Ni Binary Alloys Research Articles

Tunable the mechanical properties of β-Ti1-xMx binary alloys by transition metal M (M = Fe, Mo, Nb, Ni) substitutional doping: A first-principles study

The structural stability, electronic, and mechanical properties of Ti1-xMx (M = Fe, Mo, Nb, Ni) binary alloys were systematically investigated through first-principles calculations based on Density Functional Theory (DFT). The results indicate that the formation energy decreased with an increase in the substitutional atomic M content, accompanied by an increase in the values of C11–C12. This observation suggests a significant improvement in the structural stability of the Ti1-xMx alloys considered, with the concentration of substitutional atomic M ranging from 6.25 % to 50 %. Furthermore, the mechanical parameters, including bulk modulus B and shear modulus G, exhibited a linear increase with the concentration of the alloy element M. The Young's modulus E of Ti1-xFex and Ti1-xNbx alloys increased, whereas Ti1-xMox and Ti1-xNbx alloys reached a minimum value. In addition, the B/G ratio and Poisson's ratio ν indicated that β-Ti1-xMx alloys are fundamentally ductile materials. Moreover, using the stretching model, we demonstrate that the tensile strength of Ti1-xMx alloys was significantly improved by increasing the alloy element M concentration. The enhancement in tensile strength was primarily attributed to the enhanced bond strength between Ti and M atoms, as revealed by the analysis of the density state. These findings provide a pragmatic approach for reinforcing the strength-toughness compatibility of Ti-based alloys, rendering them suitable for aerospace industry applications.

First-Principles Study on Thermodynamic, Structural, Mechanical, Electronic, and Phonon Properties of tP16 Ru-Based Alloys

Transition metal-ruthenium alloys are promising candidates for ultra-high-temperature structural applications. However, the mechanical and electronic characteristics of these alloys are not well understood in the literature. This study uses first-principles density functional theory calculations to explore the structural, electronic, mechanical, and phonon properties of X3Ru (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) binary alloys in the tP16 crystallographic phase. We find that Mn3Ru, Sc3Ru, Ti3Ru, V3Ru, and Zn3Ru have negative heats of formation and hence are thermodynamically stable. Mechanical analysis (Cij) indicates that all tP16-X3Ru alloys are mechanically stable except, Fe3Ru and Cr3Ru. Moreover, these compounds exhibit ductility and possess high melting temperatures. Furthermore, phonon dispersion curves indicate that Cr3Ru, Co3Ru, Ni3Ru, and Cu3Ru are dynamically stable, while the electronic density of states reveals all the X3Ru alloys are metallic, with a significant overlap between the valence and conduction bands at the Fermi energy. These findings offer insights into the novel properties of the tP16 X3Ru intermetallic alloys for the exploration of high-temperature structural applications.

Dry reforming of methane for syngas production over noble metals modified M-Ni@S-1 catalysts (M = Pt, Pd, Ru, Au)

High tendency to sinter and carbon deposition becomes the choke point of Ni-based catalyst for its performance optimization in syngas generation via dry reforming of methane (DRM). Uniting the encapsulation of support with the construction of alloy interfaces, is a bright strategy to protect metallic Ni sites and synthesize highly efficient and stable Ni-based catalyst. Herein, M-Ni@S-1 catalysts (M = Pt, Pd, Ru, Au) with the same noble metal content (0.5 wt%) rather than moles were fabricated, and evaluated in DRM process. Results reveal that the type of noble metals influences the cooperating effect of the formed M − Ni alloy interface and support encapsulation degree, which achieves the best in Pt–Ni@S-1 catalyst. Therefore, Pt–Ni@S-1 catalyst exhibited outstanding sinter resistance and carbon tolerance as well as high catalytic stability, and obtained the highest methane conversion of approximately 80% at 700 °C and 60,000 mL·min−1·gcat−1 of GHSV. This can attribute to the small particle size of 3 nm, suitable metal-support interaction, abundant surface alkaline sites and stably existed Pt–Ni binary alloy interfaces.

