Two-component Metal Research Articles

Оценка антибактериальных свойств монослойных покрытий Cu-Nb и Cu-Ta на биомедицинском сплаве Ti-6Al-4V

The aim of this study: Evaluation of the antibacterial properties of two-component metal coatings based on Cu-Ta and Cu-Nb applied to samples from the biomedical Ti-6Al-4V alloy by magnetron sputtering. Methods. Two-component metal coatings based on Cu-Ta and Cu-Nb were obtained by magnetron sputtering with joint spraying of targets made of pure metals Cu, Nb, Ta. The antibacterial and antimicrobial properties of the coatings were evaluated in vitro using the disk diffusion method, also known as the radial diffusion method in agar. Results. It was found that coatings with a thickness of 10 microns demonstrated varying degrees of antimicrobial efficacy during three days of testing: the maximum inhibition zone of the Ta-Cu coating reached 24.0 mm for S. Aureus and 17.0 mm for C. Albicans. For Nb-Cu coating, the maximum inhibition zone reached 25.0 mm for S. Aureus and 15.5 mm for C. Albicans. Conclusions. The optimal parameters of direct current magnetron sputtering of Ta-Cu Nb-Cu antibacterial thin films on Ti-6Al-4V alloy substrates have been selected. The antimicrobial effect of Ta-Cu and Nb-Cu coatings is more effective against bacteria than against fungi, and with the same thickness, Ta-Cu coatings are better suited to protect the endoprosthesis from microbial infections than Nb-Cu coatings. Ta-Cu and Nb-Cu coatings are promising for the production of endoprosthesis implants with increased surface resistance to both bacteria and fungi. The results obtained are promising for the development of technologies for obtaining coatings for medical implants with increased bactericidal and biocompatible surface properties.

Theoretical predictions and experimental verification on the phase stability of enthalpy-stabilized HE TMREB2s

• Single-phase formation abilities of 120 two-component metal (transition metal and rare earth metal) diborides (TCBs) are studied by first-principles. • The thermodynamic stability of single-phase high-entropy transition and rare-earth metal diborides (HE TMREB 2 s) were quantified using the energy distribution of the local mixing enthalpies of all possible configurations. • HE TMREB 2 s were predicted to be enthalpy-stabilized materials, i.e., mixing enthalpy plays a critical role in single-phase stability. • The experimental results confirmed that enthalpy dominates the thermodynamic domain and drives the stability of REB 2 s in HE TMREB 2 s. Transition metal diborides (TMB 2 s) are the materials of choice in extreme environments due to their excellent thermal and chemical stabilities. However, the degradation of oxidation resistance of TMB 2 s at elevated temperature still hinders their applications. To cope with this challenge, it is effective to incorporate rare earth elements to form high-entropy transition and rare-earth metal diborides (HE TMREB 2 s). To obtain thermodynamically stable single-phase structures for HE TMREB 2 s, a “16 × 16 mixed enthalpy matrix” is constructed using first-principles calculations to predict the single-phase formation ability of 120 two-component diborides (TCBs). Through the use of the “16 × 16 mixed enthalpy matrix” of TCBs, specific combinations of TMB 2 s and REB 2 s that are most likely to form single-phase HE TMREB 2 s are confirmed. Subsequently, based on the energy distribution of the local mixing enthalpies of all possible configurations, the enthalpy and entropy descriptors of HE TMREB 2 s (RE = Sc, Lu, Tm, Er, Ho and Dy) are investigated. It is found that the mixing enthalpy plays a critical role in the stability of the single-phase HE TMREB 2 s, i.e., HE TMREB 2 s are enthalpy-stabilized materials. The experimental results further confirm that enthalpy dominates the thermodynamic domain and drives the stability of REB 2 s in HE TMREB 2 s. This study validates that enthalpy-stabilized HE TMREB 2 s can further expand the compositional space of ultrahigh temperature ceramics (UHTCs) and is expected to further improve the oxidation resistance and high temperature properties of UHTCs.

Enthalpy driving force and chemical bond weakening: The solid-solution formation mechanism and densification behavior of high-entropy diborides (Hf1−x/4Zr1−x/4Nb1−x/4Ta1−x/4Scx)B2

(Hf0.2Zr0.2Nb0.2Ta0.2Sc0.2)B2 was designed to improve the densification and solid-solution formation of high-entropy transition metal diborides, and its phase stability was predicted using the energy distribution of the local mixing enthalpy of all possible configurations. It was found that (Hf0.2Zr0.2Nb0.2Ta0.2Sc0.2)B2 are enthalpy-stabilized materials. The two-component metal diborides formed by transition metal diborides (HfB2, ZrB2, TaB2 and NbB2) with ScB2 are thermodynamically favorable, based on the mixing enthalpy. Therefore, the introduction of ScB2 in high-entropy metal diborides is beneficial to reduce the mixing Gibbs free energy during the boro/carbothermal reduction process, which enables the formation of single-phase solid solution at low temperatures. Even high-entropy metal diboride powders with large particle sizes, 25–57 µm, can achieve sintered density up to ~97% due to the introduction of ScB2 in high-entropy metal diborides, owing to its weakening action on the TM d - B p and the TM dd bonding.

