on the relationship between interface structure and mechanical properties of Mg/Al LMCs were reviewed. Finally, further research directions in this field were proposed. [ABSTRACT FROM AUTHOR]

Fatigue of metallic components is an important aspect in mechanical engineering. For example, the repeated pressure differences result in the fatigue of the fuselage of aircrafts. These high demands require the application of endurable and lightweight materials. In this context, laminated metal composites produced by the accumulative roll bonding process can fulfill both aspects: outstanding mechanical strength of lightweight materials, due to an ultrafine‐grained microstructure, combined with the possibility to produce fatigue‐resistant materials by varying the stacking order of the laminated metal composites. This work investigates laminated metal composites consisting of aluminum AA2024 and titanium grade 1 layers with different stacking orders in respect to their three‐point bending fatigue properties. Additional finite element method (FEM) calculations of the stress distributions in the laminated metal composites are used to explain the results. The mechanical properties of the laminates with an outer aluminum or titanium layer are discussed based on the investigations of nanohardness and crack propagations. Although maximum bending stresses at the sheet surface of laminates with outer Titanium layer are higher than in monolithic materials, these laminates exhibit good lightweight potentials due to the weight reducing aluminum in inner layers. [ABSTRACT FROM AUTHOR]

Laminated metal composites have become a key strategy for the design and manufacture of metal parts with multiple combinations of excellent properties. This paper utilizes the differences in mechanical properties and recrystallization behavior of component metals to prepare a novel 316 L/(316 L-2.5 wt%Gd)/316 L neutron shielding laminated metal composites (LMCs) through composite rolling and solution treatment processes. LMCs have an excellent combination of properties: high strength (tensile strength: 571.36 MPa), sufficient tensile ductility (fracture elongation: 60 %) and high neutron shielding properties (thermal neutron shielding rate: > 90 %). Specifically, compared to the non-composite 316 L-2.5 wt%Gd neutron shielding material, the strength of the hot-rolled LMCs has increased by 2.0 times, and the elongation at fracture has improved by 3.3 times. After solid solution treatment, the elongation of LMCs is further increased, which is 6 times higher than non-composite 316 L-2.5 wt%Gd neutron shielding materials. The specially designed soft-hard matched 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces achieved good metallurgical bonding, with significant differences in grain sizes and strains. The main reasons for the enhanced strength and plasticity of LMCs are the geometric constraints caused by the layered structure composed of ductile and brittle metallic components, as well as the back-stress strengthening and strain hardening induced by deformation incompatibility at the heterogeneous interface. • 316 L/(316 L-2.5 wt%Gd) heterogeneous interfaces with different grain sizes and obvious differences in strains were constructed. • Heterogeneous structure and interfacial constraints synergistically enhance the strength and plasticity of 316 L/(316 L-2.5 wt%Gd)/316 L laminated composites. • Provides a promising solution to the difficult problem of mutual constraints between neutron shielding properties and mechanical properties. [ABSTRACT FROM AUTHOR]

The service life of technical components is often limited by the fatigue strength of the deployed materials. The accumulative roll bonding (ARB) process, which has the ability to produce ultrafine‐grained (UFG) laminated metal composites with tailored properties, offers a unique method to significantly enhance the fatigue life of materials that are cyclically loaded in three‐point bending. Detailed microstructural investigations reveal the material‐ and load‐specific deformation and damage mechanisms. Composites that have a sufficiently high difference in strength between the different constituent layers exhibit a significantly impeded crack growth and therefore an extended fatigue life at high stress amplitudes compared with those laminates with a rather similar strength of the different constituents. In the former composites, the fatigue crack is deflected at the material interface as it propagates from the softer to the harder layer. At low stress amplitudes, a prolonged fatigue life of the composites is mainly because of a significantly increased resistance to crack initiation. On the one side, this is as a result of the introduction of an UFG microstructure. On the other side, a load transfer toward stiffer layers in the interior of the composites also accounts for the enhanced fatigue life, if elastically dissimilar materials are combined in the right manner. [ABSTRACT FROM AUTHOR]

