Foil Interlayer Research Articles

Effect of pure Cu foil interlayer on the microstructure and mechanical behavior of Mg/Al composite sheet

In this study, a Mg/Al composite sheet containing an ultrathin Cu foil interlayer was successfully fabricated by single-pass hot roll bonding. The influence of Cu foil on microstructure, mechanical properties and deformation behavior of Mg/Al composite sheet were investigated. The results show that the Mg/Al-Cu sheet exhibits a good interfacial bonding, and there is no obvious intermetallic compounds (IMCs) formation at the interface. The Cu foil is beneficial to refine the average grain size of the Mg layer and weaken the texture orientation intensity of the Mg and Al layers in the Mg/Al-Cu sheet. The Mg/Al-Cu sheet exhibits similar yield strength and ultimate tensile strength to the Mg/Al sheet, but with a significantly higher elongation of 17.3 %. Furthermore, the interfacial shear strength of Mg/Al-Cu sheet is significantly lower than that of the Mg/Al sheet, primarily due to the extensive formation of CuO on the surface of the Cu foil during the rolling process.

Effect of high pressure-low plasticity burnishing on the mechanical and microstructural behaviour of copper foil interlayered FSW aluminium alloys

Abstract This study delves into the impact of high pressure-low plasticity burnishing (HP-LPB) on the mechanical and microstructural behaviour of friction stir welding (FSW) joints, specifically involving AA5052 and AA6082 aluminium alloys. Notably, copper foil (CF) is introduced as a novel element in the HP-LPB process to enhance the weld strength. The experiments were conducted with the tool rotational speeds (TRS) of 1000, 1100, and 1200 RPM, each paired with the welding speeds (WS) of 20, 25, and 30 mm min−1, and tool tilt angle (TTA) of 0°, 1°, and 2°. Mechanical behaviour is assessed through tensile testing along with microhardness measurements, revealing the advantages of HP-LPB with CF in enhancing joint strength and toughness. The microstructural analysis reveals the dissolution of precipitates, highlighting the influential role of copper foil in the improvement of joint efficiency. From the weld without a CF interlayer, a maximum tensile strength of 188 MPa was achieved at a TRS of 1200 RPM, WS of 25 mm min−1 and TTA of 2°. The post-processed FSW sample interlayered with copper foil, exhibited an improvement in joint efficiency by 87% at the optimum process parameter. This research demonstrates that the use of copper foil interlayers combined with HP-LPB treatment can substantially enhance the mechanical properties and structural integrity of FSW aluminum alloys, offering a valuable solution for advanced industrial applications.

Influence of Al foil interlayer on performance of vacuum diffusion bonding joint of 6061 aluminium alloy

Influence of Al foil interlayer on performance of vacuum diffusion bonding joint of 6061 aluminium alloy

Advancements in joining Al-Zn-TiC-Mg composites using friction stir welding process: Influence of traverse speed

In this article, dissimilar magnesium and aluminum alloys were welded with a Zn interlayer and TiC nanoparticles by friction stir welding. Optimal joining conditions were achieved by a combination of three traverse speeds (30, 45, and 60 mm/min) and constant rotational speeds (1050 rpm). The best microstructure evolution and mechanical properties were achieved for specimens joined at rotational and traverse speeds of 1050 rpm and 45 mm/min, respectively. The grain size decreases as the traverse speed increases from 30 to 45 mm/min due to a reduction in heat input, an improvement in reinforcing distribution, and high intermixing of materials, then increases from 45 to 60 mm/min due to inadequate heat input for recrystallization process. It was shown that the TiC particles play a prominent role in the microstructure modification and enhance mechanical properties of weld samples while the Zn foil interlayer plays a vital in avoiding the formation of Al-Mg IMC phases. The obtained result under optimal welding parameters indicates that MgZn2, Mg-Al-Zn compounds, Mg and Al solid solution, were the main detected common phases in the stir zone instead of the brittle and hard Al-Mg IMCs formation. The average hardness values of 232 Hv were achieved, while the strength of the weld specimen experiences the 189 MPa value. In addition, a combination of brittle and ductile modes was observed based on the fracture surface of the weld sample after the tensile test.

