Al Interlayer Research Articles

Effect of various interlayers in NiTi to TC4 dissimilar joints by magnetic pulse welding

Magnetic pulse welding (MPW) has gained wide attention recently. In this paper, the connection of NiTi/TC4 dissimilar materials was achieved by adding pure Al, Cu, and Ni interlayers using MPW technology, and microstructure characterization and mechanical property tests were conducted to evaluate the joints. The results show that the atomic diffusion in the welding process plays a key role in the interface formation process. The interfacial morphology of joints consists of wavy and flat interfaces, and the mechanical interlocking of the wavy interface gives the joints excellent mechanical properties. The joints with the pure Al interlayer have the best mechanical properties, and the tensile shear force is 2.168 kN; the fracture forms of joints with different interlayers are all ductile fractures. In addition, the calculation results of the edge-to-edge crystal matching model show that the side with the high interface mismatch rate is where the joint failure problem occurs frequently.

Insights into Structural Changes During Scratch Deformation of Ductile Coating Systems: Plastic Flow, Microstructural Transformations, and Crack Development

This study investigates the structural changes occurring during the scratch deformation of ductile materials, focusing on a composite aluminum (Al) coating on a steel substrate fabricated using a solid-state aluminizing technique. By analyzing the results of the scratch test with transmission electron microscopy (TEM) and focused ion beam (FIB) techniques, the research provides a detailed examination of plastic flow, microstructural transformations, and crack development. Results demonstrate that strong adhesion at the interface and similar mechanical properties between steel and Al layers facilitate co-deformation, crucial for maintaining the integrity of the composite structure. The study features the formation of a rolling-like laminated structure and significant grain refinement in both the steel and Al components, driven by plastic deformation. Observed atomic-scale intermixing and the formation of an amorphous interlayer highlight extensive material interactions during deformation. The visualization of crack progression using FIB allows for an in-depth understanding of the fracture process. Subsurface cracks initiate within the thin Al interlayer and propagate toward the surface, evolving through the coalescence of nanopores into microvoids and larger cavities, ultimately leading to crack propagation. Secondary internal cracks may arise due to stress fields generated by the primary crack, contributing to a complex network of internal cracks.

Achieving high sheet resistance and near-zero temperature coefficient of resistance in NiCr film resistors by Al interlayers

Thin film resistive materials with low temperature coefficients of resistance (TCR) and high sheet resistances are essential for various electronic applications, such as embedded resistors. In this study, Al inserting layers and NiCr resistive layers were sequentially deposited on alumina ceramic substrates via DC magnetron sputtering to fabricate Al/NiCr bilayer resistive materials. The electrical properties of the bilayer films were adjusted by varying the thicknesses of the Al inserting layers and annealing conditions. When the thickness of the Al inserting layer varied from 5 to 7.5 nm, and post-annealing treatments ranging from 200℃ to 400℃ were applied, evident Al-NiCr interdiffusion occurred, forming intermediate layers at the interfaces and oxides on the film surfaces. A mixture of partial crystalline phases and amorphous phases was also observed in the cross-sectional high-resolution transmission electron microscope (HRTEM) images. The formation of intermediate layers and surface oxides and the balance between partial crystalline phases and amorphous phases collectively enhanced the electrical performance of bilayer film resistors, achieving thin film resistors with a remarkably low TCR of −6.61 ppm/K and a sheet resistance of up to 265.95 Ω/sq. By rational design of Al layers, NiCr layers and thermal treatment, thin film resistors with near zero TCRs and extremely wide sheet resistance range of 93.34–1439.01 Ω/sq can be obtained.