Laminated metal composites are a promising design since the hybrid design enables superior and tailorable material properties compared with bulk material. The article introduces for the first time, laminated metal composites consisting of multiple bilayers of alternating layers of ductile and high-strength steel processed by wire arc additive manufacturing (WAAM). The layup of the laminated metal composites is built up by alternating deposits made of ductile steel and high-strength steel type wires. Governing parameters in the fabrication process affecting the material properties, such as dilution, are discussed. Enhanced material properties of the laminated metal composites fabricated by WAAM are investigated under static tensile, impact and tension-tension high-cycle-fatigue loading and compared to the relating homogenous weld metal. Potential reasons for the retardation of crack propagation in laminated metal composites fabricated by WAAM compared to findings in roll-bonded laminated metal composites are discussed. WAAM is conducted by a collaborative robot providing a high level of flexibility in respect to geometry and scalability. Tailorability of material properties through WAAM-fabricated laminated metal composites adds an important layer of flexibility which has not been explored yet.

Abstract By rolling and diffusion bonding, multilayered Zr/Ti composites were fabricated using commercial pure titanium (CP-Ti) and zirconium (Zr702) sheet as raw materials. For the as-fabricated Zr/Ti laminated metal composites (LMCs), quenching at different temperatures were carried out to refine the microstructure. Microstructures of Zr/Ti LMCs before and after the quenching were characterized by scanning electron microscope and electron backscatter diffraction. Micro-hardness and compression tests were performed to reveal the effect of quenching temperature on the mechanical properties of the Zr/Ti LMCs. It indicates that certain part of the microstructure can be refined by phase transition during quenching. The volume fraction of the quenching-affected (refined) microstructure increase with the increase of quenching temperature. Micro-hardness tests show that the hardness is not uniform along the thickness of the Zr/Ti LMCs due to the heterogeneous chemical composition and microstructure. The compressive strength of the Zr/Ti LMCs increases with the increase of the quenching temperature, which is mainly attributed to the fact that more microstructures have been refined in higher temperature quenching. [ABSTRACT FROM AUTHOR]

In this study, the effect of layer structure on the mechanical behavior of Ti/Al laminated metal composites (LMCs) was explored, focusing on the occurrence of an additional strengthening mechanism introduced by heterogeneous microstructures between constituent layers. Experimental results showed that the change in layer structure parameters and rolling conditions had a significant effect on the microstructure of the Al layer, and the difference in shear strain scale near the interface led to the formation of a grain refinement zone (GRZ) with various microstructural characteristics during dynamic recrystallization. In addition, the recrystallized distribution and texture evolution (i.e., the increasing recrystallized fraction and the intensifying shear texture r-Cube {001} 〈110〉) revealed that the deformation storage energy as the driving force of recrystallization played an important role in the difference in the heterogeneous degree formed in various Ti/Al LMCs. On the other hand, the strength deviation between the experimental strength and the theoretical strength predicted by the rule of mixture can be detected in all LMCs with different thickness ratios after hot rolling, resulting from the pile-up of geometrically necessary dislocations (GNDs) caused by the synergetic deformation induced by mechanical incompatibility between Ti and Al layers during plastic deformation. With a change in the layer structure parameter, a considerable strength deviation in the Ti/Al LMC with a large thickness ratio indicated that the high mechanical incompatibility between the constituent layers was conducive to the enhancement of additional strengthening behavior. • Microstructural evolution and mechanical behavior of Ti/Al LMCs with various layer structures were explored. • The formation of grain refinement zone near the interface with various microstructural characteristics was analyzed • The contribution of interfacial effect introduced by mechanical incompatibility on properties were investigated. [ABSTRACT FROM AUTHOR]

