Laminated Metal Composites Research Articles

Strengthening a multilayered Zr/Ti composite by quenching at higher temperature

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.

Analysis of bending characteristics of bimetal steel composite

Analytical, numerical and experimental investigations were conducted on the bending characteristics of duplex stainless steel (2205) and low carbon steel (AH36) bimetal composite in this study, with the aim of providing a reference for the bending and forming processing optimisation of laminated metal composite. An analytical model was developed to predict the deformation behaviour of each segment and particular planes, such as neutral plane, unelongated plane and bonding interface, across thickness section under the plane strain condition during the bending process. The movement track of segments presents that it is better for the bonding interface to avoid experiencing the reverse loaded zone (RLZ) in forming fabrications for less potential defects, and the neutral plane is discontinuous while coinciding with the bonding interface. The thickness change and bending moment of bimetal plate were calculated as a function of the increasing bending curvature by the proposed theoretical model under four conditions classified by different thickness ratios and relative positions of component steel layers. The predicted results show that the relative position affects the thickness change of bent composite plate, but the thickness ratio has a more significant effect on the magnitude of bending moment, as confirmed by finite element (FE) simulation and bending experiments.

Enhanced monotonic and cyclic mechanical properties of ultrafine-grained laminated metal composites with strong and stiff interlayers

The accumulative roll bonding process allows to produce multilayered composites in which substantially dissimilar metals, both in terms of Young’s modulus as well as mechanical strength, can be brought together. For the optimization of such laminated metal composites a fundamental understanding of the microstructural interactions and deformation processes at the internal material interfaces is necessary. The influence of a gradient in hardness and Young’s modulus in ultrafine-grained laminated metal composites on the monotonic and cyclic mechanical properties is investigated in this paper. Special attention is put on aluminum/steel composites, as a high gradient in hardness and Young’s modulus is present at the layer interfaces. The mechanical properties are determined in monotonic and cyclic three-point bending tests. By scanning electron microscopy, the influence of the meso- and microstructure on the fatigue properties is intensively studied. Furthermore, the internal stresses during elastic straining are calculated using finite element simulations. The results are that for the aluminum/steel composites the monotonic and cyclic properties are drastically increased compared to aluminum mono-material sheets, as well as to composites based on two different aluminum alloys, in which only a gradient in hardness at the material interface exists and the gradient in elastic properties is absent. This is related to a pronounced crack deviation at the material interface as well as to an effective load transfer in the composites.

High Lightweight Potential of Ultrafine‐Grained Aluminum/Steel Laminated Metal Composites Produced by Accumulative Roll Bonding

The focus of this paper is the designing of ultrafine‐grained aluminum/steel laminated metal composites for innovative lightweight materials concepts used for cyclic loading. These ultrafine‐grained composites are produced by the accumulative roll bonding process. Three different aluminum/steel composites are studied, where the position of the steel layers is varied, to investigate the influence of the layer architecture. The mechanical properties are measured in monotonic and cyclic three‐point bending tests. The influence of the meso‐ and microstructure are intensively studied by scanning electron microscope observations. Furthermore, the internal stresses during elastic straining are calculated by a finite element simulation. In the composites, both monotonic and cyclic mechanical properties are strongly increased and are clearly higher as expected by a linear rule of mixtures of the constituent materials. This increase is particularly high for the fatigue properties resulting in a strongly enhanced specific fatigue limit of the composites.

Mechanical Properties of Fibre-Metal Laminates Made of Natural/Synthetic Fibre Composites

Mechanical properties are among the properties to be considered in designing and fabricating any composite to be used as a firewall blanket in the designated fire zone of an aircraft engine. The main focus of this work was to study the tensile, compression, and flexural strengths of the combination of natural/synthetic fibres with metal laminates as reinforcement in a polymer matrix. The materials included flax fibres, kenaf fibres, carbon fibres, aluminium alloy 2024, and epoxy. The two-hybrid fibre metal laminate composites were made from different layers of natural/synthetic fibres with aluminium alloy of the same thickness. The composites were made from carbon and flax fibre-reinforced aluminium alloy (CAFRALL) and carbon and kenaf fibre-reinforced aluminium alloy (CAKRALL). Based on the results obtained from the mechanical tests, the CAFRALL produced better mechanical properties, where it had the highest modulus of elasticity of 4.4 GPa. Furthermore, the CAFRALL was 14.8% and 20.4% greater than the CAKRALL in terms of the tensile and compressive strengths, respectively, and it had a 33.7% lower flexural strength. The results obtained in the study shows that both composites met the minimum characteristics required for use in the fire-designated zone of an aircraft engine due to their suitable mechanical properties.