Interfacial microstructure and mechanical properties of B4C/TC4 brazed joints based on Ag-Cu-Ti + W-AlN/Mo foil/Nb foil interlayer

Interfacial microstructure and mechanical properties of B₄C/TC4 brazed joints based on Ag-Cu-Ti + W-AlN/Mo foil/Nb foil interlayer

Investigating the influence of Ni interlayers on Fe/Al laser welded joints: A first-principles study

201 Stainless steel and 5052 aluminium alloy were laser lap welded, both with and without a Ni foil interlayer. The Ni addition enhanced the metallurgical reaction between molten stainless steel/aluminium, resulting in the formation of the Al0.9Ni1.1 intermetallic compound. First-principles calculations estimated the equilibrium lattice and properties of IMCs (intermetallic compounds). A structural model of the interface revealed that the bonding strengths of Al/IMC and Fe/IMC interfaces surpassed those of IMC/IMC interfaces, making cracks prone to initiate and expand at the latter. Joints without Ni reached a max tensile shear strength of 74.5 N/mm, while those with Ni increased significantly to 101.8 N/mm, marking a substantial 36.6% enhancement.

Interfacial microstructure and mechanical properties of diffusion bonded joints of additive manufactured 17-4 PH stainless steel and TC4 titanium alloy

A novel atomic diffusion additive manufactured 17-4 PH stainless steel and TC4 titanium alloy was successfully joined by vacuum diffusion bonding with Cu foil + Ni foil interlayers at the temperature range of 880°C–960 °C for 60 min with 2 MPa pressure. The interfacial microstructural evolution, interfacial diffusion of elements, and mechanical properties of joints were analyzed. The results indicated that the interfacial transition zone was composed of diffusion affect zone (DAZ) and interface reaction zone (IRZ). With Cu foil + Ni foil composite interlayers, reaction layers such as DAZ 1/IRZ 1/IRZ 2/DAZ 2 were formed in the transition zone, and the interface consisted of CuTi + CuTi2 eutectic phase, CuTi2, Ti (Cu, Ni) and α-Ti. Striped Ti (Cu, Ni) phases were surrounded by serrated CuTi2 phases, which contained Cu-poor, Ni poor areas, and the segregation of Ti atoms. The maximum microhardness of 693 HV0.1 and the maximum shear strength of 163 MPa were obtained at the bonding temperature of 920 °C and 960 °C, respectively.

The microstructure and mechanical properties of aluminum/steel welded joint with Ni foil interlayers by FSLW

Friction stir lap welding experiments between 6061 aluminum alloy plate and DP590 dual-phase steel plate were carried out. The effects of welding parameters and addition of Ni foil interlayers with different thickness on the microstructures and mechanical properties of the lap joints were investigated. The shear strength of the joint reached the maximum value of 6597 N and showed a mixed ductile-brittle fracture mode when the welding speed, the rotating speed and the thickness of the Ni foil intermediate layer were set to 100 mm/min, 900 rpm and 0.3 mm, respectively. A certain amount of beneficial plastic AlNi and FeNi3 intermetallic compounds are formed through the reaction of Al, Fe and Ni at the aluminum alloy/steel interface.

The microstructure and mechanical properties of aluminum/steel welded joint by FSLW

Friction stir lap welding experiments between 6061 aluminum alloy and DP590 dual-phase steel plates were carried out. The effects of welding parameters and the addition of Cu foil interlayers with 0–0.3 mm thickness on the microstructures and mechanical properties of the lap joints were investigated. The shear strength of the joint reached the maximum value of 5337 N and showed a mixed ductile-brittle fracture mode when the welding speed, the rotating speed, and the thickness of the Cu foil intermediate layer were set to 80 mm/min, 900 rpm, and 0.1 mm, respectively. The plastic Al2Cu and AlCu intermetallic compounds formed through Al and Cu reaction at the aluminium alloy/steel interface play a beneficial role in the Cu-added joint strength.