In this study, the traditional hot rolling to fabricate Al/Ti laminated metal composites (LMCs) was improved by using a pre-rolling diffusion process. The effect of the pre-rolling diffusion on microstructure and mechanical properties of Al/Ti LMCs were investigated by various methods, such as optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile tests. The results show that, with increasing diffusion temperature, the thickness in diffusion layer was increased and the mechanical properties of LMCs were improved obviously, which was attributed to the optimized interfacial structure after diffusion process. In addition, the formation of TiAl3 intermetallic compounds (IMCs) was detected in the bonding interface, which played an important role in improving the mechanical properties for Al/Ti LMCs. The predicted results of stress-strain curves from rule of mixture (ROM) indicated that, there existed an extra interfacial strengthening in Al/Ti LMCs beside the mechanical properties provided by the contribution of constituent layers. The pre-rolling diffusion process is effective for the optimization of interfacial structure and improvement of mechanical properties in Al/Ti LMCs.

The layer thickness has been reported to play a crucial role in laminated metal composites (LMCs). In this work, Al/Ti/Al LMCs with varying Ti layer thickness but a constant number of interface were fabricated by hot rolling and annealing to explore the effect of layer thickness on the enhanced strength and ductility. Ex-situ electron backscatter diffraction (EBSD) and digital image correlation (DIC) techniques were used to reveal the plastic deformation mechanisms. With the decrease of the Ti layer thickness, the extra strength and elongation caused by the layered structure increase continuously until the layer thickness is reduced to ∼0.6 mm. When the best combination of strength and elongation is achieved, the width of the interface affected zone (IAZ) in the Ti layer reaches ∼0.3 mm, which is roughly half of the layer thickness of the Ti layer. Within the IAZ of the Ti layer, more pyramidal and basal slips are activated compared with that in the central part, which contributes to the increase of strain delocalization efficiency. In addition, the geometrically necessary dislocations (GNDs) also exhibit gradient distribution following the strain gradient, resulting in hetero-deformation induced (HDI) strengthening and hardening. This work further enriches the knowledge of achieving excellent strength-ductility synergy in LMCs. [ABSTRACT FROM AUTHOR]

In the present work, the mechanical behavior of tri-metallic 7075Al/1060Al/304 stainless steel (Al/Al/Steel) composites was systematically investigated, emphasizing the effect of the strengthening mechanism introduced by interlaminar and internal microstructures of constituent layers. The results show that the excellent interface bonding of tri-metallic Al/Al/Steel composites was achieved by the combined bonding method of roll-casting and rolling bonding, and the intermetallic compounds were effectively inhibited due to the severe deformation caused by the re-bonding process. It is found that an interfacial transition zone (ITZ) appeared at the 1060Al/Steel interface for all specimens after hot rolling bonding, and the increasing thickness of ITZ can be observed with the increasing rolling reduction. The experimental observation indicated that the ITZ was independent of the intermetallic layer, and its formation was mainly due to the plastic deformation introduced by the shear effect during rolling. Compared with the bi-metallic Al/Steel, the mechanical properties of the tri-metallic Al/Al/Steel composites were significantly improved, which was attributed to the contribution of the high-performance 7075Al with precipitation strengthening behavior according to the rule of mixture. Besides, various annealing treatments were conducted to evaluate the effect of mechanical incompatibility on the mechanical properties of tri-metallic Al/Al/Steel composites. The increasing strain gradient led to considerable dislocation pile-up near the interface of the soft 1060Al layer, inducing an extra strengthening mechanism to the tri-metallic Al/Al/Steel composites, which promoted the optimization of strength and ductility. [Display omitted] [ABSTRACT FROM AUTHOR]

