Alloy Layer Research Articles

Na-Sn Alloy Regulated Protective Coating Layer Enables the Long Life Dendrite-Free Sodium Metal Batteries

Sodium metal anodes are highlighted as the most potential candidates for next-generation batteries due to their high theoretical capacity (1166 mAh/g), low electrochemical potential (-2.71 V vs standard hydrogen electrode), and cheaper material cost. However, practical application of sodium metal batteries is limited due to the uneven solid electrolyte interphase layer and insignificant coulombic efficiency. Designing a protective coating layer as an artificial solid electrolyte interphase layer on a sodium metal anode is one of the main approaches to maintaining the homogenous deposition and long-term stability during the process of electrochemical plating/stripping. Herein, a protective layer of (Na-Sn) alloy and Na-Cl insulator was formed by establishing the spontaneous self-alloying reaction. Most importantly, the proposed Na-Sn metal alloy layer has high ionic conductivity, stable chemical/electrochemical interphase, and robustness to enhance the homogenous Na ion deposition and prevent the uncontrollable sodium dendrites. Based on these effects, using the Na-Sn alloy symmetric cell exhibits the stable electrochemical performance (500 h at 2 mA/cm2 & 2 mAh areal capacity). The Full cell was assembled using the Na3V2(PO4)3 cathode and Na-Sn alloy over sodium metal anode in diglyme electrolyte, showing excellent cycle stability up to 100 cycles at 1 C rate and discharge capacity of 168 mAh/g at 0.1 C rate. This work presents a new technique to produce a uniform Na ion deposition and safe dendrites-free sodium metal batteries (SMBs).

Catalytic Activity of Au-Cu Alloy on TiO2 Nanotubes for Alcohol Oxidation

First fuel cell was discovered 180 years ago and still the ideal, namely cheap and effective catalytic materials are highly required. Such device allows to convert chemical energy into electrical one without pollutant gasses emission. In the case of alcohol fuel cells, methanol, ethanol, ethylene glycol and glycerine are considered as a power source. Platinum is commonly used for alcohol electrocatalyst, because of its high activity and stability. However, due to the high cost and limited supply platinum should be replaced by material that small amount is enough to reach satisfactory catalytic effect. In our work, we present the activity of gold-copper modified titania nanotubes toward electrocatalytic alcohol oxidation [1].The material is fabricated using three steps such as: 1) anodization of Ti plate, 2) thin 10 nm AuCu alloy layer magnetron sputtering, and 3) rapid thermal annealing in an argon atmosphere [2]. Scanning electron microscopy confirmed the presence of well-ordered TiO2 nanotubes (TiNT) with diameter of 101 ± 13 nm and length of 709± 53 nm. After AuCu alloy magnetron sputtering and thermal treatment spherical nanoparticles were formed on NT surface. Based on top view SEM images the diameter of gold copper nanoparticles is equal to 38 ± 5 nm. However, the TEM images showed that diameter of nanoparticles changes from 5 nm to 60 nm (Figure 1a-d) where the bigger particles are on the top of the nanotubes. Applied fabrication procedure allowed us to obtain electrode material that can be used in methanol, ethylene glycol or glycerine oxidation. The highest catalytic activity of AuCu alloy was obtained for glycerine oxidation. Prepared material exhibited 90 times higher current density after glycerine addition to the alkaline solution than pure TiNT (Figure 1e). Furthermore, higher current density towards alcohol oxidation was registered for thermally annealed sample (an-AuCu/TiNT) than for non-annealed one (n-AuCu/TiNT).Cyclic voltammetry measurements for the an-AuCu/TiNT in glycerine solution at different scan rates confirmed diffusion controlled process. The oxidation peak current density located at +0.3 V and +1 V grows up to 120 mV/s with slope of 51 and 81 µA/cm2 respectively, which confirmed more privilege process at +1 V vs. Ag/AgCl/0.1M KCl. We believe that the information reported in our work provide wider knowledge about new and more efficient electrodes for alcohol oxidation.Research is financed by National Science Centre (Poland): Grant No. 2019/35/N/ST5/02604[1] W. Lipińska et al. Journal of Materials Science, 57 (2022) 13345, DOI:10.1007/s10853-022-07471-7[2] W. Lipińska et al. ACS Applied Materials & Interfaces, 13 (2021) 52967, DOI:10.1021/acsami.1c16271 Figure 1

