Ni Ternary Alloys Research Articles

A novel approach to fabricating a nanotwinned surface on a ternary nickel alloy

Deformation nanotwinning is performed using molecular dynamics (MD) on a single crystal in a ternary nickel (Ni) alloy. Generalized embedded-atom method (EAM) potential functions are obtained for the ternary Ni alloy. The critical twinning stress is 4.48GPa, calculated by the MD simulations. Detwinning, restoring and regenerating of nanotwins take place during the unloading process, contributing to the remaining of the ductility. According to the MD simulations, a novel approach is proposed to fabricating a nanotwinned surface using nanoindentation at room temperature. This is different from previous reports, in which high temperature, high pressure or chemical regents are employed.

Hydrogel-Derived Nanoporous Sn–In–Ni Ternary Alloy Network for High-Performance Lithium-Storage

Nanoporous multinary alloy networks containing multiple functional components, i. e. active Li-alloying main-group metals and inactive transition-metals, possess unique structural and compositional features toward lithium storage, and are thus anticipated to manifest desirable anodic performance in advanced lithium-ion batteries (LIBs). Herein, a general and scalable one-pot hydrogel-derived route has been developed for the construction of nanoporous multinary alloy networks via facile coordination-reduction processes using novel cyano-bridged coordination polymer hydrogels (cyanogels) as precursors. The formation of nanoporous Sn–In–Ni ternary alloy network has been illustrated as an example by using a Sn(IV)–In(III)–Ni(II)–Co(III) quaternary metallic cyanogel as a precursor. Meanwhile, nanoporous Sn–Ni binary alloy and metallic In networks have also been synthesized through coordination-reduction routes using Sn(IV)–Ni(II) and In(III)–Co(III) cyanogels as precursors, respectively. Moreover, the anodic performance of the nanoporous Sn–In–Ni ternary alloy network has been examined as a proof-of-concept demonstration of its structural and compositional superiorities toward lithium storage. Compared with separate Sn–Ni and In networks, the Sn–In–Ni ternary alloy network manifests markedly enhanced lithium-storage performance in terms of reversible capacities, cycling stability, and so forth, making it an ideal anodic candidate for advanced LIBs with long cycle life and high energy/power densities. Moreover, the proposed hydrogel-derived coordination-reduction strategy would open up new opportunities for constructing nanoporous multinary alloy networks as advanced anodes for LIBs.

Ternary alloy nanocatalysts for hydrogen evolution reaction

Cu–Fe–Ni ternary alloys (size ∼55–80 nm) with varying compositions viz. CuFeNi (A1), CuFe 2 Ni (A2) and CuFeNi 2 (A3) were successfully synthesized using microemulsion. It is to be noted that synthesis of nanocrystalline ternary alloys with precise composition is a big challenge which can be overcome by choosing an appropriate microemulsion system. High electrocatalytic activity towards HER in alkaline medium was achieved by the formation of alloys of metals with low and high binding energies. A high value of current density (228 mA cm2) at an overpotential of 545 mV was obtained for CuFeNi (A1), which is significantly high as compared to the previously reported Ni 5 9 Cu 4 1 alloy catalyst.

Influence of Cu precipitation on tensile properties of Fe–Cu–Ni ternary alloy at different temperatures by molecular dynamics simulation

The influence of Cu precipitation on the tensile properties of Fe–1.1% Cu–0.9% Ni ternary alloy at different temperatures are analyzed using molecular dynamics (MD) method. The local lattice structural transition around Cu-rich clusters is generated by Cu-rich clusters forming during continuous cooling process. The formation of Cu-rich clusters and matrix of local lattice structural transition result in the decrease of tensile yield strength of the matrix material at room temperature. Therefore, the matrix becomes brittle and tends to fracture in the local structural transition area. It has been found that the formation of Cu-rich clusters reduces the yield strength of the matrix more greatly at aging temperature than room temperature. Furthermore, the higher the temperature is, the greater the degree is. Cu-rich clusters play a significant role in strengthening material at early stage, while the material strength decreases with time increase.