AA 1060/3003/1060 laminated composites were fabricated by hot-roll bonding. The effect of rolling temperature on the microstructure, texture and mechanical properties of AA 1060/3003/1060 laminated composites was investigated. The results show that the development of microstructure and texture through the thickness of Al layers was inhomogeneous in the Al/Al laminated composites. Initial grains were elongated along the direction of about 15° to the RD in the region near the surface layer of AA 1060 aluminum alloy, and the incline angle gradually decreased as the measured position moved towards the interface of 1060/3003 from the surface layer. The rolling texture of 1060 layer consisted of the r-cube and γ-fiber shear textures and the remaining cube component. The r-cube shear texture weakened gradually as the measured position moved towards the interface of 1060/3003 from the surface layer, whereas the center layer of AA 1060 aluminum alloy had the strongest γ-fiber shear texture. The interface layer of AA 3003 aluminum alloy had a completely different texture from the center layer. For the Al/Al laminated composites, the YS and UTS first increased to a maximum value at about 200 °C and then decreased with increasing rolling temperature. [ABSTRACT FROM AUTHOR]

Al 6061/Ti–6Al–4V/Al 6061 laminated composites were fabricated by hot-roll bonding. The effect of rolling temperature and reduction on the microstructure and mechanical properties of Al/Ti/Al laminated composites was investigated. The results show that the Al/Ti/Al laminated composites exhibited a good Al/Ti interfacial bonding. The reduction ratio of Ti to Al layer decreased with increasing rolling temperature and reduction. The development of microstructure through the thickness of Al layer was inhomogeneous. The number of high-angle boundaries and the misorientation angle across low-angle boundaries increased as the thickness position moved towards the surface of Al layer from the interface of Al/Ti. The initial grains near the surface of Al layer were markedly elongated at a certain angle to the RD and then fragmented into the equiaxed fine grains at larger rolling reductions. This inhomogeneity of microstructure can be attributed to the effect of the friction between the roll and sheet surface and the uncoordinated deformation between Al and Ti layers. The deformation inhomogeneity increased with increasing rolling reduction. For the laminated composites fabricated with rolling reductions of 27% and 38%, the yield and tensile strength increased to a maximum value at about 400 °C and then decreased with increasing rolling temperature. The laminated composites fabricated with a 45% reduction possessed lower strength in the temperature range from 400 °C to 450 °C than those with a 38% reduction due to the fracture of Ti layer. [ABSTRACT FROM AUTHOR]

Although laminated metal composites fabricated by accumulative roll bonding (ARB) undergo kink-band formation, there are no guidelines for optimizing their fabrication to avoid necking and shear localization without post-annealing. The necking of the composite layers during rolling generates non-uniformities that may degrade the mechanical performance of the composite. This paper proposes a model for laminated metal composites that aims to quantitatively assess and predict necking based on the work-hardening of each layer. Cu–Al-, Cu–A5052-, and Cu–A5083-laminated metal composites were fabricated using ARB at room temperature (~300 K) without post-annealing, and they were subjected to mechanical and microstructural analyses. A normalized neck amplitude was introduced as a new parameter that accurately predicted the degree of necking observed experimentally. Another new parameter, an instability index , was introduced to frame the necking criterion of the hard layers. A plastic instability criterion framed based on the new parameters accurately predicted the degree of necking in the hard layers of the as-prepared laminated metal composites. These findings may be applied to guide the fabrication of metal composites of any composition using the ARB process. [Display omitted] • Laminated metal composites (LMCs) were fabricated using ARB without post-annealing. • Normalized neck amplitude can assess the experimentally observed degree of necking. • Instability index predicts the necking of the hard layers in the LMCs. • These two parameters aid in framing plastic instability criterion for LMCs. • The findings are instrumental in fabricating stable LMCs using ARB. [ABSTRACT FROM AUTHOR]