Potential for obtaining and applying complex niobium ferroalloys

This paper provides information regarding the application of niobium in industry and the scale of its production in the world and the Russian Federation. Most of the niobium deposits in Russia consist of pyrochlore, apatitepyrochlore and columbitepyrochlore types of ores. They contain a significant amount of phosphorus. Therefore, all enrichment schemes for these ores contain a dephosphorization stage which increases the price of the product and reduces the degree of niobium extraction. The paper explores the possibility of improving the end-to-end production scheme: niobium ore – beneficiation – niobium ferroalloy. The bulk of ferroniobium is intended for steel microalloying and can be replaced by complex ferroalloys with a reduced niobium content. The paper considers the issues of obtaining complex niobium ferroalloys from a rough concentrate with a weak content of niobium. It has been established that the addition of 25 – 40 % of silicon or 12 – 30 % of aliminum to the twocomponent metal system Fe – Nb causes the transfer of niobium ferroalloys (15 – 20 % Nb) from the refractory category to lowmelting materials. The crystallization temperatures are less than 1400 °C. The substantiation of using a complex niobium ferroalloy instead of ferroniobium is given. This alloy has reduced niobium content and increased silicon or aluminum content. Higher service characteristics of the complex ferroalloy are noted in comparison with ferroniobium (temperature of the initiation of crystallization and density). They indicate an increased assimilation of niobium when using a complex ferroalloy for steel microalloying. The paper presents data on the possibility of dephosphorization of niobium concentrates in the process of pyrometallurgical production of a complex ferroalloy. An improved scheme for the production of niobiumcontaining ferroalloys is proposed. This consists of the use of niobium concentrate for melting the intermediate ferroalloy containing a reduced concentration of niobium oxides and an increased concentration of silicon (aluminum). This ferroalloy can be used effectively for steel microalloying with niobium.

Orthogonal reactivity and interface-driven selectivity during cation exchange of heterostructured metal sulfide nanorods.

We report predictive guidelines for the substoichiometric cation exchange of model two-component metal sulfide nanorods containing divalent cations of similar hardness. Unit cell volume changes, cation radii, solubility constants, and solid state interfaces influence selectivity during substoichiometric exchange of Cu+ when multiple products are possible.

Localization of Melt Components in a Crucible as a Result of Inserting Anisothermic Rod with Non-wettable Boundaries

Concentration-induced convection of a binary metal melt in a rectangular crucible has been studied numerically in the case of a mixture with a eutectic phase diagram. The calculations are performed for realistic parameters which correspond to the pair of metals Sn-Pb. A solid rod with non-wettable boundaries and a non-uniform longitudinal temperature distribution on the surface is immersed into the melt vertically at the center of the crucible. The condition of complete non-wetting allows us to consider the interface between the melt and the rod to be free. The temperature non-uniformity leads to inhomogeneity of the surface tension. As a result, the thermocapillary force generates a steady convective flow first on the surface of the rod and then in the volume. Due to this motion, the heavy component of the alloy is transferred along the rod’s surface to the butt-end. At the boundary patches with the excess of concentration it has been extracted into the volume by means of the desorption mechanism. In the presence of weak convection in the volume, this component is partially accumulated near the bottom of the crucible under the butt-end. Thus, there takes place a process of separation of heavy admixture for the two-component metal melts.

Особенности и закономерности процессов плавления и кристаллизации двухкомпонентных металлических сплавов

The processes of melting and crystallization in some two-component alloys based on the Ag-Cu model system have been investigated using high resolution differential scanning calorimetry. During crystallization or melting jumps in the heat flow upon reaching the liquidus line were detected. It is assumed that during crystallization, these phenomena are associated with the formation of a large number of local microvolumes (concentration fluctuations) in the liquid, enriched with the component leading to crystallization. Their appearance precedes the beginning of the processes of spontaneous formation and growth of numerous crystals of the new phase. The necessity of correcting the existing ideas about the crystallization and melting of two-component metal alloys is revialed.