Surface gradient structures in single-crystal nickel alloy induced by ultrasonic-assisted high-speed grinding

The gradient structures in surface layer of single-crystal nickel alloy (SX alloy) were produced (i.e., nanograin, submicron grain and coarse single crystal of bulk material) by means of ultrasonic-assisted high-speed grinding (UAHSG). The surface layer with a grain size gradient (from 29.7 to 111.8 nm) along depth from the treated surface featured impressive nano-indentation hardness (up to 12.1 GPa) beyond the initial SX alloy. The coupled effects of high rotation speed of abrasive grain (100 m/s) and the severe ultrasonic vibration impact (up to 4.3 times per contact cycle) induced large strain (up to 6.67) and ultrahigh strain rate (∼109 s−1), resulting in the superiority of such a structure gradient. This study suggests a new approach of UAHSG that can not only achieve high machining efficiency, but also make nickel alloy stronger by tailoring the surface layer gradient structures.

Experimental evaluation of a WC–Co alloy layer formation process by multibeam-type laser metal deposition with blue diode lasers

A tungsten carbide–cobalt (WC–Co) composite layer was formed on a stainless-steel type 304 (SS304) substrate using multibeam laser metal deposition (LMD) with blue diode lasers. This paper aims to provide WC–Co layer formation with low porosity and high layer formation efficiency by using the multibeam LMD process. The effects of process parameters such as laser output power and powder feed rate are tied together to explain the geometry of the melt layer as well as the fraction of the laser energy used for melting a material. The experimental results show that the porosity rate and layer formation efficiency were recorded at 0.3% and 0.0042 mm3/J, respectively, at the laser output power of 180 W and a powder feed rate of 75 mg/s. It was revealed that layer formation efficiency was dependent on the laser output power.

Electrode lifetime in resistance spot welding of coated sheets: Experiments and modeling

One of the most important challenges associated with resistance spot welding of coated sheets is short electrode life time. It has been established that the two factors-electrode tip growth and surface alloy formation-each affect negatively on electrode life when considered separately. This study's objectives were to examine the combined effects of these factors and ascertain how they relate to electrode life. Due to this, two electrodes were used to investigate the electrode life when resistance welding galvanized steel: a conventional Cu-Cr electrode with a compressive strength of 800 MPa and a dispersion strengthened copper electrode with a high volume percentage of alumina particles (3.5 %) with a compressive strength of 500 MPa. Electrode life time tests showed that the life of composite electrode (700 weld number) was reduced by about 20 % compared to Cu-Cr electrode (900 weld number). Electrode tip features showed that cracking in Cu-Cr electrode formed at about 200 weld number while in composite electrode this occurred at 600 weld number. The electrode tip cross section revealed the formation of four separate alloy layers at the tips of both electrodes, however the Cu-Cr electrode had significantly higher crack densities and a lower average thickness during life test (45 µm) than the composite electrode (55 µm). It was caused by the higher rate of electrode tip growth in Cu-Cr electrodes, which increased welding current and extended electrode life. A simple model was purposed for electrode life based on Joule heating effect that takes the effects of both electrode tip growth and electrode tip alloy formation in to account. According to the model and experiments when significant interaction occurs at the electrode tip, the some tip growth rate not only isn’t detrimental but also increases the electrode lifetime.

Study of Wear of an Alloyed Layer with Chromium Carbide Particles after Plasma Melting