Improving the strength and ductility of magnesium (Mg) alloys is a popular area of research. Many studies have indicated that laminated metal composites can be used to simultaneously yield excellent properties of all their constitutive metals. In this study, laminated Mg/Zr (AZ31/Zr702/AZ31) composites were fabricated by hot rolling-induced bonding. An Mg plate was used as the initial wedge component to obtain a wide range of rolling reductions (40%–70%) in a given Mg/Zr composite, and its microstructures and mechanical properties were then characterized. The results show that rolling reduction greater than 40% was needed to achieve a well-bonded interface for Mg/Mg (AZ31/AZ31) and Mg/Zr composites when rolled at 400 °C. With increasing rolling reduction, the strength of the Mg/Zr composite (∼180 MPa) showed no prominent change, and was higher than that of Mg/Mg composites (∼150 MPa) fabricated by using the same bonding process. In addition, the Mg/Zr composite had significantly higher bonding strength (∼6 N/mm) and ultimate peel strength (∼9 N/mm) than the Mg/Mg composites (∼2.5 N/mm and ∼3 N/mm). Finite element simulations were also used to examine the underlying strengthening mechanisms of the composites. The results here contribute to research on the strengthening and toughening of Mg alloys as well as the fabrication of laminated metal composites. [ABSTRACT FROM AUTHOR]

Abstract: Laminated metal composites (LMCs) constructed using Mg and Al have good application potential in the aerospace industry because of their light weights. In this study, two types of LMCs (Mg/Mg and Mg/Al/Mg) with different reduction ratios were prepared via warm roll bonding. Investigations regarding the microstructure and composition of LMCs discovered refined grains in the Mg and Al layers with no intermetallic compounds at the interface. Moreover, tensile and three-point bending tests were conducted to investigate the mechanical properties of the LMCs. The tensile strengths of the two types of LMCs reached their peak values at 35% reduction ratio. The delamination mechanism in LMCs significantly improved the bending properties. However, this effect decreases with increasing reduction ratio. [Copyright &y& Elsevier]

The effects of changing the test temperature from room temperature to 373 or 398 K on the fatigue crack propagation of 6090/SiC/25p-6013 and 7093/SiC/25p-7093 laminates tested in the crack arrestor orientation was investigated. The fatigue crack propagation behaviour of the individual monolithic and discontinuously reinforced aluminium alloy (DRA) layers was additionally compared to that of the laminates. The fatigue behaviour of the laminates was significantly different than that of the individual layers and was affected by changes in the test temperature as well as by a thermal exposure to high temperatures (e.g. 373 or 398 K) before testing at 298 K. Significant changes in the crack velocity also occurred upon traversing from one layer to another for the fatigue tests conducted at high temperature, or after exposure to high temperature. [ABSTRACT FROM AUTHOR]

The effect of processing variables on the growth of a titanium aluminide layer produced from elemental titanium and aluminum foils was examined, with the intention of yielding a titanium–titanium aluminide composite structure. To produce the intermetallic phase in situ, two processing techniques were employed, diffusion bonding and combustion synthesis. Microstructural examination of the titanium aluminide layer revealed striking similarities in the resulting morphology yielded by both processing techniques, in particular for those samples diffusion annealed at lower temperatures (615 °C and below) and those reacted by combustion synthesis. In both cases, an exothermic chemical reaction was responsible for aluminide formation in specimens, and in those samples processed by diffusion bonding, this reaction was observed to be rate controlled by a diffusion mechanism. Chemical analysis of the product aluminide showed the layers to be composed completely of a single phase, TiAl3, which is believed to be the result of thermodynamic stability of this phase relative to other stable equilibrium phases in the titanium aluminum system. The results of these experiments are discussed with a view of utilizing these processes to optimize the mechanical behavior of titanium aluminide by incorporating it into a laminated metal composite. [Copyright &y& Elsevier]

Laminated metal composites are a promising design since the hybrid design enables superior and tailorable material properties compared with bulk material. The article introduces for the first time, laminated metal composites consisting of multiple bilayers of alternating layers of ductile and high-strength steel processed by wire arc additive manufacturing (WAAM). The layup of the laminated metal composites is built up by alternating deposits made of ductile steel and high-strength steel type wires. Governing parameters in the fabrication process affecting the material properties, such as dilution, are discussed. Enhanced material properties of the laminated metal composites fabricated by WAAM are investigated under static tensile, impact and tension-tension high-cycle-fatigue loading and compared to the relating homogenous weld metal. Potential reasons for the retardation of crack propagation in laminated metal composites fabricated by WAAM compared to findings in roll-bonded laminated metal composites are discussed. WAAM is conducted by a collaborative robot providing a high level of flexibility in respect to geometry and scalability. Tailorability of material properties through WAAM-fabricated laminated metal composites adds an important layer of flexibility which has not been explored yet. [ABSTRACT FROM AUTHOR]