Hydrolysis hydrogen generation behavior of mechanico-chemical reaction Mg-M (M = Ni, Ce, and La) binary alloys—A feasible strategy for activating and improving environmental stability

Mg-based alloys are regard to be suitable hydrolysis materials for hydrogen generation. The mechanico-chemical reaction (MCR) strategy was employed to effectively activate Mg-based binary alloys as well as elevate their environmental stability. MCR is proved to be an effective way to activate Mg-based binary alloys and enhance the ability to resist environmental toxicity. The hydrolysis H2 generation process of MCR Mg25Ni, Mg30Ce and Mg30La samples after environmental exposure are elevated and the final H2 capacities can increase to 186.1, 204.8 and 341.4 mL·g−1 with the fastest H2 generation rates of 26.0, 24.2 and 41.5 mL·g−1·min−1, respectively. The generation capacities of the above-mentioned samples are 297, 370 and 629 mL·g−1 at 318 K within 10 min, respectively. Mg-based binary alloys can be effectively activated by MCR and Maintain high reactivity at the same time. The hydrogen generation activation energies of MCR Mg25Ni, Mg30Ce and Mg30La after environmental exposure are 26.6, 30.8 and 23.3 kJ·mol−1, respectively. The above-mentioned work may provide a feasible strategy to activate the as-cast Mg-based alloys and elevate the Resistance to environmental toxicity, which may pave the way for applying the portable hydrogen generators.

Glass formability of the Tb–Ni binary alloys and the magnetic properties of the Tb65Ni35 metallic glass

The binary TbxNi100-x (x = 60, 65, 70, 75) alloys were melt-spun into the shape of ribbons with a thickness of ∼40 μm and the glass formability of the binary alloys was studied. The mechanism for the better glass formability of the Tb65Ni35 alloy, and the factors that influence the magnetocaloric properties of the amorphous ribbon, were investigated. It was found that only the Tb65Ni35 ribbon is fully amorphous and thus the Tb65Ni35 alloy is the best glass former in the binary alloy system. The glassy ribbon shows a spin-freezing-like behavior with a spin-freezing-temperature of ∼54 K and a Curie temperature of ∼64 K. The maximum magnetic entropy change (–ΔSmpeak) of 8.7 J/(kg K) and a moderate saturation magnetostriction (λ, ∼131 ppm at 40 K and ∼242 ppm at 10 K) under 5 T were observed in the Tb65Ni35 amorphous ribbon.

ФОРМИРОВАНИЕ ОСТРОЙ КУБИЧЕСКОЙ ТЕКСТУРЫ В ЛЕНТАХ-ПОДЛОЖКАХ ИЗ СПЛАВОВ (Cu+Ni)–Me (Me=Mo, Mn, Nb) ДЛЯ ВЫСОКОТЕМПЕРАТУРНЫХ СВЕРХПРОВОДНИКОВ ВТОРОГО ПОКОЛЕНИЯ

After cold-rolling reduction with the shrinkage of more than 97 % and recrystallization annealing, the edged cubic texture develops in some fcc lattice metals with the high and medium values of stacking fault energy such as Ni, Cu, Al, Pt, and some alloys on their base. The extended bands of metals and fcc lattice alloys can be used to apply multilayer functional compositions. The authors studied the structure and crystallographic texture in bands of three-component copper-nickel-based alloys. The study showed the crucial possibility of creating multi-component alloys based on the Cu+40% Ni binary alloy doped with such elements as Mo or Nb. The paper considers the formation of an edged cubic texture in bands of Cu–Ni–Mn, Cu–Ni–Nb, and Cu–Ni–Мо alloys produced through cold deformation with rolling and recrystallization annealing performed at different temperatures. The study identified that annealing during one hour at 1050 °С was an optimal recrystallization annealing mode when on the surface of bands made of (Cu+40 % Ni)–Me alloys (where Me=Mn, Mo, Nb) deformed at ~99 %, the most perfect cubic texture was realized. According to the data obtained, after such annealing mode, from 94% to 98% of grains with orientation {001}<100> developed in the Cu–40% Ni–1.3% Mn, Cu–40% Ni–0.8% Mo, and Cu–40% Ni–0.5% Nb alloys. It opens the prospect of using these alloys as epitaxial substrates in the technology of high-temperature second-generation superconductors. The evaluation of mechanical characteristics showed that alloying contributed to an increase in the yield strength of Cu–40% Ni–1.3% Mn, Cu–40% Ni–0.8% Mo, and Cu–40% Ni–0.5% Nb alloys by 3–4 times compared with the yield strength value of a textured copper band.