Interlayer design for strong adhesion in the double-layer flexible copper clad laminate via HiPIMS deposition

By designing different interlayers (Al, Si/SixNy and Cr interlayer) and oxygen plasma pretreatment of the substrate, strong adhesion was realized for the double-layer flexible copper clad laminate on polyimide (PI) substrate via high power impulse magnetron sputtering (HiPIMS) technology. The microstructures and properties of Cu films on PI substrate were characterized by an X-ray powder diffractometer (XRD), X-ray photoelectron spectroscope (XPS), atom force microscopy (AFM), scanning electron microscope (SEM), nano-scratch test, scotch tape test and four-probe detector. With the introduction of interlayer and oxygen plasma pretreatment, the critical load of Cu film (300 nm thick) peaked at 43.5 mN and the sheet resistance ranged from 124 to 227 mΩ/sq. The oxygen plasma pretreatment resulted in the drastic oxidation to generate functional groups on the PI substrate surface, which contributed to the improvement of adhesion strength by chemical interaction in terms of the film with Si/SixNy or Cr interlayer. Besides, for the Cu film with Si/SixNy interlayer, the resistance against copper diffusion by the SixNy layer can also promote the enhancement of adhesion strength.

Characterisation of Fe, Cr and Al behaviour at the interface during diffusion bonding of ODS/Al couple

Abstract Diffusion bonding of oxide dispersion strengthened ferritic steel PM2000 1.2 mm thickness plates sandwiched by aluminium foils was carried out. This joining was achieved under laboratory air at temperatures less than 660 °C by simultaneously applying heat and sufficient compression of about 210 MPa to give a high level of plastic deformation to the Al interlayer. The resulting microstructures and phases at the interface were characterised using scanning and transmission electron microscopy and microanalyses. The formation of intermetallic phase type FeAl was detected close to the interface and the FeAl3 further away on the aluminium side. The bonded samples were heat treated under a special regime and bend tested. In the treated samples Fe–Cr compounds were noticed. The corrosion study of the heat-treated samples in laboratory air at 950 °C demonstrated a high temperature corrosion resistance.

Microstructure and mechanical properties of transient liquid phase bonding Ti3SiC2 ceramic to SUS430 steel using an Al interlayer

Microstructure and mechanical properties of transient liquid phase bonding Ti3SiC2 ceramic to SUS430 steel using an Al interlayer

Improving interfacial strength at room and elevated temperatures in ultrasonic welding of pure titanium: Interlayer-induced phase transformation and concentrated plastic deformation

Ultrasonic welding (USW) of Titanium (Ti) sheets presents several challenges, notably crack formation due to sliding friction. To overcome this problem, the present study applied USW to pure α-Ti sheets both with and without different interlayer metals (Al, Ni, and Fe). Al interlayer improved the strength at room temperature significantly to cause base metal fracture (1700 N) by inducing concentrated plastic deformation, facilitating bonding with Ti while minimizing damage. However, its strength decreased significantly at 150–300 °C, suggesting the limitation of using Al interlayer at elevated temperatures. Conversely, the Ni and Fe interlayers led to a two-phase strength development. This enhancement was due to β-phase transformation, which reduces the interfacial defects and generates a more pronounced β-stabilization effect. The Ni interlayer, which has a higher β-transus point (765 °C) and lower molybdenum equivalency, required a higher welding energy (1800 J) and longer diffusion time into Ti, resulting in a gradual increase in strength due to a slower β-Ti transformation. On the other hand, the Fe interlayer with a lower β-transus point relative to Ti (595 °C) achieved peak strength at a lower welding energy of 1200 J. Both Fe and Ni interlayers displayed only a slight decrease in strength (1500–1600 N) at 300 °C with base metal fracture, revealing better joint performance at higher temperatures. These insights suggest a strategical interlayer selection based on the operation temperature, where Al interlayers were advantageous for low-energy welding at room temperature application, Fe and Ni interlayers offer sufficient strength at elevated temperatures by facilitating the β-Ti formation.

Al interlayer enhanced interfacial strength of ultrasonically welded copper-titanium dissimilar joints

This study investigated the ultrasonic welding of Cu-Ti joints, revealing that the interfacial strength originated from mechanical interlocking. However, strength was diminished owing to interface-adjacent crack initiation due to excessive plastic strain. Introducing an Al interlayer prevented base metal damage with more frictional heat, and enhanced interfacial strength by 26%.

