Ni Alloy Research Articles

The role of Ni minor additions on the mechanical characteristics of Sn-1.5Ag-0.5 wt.% Cu (SAC155) Pb-free solder alloy

AbstractMicrostructure analysis, thermal behavior, and tensile creep characteristics of the Sn-1.5Ag-0.5Cu-x wt.% Ni (SAC155-xNi, x = 0, 0.05, 0.1, 0.2, and 0.5 wt.%) solder alloys have been examined. The Ni additions have greatly modified the microstructure of Ni-free alloy into bulky fibrous eutectic regions and included the contemporary (Cu, Ni)6Sn5, and (Ni, Cu)3Sn4 IMCs. Ni additions slightly increased solidus temperature and melting temperature of them. The results of tensile creep resistance have shown dependence on Ni content and testing temperatures due to bulky fibrous eutectic regions and finer IMCs. Creep rates vary with Ni content across all temperatures and stresses. The SAC155-0.05Ni alloy has the lowest and the SAC-0.0Ni alloy has the highest creep rates at all tested conditions. The delicate dispersed IMCs of Ag3Sn and Cu–Ni–Sn resulted in a significant increase in stress exponent (n$$\approx $$ ≈ 5–8), enhancing its deformation resistance. The $$n$$ n values of alloys decrease as the testing temperature rises due to a change in the dominant creep mechanism. The average values of activation energy (Q) of SAC155-xNi alloy ranged from 60.20 to 68.02 kJ/mol. These Q values are coherent to the process of pipe self-diffusion through dislocation cores.

Recent achievements in nickel based electrochemical biorefinery of 5-hydroxymethylfurfural

The electrochemical conversion of biomass offers a sustainable approach for energy recycling and environmental protection. Specifically, the electro-oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid is notable for its potential to produce value-added products, including biodegradable plastics and other environmentally friendly materials. A critical factor in this process is the performance of the catalysts. Nickel-based catalysts have shown high efficiency and durability, primarily due to the formation of Ni-OOH active sites. This paper reviews recent advancements in the nickel-based electrocatalytic oxidation of HMF, including the use of Ni, Ni alloys, Ni oxides, Ni hydroxides, and other Ni complex, and discusses the underlying catalytic mechanisms. Additionally, it introduces the coupling reactions, various reactor designs and outlines future research directions, focusing on exploring reaction mechanisms, developing electrocatalysts, and practical applications of this technology.

Microstructure and mechanical properties of high-strength Al-Zn-Mg-Ni alloys with excellent twin-roll castability

This paper proposes a new high-strength Al-Zn-Mg-Ni alloy with excellent twin-roll castability compared with conventional Al-Zn-Mg-Cu alloys. Thermodynamic calculations were carried out to identify the solidification range and amount of residual liquid phase in the Al-Zn-Mg-(Cu, Ni) alloys, which are factors exerting significant influence on the formation of defects in the final strips. The designed Al-Zn-Mg-Ni alloys exhibited a narrower solidification range and smaller amount of residual liquid at the final solidification temperature, resulting in excellent surface quality after twin-roll casting compared with Al-Zn-Mg-Cu alloys. A series of rolling and heat treatment processes was performed on the Al-Zn-Mg-Ni alloy strips, and the mechanical properties of the final sheets were evaluated. The results showed that the yield and tensile strength were increased without affecting the elongation up to approximately 1.0wt.% Ni addition. Additionally, compared with conventional Al-Zn-Mg-Cu alloys, equivalent or higher tensile properties were achieved after T6 tempering. In conclusion, the Al-Zn-Mg-Ni alloy exhibits high-strength with excellent twin-roll castability.

A new nanoindentation approach for determining both indentation size effect and continuous apparent activation volume during loading of nanocrystalline Ni and Ni-20 wt.% Fe alloy

A new nanoindentation approach is developed in this study to determine both indentation size effect (ISE) and continuous apparent activation volume () during loading of nanocrystalline nickel (NC Ni) and nanocrystalline nickel-20 wt.% iron alloy (NC Ni-Fe alloy). This approach involves conducting nanoindentation tests under loading modes controlled by both constant strain rate (CSR) and constant loading rate (CLR). Firstly, a new empirical expression for the parameter in the modified Nix-Gao model is established to study the strain rate dependence of the ISEs created in the CSR and CLR tests. Then, continuous data of each individual sample (indentation) during loading are obtained in the CLR test through the alternative use of continuous stiffness measurement technique. The stress dependence of is analyzed based on Duhamel et al.’s model, which considers the role of vacancies generated during inhomogeneous dislocation nucleation. Finally, based on the above experimental and theoretical work as well as transmission electron microscopy observation, the influences of loading mode, loading rate, and material properties (stacking fault energy) on resulting intrinsic hardness of NC Ni and NC Ni-Fe alloy are analyzed. The nanoindentation approach developed in this study provides profound insights into the mechanical behaviors during loading and underlying mechanisms of materials.