Depending on operating conditions, metals and alloys are exposed to various factors: wear, friction, corrosion, and others. Plasma surface alloying of machine and tool parts is now an effective surface treatment process of commercial and strategic importance. The plasma surface alloying process involves adding the required elements (carbon, chromium, titanium, silicon, nickel, etc.) to the surface layer of the metal during the melting process. A thin layer of the compound is pre-applied to the substrate, then melted and intensively mixed under the influence of a plasma arc, and during the solidification process, a new surface layer with optimal mechanical properties is formed. Copper-based alloys—Cu-X, where X is Fe, Cr, V, Nb, Mo, Ta, and W—belong to an immiscible binary system with high mechanical strength, electrical conductivity, and magnetism (for Fe-Cu) and also high thermal characteristics. At the same time, copper-based alloys have low hardness. In this article, wear tests were carried out on coatings obtained by plasma alloying of CuSn10 and CrxCy under various friction conditions. The following were chosen as a modifying element: chromium carbide to increase hardness and iron to increase surface tension. It is noted that an increase in the chromium carbide content to 20% leads to the formation of a martensitic structure. As a result, the microhardness of the layer increased to 700 HV. The addition of CuSn10 + 20% CrxCy and an additional 5% iron to the composition of the coating improves the formation of the surface layer. Friction tests on fixed abrasive particles were carried out at various loads of 5, 10, and 50 N. According to the test results, the alloy layer of the Fe-Cr-C-Cu-Sn system has the greatest wear resistance under abrasive conditions and dry sliding friction conditions.

Tin Oxide Modification of Indium Oxide Gas Sensitive Layers to Increase Efficiency of Gas Sensors

Monitoring of air pollutions is one of actual trends in the development of industrial and domestic instrumentation. There are sets of tasks for improving gas analytical instruments because of increasing demand for control of a concentration of explosive and toxic gases on a level with maximum allowable concentration. The aim of the paper was to investigate the methods of formation and elemental composition of indium oxide films modified with tin oxide on the surface of gas sensor elements as one of the promising compounds for improving the detection efficiency of explosive and toxic gases in the environment. The processes of formation of gas-sensitive films deposited on the surface of nichrome alloy information electrodes were studied in this article. Substrates of anodic aluminum oxide with area of 10 × 10 mm2 and a thickness of 45 ± 0,5 μm were chosen for research. Two layers on the surface of the samples were formed. The first layer was formed from NiCr alloy (Ni – 80 %, Cr – 20 %) with a thickness of ≈ 0.3 μm by ion-plasma sputtering. The second layer was based on indium oxide with addition of tin oxide with thicknesses from ≈ 0.3 μm to ≈ 1.0 µm and coated with sol-gel technology. Five samples of gas-sensitive films were formed with different methods of deposition and heat treatment. Scanning electron microscopy was used for study of films’ morphology and elemental compositions of samples. The most perfect continuous semiconductor films were obtained by multilayer applying of a sol-gel paste. When semiconductor films were processed at annealing temperatures of 700 °C and higher in vacuum so there was observed cracking of semiconductor films up to a layer of NiCr alloy. The developed surface of gas-sensitive films allows to reach high sensitivity and affectivity of semiconductor sensors for control of air gas composition.

Влияние высокоэнергетического воздействия при плазменной резке на структуру и свойства поверхностных слоёв алюминиевых и титановых сплавов

Introduction. Plasma cutting of various metals and alloys is one of the most productive processes for obtaining workpieces, especially when using reverse polarity plasmatrons. The use of plasma cutting in the production of workpieces of large thicknesses potentially allows to increase the productivity of the process. In the domestic industry plasma cutting equipment of foreign production is widely used, which poses the problem of import substitution of manufactured products and equipment with the corresponding parts of Russian companies. For this reason, at present the Institute of Strength Physics and Materials Science together with the company "ITS Siberia" develops plasma cutting equipment on reverse polarity currents. At the same time, in order to determine the peculiarities of influence of parameters and modes of plasma cutting process on the structure of metal in the cutting zone, it is necessary to conduct comparative studies on different metals and alloys. Aim of the work: is to identify the characteristics of the influence of high energy impact on the structure and properties of surface layers of aluminum and titanium alloys during plasma cutting using a plasma torch operating with reverse polarity currents. The research methods are optical metallography, microhardness measurement and laser scanning microscopy of the surface after plasma cutting. Results and discussions. The conducted researches show a wide range of possibilities to adjust the process parameters of plasma cutting of aluminum alloys AA5056 and AA2124, and titanium alloy Grade2. For the alloys used in this work there are optimal values of process parameters, deviations from which lead to various violations of cut quality. Aluminum alloys show a tendency to significant de-strengthening in the cutting zone, which is associated with the formation of a large crystalline structure and large incoherent secondary phases with simultaneous depletion of the solid solution with alloying elements. Titanium alloys are characterized by quenching effects in the cutting zone with increasing microhardness values. Oxides are also formed in the surface layers despite the use of nitrogen shielding gas. In the alloy Ti-4Al-1Mn, in the previously conducted works, the formation of oxide films with high hardness is not noted, while in the Grade2 alloy at cutting in the surface layers oxides are formed sharply increasing the values of microhardness of the material up to values of about 15 GPa. This situation can complicate mechanical processing of titanium alloys after plasma cutting. The obtained results indicate a rather low value of the allowance for further machining after plasma cutting of aluminum and titanium alloys.