Influence of copper foil interlayer on microstructure and bonding properties of titanium-steel explosive welded composite plate

Influence of copper foil interlayer on microstructure and bonding properties of titanium-steel explosive welded composite plate

Phase transition induced low temperature diffusion bonding of Zr-4 alloy using a pure Ti interlayer

In this paper, a low-temperature sealing of Zr-4 alloy induced by α→β phase transitions by using a pure Ti interlayer was reported. Both Ti and Zr compositions show smooth transition at the Ti/Zr interface when no phase transition happened. While a Ti, Zr elemental distribution plateau, corresponding to a light gray diffusion zone, was found at the Ti/Zr interface after a β-(Ti, Zr) phase transition happened. Results show that, to achieve the same shear strength of 294 MPa, the bonding temperature was reduced by 100 ℃ after using the pure Ti foil interlayer. Molecular dynamics (MD) simulation data show that the diffusion coefficients of Zr in β-(Ti, Zr) and α-(Ti, Zr) are 0.194 × 10−11 m2/s and 0.015 × 10−11 m2/s respectively, which further proves the β-(Ti, Zr) phase transition zone can indeed facilitate the diffusion of Zr-4/Zr-4 couples and lower the diffusion bonding temperature.

Two kinds of α/β phase transformations and enhanced strengths of the bonded interface in laminated Ti alloys

Metastable β Ti alloys are becoming increasingly competitive in the aircraft industry, while the study on diffusion bonding of this type of Ti alloy has been rarely reported up to now. Diffusion bonding of TC4/TB5 alloys with and without pure Ti foil interlayer was carried out to fabricate laminates and analyze the microstructural evolution and mechanical properties. This study reports the first-hand finding on β grains characterized by dendritic morphology at the TC4/Ti/TB5 interface, which results from retained phase due to the asynchronous precipitation and growth of α grains instead of β grains growth. In addition, there are two kinds of α precipitates from β matrix complying with the Burgers orientation relationship at the bonded interface, which is related to the two kinds of α→β phase transformations during heating. The bonded interfaces with fine α and β laths give rise to positive function to the hardness and tensile strengths of the laminated TC4/TB5 alloys.

Numerical Modelling of Thermo-Mechanical Effects Developed in Resistance Spot Welding of E304 Steel with Copper Interlayer

Resistance spot welding is a technique applied to join two or more similar or dissimilar metals, by applying pressure and electric current to the spot-weld area. Based on the electrical resistance property of metals, a great amount of heat is generated and used to carry out materials joints, by creating a molten metal nucleus between the components to be welded. The influence of an interlayer material, positioned between the parent materials, on the strength of similar or dissimilar welded joints was studied by researchers worldwide. In most cases, by optimising the process parameters, an increase in the welded joint strength was achieved. In this paper, the resistance spot welding of 1mm thick E304 stainless steel sheets, both with and without a copper foil interlayer, was investigated, by applying, in all cases, the same process parameters. The tensile test of the joints showed a decrease in the strength of joints performed with interlayer metal. A method to control the deterioration level of the joint’ mechanical properties is the Finite Element Analysis which allows to optimise the process parameters so that the negative effects of the process on the joint quality to be limited. It was found that an increase in amperage is needed to compensate for the addition of the interlayer metal and to obtain an adequate melting in the spot-weld area. This modification causes an increase of the molten core diameter that will lead to improvement of the welded joint strength, while no significant influence on the internal stress level was noticed in the processing and numerical analysis of the output data.