Improving interface joining strength of Ti6Al4V/AZ91D bimetal prepared by compound casting via Ni-coated Ti6Al4V lattice structure

The joining of titanium/magnesium (Ti/Mg) bimetals presents challenges due to the low mutual solubility and absence of metallurgical reactions between Ti and Mg. Herein we utilized the Ni-coated Ti6Al4V lattice structure to enhance the interfacial property of Ti6Al4V/AZ91D bimetal prepared by compound casting. The Box-Behnken design (BBD) was employed to optimize the lattice design. The resulting structure featured struts with a diameter (ds) of 2.4 mm, an aspect ratio (l/ds) ratio of 5.4, a tilt angle (ω) of 57°, and a node-to-strut diameter ratio (dn/ds) of 2.4. The optimized Ti6Al4V lattice structure manufactured by selective laser melting (SLM) exhibited α′ martensite with a high dislocation density, conferring exceptional tensile strength. The rough texture of the lattice surface enhanced adhesion with the Ni coating and improved wetting and reactivity between Ni and AZ91D alloy melt. This resulted in the formation of a serrated metallurgical interface with AZ91D alloy, which was primarily composed of α-Mg + Mg2Ni eutectic structure+τ-Ni2Mg3Al ternary phases. An impressive joining strength of 116.1 MPa was obtained under the optimized lattice structure, and the bimetal joint predominantly fails through the damage of AZ91D, aligning closely with simulated failure predictions.

High strength C/Si‒Ni‒C composites fabricated by reaction melt infiltration with Si‒Ni alloy at lower temperature

AbstractSilicon‒nickel alloy (Si‒Ni) was first used for fabricating continuous carbon fiber reinforced ceramic matrix composites by reaction melt infiltration process. Based on Si‒Ni phase diagram, 66.7 at.% Si‒Ni was chosen, which has a lower liquidus temperature of 1115°C. The C/Si‒Ni‒C composites were infiltrated at temperature of 1270°C‒1390°C, and the prepared composite consists of C, SiC, NiSi, and NiSi2 phases. The density of the composite is higher than 2.29 g/cm3 and their open porosity is below 3%, indicating the composite was infiltrated completely by the Si‒Ni alloy. The C/Si‒Ni‒C composite exhibits significantly higher flexural strength and fracture toughness compared to the C/C‒SiC composite infiltrated with pure silicon at 1500°C. Specifically, the flexural strength and fracture toughness of the C/Si‒Ni‒C composite infiltrated at 1390°C increase by 140% and 300%, respectively. The improvement of mechanical properties contributed to the low reactivity between silicon‒nickel with carbon fibers, and the lower infiltration temperature, which can reduce degradation of carbon fiber as reinforcement. Moreover, the NiSi2 and NiSi alloy phases in the C/Si‒Ni‒C composite replace the brittle silicon phase in the C/C‒SiC composite, which can obviously enhance the fracture toughness.

Photothermal Dry Reforming of Methane on Yolk‐Shell Co–Ni Alloy@SiO2 Catalyst

Photothermal dry reforming of methane (PT‐DRM) is an appealing pathway to convert carbon dioxide and methane into synthesis gas, a mixture of carbon monoxide and hydrogen, via photothermal heating induced by concentrated sunlight. Coke formation and sintering of active metal nanoparticles, however, are a key issue for catalyst stability. In the present study, we demonstrated Co–Ni alloy nanoparticles encapsulated with a porous SiO2 shell exhibited improved catalytic activity and stability for PT‐DRM using visible/near‐IR light irradiation without any other external heating. The addition of a trace amount of Co (1–5 mol% relative to total metal) and SiO2 encapsulation enhanced the stability by simultaneously suppressing coke formation and sintering of the metal nanoparticles. Furthermore, we revealed that the position of the light irradiation spot has a crucial role in the conversions of methane and carbon dioxide and product selectivity, presumably due to large temperature gradient under the light irradiation. These findings would contribute to designing for effective PT‐DRM catalysts with improved activity and enhanced resistance for both coke formation and sintering and emphasize the significant contribution of the temperature gradients to the performance in PT‐DRM.

