Ni-alloy Substrates Research Articles

Microstructure and wear performance of Al20Cr5Fe50Mn20Ti5 medium-entropy alloy coating deposited by laser cladding

Al20Cr5Fe50Mn20Ti5 medium-entropy alloy (MEA) coatings with different preparation process parameters were successfully fabricated by laser cladding (LC) on Inconel 718 Ni-alloy substrate. Comparison of two coatings with optimal macroscopic morphology, and the phase, micro-structure and hardness were characterized using SEM, XRD, and EBSD. The thermal stability performance of the two MEA coatings was systematically analyzed by combining phase diagram calculation and experimental tests. Compared to the substrate, the frictional wear properties of the MEA coatings at 400 °C, 600 °C and 800 °C were systematically analyzed. The results show that Al20Cr5Fe50Mn20Ti5 MEA coatings with two different parameters formed a good metallurgical bond with the substrate, contained BCC, FCC and Ti-rich phases, and both had a good thermal stability at the range of room temperature to 1000 °C. The refinement of grain size and the enhancement of dislocation density improved Al20Cr5Fe50Mn20Ti5 MEA coatings wear properties. The generation of Ti-rich phase enhanced the wear performance, while excessive fusion of Ti elements into the coating caused oxidation at high temperatures to generate brittle phases, which reduced wear performance and led to coating failure. Through this study, new designed MEA system with low cost advantage can be applied in high temperature environment.

Analytical modeling of Ni–Co based multilayer bimorph actuators involving dual insulation layers

This paper proposes a new design of multilayered bimorph electrothermal actuators based on a Ni and Co alloy (Ni–Co) substrate and analytical models to estimate their performance. The proposed bimorph actuator consists of a flexible Ni–Co substrate having high coefficient of thermal expansion (CTE) along with two insulation (low-CTE materials) and Pt heater layers. A multilayered thermo-mechanical model to estimate the tip deflection was derived based on Timoshenko’s classical model for metal bilayers. An analytical model based on the Euler–Bernoulli beam theory was also derived to calculate the blocking force of the multilayered actuators. An appropriate layer composition of the low-CTE layers was derived based on the analytical models and lattice parameters of the adjacent layers: the performance of the bimorph actuator was significantly improved when the low-CTE layers are composed of a dual layer instead of a single layer of SiO2. The analytical solutions of the simplified 3D models were then compared with finite element analysis (FEA) and experimental results. In the comparison of the tip deflection, the analytical solution of the three-layer actuator omitting the Pt heater was similar to the FEA result and the experimental result compensating for the initial dead zone. In the comparison of the blocking force, the analytical solution was also similar to the FEA results, though there was a deviation from the experimental results. Abnormal behavior of the actuator was observed in the experimental result of the blocking force, and the cause was investigated in this study.

Long-term stability of SOFC glass sealant under oxidising and reducing atmospheres

The behaviour of the 59.6SiO2–11.0Al2O3–6.6ZrO2–3.4CaO–15.4Na2O–4Y2O3 (wt. %) non-crystallising glass sealant was studied while in contact with NiO–YSZ (yttria-stabilized zirconia) ceramics and an Fe–Ni alloy after exposure to reducing and oxidising atmospheres at 850 °C and while on a Pt substrate. The sealant was completely amorphous after exposure on a Pt substrate for 1000 h in an air atmosphere. After exposure on a NiO–YSZ substrate in both oxidising and reducing atmospheres, no interaction on the NiO(Ni)–YSZ|sealant interface was observed. For the Fe–Ni alloy substrate, the formation of an Fe2SiO4 layer was observed after exposure in an oxidising atmosphere. In the reducing atmosphere, the Fe–Ni alloy substrate intensified sealant crystallisation, leading to the formation of numerous crystalline phases, but no interaction on the Fe–Ni alloy|sealant interface was observed.

In Situ Precipitation-Induced Growth of Leaf-like CuO Nanostructures on Cu-Ni Alloys for Binder-Free Anodes in Li-Ion Batteries.