In the present work, laminated Cu/Ni samples reinforced by graphene film with various thicknesses were produced via electrophoretic depositing graphene oxide (GO) on Cu foil by controlling deposition voltage, and the effect of thickness of graphene film on strengthening Cu/Ni multilayer composites were investigated in detail. Microstructural examination revealed that the fragments of graphene film were dispersed at the interface between Cu and Ni layer after hot rolling, with a range of thickness from 0.76 to 5.13 μm. The graphene film showed an excellent strengthening effect in the composites regardless of their thickness according to the tensile testing. However, the toughing effect achieved optimal as the thickness of 4.12 μm. The role of deposited graphene film played in determining the load transfer and optimizing the interface was discussed. Graphene film with appropriate thickness can effectively inhibit the severe asymmetric diffusion behavior of Cu and Ni elements, which plays an important role in strengthening and toughening clad interfaces by inhibiting the formation of Kirkendall voids. This study provides novel insights into understanding the strengthening and toughing behaviors of graphene reinforced multilayer composites, which can be developed into a technical strategy for fabricating high performance laminated metal matrix composites. [ABSTRACT FROM AUTHOR]

Al/Ti/Al laminated metal composites (LMCs), with layer thicknesses ≥800 μm, were fabricated via hot rolling bonding and annealing. The fabricated Al/Ti/Al LMCs displayed improved tensile ductility compared with both the single Ti and single Al layers. Combinational analyses based on digital image correlation and finite element modeling revealed that the width of the interface affected zones (IAZ) could exceed 150 μm, which is more than one order of magnitude larger than previously reported values. The mismatch of plastic anisotropy between the Ti layer and the Al layer may play a crucial role in realizing such a wide IAZ. Slip trace analysis indicated that more pyramidal and basal slips were activated at the Ti/Al interface than in the central part of the Ti layer, which may be attributed to the complex stress/strain state in the IAZ. Although a wide IAZ was observed, the strain hardening capability of the Al/Ti/Al LMCs did not obviously improve. In contrast, the strain rate sensitivity improved, which is assumed to play a key role in the improved ductility of the Al/Ti/Al LMCs. This study can provide a direction for the design of heterostructured materials with high strength and high ductility. • The tensile ductility of Al/Ti/Al thick LMCs is better than monolithic Ti and monolithic Al. • Al/Ti/Al thick LMCs show extra strengthening above the rule of mixture. • The width of interface affected zone in Al/Ti/Al thick LMCs can exceed 150 μm. • Plastic anisotropy may play a crucial role to obtain such wide interface affected zone. • The extra ductility of Al/Ti/Al LMCs may relate with the improved strain rate sensitivity. [ABSTRACT FROM AUTHOR]

Multilayer metal composites have great application prospects in automobiles, ships, aircraft and other manufacturing industries, which reveal their superior strength, toughness, ductility, fatigue lifetime, superplasticity and formability. This paper presents the various mechanical properties, deformation characteristics and strengthening–toughening mechanisms of laminated metal matrix composites during the loading and deformation process, and that super-high mechanical properties can be obtained by adjusting the fabrication process and structure parameters. In the macroscale, the interface bonding status and layer thickness can effectively affect the fracture, impact toughness and tensile fracture elongation of laminated metal matrix composites, and the ductility and toughness cannot be fitting to the rule of mixture (ROM). However, the elastic properties, yield strength and ultimate strength basically follow the rule of mixture. In the microscale, the mechanical properties, deformation characteristics, fracture behavior and toughening mechanisms of laminated composites reveal the obvious size effect. [ABSTRACT FROM AUTHOR]