Kinetic mechanisms of hydriding and dehydriding reactions in La–Mg–Ni alloys investigated by the modified Chou model

The phenomenon of volume change is very important in the hydriding and dehydriding reactions to clarify their kinetic mechanisms. However, few of the theoretical models take this factor into account in the study of kinetic mechanisms. In the present work, the modified Chou model with considering the volume change by Pilling-Bedworth Ratio (PBR) β is applied to interpret the kinetic mechanisms of hydriding and dehydriding reactions in La–Mg–Ni ternary hydrogen storage alloys. The calculation results agree well with the experimental data, indicating that the modified Chou model can well describe the kinetic behaviors of La–Mg–Ni alloys. Diffusion is determined to be the rate-controlling step of hydriding and dehydriding for the examples in this work. The activation energies are calculated to be 39.4 kJ/mol for hydriding reaction (β = 1.29) and 93.1 kJ/mol for dehydriding reaction (β = 0.78) of Mg–10.6La–3.5Ni nanoparticles at 453–623 K. For the hydrogen absorption kinetics of La2Mg16Ni alloy under 0.5–3 MPa at 598 K, β is 1.25 and the equilibrium hydrogen pressure is calculated to be 0.332 MPa. For the hydrogen desorption kinetics of Mgx(LaNi3)100−x alloys at 623 K, the characteristic times increase in the order of tc(x = 70,β= 0.79) < tc(x= 60, β= 0.79) < tc(x= 40, β= 0.97) < tc(x= 50, β = 0.85). The value of β is 0.77 and the hydrogen desorption rate of Mg–5La–10Ni alloy prepared by the ultrahigh pressure (UHP) method is faster than that of the alloy prepared by the as-cast method, whose characteristic times are 7428 s and 4651 s, respectively. Furthermore, the calculation accuracy can also be improved by the modified Chou model compared with the original Chou model after taking PBR into consideration.

Thermodynamic Properties of Ce–In–Ni Ternary Alloys

The mixing enthalpies of the liquid Ce–In–Ni ternary alloys have been determined by isoperibol calorimetry along three sections: (Ce0.4In0.6)1–xNix (0 < x < 0.11), (In0.15Ni0.85)1–xCex (0 < x < < 0.12), and (Ce0.21Ni0.79)1–xInx (0 < x < 0.03). The mixing enthalpies and activities of components in the Ce–In–Ni ternary alloys are calculated using various models, chosen by critical analysis. The data obtained previously for the binary subsystems are used for calculations, and new experimental data for the ternary systems are employed to verify the reliability of the models. The melts mix with release of significant amounts of heat, and the activities of their components are characterized by negative deviations from ideal solutions.

Thermodynamic modeling of Al–Co–Cr, Al–Co–Ni, Co–Cr–Ni ternary systems towards a description for Al–Co–Cr–Ni

The phase relations and thermodynamic properties of the Al–Co–Cr, Al–Co–Ni, Co–Cr–Ni ternary alloys are investigated using first principles calculations based on DFT (density functional theory). Their thermodynamic descriptions are developed by means of the CALPHAD (calculations of phase diagrams) method using experimental and computational data from the present work and the literature. Emphasis is placed on modeling the A2, B2, fcc-γ, L12-γ′ and tetragonal-σ phases in the temperature range of 1173–1623K. Liquid, A2 and fcc-γ phases are modeled using substitutional solution descriptions. A partitioning model is then used for the γ/γ′ and A2/B2 phases to effectively describe the order–disorder transitions. The critically assessed thermodynamic descriptions describe all experimentally determined phase equilibria data well. A2/B2 transitions are also shown to agree well with previous experimental findings in the Al–Co–Cr ternary system.

