Bimetal Composite Research Articles

Fabrication of Bimetal Aluminum-5 % Alumina-Bromine Composites by Warm Accumulative Roll Bonding

Abstract In this study, aluminum alloy 1050 and brass 70/30 are used to fabricate reinforced bimetal aluminum-5 % alumina (Al2O3)-bromine composites via a warm accumulative roll bonding (WARB) process. The aluminum and bromine strips were firstly welded together with the RB process up to 6 ARB cycles. In the WARB process, the rolled samples were preheated at 280°C for 7 min before each rolling cycle. The mechanical properties of the aluminum-Al2O3-bromine composite samples were evaluated in comparison to aluminum-5 % Al2O3 and bromine-5 % Al2O3 accumulative roll-bonded single-metal composite samples. It was shown that aluminum and brass deform in a similar way in the aluminum-Al2O3-bromine composites up two ARB cycles and then bromine layers began to neck. The average strength of the aluminum-Al2O3-bromine composites is higher than that of these two single-metal metal matrix composites. It was shown that the ductility and strength of the fabricated composite samples enhanced with the WARB cycles. Moreover, the fracture surfaces of bimetal composites have been studied by scanning electron microscopy.

Comparative analysis of deflection in a bimetal

A Bimetal is a combination of two different metals, which is employed in electrical appliances as a circuit breaker to prevent the overflow of current. The primary objective of this work is to examine the deflection produced in the bimetal component, due to electro-thermal load induced when the current flows through it. Copper and stainless steel are the most widely used metals having different coefficient of linear thermal expansion were taken as a bimetal composition and the same has been compared with Stainless steel and Aluminum. Modeling and analysis of the bimetal component, with different amperes, has been done using ANSYS and resulted stainless steel - Aluminium combination were shown higher deflection during the Analysis.

Microstructure and mechanical properties characterization of architectured copper aluminum composites manufactured by cold-drawing

The present study investigates the mechanical behavior of severely plastic-deformed Cu-Al composite wires with different diameters and heat-treatments. Each composite holds 61 restacked copper-clad aluminum wires. The bimetal composites were cold-worked up to diameters ranging from 1 mm to 3 mm, without any intermediate heat treatment. All the wires contain 61 hexagonal Cu-Al fibers with a continuous copper network extended from the outer surface into the center of the samples. Tensile tests were then performed on the as-drawn and heat treated wires. The latter were treated at 400 °C for 30 min and 6 h. The heat treatments firstly induce recrystallization in both constituents, giving rise to a fine-grained microstructure and secondly prompt the formation of several intermetallics. Without heat treatment after processing, the architectured composites exhibit a ductility value similar to the conventional copper-clad aluminum wires and larger yield stresses compared to them, regardless of the diameter. The intermetallic compounds, forming as a result of heat treatment, affect the yield stress, ductility and strain hardening mechanisms. Finally, the results are discussed in terms of grain size, texture, intermetallics volume fraction and mechanical coupling between the phases.

Interfacial Characteristics and Mechanical Properties of Stainless Steel/Steel Wires Reinforced GCI Composite

In this study, interfacial characteristics in bimetal composites composed of (i) grey cast iron (GCI) as a brittle matrix and (ii) stainless steel (SAE310) and steel wires (AISI1020) as ductile reinforcements were investigated. Flexural behavior of GCI and bimetal composite beams was examined under three-point bending test. Current results revealed that carbon and alloying elements diffused from the molten iron to the ductile reinforcement across the interface enhancing the metallurgical bond across the interface of produced composite beams. The diffusion of carbon from GCI into SAE310 side resulted in the formation of chromium carbides in that side near the interface. Chromium diffused from SAE310 into GCI led to the formation of M7C3 eutectic carbides in GCI near the interface. As a consequence, the ductile reinforcement may lose some of its ductility and behaves as a brittle material especially at the region near the interface. Microhardness and microstructure variations across the interface are related to the diffusion of carbon and alloying elements. The introducing of steel wires with a lower area ratio (i.e. 2.2%) into the GCI matrix bimetal composite did not reveal any obvious developments in changing failure mode of this material. Inserting SAE310 plates into composite beams resulted in a noticeable improvement in their mechanical properties as compared with GCI beam without reinforcement. Specimens of the bimetal composites with SAE310 plates failed in a ductile mode with slight plastic deformation before failure. This may be due to lower volume fraction of SAE310 plates.