CuC2 O4 ⋅x H2 O was facilely prepared on a Cu-Ni alloy substrate by in situ precipitation-induced growth by using a mixture of sodium persulfate, hydrogen peroxide, and oxalic acid. Thermal annealing allowed the conversion of CuC2 O4 ⋅x H2 O to leaf-like CuO nanostructures with a thickness of a few tens of micrometers of sub-sized nanoparticles, which were applied for fabricating binder-free anodes for lithium-ion batteries. Ni was a nucleation site for CuC2 O4 ⋅x H2 O, which was uniformly formed on the entire substrate. The concentration of each component in the mixture solution caused significant morphological changes because of the different elution of copper ions. CuO nanostructures annealed at 550 °C showed large areal and gravimetric capacity with excellent capacity retention of 95.5 % after 200 cycles at a high current density because of their appropriate structural morphology, which not only allowed the formation of a stable solid electrolyte interphase layer but also enabled a reversible reaction during the charge/discharge process.

Synthesis and stacking sequence characterization of h-BN/graphene heterostructures on Cu–Ni alloy

Novel properties are found in the vertically stacked graphene and hexagonal boron nitride (h-BN) heterostructures, the performances of which could crucially depend on the stacking sequence. Nevertheless, for most heterostructures fabricated by chemical vapor deposition (CVD), the stacking sequence is uncertain. Here we introduce a facile CVD method to synthesize the h-BN/graphene stacked heterostructures on Cu–Ni alloy substrate via subsequent formation of graphene grains underneath an h-BN-graphene in-plane heterostructure layer. An efficient and non-destructive method is developed to verify the stacking sequence by low-energy electron reflectivity (LEER) measurement. This work will facilitate both fabrication and characterization of van der Waals heterostructures (vdWHs) for the future research and applications.

Effect of different deformation and annealing procedures on non-magnetic textured Cu60Ni40 alloy substrates

In this work, a series of specimens was prepared by the casting method. Sharp cube-textured substrates were processed by heavy cold rolling and recrystallization annealing (i.e., the rolling-assisted biaxially textured substrates (RABiTS) method). Both the rolling and the recrystallization texture in the alloy tapes were investigated by X-ray diffraction and electron back-scatter diffraction, respectively. The results showed that a strong copper-type deformation texture was obtained in the heavy cold-rolled substrate. In addition, the recrystallization annealing process was found to be very important for the texture transition in the Cu–Ni alloy substrates. The cube texture content in the Cu60Ni40 alloy substrates reached 99.7% (≤10°) after optimization of the cold-rolling procedure and the recrystallizing heat-treatment process, whereas the content of low-angle grain boundaries (from 2° to 10° misorientation) in the substrate reached 95.1%.

Structure and properties of Cr–Al–Si–B coatings produced by pulsed electrospark deposition on a nickel alloy

Abstract This study investigates the kinetics of pulsed electrospark deposition (PED) on a heat resistant Ni-alloy substrate with Cr–Al–Si–B electrodes of three compositions. The optimal deposition frequency and energy mode (Е = 0.048 J, I = 120 A, f = 3200 Hz, τ = 20 μs) were established. This mode is characterized by the minimum electrode erosion at a satisfactory coating deposition velocity. Studies were conducted on the structure, phase composition and coating properties. It was shown that the electrospark coating deposition using Cr–Al–Si–B electrodes significantly increased the hardness, heat resistance and wear resistance of the nickel alloy EP718-ID (similar Inconel 718). The application of the PED process and electrodes could be recommended to protect the surfaces of functional parts and units constructed of Ni alloys.

Evolution of Cube Texture in Cu-45at.%Ni Alloy Substrates for YBCO Coated Conductors

The cube texture evolution during annealing of the heavy cold-rolled Cu-45at.%Ni alloy tapes were investigated by XRD and electron back scattering diffraction techniques. The results indicated that the fraction of Copper-type rolling texture was slightly strengthened during recovery, and then strongly reduced during recrystallization. The cube texture was formed by consuming the rolling texture components during recrystallization process, and the S, Copper and Brass orientations were consumed together via cube grain growth. A strong cube-textured Cu-45at.%Ni alloy substrate with the cube texture fraction of 98.6 % (< 10°) was obtained after annealing at 1000 oC for 1 h.