The positive contribution of Cr2O3 reinforcing nanoparticles to enhanced corrosion and tribomechanical performance of Ni–Mo alloy layers electrodeposited from a citrate-sulfate bath

The service lifetime and efficiency of the engineering materials can be enhanced by adopting an appropriate surface modification strategy. This work has endeavored to finish the surface of St37 steel by electrodeposited Ni–Mo alloy layers strengthened by various levels of suspended Cr2O3 nanoparticles in the bath, i.e., 0–8 g/L, to obtain high corrosion and tribomechanical performance. The phase structure, morphology, chemistry, and roughness of the surfaces were assessed by XRD, FESEM, EDS, and AFM, respectively. Corrosion performance of the developed films was measured using OCP, EIS, and potentiodynamic polarization techniques, as well as long-term immersion in the corrosive NaCl medium. Vickers microhardness tester and ball-on-disk tribometer were employed to evaluate the tribomechanical behavior of the coatings. While there is no change in the phase structure of the Ni–Mo alloy layer with the included Cr2O3 nanoparticles, the nanocomposite layers show a more compact and rougher surface. The microhardness of the alloy coating was enhanced by approx. 30 % with the inclusion of the 8 g/L Cr2O3 nanoparticles in the electrolyte. An increase in polarization resistance of the nanocomposite layers compared to alloy one, by 16 kΩ, demonstrated the improvement in the corrosion protection performance with the included nanoparticles. The Ni–Mo–Cr2O3 nanocomposite layers offered lower COF and wear mass loss than the Ni–Mo alloy layer, irrespective of Cr2O3 loadings. The surface modification of mild steels by the Ni–Mo–Cr2O3 nanocomposite films can promote their service lifetime and efficiency in severe industrial applications.

Preparation, microstructure, and mechanical properties of SiCp/AZ91 magnesium matrix laminar material

The SiCp/AZ91 magnesium matrix laminar material is designed to maximize the contribution of alternating soft and hard layered structures to strength-strain synergies. Its compressive strength reaches ∼622 MPa, exhibiting a remarkable improvement of 6000 % and 200 % compared to a monolithic SiC layered skeleton (10.2 MPa) and AZ91 alloy (316 MPa), respectively. The high-density SiCp/AZ91 layer enhances the strength of the composites, while the AZ91 alloy layer not only alleviates stress concentration but also inhibits crack initiation and propagation, imparting the composites with high toughness.

Antioxidation effect of coatings prepared by helium-ion implantation of copper surfaces

The antioxidation effect of a shallow alloying layer introduced by ion implantation is inadequate for many oxidizable metals, limiting its application in antioxidation technology. In this work, the feasibility of preparing an antioxidation coating using ion implantation is explored with the aim of producing copper (Cu) surfaces with strong antioxidation properties. A coating consisted of amorphous carbon and silica is prepared on a Cu surface by helium-ion implantation with pump oil. The formation of the coating is attributed to the bombardment effect of ion implantation and ion beam scanning, which dissociates the bonds of the precursor coating material and drives the redistribution of dissociated species on the Cu surface. During He+ implantation, the C–C and C–O bonds are more likely to break down, resulting in the formation of amorphous carbon. The Si and O combine to form silica because of the high bonding energy of Si–O. The prepared coating exhibits a strong antioxidation effect by blocking the diffusion of Cu cations and enhancing the adhesion of the overlying oxidized film to the substrate. This study demonstrates the feasibility of preparing antioxidation coatings using ion implantation, which could advance the application of ion implantation in antioxidation technology and Cu in microelectronics.