Dilute Pd−Ni Alloy through Low‐temperature Pyrolysis for Enhanced Electrocatalytic Hydrogen Oxidation

AbstractDesigning highly active and cost‐effective electrocatalysts for the alkaline hydrogen oxidation reaction (HOR) is critical for advancing anion‐exchange membrane fuel cells (AEMFCs). While dilute metal alloys have demonstrated substantial potential in enhancing alkaline HOR performance, there has been limited exploration in terms of rational design, controllable synthesis, and mechanism study. Herein, we developed a series of dilute Pd−Ni alloys, denoted as x% Pd−Ni, based on a trace‐Pd decorated Ni‐based coordination polymer through a facile low‐temperature pyrolysis approach. The x% Pd−Ni alloys exhibit efficient electrocatalytic activity for HOR in alkaline media. Notably, the optimal 0.5 % Pd−Ni catalyst demonstrates high intrinsic activity with an exchange current density of 0.055 mA cm−2, surpassing that of many other alkaline HOR catalysts. The mechanism study reveals that the strong synergy between Pd single atoms (SAs)/Pd dimer and Ni substrate can modulate the binding strength of proton (H)/hydroxyl (OH), thereby significantly reducing the activation energy barrier of a decisive reaction step. This work offers new insights into designing advanced dilute metal or single‐atom‐alloys (SAAs) for alkaline HOR and potentially other energy conversion processes.

Decoration of Pt–Ni Alloy on Molten Salt Etched Halloysite Nanotubes for Enhanced Catalytic Reduction of 4-Nitrophenol

Decoration of Pt–Ni Alloy on Molten Salt Etched Halloysite Nanotubes for Enhanced Catalytic Reduction of 4-Nitrophenol

Copper-promoted growth of hierarchical Cu–Co–Ni alloys on copper nanodendrites for enhanced hydrogen evolution in a wide pH range

Efficient and sustainable electrocatalysts for the hydrogen evolution reaction (HER) using earth-abundant elements are crucial for eco-friendly hydrogen production, particularly under neutral and acidic conditions. In metallic alloys, careful selection of alloying elements and control over the composition, morphology, electronic structure, and structural defects are expected to tune electrocatalytic activities. In this work, we introduce a two-step electrodeposition approach to create a 3D porous trimetallic alloy, Cu@Cu–Ni–Co, exhibiting excellent catalytic activity and stability for HER in neutral and acidic environments. The process begins with the electrodeposition of 3D copper dendrites, which was found to be crucial for the catalyst's mechanical stability, followed by the deposition of the trimetallic alloy, where copper's inclusion promotes the controlled growth of the alloy's 3D structure. The Cu@Cu–Ni–Co catalyst outperforms Cu@Ni, Cu@Co, Cu@Ni–Co, and GC@Cu–Ni–Co electrocatalysts in neutral and acidic conditions, highlighting the importance of the developed electrodeposition approach. In 1.0 M phosphate-buffer solution (PBS), Cu@Cu–Ni–Co achieves a current density of 10 mA cm−2 at an overpotential of 275 mV with a Tafel slope of 134 mV dec−1, maintaining remarkable stability in both acidic and neutral conditions at high current densities (48–165 mA cm−2) for up to 50 h without any decline in activity.

Additively Manufactured Stainless Steel Wind Tunnel Model Support Featuring Honeycomb Structures for Vibration Attenuation

Wind tunnel model support (WTMS) is an indispensable component of wind tunnel testing. However, the presence of vibrations within the model‐support system can compromise the accuracy of data and give rise to significant safety hazards. In this study, an approach for vibration attenuation by incorporating honeycomb structures into the design of the WTMS is proposed. To this end, stainless steel WTMSs with integrated honeycomb structures are fabricated by selective laser melting (SLM). Results showed that stainless steels prepared under optimized SLM processing parameters exhibit high crystallinity and consist of single‐phase Fe–Cr–Ni alloy. The stainless steels exhibited robust mechanical properties, including a tensile strength of ≈1 GPa, an elongation of ≈8%, and a compressive strength of ≈1.4 GPa. These exceptional mechanical properties can be attributed to the formation of a cellular structure and tangled dislocations. The first‐order and the third‐order resonant response of WTMS honeycomb structures can be effectively reduced. The vibration reduction mechanism can be attributed to the occurrence of local resonance when the natural frequency of the internal periodic unit of the WTMS closely matched the vibration frequency of the model. The utilization of honeycomb structures holds significant potential for achieving vibration attenuation in WTMS.