Size Characteristics of the Surface Tension of One- and Two-Component Metal Melts

A molecular theory based on the lattice gas model is employed to describe the surface tension of the vapor–liquid interfaces of one- and two-component metal melts. The surface tension of the melts are calculated in the quasi-chemical approximation of taking into account intermolecular interactions of the nearest neighbors. Parameters of the model are found from the experimental data for the bulk surface tension of the melts, which enables the calculation of the surface tensions of vapor–liquid interfaces of one- and two-component droplets with different sizes as a function of their radii. Estimates for the minimum size of small droplets of melts having the properties of a homogeneous phase inside them, which correspond to their thermodynamic stability, are obtained.

Real-time in situ dynamic sub-surface imaging of multi-component electrodeposited films using event mode neutron reflectivity.

Exquisite control of the electrodeposition of metal films and coatings is critical to a number of high technology and manufacturing industries, delivering functionality as diverse as anti-corrosion and anti-wear coatings, electronic device interconnects and energy storage. The frequent involvement of more than one metal motivates the capability to control, maintain and monitor spatial disposition of the component metals, whether as multilayers, alloys or composites. Here we investigate the deposition, evolution and dissolution of single and two-component metal layers involving Ag, Cu, and Sn on Au substrates immersed in the deep eutectic solvent (DES) Ethaline. During galvanostatically controlled stripping of the metals from two-component systems the potential signature in simultaneous thickness electrochemical potential (STEP) measurements provides identification of the dissolving metal; coulometric assay of deposition efficiency is an additional outcome. When combined with quartz crystal microbalance (QCM) frequency responses, the mass change : charge ratio provides oxidation state data; this is significant for Cu in the high chloride environment provided by Ethaline. The spatial distribution (solvent penetration and external roughness) of multiple components in bilayer systems is provided by specular neutron reflectivity (NR). Significantly, the use of the recently established event mode capability shortens the observational timescale of the NR measurements by an order of magnitude, permitting dynamic in situ observations on practically useful timescales. Ag,Cu bilayers of both spatial configurations give identical STEP signatures indicating that, despite the extremely low layer porosity, thermodynamic constraints (rather than spatial accessibility) dictate reactivity; thus, surprisingly, Cu dissolves first in both instances. Sn penetrates the Au electrode on the timescale of deposition; this can be prevented by interposing a layer of either Ag or Cu.

Effect of weld line positions on the tensile deformation of two-component metal injection moulding

Knowledge of the mechanical properties of two-component parts is critical for engineering functionally graded components. In this study, mono- and two-component tensile test specimens were metal injection moulded. Three different weld line positions were generated in the two-component specimens. Linear shrinkage of the two-component specimens was greater than that of the mono-component specimens because the incompatibility of sintering shrinkage of both materials causes biaxial stresses and enhances sintering. The mechanical properties of 316L stainless steel were affected by the addition of a coloured pigment used to identify the weld line position after injection moulding. For the two-component specimens, the yield stress and ultimate tensile stress were similar to those of 316L stainless steel. Because 316L and 630 (also known as 17-4PH) stainless steels were well-sintered at the interface, the mechanical properties of the weaker material (316L stainless steel) were dominant. However, the elongations of the two-component specimens were lower than those of the mono-component specimens. An interfacial zone with a microstructure that differed from those of the mono-material specimens was observed; its different microstructure was attributed to the gradual diffusion of nickel and copper.

Joining during shaping: two-component MIM provides new possibilities

Two-component Metal Injection Molding allows manufacturing bi-material MIM parts. The joining of the materials happens within the shaping process. It generates completely new design opportunities for MIM products of functional materials. Additional assembling operations are not required. Recent case studies with new material combinations demonstrate the potential for bi-material MIM parts.

Two-Component Metal Injection Moulding of Ti-6Al-4V and Stainless Steel Bi-Material Parts

Two-component metal injection moulding (2C-MIM) allows producing functionally graded metal parts of complex shape by co-sintering. Until now several studies have demonstrated that different material properties can be combined. Another promising material combination is titanium and iron-based materials. It can combine the biocompatibility and low density of titanium with a ductile and cost efficient stainless steel. However, co-sintering these materials reveals challenges due to a significant mismatch in sintering shrinkage and limitations in sintering temperature for both materials. The recent study showed that Ti-6Al-4V can be joined to the stainless steel 316L by 2C-MIM provided that certain constraints are taken in account. The quality of the interface before and after co-sintering is a crucial factor for intact parts after processing. By applying sinterdilatometry the mismatch in shrinkage was compensated by using adjusted powder characteristics and tailored feedstock compositions. A co-sintering cycle was defined with regard to the sintering characteristics of both materials. The developed two-component specimens revealed significant interdiffusion of alloying elements at the Ti-6Al-4V / 316L interface and a tensile strength of 282 MPa after co-sintering.