Study on Deformation Characteristics and Microstructure Evolution of 2205/AH36 Bimetal Composite in a Novel Hot Forming Process

A new hot forming process of a hot-rolled 2205 duplex stainless/AH36 low-carbon steel bimetal composite (2205/AH36 BC) was proposed in this study, using the Gleeble 3500 thermal-mechanical simulator and hot bending tools. The deformation characteristics of 2205/AH36 BC were studied by hot tensile tests at temperatures from 950 to 1250 °C and strain rates ranging from 0.01 to 1 s−1. The tensile temperature has a great influence on the peak flow stress of the bimetal composite. The main microstructure evolution mechanisms, including dynamic recovery (DRV) and dynamic recrystallization (DRX), changed with the deformation temperatures. The different strain rates and the change of strain rates during the deformation process have an influence on the flow behavior of the bimetal composite. During the hot bending process, qualified parts could be formed successfully without obvious cracks in the interfacial zone. Phase and grain orientation spread (GOS) maps of specimens after hot tensile and forming tests were obtained by the electron backscatter diffraction (EBSD) technique to study the microstructure evolution, respectively. It is found that the effect of the working temperature on microstructure evolution is larger than that of the stacking sequence for 2205/AH36 BC. The considerable geometrically necessary dislocation (GND) accumulation occurs around the interface of 2205/AH36 BC under all imposed working conditions after the hot bending process, due to the interfacial micro-defects and complex stress states.

On the rule of mixtures for bimetal composites without bonding

Abstract In the present study, three types of bimetal composites, Al 6082 sleeve/Al 6082 core, Mg AZ31 sleeve/Mg AZ31 core and Al 6082 sleeve/Mg AZ31 core, were fabricated by drilling and assembling. The rule of mixtures (ROM) for the flow curves and yield strengths during compressive test were addressed. Our results show that the ROM can predict well the experimental flow curves and yield strengths of bimetal composites without bonding, irrespectively of the different strain hardening behavior between the two components.

Hot deformation behaviour and interfacial characteristics of bimetal composite at elevated temperatures

The hot deformation behaviour and interfacial microstructure evolution have a critical influence on the hot workability and mechanical properties of bimetal composite. This study investigated the flow performance and interfacial characteristics of 2205 duplex stainless steel/AH36 low carbon steel bimetal composite (2205/AH36 BC) at elevated temperatures, based on the hot tensile tests over the temperature range of 950–1250 °C and strain rate range of 0.01–1 s−1. The results indicate that the deformation behaviour of 2205/AH36 BC is similar to that of AH36 low carbon steel at high temperatures, and the softening mechanism of bimetal composite significantly depends on the imposed working temperatures and strain rates, which has been verified by the electron backscatter diffraction (EBSD) observation of microstructure evolution. Extra geometrically necessary dislocations (GNDs) were observed to accumulate in AH36 carbon steel layer adjacent to the interface after the hot working test at relatively low strain rates, resulting from the different thermal expansions and hot ductility between the 2205 stainless steel and AH36 carbon steel, and some existing defects on the interface from the previous hot rolling process. These observations can be employed as a reference to make the medium-thick bimetal composite be fabricated to the final products with hot working process in practice.

Optimisation of sintering parameters for bonding nanocrystalline cemented tungsten carbide powder and solid high strength steel

ABSTRACT In this study we examined the effects of compaction pressure for bonding nanocrystalline cemented tungsten carbide (WC-10Co) and high-strength steel (AISI4340) and successfully fabricated a bilayered composite of ceramic and steel. The obtained results were compared with our previous studies, and then the optimised sintering conditions were suggested. The compaction pressure examined varied from 120–200 MPa at 1150°C for 20 min. The study shows that the change in experimental parameters has significant effects on both the sintering properties of nanocrystalline WC-10Co powders and their bonding with AISI4340 steel. The microstructure reveals a successful metallurgical bonding between ceramic and steel. Bonding temperature determines, to a great extent, the diffusion processes across the bonding interface and has found to be the most influential variable compared to sintering time and compaction pressure. The obtained average maximum bonding strength of the bimetal composite is 226 MPa, which is higher than that of previous studies.