AA7075/AA1100 laminated metal composites (LMCs) were successfully produced by accumulative roll bonding (ARB). Also, to investigate the effect of annealing on mechanical properties and microstructure evolution, the composites were subject to annealing treatment at three different temperature (200, 300 and 400 °C) for 1 h. The microstructure evolution was evaluated by scanning electron microscopy (SEM) equipped with an energy dispersive spectroscopy (EDS) and electron back scatter diffraction (EBSD). Tensile tests were performed to measure the mechanical properties of composites. It was observed that elemental diffusion occurred in the constituent layer interfaces, indicating that superior bonding was achieved between the layers with annealing temperature increased. By increasing the annealing temperature, the presentation of a relatively strong {100}<001>Cube recrystallization textures has been attributed to strain-induced boundary migration (SIBM) caused by a preference for the Cube-oriented grains to grow into adjacent S-oriented grains with higher stored energy. In addition, the effect of pre-recovery on anisotropy was discussed in detail. Tensile tests revealed that the plane anisotropy after the two-step annealing (TSA) process was evidently diminished in compare with the single annealing (SSA) process due to the reduced Cube texture strength and the formation of equiaxed crystal structures. • Effect of annealing treatment on microstructure of Al/Al laminated composite was investigated. • The evolution of microstructure and recrystallized texture for different annealing treatment was analyzed systematically. • The mechanical anisotropy of laminated composite was improved by two-step annealing process. [ABSTRACT FROM AUTHOR]

The bonding interface plays an important role in the mechanical properties of laminated metal composites (LMCs). Compared with a straight interface, larger bonding area is achieved by a wavy interface, which provides higher debonding resistance for a given bonding strength. Herein, Al/Ti/Al LMCs with straight and wavy bonding interfaces are fabricated using Ti strips with initial straight and wavy profiles. The mechanical properties are investigated with in‐plane uniaxial tension tests. Microstructures in the region of the interface before and after tension are characterized by scanning electron microscopy and electron backscatter diffraction. Finite element simulations of the rolling‐bonding process and tension are conducted to investigate the effect of the wavy profile on the fabrication and mechanical properties of Al/Ti/Al LMCs. Compared with an initial straight profile, Al and wavy Ti strips are successfully bonded at a lower rolling reduction because of the larger local strain and higher local contact stress. Wavy interfaces between the Al and Ti layers are formed. Similar strength and ductility are obtained for Al/Ti/Al LMCs with straight and wavy interfaces when a proper rolling reduction and annealing are applied. [ABSTRACT FROM AUTHOR]

This study presents a method to obtain aluminum alloy laminated composites with high yield strength and good ductility through a multiscale coarse/ultrafine-grained design, which are fabricated by accumulative roll bonding (ARB) and subsequent annealing treatment. Experimental results showed that an outstanding combination of strength and ductility was achieved in 1100/7075 Al alloy laminated composites after annealing at 300 °C for 60 min. Deviation between experimental and predicted results from stress-strain curves indicated that an extra strengthening effect was present in the laminated metal composites. Moreover, to analyze the effect of the magnitude of mechanical incompatibility on the mechanical properties during deformation, laminated metal composites with constituent layers possessing different flow properties were comparatively studied. Laminated metal composites with multiscale grain size distributions were obtained using different rolling strain paths and annealing treatments, which was attributed to differences in the recrystallization of constituent metals. It was determined that cross rolling, compared with direct rolling, gave rise to more effective improvements in the mechanical properties after annealing treatments due to higher mechanical incompatibility across the interface. For the Al alloy laminated composites, the difference in flow properties between the constituent layers plays an important role in additional interfacial strengthening by appropriate collocation of component strengths. During tensile deformation, a high density of geometrically necessary dislocations (GNDs) was distributed in the interface of the soft layer due to the mechanical incompatibility across the interface. The high yield strength with a multiscale interfacial structure is attributed to the back stress strengthening associated with the formation of GNDs and the good ductility results from the high strain hardening rate during plastic deformation. [ABSTRACT FROM AUTHOR]