Development of magnetic/non-magnetic stainless steel parts produced by two-component metal injection molding

The paper describes results that were achieved by joining the ferritic stainless steel AISI 430 and the austenitic stainless steel AISI 314 by two-component metal injection molding. Sinterdilatometry was used to compare the sintering response of the materials. To compensate discrepancies in shrinkage during co-sintering, several gas-atomized powder fractions were combined. Using this approach, feedstock combinations which did not exceed a shrinkage mismatch of 5% were processed into micro tensile test specimens by sequential or simultaneous co-injection molding. The ferritic/austenitic interfaces were characterized with a focus on interdiffusion of alloying elements and mechanical properties. Defect-free and well-connected bi-material specimens with magnetic/non-magnetic properties were obtained. Results showed that the interdiffusion between the utilized steels resulted in a local strengthening effect that increased the hardness and mechanical properties of the interface. The tensile strength was comparable to the strength of the base material and all specimens failed outside the interface. It demonstrates that the investigated material combination is suitable to produce magnetic/non-magnetic parts by two-component metal injection molding.

Thermodynamics of the Segregation of a Kinetically Trapped Two-Dimensional Amorphous Metal–Organic Network

Surface-confined self-assembled molecular networks are commonly described as crystalline structures with short- and long-range order. Few exceptions to this trend are found in the literature reporting on amorphous and glassy networks and discussing the origins of their disordered nature at the atomic scale. Here, we show that an amorphous two-component metal–organic network can be synthesized on a crystalline metal surface at room temperature by vapor deposition of organic molecules and metal atoms. Scanning tunneling microscopy reveals the transformation of a crystalline close-packed organic layer into a disordered porous layer formed through the self-assembly of an organic semiconductor functionalized with two cyano groups upon introduction of iron atoms on Ag(111). In contrast to the commonly observed preference for trigonal crystal symmetry in 2D systems that form glassy networks, our metal–organic network favors rhombic or square tessellation of the surface. Statistical analysis of the network’s morp...

Effects of configurational changes on electrical resistivity during glass-liquid transition of two bulk metal-alloy glasses.

Consequences of increase in structural fluctuations on heating Pd40Ni10Cu30P20 and Zr46.75Ti8.25Cu7.5Ni10Be27.5 through their glass to liquid transition range were investigated by measuring the electrical resistivity, ρ, an electron scattering property. The temperature coefficient of resistivity (TCR = (1/ρ) dρ/dT) of the liquid and glassy states is negative. The plots of their ρ against T in the Tg (glass to liquid transition) range show a gradual change in the slope similar to the change observed generally for the plots of the density, elastic modulus, and refractive index. As fluctuations in the melt structure involve fewer configurations on cooling, ρ increases. In the energy landscape description, the melt's structure explores fewer minima with decrease in T, vibrational frequencies increase, and electron scattering and ρ increase. Plots of (-dρ/dT) against T resemble the plot of the specific heat of other glasses and show a sub-Tg feature and a rapid rise at T near Tg. Analysis shows that the magnitude of negative TCR is dominated by change in the phonon characteristics, and configurational fluctuations make it more negative. The TCR of the liquid and glassy states seems qualitatively consistent with the variation in the structure factor in Ziman's model for pure liquid metals as extended by Nagel to metal alloys and used to explain the negative TCR of a two-component metal glass.