Interfacial characteristics and mechanical properties of duplex stainless steel bimetal composite by heat treatment

The interfacial morphologies play a crucial role in mechanical properties of laminated/bimetal composite. This study investigates the effects of heat treatments on the interfacial characteristics, mechanical properties and fracture behaviour of a 2205 duplex stainless steel/AH36 carbon steel bimetal composite with varying interface situations fabricated by the hot-rolling and subsequent heat treatments. The bimetal composite was annealed from 850 °C to 1150 °C in steps of 100 °C with soaking 1 h. Heterogeneities of grain size and element concentration exist in the microstructural evolution of bonding zone adjacent to interface after annealing treatments, which were observed by the optical microscope and scanning electron microscope (SEM) coupled with the energy dispersive X-ray spectroscopy (EDS). It was found that the diffusion transition zone of Cr and Fe alloy elements between component 2205 and AH36 steel layers present an increasing trend with the rise of annealing temperature. The results of conventional, shear and compact tensile test indicate that the tensile strength of 2205/AH36 bimetal composite gradually decreases but the fracture elongation increases with the rising annealing temperature, the thicker alloy element diffusion zone results in the stronger interfacial shear strength and better ductility of bimetal composite, but the thick and strong interface has less positive effect than the mechanical properties of bimetal composite itself on preventing the fatigue crack growth across the interface.

Influence of Tinning Material on Interfacial Microstructures and Mechanical Properties of Al12Sn4Si1Cu /Carbon Steel Bimetallic Castings for Bearing Applications

Fluxing and tinning processes are usually used to improve the adhesion of the Al bearing layer on steel substrate. Commonly after grinding the surface of the steel substrate, it is briefly immersed in flux solution followed by coating steel surface with either pure Sn (in a process known as tinning process) to promote adhesion between the bearing alloys and the steel. The current work is designated to investigate the influence of tinning material for carbon steel substrate using simultaneous fluxing and tinning mixture technique. The influence of three different tinning materials on the interface structure and shear strength of cast Al-Sn bearing alloy/steel bimetal composite is evaluated for compound casting technique. Sn pure, Sn-3Cu alloy and Sn-7.5Sb-3Cu powder alloys mixed individually with flux are used as tinning materials. It was found that using of different tinning materials have a significant effect on the bonding of interface area and the shear strength of interface as well. The shear strength of the bimetal fabricated using tinning mixture contains Sn+3% Cu with flux significantly increases by 59% compared to that fabricated using tinning mixture contains pure Sn. This increment is mainly due to the improvements of the interface bond structure and lower percentage of tin oxides. Such kind of phenomena can be explained in the fact that Cu minimizes the possibility of Sn oxidation during tinning process and during preheating of tinned steel substrate before casting of Al12Sn4Si1Cu bearing alloy as well.

Porous amorphous FeCo alloys as pre-catalysts for promoting the oxygen evolution reaction

The design and development of efficient electrocatalysts composed of earth-abundant elements for oxygen evolution have gained significant attention. In this study, a FeCo alloy electrocatalyst with an amorphous and porous structure was designed and prepared. The electrochemical test results showed that the amorphous alloy product with a Co:Fe molar ratio of 2:1 showed an optimal intrinsic catalytic activity for oxygen evolution. At a current density of 10 mA cm−2, only a small overpotential of 290 mV was required in a KOH solution (1 mol L−1), which is much lower than that for the monometallic catalyst (428 mV for amorphous cobalt for the same current density). The bimetal composition of this catalyst induced a strong synergistic effect. Moreover, it exhibited an amorphous and porous structure with a large number of exposed active sites along with high conductivity. These factors contributed to the excellent catalytic performance of this catalyst. This study provides an insight into the design of advanced oxygen evolution reaction catalysts.

Reducing Yield Asymmetry between Tension and Compression by Fabricating ZK60/WE43 Bimetal Composites.