The effect of the Ni/Cu ratio on H-induced ductility loss and its mechanism in Cu–Ni binary alloy system

The effect of the Ni/Cu ratio on hydrogen embrittlement (HE) behavior is studied in the context of the Cu–Ni binary alloy system. When classifying HE sensitivity as a function of the Ni fraction, two regimes are obtained: Regime 1 (wherein Ni fraction is less than 80 wt%) with moderate HE and Regime 2 (where Ni fraction exceeds 80 wt%) with more severe HE, although hydrogen- (H-)induced intergranular (IG) cracking is noted to be the common primary cause of H-induced degradation. Necessities of H-transportation towards grain boundaries (GBs) via H–dislocation interaction and/or dynamic H-diffusion are discussed via the slow strain rate tensile tests at −196 °C. Specifically, in Regime 1, H-transportation is necessary for the triggering of IG cracking. Conversely, in Regime 2, such H-transportation plays a minor role and the initially concentrated hydrogen along GBs can sorely cause IG cracking.

Alloying non-precious metals into Ni-based electrocatalysts for enhanced hydrogen oxidation reaction in alkaline media: A computational study

Alkaline anion exchange membrane fuel cells (AAEMFCs) are promising energy conversion devices because they can circumvent the use of precious metal catalysts. Hydrogen oxidation reaction (HOR) is the limiting reaction of the AAEMFC. Alloying metals with Ni is one method to enhance the HOR activity. However, the alloying effects are not fully identified. In this work, we investigated the HOR activity of non-precious Ni binary and ternary alloys using density functional theory (DFT) calculations. Together with the descriptor, H adsorption free energy (ΔGH∗), free energy profiles based on the bifunctional mechanism suggest the Cu-doped Ni3Ti as the best catalyst. This result is further confirmed by the microkinetic model, where Cu-doped Ni3Ti exhibits ΔGH∗ and OH adsorption free energy (ΔGOH∗) closest to the optimum values (0 and 0.8 eV, respectively). The adsorption trend is understood via the d-band center and magnetic moment of the surface atoms. Our investigation revealed the alloying effects on the HOR activity and provided theoretical guidance for improving the performance of Ni alloy based AAEMFCs.

A theoretical calculation of stacking fault energy of Ni alloys: The effects of temperature and composition

Combining cluster expansion (CE) method with one dimensional axial Ising model, this work investigated the effects of alloying elements and configurational variations due to temperature on the stacking fault energy (SFE) of FCC Ni binary alloys. Ensembles of large numbers of atomistic structures, each with more than ~400 atoms, were generated to consider sufficient long-range chemical disorder and temperature effects due to configurational entropy. A Monte Carlo Metropolis algorithm was used to generate these structures, whose energies were then evaluated based on the effective cluster interactions obtained from CE. As a baseline, this work had shown the SFE of pure Ni and Al to be 127 mJ/m2 and 137 mJ/m2, respectively, which agreed with the experimental values of 125 mJ/m2 and 150 mJ/m2 reported in the literature. Additions of Al, Ti, Cr and Co to pure Ni were found to decrease the SFE to different extents. Although temperature does not strongly influence the SFE of the FCC Ni-Al and Ni-Cr binary alloys, it can lead to significant changes to the SFE of the FCC Ni-Ti and Ni-Co alloys. While effects of temperature and composition on SFE observed in this work were calculated from binary Ni alloys, the general trends are nonetheless expected to be valid in the γ phase of multicomponent Ni superalloys.

