Effect Of Ni Content Research Articles

Microstructure and corrosion properties of CoCrCuFeMnNix high‐entropy alloys prepared by powder metallurgy

AbstractCoCrCuFeMnNix (x = 0.5, 1.0, 1.5, 2.0 mol, named Ni0.5, Ni1.0, Ni1.5, and Ni2.0, respectively) high‐entropy alloys (HEAs) were prepared by powder metallurgy. The effects of Ni content on its microstructure and corrosion resistance in a 3.5% NaCl solution were studied. The HEAs with low Ni content consisted of FCC1 primary phase, FCC2 secondary phase, and a few σ phases. While the Ni2.0 alloy was composed of the FCC phase and a small amount of σ phase. The results of polarization corrosion in 3.5% NaCl solution show that the increase of Ni content led to the increase of corrosion potential of the alloy and the decrease of corrosion current density and average corrosion rate. Among them, Ni2.0 alloy had the best corrosion resistance. The electrochemical impedance spectroscopy analysis showed that the increase in Ni content promoted the increase of the polarization resistance of the alloy RCPE and the thickness of the passive film, thus improving the corrosion resistance of the alloys.

Effect of Ni content and crystallographic orientation on mechanical properties of single-crystal (CoCr)100-x Ni x medium-entropy alloy

Nanoindentation analyses of (CoCr)100-x Ni x medium-entropy alloys with different Ni contents and crystal orientations were carried out by molecular dynamics simulations. Analyses show that the force-displacement curves during elastic deformation are in good accordance with the Hertz contact theory and the elastic modulus is closely related to the Ni contents and crystal orientations. The elastic-plastic transition point appears later in (CoCr)67Ni33 than in other alloys. The plastic deformation was studied by exploring the instantaneous microstructure, which was found to be dominated by homogeneous nucleation of Shockley partial dislocations and the accumulation of stacking faults, and different levels of dislocation density were produced in the alloys with different Ni contents and crystal orientations. By analyzing the evolution of dislocation density and hardness, a linear relationship between the square root of dislocation density and hardness can be revealed, which agrees well with the classical Taylor hardening model, and the empirical constant is found closely related to crystal orientations.

Revealing the Effect of High Ni Content in Li-Rich Cathode Materials: Mitigating Voltage Decay or Increasing Intrinsic Reactivity.

Li-rich layeredoxides are considered as one of the most promising cathode materials for secondary lithium batteries due to their high specific capacities, buttheissueofcontinuous voltage decay during cycling hinders their market entry. Increasing the Ni content in Li-rich materials is assumed to be an effective way to address this issue and attracts recent research interests. However, a high Ni content may induce increased intrinsic reactivity of materials, resulting in severe side reactions with the electrolyte. Thus, a comprehensive study to differentiate the two effects of the Ni content on the cell performance with Li-rich cathode is carried out in this work. Herein, it is demonstrated that a properly dosed amount of Ni can effectively suppress the voltage decay in Li-rich cathodes, while over-loading of Ni, on the contrary, can cause structural instability, Ni dissolution, and nonuniform Li deposition during cycling as well as severe oxygen loss. This work offers a deep understanding on the impacts of Ni content in Li-rich materials, which can be a good guidance for the future design of such cathodes for high energy density lithium batteries.

Effect of Ni Content on Microstructure, Mechanical Properties, and Abrasion Behavior of Fe-B-C Alloy

The microstructure, mechanical properties, and abrasion resistance of an Fe-2wt%B-0.35wt%C alloy with various Ni contents were analyzed. As the Ni addition increases, the Ni content of the matrix and M2B (M indicates Fe, Cr, and Mn) increases linearly with the relationships of y = 0.992x and y = 0.224x, respectively. With the Ni content increasing from 0 wt% to 1.2 wt%, the critical cooling rate of the alloy changes from 0.5 °C/s to 0.1 °C/s, which decreases the volume fraction of as-cast pearlite from 72.86 vol% to 3.49 vol%. Moreover, the Ni atom replacement is helpful in the formation of edge dislocation in the M2B, facilitating an increase in the toughness characteristic δ A of M2B from 2.85 to 3.04. Interestingly, when the Ni content is less than 0.9 wt%, the heat treatment makes a huge contribution to the macrohardness, bending stress, and abrasion resistance of alloy, owing to the formation of martensite. However, once the Ni content exceeds 0.9 wt%, heat treatment plays a negative role in the macrohardness, bending stress, and abrasion resistance of the alloy, because of the precipitation of M23(B,C)6.