This study investigates the effect of strain rates and temperatures on the mechanical behavior of ultrasonically consolidated Titanium–Aluminum thin foils to understand and characterize their formability. To this goal, laminated composite samples with a distinct number of layers were bonded using ultrasonic consolidation. Then, tensile and biaxial hydraulic bulge tests at different strain rates and temperature conditions were conducted. The effect of the sample orientation on the mechanical response was also examined. Tensile and hydraulic bulge tests results were compared to observe differences in ultimate tensile strength and strain levels under uniaxial and biaxial loading conditions. The effects of loading condition, strain rate, and temperature on the material response were analyzed and discussed on the basis of test results. In general, it was concluded that the maximum elongation values attained were higher for the samples subtracted along the sonotrode movement direction compared to those obtained from the normal to sonotrode movement direction. The elongation was obtained as high as 46% for seven bi-layered samples at high-temperature ranges of 200–300 °C. Hydraulic bulge test results showed that elongation improved as the number of bi-layers increased, yet the ultimate strength values did not change significantly indicating an expansion of the formability window. [ABSTRACT FROM AUTHOR]

In this study, the traditional hot rolling to fabricate Al/Ti laminated metal composites (LMCs) was improved by using a pre-rolling diffusion process. The effect of the pre-rolling diffusion on microstructure and mechanical properties of Al/Ti LMCs were investigated by various methods, such as optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile tests. The results show that, with increasing diffusion temperature, the thickness in diffusion layer was increased and the mechanical properties of LMCs were improved obviously, which was attributed to the optimized interfacial structure after diffusion process. In addition, the formation of TiAl3 intermetallic compounds (IMCs) was detected in the bonding interface, which played an important role in improving the mechanical properties for Al/Ti LMCs. The predicted results of stress-strain curves from rule of mixture (ROM) indicated that, there existed an extra interfacial strengthening in Al/Ti LMCs beside the mechanical properties provided by the contribution of constituent layers. The pre-rolling diffusion process is effective for the optimization of interfacial structure and improvement of mechanical properties in Al/Ti LMCs. [ABSTRACT FROM AUTHOR]

Abstract Direct alloying is very difficult for immiscible alloy systems owing to the absence of driving force at equilibrium. To realize alloying for immiscible alloy systems, a method, named as irradiation damage alloying (IDA), is developed and used to prepare W/Ag, Mo/Ag and Mo/Cu laminated metal composites (LMCs) in this work. The IDA process mainly includes three steps: firstly, the multi-energy Ag (or Cu) ions were implanted into the surface of the W (or Mo) matrix; secondly, an Ag (or Cu) coating layer was deposited on the damaged W (or Mo) matrix by vacuum evaporation; thirdly, the obtained W/Ag (Mo/Ag or Mo/Cu) laminated bimetallic samples were annealed at 950 °C in hydrogen for 8 h. It is confirmed that diffusion alloying of immiscible metal atoms indeed takes place and metallurgical bonding interfaces have been constructed successfully. Additionally, to reveal the underlying mechanism of IDA, a thermodynamic model is introduced. It is shown that the storage energy caused by irradiation damage in the matrix metal and the surface energy of the coating layer dominate the thermodynamic driving force. Besides, the storage energy has been confirmed to play a decisive role for the microstructure development of the metallurgical bonding interface. Graphical abstract Unlabelled Image Highlights • The newly developed IDA is a feasible way to realize direct alloying for immiscible systems. • W/Ag, Mo/Ag and Mo/Cu metallurgical bonding interfaces have been constructed successfully by means of IDA. • The storage energy caused by irradiation damage and surface energy of coating layer dominate thermodynamic driving force. • The decisive role for the microstructure development is the storage energy caused by irradiation damage. [ABSTRACT FROM AUTHOR]