Effect of the annealing process on the microstructure and mechanical properties of multilayered Zr/Ti composites

To explore the potential application of Zr-based alloys as structural materials, multilayered Zr/Ti composites were fabricated by a vacuum diffusion annealing bonding process. Scanning electron microscopy (SEM) in tandem with energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD) was used to characterize the microstructures and chemical elemental distributions of the Zr/Ti laminated metal composites (LMCs). Micro-hardness and in-plane compression tests were conducted to evaluate the mechanical properties of the Zr/Ti LMCs. It is revealed that the microstructure of the Zr/Ti LMCs is composed of alternating Zr layers, Ti layers and Zr-Ti mutual diffusion layers (interface layers). The width of the interface layer increases with increased annealing temperature and time. The micro-hardness test results show that the hardness distribution is uneven among the different layers and that the interface layer has the highest hardness. Compression results indicate that the strength of the Zr/Ti LMCs are higher than that of the constituent materials due to the contribution of the interface layer. The diffusion coefficient and the relation between the microstructure and yield strength are also discussed in this study.

Ballistic impact velocity response of carbon fibre reinforced aluminium alloy laminates for aero-engine

Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine shield due to higher values of impact strength and specific perforation energy as highlighted by the test results.

Feasibility of underwater laser forming of laminated metal composites

ABSTRACTLaminated metal composites are of great interest in various industries. Previous studies demonstrate undesired mechanical or microstructural changes in these composites during the laser forming process due to rapid temperature gradient. In this research, underwater laser forming is proposed to minimize this effect. This process could also be an effective method for on-site forming or repairing of large metal/composite sheets used in underwater applications, such as marine equipment, ships, and lake/sea-based offshore oil platforms. The underwater laser forming process is performed experimentally on a three-layered stainless steel/copper/stainless steel composite and compared with the results of in-air tests. Total forming time, bending rate, and microstructural changes are compared for both underwater and in-air conditions. The effects of forming parameters, such as the number of irradiations, laser beam velocity, diameter, and power, are also compared and discussed. It is shown that the bending angle per irradiation in underwater forming is significantly lower in comparison with in-air condition, but the production time is less due to the elimination of cooling time. Also, the microstructure of stainless steel at heat-affected zone was unchanged, and the hardness of upper layer experienced smaller changes when formed under water. The underwater laser forming process is demonstrated to be feasible and can be applied for underwater applications with a high degree of reliability.

Layer architecture and fatigue life of ultrafine-grained laminated metal composites consisting of different aluminum alloys

The influence of the layer architecture on the fatigue properties of ultrafine-grained laminated metal composites is studied. Composites with different stacking sequences of the aluminum alloys AA1050, AA5005, and AA2024 were produced by accumulative roll bonding and characterized by microstructural analysis and nanoindentation experiments. The fatigue properties were determined by 3-point bending tests performed on a vibraphore testing machine. Subsequently, the crack path was analyzed using a scanning electron microscope. It was observed that the fatigue crack bifurcates close to the interface if the hardness difference between both materials is high. The crack then spreads parallel to the interface within the softer material. This crack branching is more pronounced at high stress amplitudes caused by a significant accumulation of plastic deformation in front of the interface. Consequently, at high stress amplitudes the fatigue lives are significantly higher for composites with a high hardness difference between the layers. At low stress amplitudes, at which crack initiation is the dominating fatigue mechanism, the material of the outer layer mainly determines the fatigue lives. Composites with the same outer layer, but different interlayers, show very similar high cycle fatigue lives. Thus, by an appropriate layer architecture ultrafine-grained laminated metal composites with significantly enhanced fatigue properties can be designed.

Optimized layer architecture for an extended fatigue life of ultrafine-grained AA1050/AA5005 laminated metal composites

The influence of interfaces on the fatigue life in AA1050/AA5005 ultrafine-grained laminated metal composites was investigated. At constant sheet thickness, the layer thickness and the number of material interfaces was varied by performing different cycles of accumulative roll bonding. It is found that crack deviation occurs if the crack approaches the soft to hard (AA1050/AA5005) material interface resulting in strongly enhanced fatigue lives compared to the mono-material. The most favourable layer architecture for enhanced fatigue life strongly depends on the applied stress amplitudes. At intermediate stress amplitudes a large layer thickness of 500 μm (N4) and 8 material interfaces gives the longest fatigue life. In contrast, at low stress amplitudes the sheets with 32 material interfaces and a layer thickness of 125 μm (N6) shows the longest fatigue life.