Molecular Dynamics Simulation of NiTi Shape Memory Alloys Produced by Laser Powder Bed Fusion: Laser Parameters on Phase Transformation Behavior.

In this study, the deposition, powder spreading, and laser fusion processes during the laser powder bed fusion (L-PBF) process were studied using molecular dynamics (MD) simulation. The effect of Ni content on the characteristic phase transformation temperatures was also investigated. Shape memory effect and superelasticity of NiTi alloys with Ni content ranged from 48.0% to 51.0% were analyzed. By employing MEAM potentials, the effects of the laser power, spot diameter, and scanning speed on the molten pool size and element evaporation were studied. Simulation results showed that a larger spot diameter renders a higher Ni content in the molten pool, also a larger molten pool. A faster scanning speed leads to a higher Ni content in the molten pool, and a smaller molten pool. The element is difficult to evaporate using small laser power and a large spot diameter. The element in the molten pool expresses a great evaporation effect when the Es is larger than 0.4 eV/ų. According to Ni content within the molten pool during laser fusion, characteristic phase transition temperatures in single crystalline NiTi alloys with variant Ni content were investigated by employing a 2NN-MEAM potential. Characteristic phase transition temperature changes as the Ni content increases from 48.0% to 51.0%. Austenite boundaries and Ni content in the boundary were found to be the keys for controlling the characteristic phase transformation temperature.

Reaction Behavior and Formation Mechanism of ZrB2 and ZrC from the Ni-Zr-B4C System during Self-Propagating High-Temperature Synthesis

Self-propagating high-temperature synthesis (SHS) is a good way to prepare ZrB2-ZrC/metal cermet composites. In this work, ZrB2-ZrC/Ni cermet composites with various Ni contents were successfully fabricated by SHS using the Ni-Zr-B4C system. The effects of Ni content and particle size of the B4C powder on the SHS reaction were investigated. The results indicated that with an increase in Ni content, the adiabatic temperature, maximum combustion temperature, ignition delay time, and ceramic particle size in the product all showed a gradually decreasing trend. The SHS products and the ignition of the SHS reactions were significantly dependent on the B4C particle size. The formation mechanism of ZrB2 and ZrC during SHS from the Ni-Zr-B4C system was proposed based on the combustion wave quenching experiment.

Self-activating metal-polymer composites for the straightforward selective metallization of 3D printed parts by stereolithography

The integration of multifunctional elements directly embedded in three-dimensional (3D) printed parts is the cutting-edge of additive manufacturing (AM) and it is crucial for enlarging as well as for strengthening AM role in industrial applications. Here, a straightforward and low-cost method that synergically combines stereolithography (SLA) and selective electroless metallization (EM) is presented for the fabrication of 3D parts characterized by complex shapes and end-use multifunctionalities (conductive, magnetic, mechanical properties). To this end, a novel photocurable composite based on acrylate resin loaded with nickel (Ni) particles is developed for high-resolution SLA-printing of features with self-catalytic properties for EM. Ni particles are loaded in the resin to trigger metal deposition avoiding time consuming and expensive laser-based surface activation. The effect of Ni content on SLA behavior as well as on the efficiency of EM process is studied. Metallized SLA cured samples show good electrical and magnetic properties as well as improved robustness with respect to their non-loaded counterparts. Then, selective metallization of 3D printed parts is successfully achieved by implementing a multi-material SLA-printing where loaded and non-loaded resins are properly interchanged with strong adhesion at the interface, thus offering a cost-effective approach for rapid prototyping of functional free-form features on 3D structures.

Identifying the effect of Ni solubility on the thermoelectric properties of HfNiSn-based half-Heuslers

Phase diagrams provide important guidance for the optimal design of thermoelectric materials. Previous studies demonstrated a specific solubility of Ni atoms in TiNiSn and ZrNiSn, which can impede phonon transport and regulate the electronic band structure. But the thermodynamic investigation and the effect of Ni content on thermoelectric properties for the HfNiSn system are absent. In this work, we constructed an isothermal section phase diagram of the Hf-Ni-Sn ternary system at 1173 K and determined the solubility of Ni in the vacant position to be 0.04 < x < 0.16. At this temperature profile, the stoichiometric ratio HfNiSn is located in the two-phase region of HfNi1+xSn + Sn when it is in equilibrium, and the homogeneity region may be broken by the process of ball milling and sintering. Calculation results indicate that the excess-Ni in HfNiSn will generate impurity levels in the forbidden band and localized phonon modes above the acoustic branch. The intermediate-Heusler phase formed by extra Ni atoms can work as a phonon scattering center and reduce the lattice thermal conductivity near room temperature, but the Sn impurities generated by the disrupted thermal equilibrium will neutralize this effect at high temperatures. Overall, the impact of the Ni-rich environment on HfNiSn-based half-Heusler is very different from that of alloys TiNiSn and ZrNiSn, which is of great significance for the comprehensive understanding of (Ti, Zr, Hf)NiSn system.