In-Situ Wettability Analysis of Al Coating Influence on Hot-Dip Galvanizing Properties of Advanced High-Strength Steels

We investigated the influence of steel surface properties on the wettability of zinc (Zn). Our main objective is to address the selective oxidation of solute alloying elements and enhance the wetting behavior of Zn on advanced high strength steel (AHSS) by employing an aluminum (Al) interlayer through the physical vapor deposition technique. The deposition of an Al interlayer resulted in a decrease in contact angle and an increase in spread width as the molten Zn interacted with the Al interlay on the steel substrate. Importantly, the incorporation of an Al interlayer demonstrated a significant improvement in wettability by substantially increasing the work of adhesion compared to the uncoated AHSS substrate.

Charge generation layer with Yb assistant interlayer for tandem organic light-emitting diodes

Tandem organic light-emitting diode (OLED) devices require an efficient charge generation layer (CGL) between two stacked OLED units. In this study, a CGL with an Yb assistant interlayer was fabricated and investigated. The optical transmittance and charge generation performances of the CGLs were analyzed with respect to the Yb thickness. The best result was obtained at a Yb thickness of 3 nm, at which both the electrical and optical properties exhibited optimal performances. The optical transmittance was greater than 90 %; this was superior to the performances using Ag and Al interlayers. The insertion of a 3-nm Yb layer reduced the threshold voltage from 18 to 6 V. Capacitance measurements revealed that the insertion of the Yb layer enhanced charge generation in the CGLs, reducing the threshold voltage and enhancing charge transport. The tandem OLED device fabricated using Bphen:Liq/Yb/MoO3/TAPC as a CGL exhibited a 1.92 × enhancement in the current efficiency, which is nearly twice the ideal value, compared to a single-unit device. Thus, Yb is a promising candidate for use as an assistant interlayer in CGLs for high-performance tandem OLED devices.

Influence of Interlayers on Adhesion Strength of TiN Film on Mg Alloy

The wide application of Mg alloys has been restricted because of their poor corrosion and wear resistance. Titanium nitride ceramic films prepared via magnetron sputtering can improve the corrosion and wear resistance of Mg alloys. However, residual stress produced at the interface between the film and the Mg alloy substrate causes the TiN film to spall off and reduces its service life. One potential approach to mitigating residual stress involves enhancing the adhesive strength between the film and the substrate, thereby potentially extending the service life of the film. To increase the adhesion strength between the TiN film and the Mg alloy substrate, a Ti or Al interlayer was deposited on the Mg alloy by magnetron sputtering. Subsequently, the adhesion strengths of TiN/Ti and TiN/Al were determined under a single high shear force by scratch tests and were determined under multiple low shear forces by friction and wear tests. The results of scratch tests show that TiN with the Ti interlayer on the Mg alloy substrate has superior adhesion strength under a single high shear force. And the results of friction and wear tests show that both the TiN/Al and TiN/Ti films provided protection to the Mg alloy substrate against friction and wear, and TiN with the Ti interlayer on the Mg alloy substrate has superior adhesion strength under multiple low shear forces. This work can provide guidance for the selection of interlayers between Mg alloy substrates and hard ceramic films.

Stabilization the interface of NASICON-type solid electrolyte and Li metal by Al interlayer

Solid-state lithium-ion batteries with intrinsic safety and stable performance have emerged as alternative to liquid electrolyte-based systems. NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) with high ionic conductivity is a promising solid electrolyte to be commercialized. However, the incompatibility of LATP with Li metal hinders its application in high energy density solid-state systems. Herein, we apply a 60 nm thick protective Al layer by PVD to construct a stable interface with metallic Li. The Al-coated LATP enables better electrochemical performance in a symmetric cell than bare LATP. Al-coated LATP is stable at 0.1 mA cm−2 for 100 cycles without building up polarization. The overpotential and the interfacial resistance are significantly reduced as direct contact between Li and LATP is avoided. The Al coating inhibits the reduction of Ti4+ to Ti3+ of LATP pellet during cycling. This work resolves the prominent limitations of LATP and strengthens the interfacial connectivity in solid-state system, pointing an environmental friendly and low cost modification strategy to improve the solid-state lithium-ion batteries.