Effect of initial texture and microstructure of Mg on mechanical properties of Mg – Stainless steel laminated metal composites

Laminated metallic composites consisting of an AZ31 magnesium alloy layer and two SS304 austenitic stainless steel layers were fabricated by a reactive transient liquid phase bonding method to achieve a metallic composite exhibiting an exceptional combination of specific strength and ductility. Three different initial microstructures were selected for the Mg layer on the basis of initial texture and grain size distribution (hot-rolled small grains, hot-rolled large grains and hot-extruded large grains). During deformation, the overall texture of all three samples approached the same preferential orientation. Since the original texture of the hot-extruded sample was very different from the final preferential orientation, its slip systems were able to accommodate more deformation in the Mg layer before saturation. It was also found that the initial texture plays an important role in the coalescence of micro cracks initiating failure. A strong initial texture facilitates the joining of micro-cracks, which leads to premature failure considerably before the predicted diffuse necking.

Tensile Fracture strength of Boron (SAE-1042)/Epoxy/Aluminium (6061-t6) laminates

To identify the mechanical property of a component is extremely significant, before it is used as an application to avoid any failure. Composite structure in practice can be subjected to various types of loads. One of the prime loads among such is tensile load. This paper shows experimental study and results of the rectangular dog bone tensile specimen of Boron (SAE-1042)-Epoxy/Aluminum (6061-t6) (B/Ep/Al) laminated metal composite (LMC). LMCs are a sole form of composite material in which alternating metal or metal containing layers are bonded together withs separate interfaces. Boron metal is among the hardest materials from the earth’s crest coupled with the aluminium metal, it is known that one side of boron and aluminum plates are properly knurled and later adhesively bonded with an epoxy which acts as binder and consolidated by using heavy upsetting press. Processes of tensile tests have been conducted with a hydraulic machine where three specimens with identical geometry were tested which all of them showing similar stress-strain curves. These results of tensile tests were clearly indicated the nature of ductility.

Induction of diffusion and construction of metallurgical interfaces directly between immiscible Mo and Ag by irradiation-induced point defects

As advanced materials, Mo/Ag laminated metal composites (LMCs) can be used for the interconnectors of spacecraft solar arrays and extend spacecraft orbital lifetime effectively.

Investigación sobre fusión de contacto en materiales compuestos laminados Cu/Al

Se presentan los resultados de composición química, microdureza y conductividad eléctrica obtenidos en materiales compuestos laminados Cu/Al, tratados térmicamente a temperaturas superiores a las del eutéctico Cu - Al. El bimetal Cu/Al fue obtenido por soldadura por explosión. La composición química del material tras los tratamientos térmicos se analizó por medio de análisis EDS (Espectroscopia de Energías Dispersiva de Rayos X). La conductividad eléctrica se midió mediante ensayos con corrientes Eddy. Las zonas endurecidas en el material soldado por explosión fueron identificadas. El valor experimental obtenido de la conductividad eléctrica está en concordancia con el calculado por la regla de las mezclas. Los tratamientos térmicos dan lugar a la formación de múltiples intercaras de alta dureza, compuestos de intermetálicos. La conductividad eléctrica de las intercaras identificadas es significativamente menor que las correspondientes al Cu y al Al.

Investigation of the Diffusion Processes at the Interface of the Cu/Ti Metal Composite

In this study the impact of heat treatment on the structure of Ti/Cu laminated metal composite was investigated. The composite was fabricated via explosion welding and was subsequently hot rolled. Optical tests, SEM microscopy and microhardness tests were utilized to identify the phase composition and the structure of diffusion zones formed at the interface between metals during heat treatment. Heat treatment of the composite for less than 1 hour results in the formation of two interlayers with the Tiα+Ti2Cu and TiCu phase composition respectively. The increase in the heat treatment duration up to 10 hours results in the formation of two additional interlayers with the Ti3Cu4 and Cuα + βTiCu4 phase composition.

Fabrication of Metal Laminate Composites with Interface Reinforcement by Semi-Solid Sintering

Semi-solid sintering technique has been introduced to alter the interfaces of a metal laminate composite material. A thin layer of reinforcement nanoparticles was applied on substrate metallic sheets using an ultrasonic spray deposition method. The sheets were then stacked, pressed, and sintered in the semi-solid regime of the metallic sheet. The liquid phase present in the matrix material penetrates and diffuses into the nanoparticle layer during consolidation and helps to form a gradual, nanostructured interface. Aluminum (Al6061) and magnesium (AZ31) alloy foils were used as the matrix sheets while various species of reinforcement particles were investigated, including silicon carbide (SiC), silicon (Si), and a mix of Si+SiC. Multilayered metal composites with nanostructured interfaces were successfully consolidated and were evaluated by performing a three-point bend test. AZ31 composites reinforced with SiC nanoparticle interface showed an improvement of 49% in flexural yield strength when compared with a reference sample without such interfaces.