Effect of Ni content on the corrosion performance of Cu-10Al-Ni ternary alloys in neutral sulfate solutions

Effect of Ni content on the corrosion performance of Cu-10Al-Ni ternary alloys in neutral sulfate solutions

Effect of Ni content, temperature on the electrical and colorimetric properties of nano NixZn(1-x)O blue pigments

Nanosized Ni doped ZnO (NixZn1-xO, with 20 ≤ × ≤ 70) were synthesized by simple coprecipitation method at different calcinations temperature (400, 600, 800 and 1000 o C). All synthesized oxides well characterized by XRD, scanning electron microscopy (SEM). The electrical properties and the colorimetric parameters (CIEL L* a* b*) were measured. The results obviously show that Ni2+ ions incorporated into the ZnO structure without difficulty. For the highest concentration of Ni2+ for x = 0.40 and 0.70 of Ni2+ doping, the XRD revealed an extra diffraction peak characteristic to NiO, indicating an upper limit of Ni concentration. The crystallite size was discovered to be between 13 and 109 nm. With the addition of Ni to the ZnO, the temperature dependency of electrical conductivity of samples increases. The temperature dependence of dielectric constant of samples is found to decrease with incorporation of Ni in the solution. The samples show very good blue color with load 20% of Ni.

Effects of Ni Content on Particle Size of Secondary Phase in Cu-Based Alloys with Liquid Immiscibility by Laser-Melting

Effects of Ni Content on Particle Size of Secondary Phase in Cu-Based Alloys with Liquid Immiscibility by Laser-Melting

Material properties of gradient copper‐nickel alloy fabricated by wire arc additive manufacturing based on bypass-current PAW

In this paper, the bypass-current plasma arc welding (BC-PAW) based on PAW was employed to fabricate copper-nickel (Cu-Ni) gradient thin-walled structures. The effect of forming accuracy and compositional homogeneity of the bypass current Cu-Ni structure was first verified by controlled experiments. The effect of Ni content on the microstructure and mechanical properties of Cu-Ni gradient structures fabricated using bypass current was then investigated, with a focus on grain orientation and texture analysis of the three intermediate Cu-Ni mixed gradient layers. The results showed that the use of bypass current in the additive manufacturing of Cu-Ni gradient structures can improve the forming accuracy and effectively eliminate lateral composition deviations within the gradient layers. In the Cu-Ni mixed gradient layers, the average grain size of the gradient layers decreased with increasing nickel content, and unusually large secondary grains appeared in different gradient layers. Due to the different Ni content, different degrees of amplitude modulation decomposition occurred in different gradient layers, resulting in changes of grain orientation and texture composition. Under the combined effects of solid solution strengthening, fine grain strengthening and amplitude modulation decomposition, the microhardness and tensile strength increased with increasing nickel content and then decreased, reaching a maximum near the side of the gradient composition biased toward nickel. The fracture analysis showed a transition from ductility to quasi-fracture.

Bainite nucleation mechanism and mechanical properties in low carbon bainite deposited metals with different nickel additions

Exploring the transformation mechanism of bainite is necessary to achieve the matching of high-strength and accepted damage tolerance for low carbon bainite deposited metals. In this work, the effect of Ni content on the bainite transformation mechanism and mechanical properties has been investigated systematically with Ni contents change from 4 wt. % to 9 wt. %. Scanning electron microscope, transmission electron microscope, and electron backscatter diffraction were used for the characterization of the microstructure. Results indicated that the nucleation method of bainite ferrite (BF) laths changed from autocatalytic nucleation to classical nucleation when the Ni content exceeded 5.5%. The deposited metals with BF laths nucleated by autocatalysis had excellent combinations of strength and toughness while the toughness severely deteriorated as the classical nucleation replaced the autocatalytic nucleation. The presence of autocatalytic nucleation resulted in the refinement of microstructure, and the density of high-angle grain boundaries had been improved effectively. In particular, apparent variant selection tendency in microstructure occurred accompanied by the disappearance of autocatalytic nucleation. Moreover, the strong variant selection tendency resulted in numerous identical variants growing next to each other and coarsening the microstructure. In particular, the key factor for the generating of autocatalytic nucleation was that the lower interfacial energy for the new BF laths nucleated through autocatalytic nucleation, and resulted in a lower nucleation activation energy. Therefore, autocatalytic nucleation tends to occur in the deposited metals with low bainite transformation speed due to enough time and space for new BF laths nucleates at existing BF lath.