Assessment of diffusion mobility for bcc phase of Ti–Al–Ni ternary system

The experimental diffusion coefficients of the Ti–Ni binary and Ti–Al–Ni ternary bcc phase were critically evaluated to assess the diffusion mobilities by the DICTRA-type phenomenological treatment. The calculated diffusion coefficient shows reasonable consistency with the diffusion coefficient extracted in the experiment, including the impurity and inter-diffusion coefficients in bcc Ti–Ni binary alloy and the main interdiffusion coefficient in bcc Ti–Al–Ni ternary alloy. The difference between the calculated and experimental ternary cross coefficients is within appropriate relative errors. The predicted composition profiles and diffusion paths reasonably represent the diffusion processes that occur in Ti–Ni binary and Ti–Al–Ni ternary diffusion couples, thereby validating the mobility database assessed in the present work.

Phase-field simulation of solidification microstructure in Ni and Cu–Ni alloy using the Wheeler, Boettinger and McFadden model coupled with the CALPHAD data

This research article focuses on coupling the CALPHAD approach and the phase-field model for simulating dendritic solidification microstructure for Ni and Cu–Ni binary alloy. The unique feature of this work is to reformulate the governing equations of the Wheeler, Boettinger, and McFadden (WBM) model for usage of the CALPHAD data. Compared to the conventional WBM simulations where the liquid (L) and the fcc_a1(α) phases are treated as ideal solutions, the current work can reflect the non-ideal behaviors of these phases according to the CALPHAD contribution. CALPHAD can contribute for the phase-field model to treat L and α as real solutions. This work also discusses the phase-field simulation for Ni, the feasibility of CALPHAD contribution for Ni simulation and numerical method to solve the governing equations for Ni and Cu–Ni alloy.

Comparative study of hydrogen-induced intergranular fracture behavior in Ni and Cu–Ni alloy at ambient and cryogenic temperatures

In order to clarify the contribution of dislocation‒hydrogen interaction on the hydrogen embrittlement (HE) of pure Ni and of Cu‒55 wt% Ni binary alloy, slow strain rate tensile (SSRT) tests were conducted at room temperature (RT) and at 77 K on hydrogen-precharged specimens. Regarding the SSRT test at RT, hydrogen increased the flow stress and induced intergranular fracture in both pure Ni and Cu–Ni alloy. Furthermore, based on scanning transmission electron microscopy investigations, it was suggested that the evolution of dislocation structures had been enhanced by hydrogen, but only in the case of pure Ni. At 77 K, the ductility of pure Ni was degraded by hydrogen, whereas that of Cu–Ni alloy was not. The difference in temperature dependence of the dislocation‒hydrogen interaction between pure Ni and Cu–Ni alloy was discussed, based on the previously proposed HE mechanisms.

Transient directional solidification of a eutectic Al–Si–Ni alloy: Macrostructure, microstructure, dendritic growth and hardness

The Al-11 wt%Si-5 wt%Ni eutectic alloy was directionally solidified (DS) under transient heat flow conditions at cooling rates in a range of about 1–25 °C/s along the length of the casting. For comparison purposes binary Al-11 wt%Si and Al-5 wt%Ni alloys were also solidified under similar experimental conditions. Initially characterized by columnar grains, the macrostructure of the ternary DS alloy casting evolved during solidification to a columnar to equiaxed transition (CET) at critical cooling rates of about 1.3–1.6 °C/s, i.e. more than 7 times higher than the CET critical value determined in the literature for Al–Ni and Al–Si alloys. The microstructure of the ternary alloy casting is shown to be constituted by primary Si crystals and α-Al dendritic branches surrounded by the eutectic phase (α-Al+Si+Al3Ni), with the Al3Ni phase having initially a plate-like morphology, which with the decrease in the solidification kinetics, evolved to a fishbone morphology. The pertinent scaling laws representing the dendritic growth of the eutectic ternary alloy, properly compared to those of the examined Al–Si and Al–Ni binary alloys are outlined. The scale of the dendritic α-Al phase is shown to affect the Vickers hardness (HV) along the length of the ternary eutectic alloy casting, and a Hall–Petch type equation is proposed relating HV to the secondary dendritic arm spacing.