A low cost and highly active non-noble alloy electrocatalyst for hydrazine oxidation based on nickel ternary alloy at the surface of graphite electrode

The electrocatalytic oxidation of hydrazine was studied over Ni, Cu, Co and Ni-based ternary alloy on graphite electrodes in alkaline solution. The catalysts were prepared by cycling the graphite electrode in solutions containing Ni, Cu and Co ions at cathodic potentials. The synergistic effects and the catalytic activity of the modified electrodes were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). It was found that, in the presence of hydrazine, the modified Ni-based ternary alloy electrode (G/NiCuCo) exhibited a good catalytic activity for the oxidation of hydrazine at a reduced overpotential and it has a significant high response for hydrazine oxidation. During CA regime the reaction follows a Cottrellin behavior and the diffusion coefficient of hydrazine is found to be 6.28×10−6cm2s−1. EIS studies were used to investigate the catalytic oxidation of hydrazine on the surface of the modified electrode.

Effects of Ni content on nanocrystalline Fe–Co–Ni ternary alloys synthesized by a chemical reduction method

Magnetic properties of Fe–Co–Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe50Co50−xNix nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe50Ni50 nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe–Co–Ni alloys could be adjusted by varying the Ni content.

Nanoindentation study on solid solution softening of Fe-rich Fe2Nb Laves phase by Ni in Fe–Nb–Ni ternary alloys

In an attempt to understand the solid solution softening by Ni of an Fe-rich Fe2Nb Laves phase that is in equilibrium with γ-Fe, we have examined the defect structure in the Laves phase in Fe–Nb–Ni alloys by transmission electron microscopy, and its hardness as a function of orientation and solute (Ni) content by nanoindentation. The binary Fe-rich Laves phase and the ternary Laves phases with lower Ni content (18%) exhibit a featureless morphology with low dislocation density, whereas the ternary Laves phase with higher Ni content (33%) includes basal planar faults extending to several micrometers, producing a local change in the stacking sequence of the three 36-nets (triple layer) of the C14 structure. The hardness of the binary and the ternary Laves phases with 18% Ni in solution is almost constant and independent of orientation, whereas the ternary Laves phase with 33% Ni in solution exhibits a substantial dependence of hardness on orientation and this dependence appears associated with the ease of basal slips evidenced by slip traces around nanoindents. The relative ease in activating basal slip in the presence of a large amount of Ni in solution is thought to be the dominant contributor to the observed solid solution softening.

Synergistic effect of cobalt and copper on a nickel-based modified graphite electrode during methanol electro-oxidation in NaOH solution

The electrocatalytic oxidation of methanol was studied over Ni, Co and Cu binary or ternary alloys on graphite electrodes in a NaOH solution (0.1 mol/L). The catalysts were prepared by cycling the graphite electrode in solutions containing Ni, Cu and Co ions at cathodic potentials. The synergistic effects and catalytic activity of the modified electrodes were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). It was found that, in the presence of methanol, the modified Ni-based ternary alloy electrode (G/NiCuCo) exhibited a significantly higher response for methanol oxidation compared to the other samples. The anodic peak currents showed a linear dependency on the square root of the scan rate, which is a characteristic of a diffusion controlled process. During CA studies, the reaction exhibited Cottrellin behavior and the diffusion coefficient of methanol was determined to be 6.25×10−6 cm2/s and the catalytic rate constant, K, for methanol oxidation was found to be 40×107 cm3/(mol·s). EIS was used to investigate the catalytic oxidation of methanol on the surface of the modified electrode.

Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction.

We report a Ni-Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline electrolyte. The HER kinetics of numerous binary and ternary Ni-alloys and composite Ni/metal-oxide/C samples were evaluated in aqueous 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni-Cr materials which exhibit metallic Ni as well as NiO x and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to numerous binary and ternary Ni-alloys, including Ni-Mo materials. It is likely that at adjacent Ni/NiO x sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a sink for the Hads intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO x content and that the Cr2O3 appears to stabilize the composite NiO x component under HER conditions (where NiO x would typically be reduced to metallic Ni0). Furthermore, in contrast to Pt, the Ni(O x )/Cr2O3 catalyst appears resistant to poisoning by the anion exchange ionomer (AEI), a serious consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.