The effect of Ni content on phase transformation behavior of NiTi alloys: An atomistic modeling study

In this study, the thermodynamic behavior of single- and poly-crystalline NiTi shape memory alloys (SMAs) with different Ni contents was investigated by molecular dynamics (MD) simulations. By employing the 2NN-MEAM potential, the influence of Ni content on phase transformation temperature is analyzed for single- and poly-crystalline NiTi. Our simulation results show that the characteristic phase transformation temperature increases and then decreases as the binary NiTi alloy changes from Ti-rich to Ni-rich state. In addition, the change of Ni content also dramatically affects the formation of martensite variants and twins, whereas it shows slight effect on the formed types of variants. According to the characteristic phase transformation temperature obtained by thermally induced phase transformation, temperatures of 500 K, 600 K, 700 K and 300 K, 400 K, 500 K, three for each type of alloys, are selected to discuss the superelastic effect of single- and poly-crystalline NiTi. By conducting uniaxial loading and unloading under different constant temperature conditions, corresponding stress–strain responses are obtained. The microstructure and grain orientation of each model are studied. The herringbone structure exists in nanocrystals with different Ni contents, but is not identified in single crystals, whether under thermally induced or stress-induced phase transformation conditions.

CO2 Methanation of Biogas over Ni-Mg-Al: The Effects of Ni Content, Reduction Temperature, and Biogas Composition

Biogas is mainly composed of CH4 and CO2, so it is used as an alternative energy to CH4 with high energy density by separating and removing CO2 from biogas. In addition, it can be utilized by producing synthesis gas (CO and H2) through thermal decomposition of biogas or by synthesizing CH4 by methanation of CO2. The technique of CO2 methanation is a method that can improve the CH4 concentration without CO2 separation. This study aims to produce more efficient methane through CO2 methanation of biogas over Ni-Mg-Al catalyst. So, the effect of Ni contents in catalyst, catalyst reduction temperature, CO2 concentration in biogas, and the initial concentration of CH4 on CO2 conversion rate and CH4 selectivity was investigated. In addition, the effect of increasing CO2 concentration, H2/CO2 ratio, and GHSV (gas space velocity per hour) on H2 conversion, CH4 productivity, and product was investigated. In particular, the durability and stability of CO2 methanation was tested over 60 wt% Ni-Mg-Al catalyst at 350 °C and 30,000/h for 130 h. From the long-term test results, the catalyst shows stability by maintaining a constant CO2 conversion rate of 72% and a CH4 selectivity of 95%.

Effect of Ni Content on Solidification Behavior and Hot-Tearing Susceptibility of Co–Ni–Al–W-Based Superalloys

Effect of Ni Content on Solidification Behavior and Hot-Tearing Susceptibility of Co–Ni–Al–W-Based Superalloys

Dry Reforming of Methane on Ni/Nanorod-CeO2 Catalysts Prepared by One-Pot Hydrothermal Synthesis: The Effect of Ni Content on Structure, Activity, and Stability

The nanorod morphology of the CeO2 support has been recognized as more beneficial than other morphologies for catalytic activity in the dry reforming of methane. Ni/nanorod-CeO2 catalysts with different Ni contents were prepared by one-pot hydrothermal synthesis. Samples were characterized by X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), H2-temperature-programmed desorption (H2-TPD), field emission scanning electron microscopy/energy dispersive spectroscopy (FE-SEM/EDS), Brunauer–Emmet–Teller (BET) and Barrett–Joyner–Halenda (BHJ) analysis. The effect of Ni content on the size and the intrinsic strain of ceria was analyzed by the Size–Strain plot and Williamson–Hall plot of XRD data. The average Ni particle size and Ni dispersion were determined by H2-TPD. XRD and H2-TPR analysis revealed a strong Ni–support interaction that limited nickel sintering. The activity for the dry reforming of methane was tested with the stoichiometric mixture CO2:CH4:N2:He = 20:20:20:140, gas hourly space velocity (GHSV) = 300 L g−1 h−1, and temperatures in the range of 545–800 °C. The turnover frequency (TOF) value increased linearly with the average Ni particle size in the range of 5.5–33 nm, suggesting the structure sensitivity of the reaction. Samples with Ni loading of 4–12 wt.% showed high H2/CO selectivity and stability over time on stream, whereas the sample with a Ni loading of 2 wt.% was less selective and underwent rapid deactivation. Only a small amount of nanotubular carbon was observed by FE-SEM after the time-on-stream experiment. Deactivation of the low-Ni-content sample is ascribed to the easier oxidation of the small Ni particles.