Effect of alloying elements on defect evolution in Ni-20X binary alloys

The effect of alloying elements on radiation-induced microstructural evolution in Ni and Ni-20X (X = Fe, Cr, Mn and Pd) binary alloys was investigated using ion irradiation and cross-sectional transmission electron microscopy. The three-dimensional migration mode is identified to be the dominating migration mechanism for interstitial clusters in these binary alloys, contrary to the one-dimensional mode that dominates in the well-studied dilute alloys. The results reveal that: (1) the average size of defect clusters decreases as the solute atomic volume size factor increases. Smaller void size in Ni-20Cr is attributed to faster vacancy mobility in the near surface region, and weaker vacancy binding energy beyond the irradiation peak than Ni-20Fe. The smaller voids observed in Ni-20Mn and Ni-20Pd beyond the damage peak are due to the stronger Mn/Pd-vacancy binding effect of largely oversized solute atoms. (2) Oversized solutes can act as strong trapping sites for interstitials. The larger the solute atomic volume factor, the stronger the trapping force. This leads to a more significantly sluggish interstitial migration and smaller dislocation loop size. The average dislocation loop size in Ni-20Fe was four times larger than Ni-20Pd (atomic volume factor being 10.6% and 41.3%) but an order of magnitude lower in density. The smaller dislocation loop size in Ni-20Cr is attributed to stronger interstitial binding of Cr-Ni. Overall, the alloying effect on defects is more significant in concentrated binary alloys than in dilute binary alloys, due to the concentration difference of alloying atoms and the interstitial dominant migration mechanisms in the main irradiated region.

Corrosion and Carburization Behaviour of Ni-xCr Binary Alloys in a High-Temperature Supercritical-Carbon Dioxide Environment

Pure Ni and Ni-xCr (x = 7, 14, 22 and 27 wt%) binary alloys were exposed to supercritical-carbon dioxide environment at 600 °C and 20 MPa for 200 h. For pure Ni, a thick NiO layer was formed on the surface. Meanwhile, for Ni-7Cr alloy, an inner oxide layer consisted of rather irregular chromia and NiO was formed below the outer NiO layer. When Cr content was greater than 14%, a continuous chromia layer was formed, resulting in much lower weight gain and oxide thickness. However, amorphous carbon layers had developed along the oxide–matrix interface when chromia was formed. The presence of the carbon layer was explained in view of the high C activity corresponding to the low equilibrium oxygen potential of chromia.

Microstructure and Mechanical Properties of Copper, Nickel and Ternary Alloys Cu-Ni-Zr Obtained by Mechanical Alloying and Hot Pressing

ABSTRACTElemental powders of Cu and Ni, binary alloys (Cu-Ni and Cu-Zr) and ternary alloy (Cu-Ni-Zr) obtained by mechanical alloying and uniaxial compaction hot microstructure and mechanical properties were investigated. The alloys studied were: pure Cu, pure Ni, binary alloys (Cu-Ni; Cu-Zr) and ternary alloys (Cu-Ni-Zr) under the same mechanical milling and hot pressing conditions. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM); the mechanical properties were studied by compression tests and hardness in Vickers scale (HV0.5) on polished surfaces at room temperature. According to XRD results, hot pressing process crystallite size increase and microstrain decreases in the compact samples due to the release of crystalline defects. The compacted samples have porosity of approximately 20%. The milling powder samples have a higher hardness than the unmilled samples, this because during milling crystal defects are incorporated together with the microstructural refinement. Ternary alloy is the one with the highest hardness of all systems studied, reaching 689 HV0.5. In compression tests determined a strain 5 %, Zr-containing samples become more fragile presenting the lowest values of compressive strength. In contrast, samples of Ni and Cu-Ni binary alloy are more resistant to compression.

Determination of the intrinsic α/γ interface mobility during massive transformations in interstitial free Fe-X alloys

Kinetics of the austenite (γ) to ferrite (α) transformation and the reverse ferrite (α) to austenite (γ) transformation in a series of Fe-X (X = Ni, Mn and Co) binary alloys has been experimentally and theoretically investigated. A transition from partitioning to partitionless transformation has been predicted to occur during both the γ→α and α→γ transformations by a so called Gibbs Energy Balance (GEB) model, in which the chemical driving force is assumed to be equal to the energy dissipation due to interface friction and diffusion of X inside the migrating interfaces. The transition temperature is found to depend on the kind of X and its concentration, which is in good agreement with experimental results. The intrinsic mobility of the α/γ interface has been derived from the kinetic curves of both the γ→α and α→γ transformations in the investigated alloys, and its value seems to be marginally affected by the transformation direction and alloying elements.