On the Strengthening Mechanism in Lath Martensite of As-Quenched Fe–Ni Alloys

On the Strengthening Mechanism in Lath Martensite of As-Quenched Fe–Ni Alloys

Interaction of microstructure evolution mechanism in Ti-0.3Mo-0.8Ni alloy with initial lamellar microstructure during isothermal compression below the β-transus

The flow behavior and interaction of microstructure evolution mechanisms for a near α Ti-0.3Mo-0.8Ni alloy with as-cast lamellar microstructure are investigated at temperatures of 800∼880 °C in the α+β region with wide strain rate range from 0.01s−1 to 30s−1 during isothermal compression. It is demonstrated that the main reasons of flow softening in the true stress-true strain curves are the kinking of lamellar α, dynamic α→β transformation (DT), dynamic spheroidization (DS), and dynamic recovery (DRV) of β grain. The instability phenomena such as adiabatic shear band (ASB) and flow localization (FL) are the main causes of the stress collapse in the curves at higher strain rate. The dislocation density at the kinking position of initial lamellar α is higher. With the increase of strain rate, the mechanism of the DS changes from flat separation to slat shear. The diffusion of the β-stabilizer results in starting the DT, promoted by the thermodynamic coupling. The interactions between different microstructure evolution mechanisms are extremely complex. In the early stage of hot deformation, the DT promotes the kinking of lamellar α. With the increase of deformation amount, the DT inhibits the DS at higher strain rates, and conversely, the DS promotes the DT. At lower strain rates, the DT and DS accelerate each other in the middle and late stages of hot deformation. The DT and DS are restricted by the process of lamellar α kinking in the middle and late stages of hot deformation.

Hardfacing of GX40CrNiSi25-20 cast stainless steel with an austenitic manganese steel electrode

Abstract To enhance the wear and corrosion resistance of engineering components, various surface modification techniques have been devised. Among these, arc welding processes employing specialized electrodes offer relatively straightforward methods with low production costs for hardfacing applications. This paper focuses on the hardfacing process using pulsed current arc welding to reinforce cast austenitic steel structural components, aiming to prolong their lifespan. Typically, hardfacing coatings utilize Fe, Ni, and Co-based alloys. Among these, Fe-based alloys, such as manganese austenitic alloys employed in our experiments, are favored for their robust mechanical work hardening capacity, resulting in significant hardness enhancements (from 186–219 HV5 in the as-deposited layer to 468–492 HV5 after mechanical work hardening) under intense wear and impact conditions. The innovation of the hardfacing process developed in this study lies in utilizing a universal TIG source adapted for manual welding with a covered electrode in pulsed current mode. This hardfacing technique can be applied to both worn components in operation and new ones before being put into service, thereby ensuring long-term durability and reducing maintenance costs.

Dissimilar fabrication of the TC4/Ni60 bimetallic structure by laser melting deposition using a V/Cu transition bilayer

The bonding of Ti and Ni alloys to manufacture high-quality bimetallic structures represents an optimal integration strategy for fully leveraging their superior performance. However, the metallurgical bonding between TC4 and Ni60 dissimilar metals is extremely challenging due to the formation of TiNi, TiC and TiFe brittle intermetallic compounds and the differences in thermophysical properties. To address this issue, this paper presents a solution based on the compatibility of elemental components. A V/Cu transition bilayer was designed to achieve defect-free bonding between TC4 and Ni60 by laser melting deposition. The microstructure of the TC4/Ni60 bimetallic structure was analyzed by SEM, XRD and EBSD to evaluate its feasibility. The results indicate that the generation of brittle intermetallic compound phases was reduced to a certain extent when a V/Cu transition bilayer was employed, thus preventing cracking and peeling of the TC4 substrate and Ni60 cladding layer. Additionally, the mechanical properties of the bimetallic structure were evaluated through micro-shear tests and tensile tests. The micro-shear test results indicate that the weakest layer of the bimetallic structure is the Cu transition layer with a shear strength of 183.0 ± 108.8 MPa and an indentation rate of 8.25 ± 3.3 %. The room temperature tensile results demonstrate that the developed bimetallic structure fractured at the Cu/Ni60 interface, exhibiting a tensile strength of 286.3 ± 54.1 MPa and an elongation of 6.3 ± 0.5 %. The expected research can provide valuable references for improving the mechanical properties of TiNi dissimilar bimetallic structures produced by laser melting deposition.