SiO2나노입자가 분산된 TiO2나노섬유의 제작 및 광촉매 특성 분석

본 연구에서는 전구체 각각의 독립제어가 가능한 이성분계 금속산화물을 얻기 위해 졸-겔법으로 합성한 실리카 나노입자를 <TEX>$TiO_2$</TEX> 전구체와 교반시켜 전기방사법을 이용하여 실리카가 고르게 분산된 <TEX>$TiO_2$</TEX> 나노섬유를 성공적으로 제작하였다. 제작된 나노섬유는 FE-SEM, XRD, EDS를 이용해 구조적 특성분석과 UV-VIS, 광촉매 반응기를 통해 광촉매 특성 분석을 하였다. 그 결과, 실리카가 분산된 <TEX>$TiO_2$</TEX> 나노섬유는 실리카가 분산되지 않은 <TEX>$TiO_2$</TEX> 나노섬유 보다 광촉매 효율이 10% 가량 향상되었다. 이는 실리카 나노입자가 첨가됨으로써 <TEX>$TiO_2$</TEX>가 흡수하지 못하는 380~440 nm 가시광선 영역을 흡수하여 광학적 특성 향상되었으며 Ti와 Si 두 금속산화물간에 <TEX>$Br{\o}nsted$</TEX> acid site가 생성되어 OH 라디칼을 증가시킴으로써 광조사에 의해 여기된 전자를 잡아 재결합 손실을 억제하는 역할을 하여 화학적 특성이 개선되어 광촉매 효율이 증가되었을 것으로 사료된다. In this study, we suggest a facile method to control conditions of single component independently when preparing consisting two-component metal oxides nanofiber by simply dispersing nanoparticles in precursor solution. The well dispersed <TEX>$SiO_2$</TEX> nanoparticles in <TEX>$TiO_2$</TEX> nanofibers were successfully synthesized through a simple electrospinning process. The as-synthesized nanodfibers were investigated via FE-SEM, XRD and EDS for structural studies, furthermore, the analysis of UV-VIS and photocatalytic activity were carried out for demonstrate the effect of <TEX>$SiO_2$</TEX> nanoparticles dispersed in <TEX>$TiO_2$</TEX> nanofibers. As a result, <TEX>$TiO_2$</TEX> nanofibres dispersed with <TEX>$SiO_2$</TEX> nanoparticles have enhanced photocatalytic activity than that of <TEX>$TiO_2$</TEX> nanofibres only. In this strategy, the introduction of <TEX>$SiO_2$</TEX> nanoparticles in <TEX>$TiO_2$</TEX> nanofibers were attribute to enlarge absorption in the visible region (380~440 nm). Additionally, <TEX>$Br{\o}nsted$</TEX> acid sites generated in each metal oxide of Ti and Si increase OH radicals efficiently as well as it limit recombination loss by holding photogenerated electrons for high efficient photocatalytic activity.

Special Features of disordering in Crystallization of Two-Component Metal Melts in the Model of Two-Phase Transitive Zone

UDC 669.017.3:536.421.4 The special features of the crystallization processes of 50% two-component metal melts in the model of transitive two-phase zone (TTZ) whose structure is described by the system of stationary kinetic transcendental equations are investigated. The influence of the TTZ structure and crystallization temperature of the system two-component metal melt – crystal on the frequencies of joining of step-growth monomers to TTZ monolayers is considered. It is demonstrated that in this case, the disordering process of two-component crystals at temperatures smaller than the Curie temperature follows the Bragg–Williams thermodynamic transition. It is noted that at the point of the two-component crystal disordering, the average crystallization rate has a singularity in the form of a finite jump whose value is proportional to the squared long-order parameter.

Structure of the Transitive Two-Phase Zone in Crystallization of Two-Component Metal Melts

The structure of the so-called transitive two-phase zone (TTZ) in space of concentrations of step-growth monomers belonging to two aggregate states – melt and crystal ones – is considered for the kinetic crystallization regime of two-component metal melts. Dependences of the frequencies of joining of step-growth monomers to TTZ monolayers on the temperature of the crystallizing system and the binding energy of the two nearest neighboring particles (step-growth monomers in the TTZ model) belonging to different aggregate states are considered. Variants of systems of stationary kinetic equations describing the TTZ structure are presented that can be used to investigate the disordering processes in two-component crystals with simple cubic lattice.

Investigation of Material Combinations Processed via Two-Component Metal Injection Moulding (2C-MIM)

Joining materials with different properties into a single component is an attractive solution that allows producing parts with unique properties. In this respect, Two-Component Metal Injection Moulding (2C-MIM) presents numerous advantages, since the moulding and joining stage are performed in a single process step. In this work, the challenges, which occur when different materials are combined, are elucidated. Furthermore, the contact between metals with unequal chemical compositions leads to atomic interdiffusion that forms an interface layer. The interface quality is crucial to the production of intact parts after processing. Different material combinations are co-sintered and the interfaces are characterized by means of optical microscopy and EDX/SEM line scans. Further, thermodynamic and kinetic simulations are used to examine the interdiffusion in detail. The results show promising possibilities to combine different materials and helpful methods to examine the interface.

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Selective laser sintering (SLS) of a two-component metal powder layer on the top of multiple sintered layers by a moving Gaussian laser beam is modeled. The loose metal powder layer is composed of a powder mixture with significantly different melting points. The physical model that accounts the shrinkage induced by melting is described by using a temperature-transforming model. The effects of the porosity and the thickness of the atop loose powder layer with different numbers of the existing sintered metal powder layers below on the sintering process are numerically investigated. The present work will provide a better understanding to simulate much more complicated three-dimensional SLS process.