Study of Electrolyte pH in Production of Cu–Co–Ni Ternary Alloys and Its Effect on Microstructural and Magnetic Properties

Ternary Cu-Co-Ni alloys were electrodeposited in the mediums that have different pH levels to investigate the microstructuremagnetic relationship. The electrolyte pH was considered as high (4.2) and low (2.5) levels. For both levels, the anomalous codeposition occurred in the deposition of the alloys. The face centered cubic crystalline structure was observed in the ternary alloys grown at high and low electrolyte pH levels. In addition, a significant decrease in average grain size of the crystallites, from 60 to 21 nm, occurred when the pH was reduced from 4.2 to 2.5. A dendritic structure was detected in the surface of the alloy deposited from electrolyte with the high pH level, whereas the alloy grown at the low pH has a surface without dendritic clumps. According to magnetic analysis, an increase in the saturation magnetization, caused by the increase of Co content, was detected when the pH was reduced. The coercivity H c levels were 89 and 80 Oe for the alloys grown at high and low pH, respectively. The change of H c was attributed to the changes in microstructural properties, i.e., different average grain sizes of the crystallites and surface morphologies, occurred when the electrolyte pH changed. The anisotropic magnetoresistance (AMR) was exhibited by the alloys and the AMR ratio was enhanced from ~3% to ~3.5%-4% when the pH decreased.

Local melting in Al embedded with TiNi powder induced by microarea self-propagating high-temperature synthesis

Microarea self-propagating high-temperature synthesis (microSHS) was ignited by the heat of mixing generated at the boundaries between an Al matrix and TiNi particles during plastic deformation at room temperature. The temperature of the boundaries was rapidly increased by microSHS; the temperature elevation resulted in local melting of the TiNi particle and the surrounding Al matrix, because the heat of mixing was localized in the vicinity of the TiNi particle although the amount of the heat of mixing was limited. Since the amount of the local melting region induced by microSHS is restricted, not only major elements (i.e. Al, Ti and Ni) but also impurities were involved in the solidification followed by local melting. As a result, FeNi nanoprecipitates, which have not been reported in SHS studies, were formed by inclusion of Fe, initially included as an impurity in raw materials. The formation mechanism of FeNi nanoprecipitates is discussed based on reference to the Al–Fe–Ni ternary alloy phase diagram. It is expected that local melting induced by microSHS is a key phenomonon for amorphization during severe plastic deformation of elemental sheets.

Development of alloys with high strength at elevated temperatures by tuning the bimodal microstructure in the Al–Cu–Ni eutectic system

The development of high-strength aluminum alloys that can operate at 250 °C and beyond remains a challenge to the materials community. In this paper we report preliminary development of nanostructural Al–Cu–Ni ternary alloys containing α-Al, binary Al2Cu and ternary Al7Cu4Ni intermetallics. The alloys exhibits fracture strength of ∼1 GPa with ∼9% fracture strain at room temperature. At 300 °C, the alloy retains the high strength. The reasons for such significant mechanical properties are rationalized by unraveling the roles and response of various microstructural features.

Reversible de-/hydriding characteristics of a novel Mg18In1Ni3 alloy

The present work demonstrates the reversible hydrogen storage properties of the ternary alloy Mg18In1Ni3, which is prepared by ball-milling Mg(In) solid solution with Ni powder. The two-step dehydriding mechanism of hydrogenated Mg18In1Ni3 is revealed, namely the decomposition of MgH2 is involved with different intermetallic compounds or Ni, which leads to the formation of Mg2Ni(In) solid solution or unknown ternary Mg–In–Ni alloy phase. As a result, the alloy Mg18In1Ni3 shows improved thermodynamics in comparison with pure Mg. The Ni addition also results in the kinetic improvement, and the minimum desorption temperature is reduced down to 503 K, which is a great decrease comparing with that for Mg–In binary alloy. The composition and microstructure of Mg–In–Ni ternary alloy could be further optimized for better hydrogen storage properties.