In this study ZK60/WE43 bimetal composite rods were manufactured by a special method of hot diffusion and co-extrusion. Interface microstructure, deformation mechanism, and yield asymmetry between tension and compression for the composite rods were systematically investigated. It was observed that the salient deformation mechanism of the ZK60 constituent was {10-12}<−1011> extension twinning in compression and prismatic slip in tension, and different deformation modes resulted in yield asymmetry between tension and compression. In contrast, the WE43 constituent tends to be more isotropic due to grain refinement, texture weakening, solid-solution and precipitation strengthening, which were deformed via basal slip, prismatic slip, and {10-12}<−1011> extension twinning in both tension and compression. Surprisingly, it was found that yield asymmetry between tension and compression for the ZK60/WE43 composite rods along the extrusion direction was effectively reduced with a compression-to-tension ratio of ~0.9. The strongly bonded interface acting as a stress transfer medium for the ZK60 sleeve and WE43 core exhibited the coordinated deformation behavior. This finding provides an effective method to decrease the yield asymmetry between tension and compression in the extruded magnesium alloys.

Casting temperature dependent wear and corrosion behavior of 304 stainless steel reinforced A356 aluminium matrix bimetal composites fabricated by vacuum-assisted melt infiltration casting

This study aims to determine optimum casting temperature to achieve maximum wear and corrosion resistance in 304 stainless steel (SS) reinforced A356 matrix bimetal composites, which have been developed for use where conventional ceramic reinforced metal matrix composites have been used. Vacuum-assisted melt infiltration casting technique was used to manufacture bimetal composites at the various casting temperatures from 630 °C to 880 °C. The composite samples were subjected to dry sliding ball-on-disc tests using Al2O3 ball and immersion test in 3.5% NaCl solution for 7–21 days. θ (Fe4Al13) and η (Fe2Al5) phases developed at A356/304 interfaces and thickened with increasing temperature. Abrasion and adhesion as predominant wear mechanisms were observed in worn surface examinations, while pitting and galvanic corrosion occurred in corroded surfaces. The most suitable casting temperature was found to be 730 °C, considering the wear and corrosion properties of produced bimetal composites under certain conditions.

Bimetal composites for photocatalytic reduction of CO2 to CO in the near-infrared region by the SPR effect.

A major challenge in the field of photocatalytic carbon dioxide (CO2) reduction is to design catalyst systems featuring high selectivity for CO production, long-term stability and a composition of Earth-abundant elements. Here, we present a metal-organic framework (MOF) based catalyst to mitigate the technical problems associated with the above-mentioned features. We report a carbon-coated CuNi alloy nanocatalyst obtained by high temperature vacuum treatment of a MOF material (CuNiBTC). The resulting carbon encapsulated CuNi (denoted as CuNi/C) nanoparticles possess a well-designed core-shell composite structure with graphene shells. Meanwhile, we investigated the reaction mechanism of CO2 on the surface of the CuNi/C photocatalyst in an aqueous solution containing triethanolamine. The experimental results show that the activity and catalytic yield of CuNi/C are much higher than those of Cu/C and Ni/C alone. At the same time, the catalytic activity of CuNi/C is also affected by changing the reaction temperature in the preparation process. As a result, the CuNi/C samples can achieve nearly 90% selectivity for NIR-light-driven CO2 reduction to CO. Our approach demonstrates the potential of non-semiconductor materials as catalysts for efficient and selective reduction of CO2 to CO.

Review of preparation and application of copper–steel bimetal composites

With the rapid development of modern science and industrial technology, single metals or alloys are restricted by working conditions and cost. It is challenging to meet the requirements for current applications. Copper (Cu)–steel bimetal composites, composed of copper and steel, have performances of the two metals and low cost. They have drawn extensive attention worldwide and have been developed by many scholars for many years. The new preparations are studies to promote performances of the copper–steel bimetal composites and many literatures have also reported different applications of the copper–steel bimetal composites. Up to today, the developing copper–steel bimetal composites have made a great progress. This paper is mainly concerned with the progress of research on the preparation of copper–steel bimetal composites. The preparations are classified according to the forming state of copper and steel. Furthermore, the industrial applications of copper–steel bimetal composites and the prospects of future development are introduced.