A novel method to examine the effect of Al addition on the microstructure of CoCrFeNiMn high-entropy alloy

A novel approach was employed to investigate the effect of Al addition on the microstructure of a CoCrFeNiMn high-entropy alloy (HEA). A two-layer structure consisting of CoCrFeNiMn with a low-melting Al interlayer was subjected to heat treatment at temperatures of 600, 700, and 800 °C for up to 48 h. The purpose was to directly examine phase formation and phase stability in Al-added alloys. As a result, the heating process at 700 and 800 °C led to the formation of a few microns multilayers, primarily composed of B2-type NiAl and σ phases at the interface and the earlier temperature showed relatively good bonding. These experimental findings were complemented by CALPHAD predictions and considered physical aspects for phase prediction. This concept holds significant benefits for alloy design as it offers a cost-effective and time-saving method to investigate phase formation and stability at different temperatures in complex multi-component alloys.

Mechanical properties and fracture mechanism of Fe/Cu composite sheets with Al interlayer after annealing treatment

Mechanical properties and fracture mechanism of Fe/Cu composite sheets with Al interlayer after annealing treatment

Comparison of structure and solar-selective absorbance properties of Al2O3 thin films with Al and Ni reflector interlayers

This work aims at evaluating the selective solar absorbance (SSA) of Al2O3 thin films deposited by physical vapor deposition (PVD) with two different metallic reflector interlayers. Al2O3 thin films are deposited on the same substrate stainless steel (SS) 304L, with two different interlayers between the thin film and the substrate, namely, nickel (Ni) and aluminum (Al) are used as the reflector interlayer SS304L/Al/Al2O3 and SS304L/Ni/Al2O3. A scanning electron microscope (SEM) was utilized to characterize the chemical composition by energy dispersive X-ray analysis (EDX) and surface morphology of the deposited thin films. The phases of the thin films were analyzed and identified by X-ray diffraction (XRD) to detect the present phases. The surface topography and the thickness of the deposited thin films were investigated using an atomic force microscope (AFM). The optical properties of the substrate and the deposited thin films (absorbance & emittance) in two conditions were identified by Fourier transform infrared spectroscopy (FTIR) and spectrophotometer. The obtained results demonstrate that both SS304L/Al/Al2O3 and SS304L/Ni/Al2O3 show good performance, such as high solar absorbance and low thermal emittance. However, the Al/Al2O3 thin film provides high selectivity (absorbance/emittance (α/ε)) of 0.916/0.05, compared to 0.913/0.15 for the Ni/Al2O3 coating. The effect of different properties and microstructure on the efficiency of deposited thin films showed that the SS304L/Al/Al2O3 has higher absorbance (92%) in visible and ultraviolet (UV) regions; and lower emittance (5%) than the SS304L/Ni/Al2O3. This work shows that the intermediate IR layer has a more pronounced effect on the emittance properties rather than the absorbance properties of the Al/Al2O3 layer.