Lignin‐assisted alloying engineering of CoNiRu trimetallic nano‐catalyst for effective overall water splitting

AbstractThe development of inexpensive and robust bifunctional electrocatalysts for hydrogen evolution reactions (HER) and oxygen evolution reactions (OER) was crucial for renewable energy systems. Herein, a novel strategy for preparing CoNiRu alloy nano‐electrocatalyst capsulated by nitrogen‐doped biochar (CoNiRu@NLC) using carboxymethylated lignin macromolecules was proposed. CoNiRu@NLC exhibited excellent HER and OER performance, and the overall water splitting voltage was only 1.47 V at 10 mA/cm2 with excellent catalytic stability, which was superior to the noble metal catalysts Pt/C ‖ RuO2. Theoretical calculations confirmed the strong electron interaction between CoNiRu alloy and carbon layer, and XPS patterns proved that the electrons transfer from Ru to CoNi, significantly boosted the electrocatalytic activity. This study demonstrated the importance of lignin‐driven alloying on enhancing catalytic performance and provided a concept for the development of high‐efficiency catalysts and high‐value utilization of polyphenol biomass.

Structure Formation in Surface Layers of Aluminum and Titanium Alloys during Plasma Cutting

Structure Formation in Surface Layers of Aluminum and Titanium Alloys during Plasma Cutting

The Effect of Laser Shock Peening on the Physical and Mechanical Properties of the Surface Layer of D16 Aluminum Alloy

The Effect of Laser Shock Peening on the Physical and Mechanical Properties of the Surface Layer of D16 Aluminum Alloy

Structural Features and Morphology of Surface Layers of AA2024 and AA5056 Aluminum Alloys During Plasma Cutting

Structural Features and Morphology of Surface Layers of AA2024 and AA5056 Aluminum Alloys During Plasma Cutting

Elucidating the mechanical response and microstructure evolution of the constituent layers in gradient-structured Cu alloys

The design of gradient structure (GS) in metallic materials has been reported to obtain superior mechanical properties due to the interaction between the GS layer and the coarse-grained (CG) matrix. In this study, the mechanical response and microstructural evolution of the corresponding constituent layers of GS Cu-4.5Al alloy at different pre-strains were systematically investigated. The tensile results showed that the strain hardening capability of the GS layer was improved due to the constraint of the CG matrix. Meanwhile, an extra strengthening was observed at the interface between the GS layer and the CG matrix, resulting in a higher yield strength of the CG matrix constrained by the GS layer than that of the CG matrix without the GS layer constraints. Moreover, the extra strengthening at the interface of the GS and CG matrix was gradually reduced with increasing pre-strain due to the weakening of the interaction at the interface. Microstructural observations at the interface between the GS layer and the CG matrix revealed that more dislocations and twins were activated during pre-strain in the CG matrix having GS constraints than that of the CG matrix without GS constraints. The present work provides important insights on the interaction between constituent layers, in terms of the mechanical response and microstructure evolution.

Microstructure and properties of Ni-Ti based gradient laser cladding layer of Ti6Al4V alloy by laser powder bed fusion

An economical gradient layer was successfully prepared on Ti6Al4V alloy produced by laser powder bed fusion (L-PBF) using only composition design, gravity segregation, and laser cladding of micrometer-sized Ni powder, nanoscale SiC and Y2O3 powders. The microstructure of the layer was systematically studied to analyze the reasons for its improved wear and corrosion resistance. The results indicated that the cladding layer comprised top, middle, lower, and bottom layers. The main phases in top layer were Ti2Ni and β-Ti. Whereas the middle layer is composed of two regions, one with a similar structure to the top layer, and the other is the nickel-enriched area denoted as NEAm where the main phases were Ti2Ni, TiNi, and amorphous. The main phase of the lower layer was TiNi. Owing to the close distance between the bottom layer and the substrate, there was a significant increase of Ti in the bottom layer, and so the bottom layer and the top layer contained the same main phases. The soft phase of TiNi in lower layer would prevent the propagation of cracks that may occur in the top layer. The solidification and formation process of the gradient structure of the cladding layer was analyzed with Scheil model, and the simulation results were consistent with the experimental results. A nanocomposite system consisting of Ti3Si, α-Ti, and β-Ti was found for the first time in this study. The relationship between Ti3Si and α-Ti was coherent, and the relationship between α-Ti and β-Ti satisfied the Burgers orientation relationship. The mechanism of the nanocomposite system generation was that Si was enriched at the grain boundaries after the formation of Ti2Ni, where Ti and Si combined to form Ti3Si, and then Ti3Si was used as nucleating particles to form β-Ti/α-Ti. The α-Ti and β-Ti in the fusion line area at the bottom layer also satisfied the Burgers coherent relationship, indicating excellent bonding strength between cladding layer and substrate. A large number of solute atoms in the solid solution, pinning of second-phase particles, and the amorphous were the fundamental reasons for the substantial improvement in hardness and wear resistance. A small amount of Ni in the top layer increased the polarization of the cathodic reaction, keeping the corrosion current low. In addition, numerous dispersed fine phases in the top layer increased the resistance of charge transfer at the phase interfaces, which was the fundamental reason for the improved corrosion resistance.