Ordered NiO-TiO2 nanotube arrays as an efficient catalyst support for methanol oxidation

Ordered NiO–TiO2 nanotube arrays (NiO–TiO2NTs) were fabricated on titanium–nickel (Ti–Ni) alloy substrate by anodic oxidation of Ti–Ni alloy foil and subsequently investigated as a catalyst support for methanol oxidation. The field emission scanning electron microscopy (FESEM) results demonstrate that NiO–TiO2NTs have the feature of regular tubular structure, which is advantageous to support catalysts for methanol oxidation reactions. The electrochemical results show that Pt nanoparticles supported on NiO–TiO2NTs have similar functionalities as PtNi alloy nanoparticles supported on TiO2 nanotube arrays for methanol oxidation. The NiO–TiO2NTs catalyst support developed here can be easily synthesized and thus show promising application prospect in direct methanol fuel cells (DMFC).

Effect of surface shear on cube texture formation in heavy cold-rolled Cu–45 at%Ni alloy substrates

Two types of Cu–45at%Ni alloy thin tapes with and without surface shear were obtained by different heavy cold rolling processes. The deformation and recrystallization textures of the two tapes were thoroughly investigated by electron back scattering diffraction technique. The results showed that a shear texture mainly covered the surface of the heavy deformed tapes because of the fraction between the surface of rolling mills and the thin tapes when the rolling force strongly reduced at high strain, which significantly reduced the fraction of rolling texture on the surface of the Cu–45at%Ni alloy thin tapes, retarded the cube grain growth during recrystallization and affected the strong cube texture formation after high temperature annealing.

Characteristics of electroformed low thermal expansion Fe-42 wt. %Ni alloy substrates for thin film silicon solar cells

Differences in the thermal expansion of the semi-conductor layer and the substrate of thin film solar cells can lead to thermal deformation of the cell during thermal processing. To control this deformation, the substrate needs to have a thermal expansion behavior similar to that of the semi-conductive layer of the cell. In order to develop such a metal substrate for thin film silicon solar cells, a Fe-42 wt. %Ni alloy with low thermal expansion characteristics was fabricated by electroforming. The thermal expansion behaviors of as-deposited and heat-treated Fe-42 wt. %Ni alloys were measured using a Thermal Mechanical Analyzer. A rapid change in thermal expansion was observed between 350 and 400 °C in the as-deposited Fe-42 wt. %Ni alloy. However, when the alloys were heat treated at temperatures higher than 500 °C, their thermal expansion behaviors were stable and their thermal expansion coefficients were 4–5 × 10−6/ °C. Based on such data, Finite Element Analysis was applied to calculate the thermal deformation of the cell that occurs during cooling from a virtual coating process temperature to room temperature, using the Algor program. The analyses showed that the cell on the heat-treated Fe-42 wt. %Ni alloy substrate had less residual stress and a lower amount of deformation compared to that on a commercial stainless steel substrate.

In-situ spectroscopic ellipsometry of microcrystalline silicon deposited by plasma-enhanced chemical vapor deposition on flexible Fe–Ni alloy substrate for photovoltaic applications

Crystallinity and material quality of hydrogenated microcrystalline silicon (μc-Si:H) films change during their growth, leading to a complex material structure. In order to identify the composition of those inhomogeneous films, deposited on iron–nickel (Fe–Ni) alloy substrates, in-situ ellipsometric data were taken during the thin film growth at regular time intervals. The analysis of the in-situ data taken at the photon energy range between 2.8 and 4.5eV allowed us to identify the composition of the thin film surface as it grows. The time evolution of the crystalline and amorphous silicon fractions and the surface roughness shows clearly three important phases of the thin film growth: the initial growth of nanocone shaped crystals, the collision phase of neighboring crystals, and the semi-homogeneous material growth until the end of the deposition. The analysis of in-situ data taken during depositions on three different Fe–Ni alloy substrates with different crystal sizes and surface textures shows significant differences in the crystalline silicon fraction of deposited films. The proposed method provides the means to analyze the growth process on flexible Fe–Ni alloy substrates and to optimize the quality of deposited μc-Si:H films by finding the most suitable Fe–Ni substrates.