Preparation and Performance Study of Zinc Dibenzyl Dithiocarbamate Self‐Assembled Film on Electrodeposited Cu–Ni Alloy Surface

ABSTRACTThis study developed a green and efficient surface protection method for Cu–Ni alloys. A zinc dibenzyl dithiocarbamate film was prepared on the surface of electrodeposited Cu–Ni alloys using the self‐assembly method to improve the material's corrosion resistance in seawater. The influence of zinc dibenzyl dithiocarbamate concentration and self‐assembly time on the corrosion resistance of the self‐assembled films was investigated through electrochemical testing. The findings revealed that at a zinc dibenzyl dithiocarbamate concentration of 10 mmol/L and a self‐assembly time of 20 min, the self‐assembled film exhibited the most robust corrosion resistance, achieving a maximum corrosion inhibition efficiency of 97.70%. The self‐assembly and adsorption mechanism of zinc dibenzyl dithiocarbamate were explored using molecular dynamics simulations and adsorption isotherms. The protective effect of self‐assembled films was visually observed through salt spray testing. Zinc dibenzyl dithiocarbamate self‐assembled film technology has high application prospects in the field of marine anti‐corrosion.

Effect of Co Addition on the Microstructure and Mechanical Properties of an Al-2wt.%Ni Alloy

Effect of Co Addition on the Microstructure and Mechanical Properties of an Al-2wt.%Ni Alloy

Strengthening effects from Mg and Ni in Al-mischmetal eutectic alloys: Insights from microstructures and Bayesian analysis

This study investigates, both experimentally and via machine-learning modeling, the strengthening mechanisms and effects of Mg and Ni additions to Al-MM (mischmetal, a sustainable Ce+La+Nd mixture to replace Ce) alloys, aiming to develop creep- and coarsening-resistant Al-MM-Mg-Ni alloys with a focus on twin eutectic co-solidification microstructures. Based on near-eutectic Al-9MM (wt%) alloy, the Mg and Ni additions introduce solid-solution and eutectic strengthening, respectively. Ternary hypo-eutectic Al-9MM-0.25/0.5/0.75Mg variants improve hardness up to 592 MPa. Ternary Al-9MM-2/4Ni display hypo-eutectic microstructures. Al-9MM-2Ni shows separated growth of Al11MM3 and Al3Ni eutectic phases, while Al-9MM-4Ni features finely intertwined Al11MM3-Al3Ni fibers from co-solidification. The hyper-eutectic Al-9MM-5Ni contains primary Al3Ni particles alongside the intertwined fibers, raising the hardness to 739 MPa. Finally, quaternary Al-9MM-0.5/0.75Mg-4/4.5Ni alloys maintain hypo-eutectic microstructures with a significant increase of hardness to 929 MPa. The series Al-9MM, Al-9MM-0.75Mg, Al-9MM-4Ni, and Al-9MM-4.5Ni-0.75Mg exhibits increasing tensile yield strengths of 70, 83, 88, and 105 MPa, with decreasing ductility of 12.0, 5.8, 2.0, and 0.8 %. All Al-9MM-Mg-Ni alloys exhibit excellent hardness retention and coarsening resistance after thermal exposure at 300 or 350°C for up to 11 weeks. A machine-learning model accurately predicts the alloy's hardness evolution under thermal exposure. Feature analysis quantitively shows the strengthening impact of MM, Ni, and Mg addition and demonstrate enhanced strengthening retention, under thermal exposure, of Al11MM3 over Al3Ni, alongside the beneficial effects of Mg homogenization. At 300 °C, Al-9MM-Mg-Ni alloys demonstrate higher creep resistance than most precipitation-strengthened Al-Sc-Zr-based alloys and solid-solution-strengthened Al-Mg alloys, with Al-9MM-4Ni as the best performer.

New insights into the crystal structure and physical properties of the antiferromagnetic Mn2MAl (M = Fe, Co, Ni) alloys

New insights into the crystal structure and physical properties of the antiferromagnetic Mn2MAl (M = Fe, Co, Ni) alloys

Analysis of Corrosion Potential of Zn, Ni, and Zn-Ni Alloy Using Ab Initio Calculations Supported by Experimental Thermodynamics Data

The purpose of this study is to investigate the corrosion properties of Zn, Ni, and Zn - Ni alloy using density functional theory (DFT). DFT can assist in predicting the thermodynamic properties of challenging compounds such as metals, alloys, and transition metal oxides. In the present work, DFT is used to predict Zn, Ni, and Zn - Ni alloy phase diagram. The Hubbard correction (U) and dispersion correction (D) are used to minimize the inherent error associated with the DFT. We studied the crystal structure, electronic structures, and thermodynamic energies of Zn and Ni compounds using the generalized gradient approximation (GGA) density functional employing Perdew–Burke–Ernzerhof (PBE). We have developed the corresponding Pourbaix diagram of Zn, Ni, and their alloy to compare the performance of density functional theory with the experimental observations. The corrosion behavior of various alloys including Zn11Ni2,ZnNi,ZnNi3 are compared and discussed. This can be useful for predicting the corrosion-resistant properties of these alloys.