New Approach for Manufacturing Ti–6Al–4V+40%TiC Metal-Matrix Composites by 3D Printing Using Conic Electron Beam and Cored Wire. Pt. 1: Main Features of the Process, Microstructure Formation and Basic Characteristics of 3D Printed Material

In this paper, a new approach for additive manufacturing metal-matrix composites based on Ti–6Al–4V titanium alloy reinforced with titanium carbide particles, as well as layered structures consisted of such composite and Ti–6Al–4V alloy layers is considered. The approach is based on 3D printing with a conical electron beam using a special cored wire, whose composition corresponds to metal-matrix composite. The issues of production such a wire, the features of the 3D printing process, when using it, as well as the features of formation of the microstructure and phase composition of the printed composite material are described. The issues of titanium-carbide particles’ wetting with Ti–6Al–4V melt during process of 3D printing, as well as possible thermogravitational effects (floating or drowning) for solid TiC particles within the melt are considered in detail with additional experiments. The influence of individual components of the wire composition on the formation of the microstructure and its uniformity over the cross section of the printed layer is shown. The possibility of controlling the formation of homogeneous structural state and obtaining sufficiently high values of the hardness (of above 600 HV) of the metal-matrix composite layer printed on the Ti–6Al–4V baseplate is shown.

Optimizing isothermal oxidation behavior of the Y-containing Nb-Ti-Si based alloy: The role of precursor Y2O3

The effect of Y2O3 on the oxidation resistance of Nb-Ti-Si based alloys was investigated. Acicular Y2O3 is generated with Y content exceeding 0.3 at%. Oxidation tests reveal that the mass gain per unit area of the Y-containing alloys is lower than that of the Y-free alloy at 800 °C and 1200 °C. The oxide layer of the Y-free alloy will fracture and even pesting. After adding Y, the Y2O3 can react with Nb2O5 and TiO2 to generate YNbTiO6. The pinned YNbTiO6 at the interface enhances the adhesion between the oxide layer and substrate, slowing down the growth of the oxide layer.

Effect of Cavitation Water Jet Peening on Properties of AlCoCrFeNi High-Entropy Alloy Coating

High-entropy alloys have been widely used in engineering manufacturing due to their hardness, good wear resistance, excellent corrosion resistance, and high-temperature oxidation resistance. However, it is inevitable that metallurgical defects, such as micro cracks and micro pores, are produced when preparing the coating, which affects the overall performance of the alloy to a certain extent. In view of this situation, cavitation water jet peening (CWJP) was used to strengthen the AlCoCrFeNi high-entropy alloy coating. The effect of CWJP impact time on the microstructure and mechanical properties of CWJP were investigated. The results show that CWJP can form an effective hardening layer on the surface layer of the AlCoCrFeNi high-entropy alloy. When the CWJP impact time was 4 h, the microhardness of the surface layer of the specimen was harder than that of 2 h and 6 h, and the CWJP impact time had little effect on the thickness of the hardening layer. Observing the surface of the untreated and CWJP-treated specimens using the EBSD test, it was evident that the microstructure was significantly homogenized, the grains were refined, and the proportion of small-angle grain boundaries increased. The system reveals the grain refinement mechanism of the AlCoCrFeNi high-entropy alloy coating during plastic deformation. This study aims to provide a new surface strengthening method for obtaining high-performance AlCoCrFeNi high-entropy alloy coatings.