Peculiarities of Phase Transitions and Structure Formation in a Ternary Al-Cu-Ni Alloy with Four-Phase Peritectic Reaction

The structure formation in peritectic Al-4.5at.%Cu-11at.%Ni ternary alloy with four-phase peritectic reaction was investigated using the quantitative phase-field model of eutectic growth. This model, extended to an arbitrary number of phases, guarantees the stability requirements on individual interfaces. The thermal noise terms disturb the stability and produce the heterogeneous nucleation of secondary phases in accordance to the energetic and concentration conditions. In our recent work it was shown that in differential thermal analysis (DTA) experiments specific microstructure parts in Al-4.5at.%Cu-11at.%Ni alloy with a four-phase peritectic reaction were observed, which cannot be explained by Scheil calculation or simple phase-field modeling. In this work, it was found by numerical experiments that, due to the formation of anisotropic quasi-primary Al3Ni2 crystals and the suppression of the nucleation of (Al) phase, the eutectic-like coupled growth of Al3Ni2 and Al3Ni phases can be observed. In addition, at further cooling the anisotropic shape of quasi-secondary Al3Ni crystals promotes the nucleation of the (Al) phase. The simulated final structure is comparable to the experimental one which is characterized by large Al3Ni2 crystals enveloped by the Al3Ni phase.

Structures and properties of Mg–La–Ni ternary hydrogen storage alloys by microwave-assisted activation synthesis

It is a challenge to prepare a material meeting two conflicting criteria – absorbing hydrogen strongly enough to reach a stable thermodynamic state and desorbing hydrogen at moderate temperature with a fast reaction rate. With the guide of the Mg–La–Ni phase diagram, microwave sintering (MS) was successfully applied to preparing Mg–La–Ni ternary hydrogen storage alloys from the powder mixture of Mg, La and Ni. Their phase structures, morphologies and hydrogen absorption and desorption (A/D) properties have been studied by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), pressure-composition-isotherm (PCI) and differential scanning calorimetry (DSC). The metal hydride of 70 Mg–9.72 La–20.28 Ni (wt pct) has the best comprehensive hydriding and dehydriding (H/D) properties, which can absorb 4.1 wt.% H2 in 600 s and desorb 3.9 wt.% H2 in 1500 s at 573 K. The DSC results reveal its onset temperatures of hydrogen A/D are the lowest among all the samples, which are 671.4 and 600.9 K. Its activation energy of dehydriding reaction is 113.5 kJ/mol H2, which is the smallest among all the samples. Also, Chou model was used to analyze the reaction kinetic mechanism.

Influence of Ni on Cu precipitation in Fe—Cu—Ni ternary alloy by an atomic study

The early aging Cu precipitations in Fe—3%Cu and Fe—3%Cu—4%Ni ternary alloys are investigated by molecular dynamics (MD) simulations. The results show that the average size of Cu clusters in Fe—3%Cu—4%Ni alloy is larger than that in Fe—3%Cu alloy. The diffusion of Cu is accelerated by Ni according to the mean square displacement (MSD). Furthermore, the whole formation process of Cu-rich clusters is analyzed in detail, and it is found that the presence of Ni promotes small Cu-rich clusters to be combined into big ones. Ni atoms prefer to stay at the combination positions of small clusters energetically due to a large number of the first nearest neighbor Cu—Ni interactions, which is verified by first-principles calculations based on density functional theory (DFT).

Nitridated Si–Ti–Ni alloy as an anode for Li rechargeable batteries

Nitridated Si–Ti–Ni (STN) ternary alloy as an anode for lithium ion batteries is prepared by the NH3 nitridation of STN alloy. The nitridated STN electrode shows 14% increased reversible capacity and 4 times higher rate capability at 3 C compared to those of pristine STN electrode. These improvements are attributed to the formation of nitride compounds (such as SiNx/SiNxOy, TiNx/TiNxOy and NiNx/NiNxOy) on STN alloy, which benefits both mechanics and kinetics.