Cube Texture Formation of Cu-33at.%Ni Alloy Substrates and CeO<sub>2</sub> Buffer Layer for YBCO Coated Conductors

Cube texture formation of Cu-33 at.%Ni alloy substartes and CeO2buffer layer prepared by chemical solution deposition on the textured substrate were investigated by electron back scattered diffraction (EBSD) and XRD technics systematically. The results shown that a strong cube textured Cu-33at.%Ni alloy substrate with the cube texture fraction of 99.8 % (< 10°) was obtained after annealing at 1000°C for 1 h. The full width half maximum (FWHM) values for the X-ray (111) phi-scan and (002) omega-scan in this substrate were 7.31° and 5.51°, respectively. Furthermore, the cube texture fraction of epitaxially grown CeO2buffer layer was 95 % (< 10°), and the FWHM values of phi-scan and omega-scan being 6.98° and 5.92°, respectively.

Characterization of Engineered Nickel-Base Alloy Surface Layers Produced by Additive Friction Stir Processing

Additive friction stir processing (AFSP) was used as a novel method to create consolidated γ′-strengthened superalloy surface layers on non-age-hardenable Ni-alloy substrates. A Ni–Cr–Mo superalloy (Haynes Alloy 282) was deposited onto Ni–Cr–Fe alloy (INCONEL™ Alloy 600) plate using a cold-wire gas tungsten arc process and subsequently friction stir processed. Alloy 282 was incorporated into the surface and led to increases in near-surface hardness to levels over 275 HV0.3 as-processed. Heat treatment response and precipitate distribution also improved as a result of AFSP. The application of AFSP led to a 2-fold increase in hardness after a direct age heat treatment relative to the as-deposited GTAW weld overlay without AFSP. Enhancement of precipitate formation kinetics was attributed to stored energy from mechanical stirring of the additive Alloy 282 at high temperature. Electron backscatter diffraction and transmission electron microscopy of AFSP regions showed increased dislocation density for low AFSP heat input processing parameters.

Characterisation and corrosion studies of cold sprayed copper coatings on ASTM B 435 alloy

In this research paper, copper coatings were successfully deposited on Ni alloy (ASTM B 435) substrate using cold spray process with an aim to avoid the contact of dissimilar materials frequently encountered in industrial applications. The coatings were deposited using air as carrier gas by varying process parameters, i.e., powder feed type, stagnation temperature, stagnation pressure and stand-off distance. The deposited coatings were characterised using the combined techniques of XRD, FESEM, EDS and EPMA. EDAX, XRD and EPMA. It is found that the main constituent in the coating is Cu which resembles the sprayed powder used for the study. The developed coatings have a uniform and dense microstructure, with uniform hardness value in the range of 108–140 Hv, average coating thickness 13–58 mils and average surface roughness 6–11 µm. A very small fraction of phases of other elements have formed in the microstructure of the coating in the form of either inter-splat lamellae or globules.

Copper nanowall array grown on bulk Fe–Co–Ni alloy substrate at room temperature as lithium-ion battery current collector

Large-scale copper nanowall array on the bulk Fe–Co–Ni alloy substrate has been prepared in aqueous solution at room temperature via an electroless deposition method. The thickness of the nanowalls is about 15 nm. A possible growth mechanism of the nanowalls was proposed. The effects of reaction temperature, reaction time and the amount of critical agent (Fe 3+) on the morphology and crystalline phase of the nanowalls were investigated. Furthermore, the electrochemical performance of Sn film supported on the as-prepared copper nanowalls current collector is enhanced in comparison with that on the commercial copper foil when used as anode for Li-ion batteries with the operating voltage window of 0.01–2.0 V (vs. Li). After 20 cycles, the discharge capacity of Sn–Cu nanowalls anode still remained 365.9 mAh g − 1 , that is, 40% retention of the reversible capacity, while the initial charge capacity of Sn film cast on commercial Cu foil was 590 mAh g − 1 , dropping rapidly to 260 mAh g − 1 only after 10 cycles.