Performance of Pt-Ni Alloy Nanoparticles Supported on Carbon Nanotubes in Proton Exchange Membrane Fuel Cell

Proton exchange membrane fuel cells (PEMFCs) have attracted a lot of attention for alternative and green energy sources owning to their low-carbon emissions and high efficiencies. Pt-based electrocatalysts used in PEMFC electrodes are the main contributor to the high cost. More research focusing on the use of Pt group alloys is still required to achieve enhanced catalytic activity while decreasing the Pt loading. In this study, Pt-Ni binary catalysts by pulse electrodeposition and electroless-deposition process were developed for the enhancement of oxygen reduction reaction. The Pt-Ni catalysts were deposited on carbon nanotubes (CNTs) directly grown on carbon cloths. CNTs used for catalyst nanostructured supports can decrease the needs of Pt and improve the performance of fuel cells. The nickel nanoparticles were deposited on CNTs by pulse electro-planting to form large-area flake structures. Then the platinum nanoparticles were reduced on them in a potassium hydroxide solution containing platinum precursor and ethylene glycol at 75 oC for the deposition time of 3, 4, 5 hours. The sample with the commercial Pt/C and Pt/CNTs were also prepared for comparison. Structure and elementary composition of catalysts were measured by SEM, XRD and ICP-MS. Ni/CNTs sample showed a uniform distribution of Ni nanoparticles on the surface of CNTs, which was provided for the deposition of Pt nanoparticles with average particle size of about 5 nm. Electrochemical characteristics of PtNi/CNTs and Pt/CNTs samples were investigated via cyclic voltammetry (CV) analysis and rotating disk electrode (RDE) test in 0.1 M perchloric acid solution. In terms of both limiting current density and onset potential, the PtNi/CNTs samples were better than those of Pt/CNTs samples. All PtNi/CNTs samples with different Pt deposition time showed very similar LSV curves using RDE tests. In single cell test, the PtNi/CNTs, as the cathode catalyst, has a higher maximum power density (763 mW/cm2) than the commercial Pt/C. Among the PtNi/CNTs samples, the better performance of PtNi/CNTs sample with 4-hours Pt deposition time can be attributed to the more convenient Pt availability for the oxygen reduction reaction (ORR). It can be also found that the open circuit voltage of this sample could reach up to 1V due to a significant decrease of the polarization loss. The main outcome of this study was that Pt–Ni binary alloy catalysts had better oxygen reduction reaction for cathode of PEMFC.

Thermodynamic Properties of La–Ni Alloys

The mixing enthalpies of the La–Ni binary liquid alloys are determined by isoperibol calorimetry in the composition range 0 < x<0.45 at 1430 K and 0.75 < x< 0.80 at 1800 K. The thermodynamic properties of the La–Ni binary liquid alloys are calculated for the entire composition range using the model of ideal associated solutions and reliable published data. The thermodynamic activities of components show negative deviations from the ideal behavior; the mixing enthalpies are characterized by exothermic effects. The minimum mixing enthalpy of the melts is –28.0 ± 0.2 kJ/mol at x= 0.6.

Simulation of the effect of volume size factor of solute atoms and their clusters on one dimensional motion of interstitial clusters in Ni binary alloys

The effect of the volume size factor of solute atoms and their clusters on the one-dimensional motion of interstitial clusters was studied by computer simulations. Solute atoms were placed on the migration path of the interstitial clusters, and the change in the migration energy of the interstitial clusters was obtained by the static method. The volume size factor of Au atoms in a Ni-Au binary alloy was systematically changed from −30% to +100%. When the volume size factor of the solute atoms was larger or smaller than Ni atoms, the migration energy of the interstitial clusters increased. The average migration energy required for the interstitial clusters to pass through one, two, three, and four solute atoms (volume size factor: +63.7%) was 0.57, 1.28, 2.09, and 2.47eV, respectively. If the solute atom clusters grow and their density is sufficiently high, the jump frequency of the interstitial clusters is so low that the interstitial clusters cannot move through the solute atom clusters under an irradiation temperature of 573K.