An Al2O3/Ni–Al tritium permeation barrier coating for the potential application in thorium-based molten salt reactor

The Al2O3/Ni–Al composite coating was formed on the outside surface of GH3535 superalloy by pack aluminizing and subsequent in-situ oxidation, and deuterium permeation tests were carried out to assess the tritium permeation barrier performance of the coating. Scanning Electron Microscopy (SEM) showed that the surface of Al2O3 films was dense, homogeneous, and crack-free. Transmission Electron Microscopy (TEM) photos manifested that the interface between γ-Al2O3 film and Ni–Al interlayer was distinct without micropores, and the thickness of Al2O3 film with the structure of γ-phase is approximately 80 nm. The Arrhenius equation for permeability of GH3535 was obtained as Φ=1.37·10−7·exp(−57.92(KJ mol−1)/RT) by deuterium permeation tests. The deuterium permeation reduction factor of Al2O3/Ni–Al coating kept 2–3 orders of magnitudes at a temperature from 400°C to 700°C. The D-permeation resistant performance of this coating still has the potential to be further improved.

Microstructure and properties of magnesium/steel dissimilar metals by interlayer assisted laser welding

AbstractThe experiments of laser welding were carried out for AZ31B magnesium alloy and DP590 dual-phase steel in an overlap magnesium-on-steel configuration with interlayer addition. The interlayer elements were selected based on the calculation of thermodynamic properties and intrinsic mechanical properties, and the changes of microstructure and properties of magnesium/steel joint were analyzed. The results showed that with the addition of Sn and Al interlayers, the maximum load of the joint was 730 and 590 N, respectively, which was 2.04 times and 1.46 times higher than that without interlayer. With the addition of Al interlayer, the brittle Mg17Al12 compound was formed at the magnesium/steel interface, which limited the improvement of the mechanical performance of magnesium/steel joint. In the case of adding Sn interlayers, Mg2Sn with relatively low brittleness and Fe3Sn with a certain ductility were formed at the magnesium/steel interface, which was a vital reason that the properties of joint with Sn interlayer were higher than those with Al interlayer.

Hydrofluoric Acid-Free Synthesis of Ti3C2Tx MXene Nanostructures for Energy Applications

The preparation of titanium carbide (Ti3C2Tx) thin sheets (T represents surface termination), an emerging class of two-dimensional materials, heavily relies on the etching of interlayered aluminum (Al) of MAX (M, A, and X represent transition metals, Al, and carbon, respectively) using concentrated hydrofluoric acid (HF). However, HF is an acutely toxic chemical. Herein, for the first time, we propose a dissolution-driven delamination method to prepare Ti3C2Tx MXene thin sheets using an HF-free solvent to remove the interlayers of Al. Bis(trifluoromethanesulfonyl)imide (TFSI) is a delaminating agent that can directly and effectively dissolve the Al interlayers of MAX. The role of TFSI in this delamination process, i.e., the preferential formation of the surface of a Ti3C2Tx thin sheet, is a key parameter for superior supercapacitor application. The prepared Ti3C2Tx sheets were loaded on Ni foam (NF) via a hydrothermal reaction to form a Ti3C2Tx MXene/NF-4 h composite electrode. This Ti3C2Tx MXene/NF-4 h composite electrode exhibits the highest unprecedented capacitance of 3090 F/g at a current density of 10 A/g in a 1 M KOH electrolyte. It also exhibits excellent rate capabilities at different current densities (from 10 to 30 A/g) while maintaining 76.4% capacity retention after long life cycles. This study provides fundamental insights into the effect of the dissolution of interlayered Al of Ti3AlC2 on the preparation of Ti3C2Tx thin sheets as well as sheds light on the development of next-generation flexible and simple integrated supercapacitors with excellent gravimetric performance.

Aluminum-doped cadmium sulfide homojunction photoelectrode with optimal film quality and water-splitting performance

The impact of CdS:Al interlayer in MoS2/CdS photoanode on PEC performance is studied. The CdS:Al interlayer allows improved photocurrent and suppressed dark current. The film chemical features of MoS2/CdS:Al/CdS photoanode is optimized.

Benchmarking the performance of lithiated metal oxide interlayers at the LiCoO2|LLZO interface

Lithiated Nb, Al, or Ti metal oxide interlayers improve the LiCoO2/LLZO interface, whereby the Li–Nb–O interlayer exhibits the highest performance.