Rapid growth of Fe 3O 4 nanowires with oxide assisted vapor–solid process

Oxide assisted vapor–solid (VS) process has been used for rapid crystal growth of Fe 3O 4 nanowires (NWs) on Fe:Ni (1:1) alloy substrate. Oxide layers have been created initially on the substrate by heating it inside the quartz tube of a single tube furnace at 600 °C in air. On rising the temperature of the chamber to 700 °C in vacuum and flowing argon (Ar) at a flux 10 sccm for 20 min NWs of lengths up to 10 μm and average width 120 nm can be grown on the oxidized substrate. Capillarity model and resident time theorem have been combined to analyze the nanowire growth process. Energy dispersive X-ray (EDX), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) studies show that the product formed are Fe 3O 4 NWs which are magnetic materials.

Comparison of corrosion resistance between Al2O3 and YSZ coatings against high temperature LiCl-Li2O molten salt

In this study, the high-temperature corrosion resistance of plasma-sprayed ceramic oxide coatings has been evaluated in a LiCl-Li2O molten salt under an oxidizing environment. Al2O3 and YSZ coatings were manufactured by atmospheric plasma spraying onto a Ni alloy substrate. Both the plasma-sprayed Al2O3 and YSZ coatings had a typical splat quenched microstructure which contained various types of defects, including incompletely filled pores, inter-splat pores and intra-splat microcracks. Corrosion resistance was evaluated by the thickness reduction of the coating as a function of the immersion time in the LiCl-Li2O molten salt at a temperature of 650 °C. A linear corrosion kinetic was found for the Al2O3 coating, while no thickness variation with time occurred for the YSZ coating. The ceramic oxide coatings were reacted with LiCl-Li2O molten salt to form a porous reaction layer of LiAl, Li5AlO4 and LiAl5O8 for the Al2O3 coating and a dense reaction layer of non-crystalline phase for the YSZ coating. The reaction products were also formed along the inside coating of the porous channel. The superior corrosion resistance of the YSZ coating was attributed to the formation of a dense protective oxide layer of non-crystalline reaction products on the surface and at the inter-splat pores of the coating.

Single-crystal-like, c-axis oriented BaTiO3 thin films with high-performance on flexible metal templates for ferroelectric applications

Epitaxial, c-axis oriented BaTiO3 thin films were deposited using pulsed laser ablation on flexible, polycrystalline Ni alloy tape with biaxially textured oxide buffer multilayers. The high quality of epitaxial BaTiO3 thin films with P4mm group symmetry was confirmed by x-ray diffraction. The microscopic ferroelectric domain structure and the piezoelectric domain switching in these films were confirmed via spatially resolved piezoresponse mapping and local hysteresis loops. Macroscopic measurements demonstrate that the films have well-saturated hysteresis loops with a high remanent polarization of ∼11.5 μC/cm2. Such high-quality, single-crystal-like BaTiO3 films on low-cost, polycrystalline, flexible Ni alloy substrates are attractive for applications in flexible lead-free ferroelectric devices.

Composite ${\rm Y}_{2}{\rm O}_{3}-{\rm Al}_{2}{\rm O}_{3}$ as Diffusion Barrier/Nucleation Layer for HTS Coated Conductors Based on IBAD MgO

A composite layer has been successfully implemented in high temperature superconducting (HTS) coated conductors (CCs) based on ion beam assisted deposition (IBAD) MgO technology. This layer serves a dual function: a nucleation layer for the growth of high quality biaxially aligned MgO and a diffusion barrier to inhibit interdiffusion between the Ni-alloy substrate and the superconductor. The composition of the composite Y2O3-Al2O3 influences the texture and superconducting properties of YBCO films grown on STO buffered MgO/Y2O3-Al2O3/Ni-alloy. Our experimental results demonstrate that the superconducting properties of YBCO grown on STO buffered MgO/Y2O3-Al2O3/Ni-alloy are comparable with those of YBCO on standard architecture. The use of a single composite Y2O3-Al2O3 layer instead of individual layers of Y2O3 and Al2O3 for the fabrication of HTS CCs based on IBAD MgO provides advantages such as simplified architecture and potentially reduced cost due to the reduced number of fabrication steps.