Moisture Resistant and Stable Wireless Wind Speed Sensing System Based on Triboelectric Nanogenerator with Charge‐Excitation Strategy

AbstractWind energy harvesting from the ambient environment by triboelectric nanogenerator (TENG) is highly important for powering wireless sensing systems. However, the output of TENG is greatly affected by ambient humidity, which seriously limits the measurement accuracy and stability of sensors. Herein, a flutter‐driven TENG composed of an Al foil interlayer sealed by FEP membranes (FEP/Al/FEP) is proposed to isolate Al foil from the external environment. A self‐charge excitation circuit is used to inject charges into the Al foil interlayer to achieve high charge density on it, greatly reducing the dependence on triboelectrification. In addition, an elastic steel sheet connected to a fluttering membrane at the fixed end is designed to get high stability of vibration. Consequently, the interference of humidity and other external environmental factors of this new type of elastic‐assisted TENG (EA‐TENG) with self‐charge excitation is greatly reduced and the output performance is greatly enhanced compared with traditional flutter‐driven TENGs. To demonstrate a practical application, a wind speed monitoring and alarming system are designed, which realizes real‐time wind speed detection and wind speed threshold alarm. The moisture‐resistant and stable wireless wind speed sensing system in this study has great applications in building large‐scale sensor networks.

Coupling effect of bonding temperature and reduced interlayer thickness on the interface characteristics and quality of the diffusion-bonded joints of Zr alloys

Zr705 alloys with 10-μm-thick Cu interlayers, bonded via vacuum diffusion bonding at 880–940 °C for 60 min, exhibited superior performance compared to previous studies on Zr705 alloys with 30-μm-thick Cu foil interlayers at the same temperature. The ultimate tensile strength (UTS) and elongation (EL) of the bonded joints increased with bonding temperature. The optimal UTS and EL (580 MPa and 32%, respectively) were obtained at 940 °C and are better than the optimal tensile properties obtained previously (30-μm-thick at 940 °C). The fracture form of the bonded joints was changed from brittle fracture at 880 or 900 °C to ductile fracture at 920 or 940 °C. A Zr–Cu intermetallic compound layer was formed on the bonding interface at 880 and 900 °C, which included Zr2Cu, ZrCu, Zr3Cu8, and ZrCu5 phases; the residual β phase was rich in Nb, and numerous Zr2Cu particles were precipitated along with this phase on the base material near the interface according to transmission electron microscopy analysis. At 940 °C, a broad Zr–Cu solid solution zone formed at the interface, in which no intermetallic compound was observed. The coarse grains with grain boundary migration were observed at the interface, and the entire base material exhibited a Widmanstätten microstructure at this temperature. The tensile tests and microstructure observations show that reducing the interlayer thickness lower the bonding temperature in some extent and improves the mechanical properties of bonded joints.

Effect of Annealing Temperature on the Interfacial Microstructure and Bonding Strength of Cu/Al Clad Sheets with a Stainless Steel Interlayer.

To explore the influence of annealing temperatures on the interfacial structure and peeling strength of Cu/Al clad sheets with a 304 stainless steel foil interlayer, an intermediate annealing treatment was performed at temperatures of 450 °C, 550 °C, and 600 °C, separately. The experimental results indicate that the interfacial atomic diffusion is significantly enhanced by increasing the intermediate annealing temperature. The average peeling strength of the clad sheets annealed at 550 °C can reach 34.3 N/mm and the crack propagation is along the steel/Cu interface, Cu-Al intermetallic compounds layer, and Al matrix. However, after high-temperature annealing treatment (600 °C), the liquid phase is formed at the bonding interface and the clear Cu/steel/Al interface is replaced by the chaotic composite interfaces. The clad sheet broke completely in the unduly thick intermetallic compounds layer, resulting in a sharp decrease in the interfacial bonding strength.

Effect of Ni interlayer on microstructure and mechanical properties of Al/Mg dissimilar friction stir welding joints

In this work, friction stir welding (FSW) was carried out for the flat butt welding tests of Al/Mg dissimilar alloys by introducing Ni foil interlayer with different thickness. The effect of the thickness of interlayer on microstructure and mechanical properties of the FSW joints was explored. The results revealed that with the increase of the thickness of Ni, the effective bearing area of the weld nugget zone (WNZ) increased. It achieved the maximum value when the thickness of interlayer was 0.3 mm, and a dense ‘onion rings’ structure which was composed of the cross distributions trips of magnesium alloy, aluminium alloy and the intermetallic compounds (IMCs), as well as the Ni particles of varying sizes were formed. Compared to the joint without introducing Ni, the introduction of Ni made the joints generate Mg2Ni and the Al3Mg2 was partially replaced and led to the ultimate tensile strength (UTS) increased by 13.5%.