Analysis of flow behaviour and strain partitioning mechanism of bimetal composite under hot tensile conditions

The flow behaviour and strain partitioning of 2205 duplex ferritic-austenitic stainless steel/AH36 low carbon steel bimetal composite (2205/AH36 BC) were investigated at elevated temperatures in this study. A physically-based constitutive model was established to describe the flow behaviour of bimetal composite based on the stress–strain relationships obtained from hot tensile tests, which were performed on a Gleeble 3500 thermal-mechanical test simulator over the temperature range of 950–1250 °C and strain rate range of 0.01–1 s−1. The stress and strain partitioning of bimetal composite was analysed to develop a mixture law of flow stress under those hot working conditions, due to the different strain contributions of each material on the total flow behaviour of bimetal composite. The developed constitutive model and the mixture law considering strain partitioning were both adopted to predict the stress–strain curves and used in finite element (FE) simulation model to calculate the peak loads of 2205/AH36 BC at 1000 °C. It is found that the softening mechanisms of 2205/AH36 BC changes depending on the externally imposed working temperatures and strain rates. The contribution of AH36 carbon steel layer on total stress is relatively more than that of 2205 stainless steel layer at high temperatures, as a result of the occurrence of stress partitioning. The proposed constitutive model, instead of the mixture law, is recommended to be used in the FE simulation of practical hot working of bimetal composite due to its high accuracy.

Fabrication, microstructure, and properties of interface-reinforced Mg/Mg bimetal composites by long-period stacking ordered structures

Interface-reinforced Mg–6Zn–Zr/Mg–4Y-2Gd–Nd (wt. %) bimetal composites by long-period stacking ordered (LPSO) structures were fabricated and the interfacial microstructures and properties were investigated. Results revealed the presence of a (Mg, Zn)3RE phase (RE: Y, Nd, Gd), stacking faults, and variations in chemical composition at as-cast bonding interface. After heat treatment, interfacial LPSO structures, characterized as 14H and 24R types, were formed. The novel composites exhibited an interfacial shear strength superior to that of base metals and other light bimetal composites due to the generation of LPSO structures and kink-deformation bands. This finding provides a new approach for the design of high-performance bimetal composites.

Formation Mechanisms and Microstructure Characterization of Al/Al3Ni In-situ Composite by Compound Casting

The Compound casting method was used to produce an Al/Ni bimetal composite. The mechanisms of formation of the reinforcing intermetallic phases were studied and the produced bimetal composite’s microstructure was then characterized. The results showed that the Al/Ni interface consisted of two intermetallic layers including Al3Ni2 and Al3Ni. It is suggested that the Al3Ni reinforcing particles of the composite originated from two sources. (1) Some Al3Ni particles detached from the Al3Ni layer formed at the interface between the Ni core and the Al melt and dispersed in the liquid Al and (2) Al-Al3Ni eutectic phase, which formed during the solidification process. The increase in the temperature led to the formation of more reinforcing particles and extended the depth of dispersion of the particles in the Al matrix.

Microstructure and mechanical properties of Mg/Mg bimetal composites fabricated by hot-pressing diffusion and co-extrusion

In the present study, the bimetal composite rods composed of a softer AZ31 sleeve and a harder WE43 core were fabricated via a special process by combining hot-pressing diffusion with co-extrusion, with particular attention to the characterization of microstructure and mechanical properties. The results showed that a well-bonded interface with a diffusion layer of ~20 μm in thickness was achieved. The texture in the interfacial region adjacent to the WE43 core changed with the basal poles largely perpendicular to the extrusion direction. Compared with the monolithic Mg billet, the co-extruded AZ31/WE43 bimetal composite rods could achieve a gradient of both composition and microstructure. Such gradients along with the superior interfacial bonding led to a higher compressive and tensile yield strength of AZ31/WE43 bimetal composite rods compared with the AZ31 sleeve. This study indicated that combining hot-pressing diffusion with co-extrusion is an effective method to fabricate the bimetal composites with superior mechanical properties.

Interfacial microstructure and mechanical behavior of Mg/Cu bimetal composites fabricated by compound casting process

Abstract Mg/Cu bimetal composites were prepared by compound casting method, and the microstructure evolution, phase constitution and bonding strength at the interface were investigated. It is found that a good metallurgical bonding can be achieved at the interface of Mg and Cu, which consists of two sub-layers, i.e., layer I with 30 μm on the copper side composed of Mg2Cu matrix phase, on which a small amount of dendritic MgCu2 phase was randomly distributed; layer II with 140 μm on the magnesium side made up of the lamellar nano-eutectic network Mg2Cu+(Mg) and a small amount of detached Mg2Cu phase. The average interfacial shear strength of the bimetal composite is measured to be 13 MPa. This study provides a new fabrication process for the application of Mg/Cu bimetal composites as the hydrogen storage materials.