Enhanced fatigue lives in AA1050A/AA5005 laminated metal composites produced by accumulative roll bonding

In this work laminated metal composites with alternating layers of commercial pure aluminum AA1050A and aluminum alloy AA5005 were produced by ARB. In order to vary the layer thickness and the number of interfaces different numbers of ARB cycles (4, 8 and 12) were applied. Subsequently, fatigue tests were performed and the related deformation and damage mechanisms were investigated. At high amplitudes crack growth occurs very straight through the whole sheet and is more or less unaffected by the interfaces of the individual layers in the composite. At lower amplitudes, where pronounced grain coarsening of the AA1050A layers occurs, the cracks deflect in front of the AA5005 layers and propagate in the coarsened AA1050A layers parallel to the bonding plane and the loading direction. Contrary to the composite, in both conventionally ARB processed AA1050A and AA5005 mono-material sheets grains are only locally coarsened around the crack tip and the fatigue cracks propagate very straight through the sheet width. Compared to AA1050A mono-material ARB sheets fatigue life and the cyclic stability are clearly enhanced in all composites.

Microstructure and Mechanical Properties of Accumulative Roll-Bonded AA1050A/AA5005 Laminated Metal Composites

Laminated metal composites (LMCs) with alternating layers of commercial pure aluminum AA1050A and aluminum alloy AA5005 were produced by accumulative roll-bonding (ARB). In order to vary the layer thickness and the number of layer interfaces, different numbers of ARB cycles (4, 8, 10, 12, 14 and 16) were performed. The microstructure and mechanical properties were characterized in detail. Up to 8 ARB cycles, the ultrafine-grained (UFG) microstructure of the layers in the LMC evolves almost equally to those in AA1050A and AA5005 mono-material sheets. However, the grain size in the composites tends to have smaller values. Nevertheless, the local mechanical properties of the individual layers in the LMCs are very similar to those of the mono-material sheets, and the macroscopic static mechanical properties of the LMCs can be calculated as the mean value of the mono-material sheets applying a linear rule of mixture. In contrast, for more than 12 ARB cycles, a homogenous microstructure was obtained where the individual layers within the composite cannot be visually separated any longer; thus, the hardness is at one constant and a high level across the whole sheet thickness. This results also in a significant higher strength in tensile testing. It was revealed that, with decreasing layer thickness, the layer interfaces become more and more dominating.

Flexible decision support system for ultrasound evaluation of fiber–metal laminates implemented in a DSP

Ultrasound testing has been widely applied for material characterization. The method accuracy usually relies on operator experience, considering this, an automatic decision support system may contribute to increase the evaluation efficiency. This paper presented an embedded electronic system for decision support in ultrasound evaluation of fiber–metal laminate composites. The proposed system comprised analog to digital conversion and digital signal processing algorithms. Discrete Fourier, wavelet and cosine transforms were used for feature extraction and principal component analysis was applied for efficient feature selection. The automatic classification was performed using an artificial neural network. The results demonstrated that it was possible to produce, in a short time latency, high-quality decision support information for two different types of test objects.

Interface Shear Actions and Mechanical Properties of Nanostructured Dissimilar Al Alloy Laminated Metal Composites

The laminated metal composites (LMCs) of dissimilar metals (aluminium alloys: AA1100/AA7075) were fabricated using the accumulative roll bonding technique in conjunction with cold rolling. The LMCs of ultrafine grained AA1100 and nanostructured precipitates of AA7075 achieved metallurgical bonding. The microstructure of the bonding interfaces and constituent metals was investigated using scanning electron microscopy and transmission electron microscopy for the LMCs with different layers. The deformation incompatibility and shear actions were analyzed using the microanalysis of dissimilar bonding interfaces. The mechanism of grain refinement of LMCs was investigated and described based on the microstructure characterization. The mechanical properties, strengthening mechanism, and fracture mechanism of LMCs were also investigated. The research results showed that the strengthening mechanism of LMCs is the recombination action of grain refinement, dislocation, and laminated interfacial strengthening. The coordinated deformation of dissimilar metals and the layer thickness are important in improving the mechanical properties of LMCs consisting of dissimilar metals.