Enhancing the mechanical performances of friction stir lap welded Al-Zn-Mg-Cu alloy joint by promoting diffusion of alloying element Zn toward the pre-positioned Cu interlayer

The present study aims to enhance the mechanical performances of friction stir lap welded Al-Zn-Mg-Cu aluminum alloy joint by using a Cu foil interlayer at the faying surface. The results show that the diffusion of alloying element Zn of the Al-Zn-Mg-Cu aluminum alloy is promoted towards the Cu interlayer at faying surface during friction stir lap welding. Furthermore, Cu(Zn) solid solution rather than Cu-Zn intermetallic compounds is mainly produced after the diffusion of Zn atoms into Cu interlayer. Worthy of note is that the presence of Cu interlayer has an evidently positive effect on joint strength. Such a design to improve the bonding strength through adding metal foil interlayer provides a new technological approach for high-quality friction stir lap welding or even friction stir additive manufacturing.

Structural performance of a novel liquid-laminated embedded connection for glass

Connections between load-bearing glass components play a major role in terms of the structural integrity and aesthetics of glass applications. Recently, a new type of adhesive connection, known as embedded laminated glass connections, has been developed where a metallic insert is embedded within a laminated glass unit by means of transparent polymeric foil interlayers and assembled through an autoclave lamination process. In this study, a novel variant of this connection, consisting of a thin steel insert encapsulated by a transparent cold-poured resin, is proposed and examined. In particular, the axial tensile mechanical response of this connection is assessed via numerical (FE) analyses and destructive pull-out tests performed on physical prototypes at different displacement rates in order to assess the effect of the strain rate-dependent behaviour of the resin interlayer. It was found that the pull-out stiffness, the maximum load-bearing capacity and the failure mode of the connection are significantly affected by the imposed displacement rate. The numerical (FE) analysis of the pull-out tests, performed in Abaqus, showed that the complex state of stress in the vicinity of the connection is the result of two load-transfer mechanisms and that the relative contribution of these mechanisms depends on the insert geometry and the relative stiffnesses of the constituent materials. Overall, it is concluded that the prototypes are promising in terms of manufacturability, aesthetics and structural performance and thus the novel variant connection considered in this study offers a promising alternative to existing load-bearing connections for laminated glass structures, but further investigations are required to ascertain its suitability for real-world applications.

Effects of a stainless steel interlayer on the interfacial microstructure and bonding strength of Cu/Al clad sheets prepared via the powder-in-tube method

Cu/Al clad sheets with a 304 stainless steel foil (SUS304) interlayer are successfully fabricated by the powder-in-tube method. The influence of SUS304 thickness on the interfacial structure, elemental diffusion, and peeling strength of the clad sheets is studied. Experimental results indicate that the initial Cu/Al interface is partially transformed into a Cu/SUS304/Al interface after introducing the SUS304 interlayer. The proportion of SUS304 fragments at the bonding interface is shown to increase with thickness of the SUS304 interlayer. Differences in deformability between SUS304 interlayer and Cu/Al matrix promote the occurrence of shear deformation at the bonding interface via the cladding process, enhancing atomic diffusion at the Cu/SUS304/Al interface. Peeling tests reveal that interfacial cracks in clad sheets with an SUS304 interlayer propagate along the Cu/SUS304 and Cu/Al interfaces. Under combined effects of interfacial transfer and large shear strain, the interfacial strength of clad sheets is apparently improved. Clad sheets with the thickest SUS304 interlayer (30 μm) exhibit highest peeling strength (30.9 N/mm), demonstrating 73.6% improvement over clad sheets without an interlayer. These findings provide novel insights into the innovative design of clad sheets possessing extraordinary interfacial strength.