The effect of Ni on Fe and Al impurities by MIVM model for the silicon production

Many impurities in industrial silicon significantly affect the production of solar-grade silicon. Based on a large amount of actual production data, the effect of Ni content on the Fe and Al contents in an actual production process was evaluated using statistical methods and MIVM models in this study. The results obtained by statistical analysis (linear regression) based on the big data of an actual production are consistent with the results of Si–P–Fe and Si–P–Al calculated using the MIVM model. The presence of Ni is beneficial to the removal of Fe and Al in Si. When the content of Ni in Si is high, pickling and refining removal of Fe and Al will increase. The effect of impurities in Si–Ni–Fe and Si–Ni–Al ternary systems and Si–Fe–Al–Ni quaternary system calculated using the MIVM model is consistent. In the actual production process, the remaining low-concentration impurities have a slight effect on the results. The nickel content can be adjusted based on the MIVM calculation results. The power consumption of industrial silicon production can be increased by first removing the Fe and Al and then removing the Ni, which is helpful for preparing solar-grade polysilicon using the metallurgical method.

Effects of Ni content on microstructure and wear behavior of Al–13Si–3Cu–1Mg-xNi-0.6Fe-0.6Mn alloys

As one of the lightweight and wear-resistance metallic structural materials, cast Al–Si alloys have been widely studied in automobile and defense industries to meet the greater demands for elevated-temperature wear-resistance properties. In this study, the effect of Ni content on the microstructure and wear behavior of Al–13Si–3Cu–1Mg-xNi-0.6Fe-0.6Mn alloys were investigated by thermodynamic modeling, X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and ball-on-disk reciprocating sliding test. The results show that the θ-Al2Cu and γ-Al7Cu4Ni phases are disappeared, while the δ-Al3CuNi, ε-Al3Ni, and T-Fe phases are formed with the increasing of Ni contents. The 3-D network structure is composed of α-Al matrix, eutectic Si, Q, Ni-rich, and Al15(Mn, Fe)3Si2 phases, which leads to the best hardness and wear-resistance of the alloy with 2 wt% Ni. The fracture and debonding of excessive coarse ε-Al3Ni phase deteriorate the wear-resistance and ductility of the 3Ni alloy. The main wear mechanisms of the tested alloys are abrasive, delamination and oxidative wear at 25 °C and convert to adhesive wear at 350 °C.

Hydrogen storage kinetics and thermodynamics of Mg‐based alloys by rare earth doping and Ni substitution

AbstractBACKGROUNDThe traditional means of hydrogen storage cannot meet the widespread application of hydrogen energy. Therefore, developing new and efficient hydrogen storage materials and safe hydrogen storage technology is a top priority, which can effectively solve the problem of hydrogen storage and delivery. Its development and application are of great significance to environmental protection and energy development.RESULTSPr5Mg95−xNix (x = 5, 10, 15) were prepared by induction furnace melting, and the effect of Ni content on the kinetics and thermodynamics of the alloys were systematically investigated. The phase composition, microstructure and storage properties of gaseous hydrogen were investigated using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the change in Ni content significantly improves the kinetic properties of the alloys in terms of adsorption and desorption. However, it has little effect on the thermodynamic properties of the alloys.CONCLUSIONThe lattice of the alloys expands after hydrogenation and shrinks after the release of hydrogen. The change of lattice stress leads to cracking or even fracture of alloy particles and, the higher the nickel content, the more cracks there are. Thus, the specific surface area of the alloys is increased and the contact area with hydrogen is expanded, promoting hydrogen diffusion within the material and improving the hydrogen absorption and desorption rate. Furthermore, as the Ni content increases, the dehydrogenation activation energy of the alloys decreases significantly, which is the main reason for the improved dehydrogenation kinetics of the alloys. © 2021 Society of Chemical Industry (SCI).