Dual-phase Material Research Articles

Structural and Phase Engineering of a Hierarchical 2D-2D Nickel MOF/Hydroxide-Derived Ni0.85Se/NiTe2 Heterointerface for Robust HER, OER, and Overall Water Splitting.

The development of a nonnoble metal-based cost-effective, efficient, and durable bifunctional electrocatalyst is crucial to achieving the goal of carbon neutrality. In this study, a structural and interfacial engineering approach is employed to design a 2D-2D hierarchical nickel MOF/nickel hydroxide-derived nickel selenide/nickel telluride dual-phase material through a single-step selenotellurization process. The rational design of highly ordered nanoarchitectures provides well-defined voids and ample pathways for ion diffusion. Furthermore, hierarchical nickel selenide/nickel telluride works synergistically at heterojunctions, providing a local ion enrichment mechanism for the catalytic process. As a result, Ni0.85Se/NiTe2@Ni-NH@CC needs an overpotential of 69 and 240 mV to deliver a current density of 10 mA cm-2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, with an outstanding stability observed for over 100 h. Moreover, the Ni0.85Se/NiTe2@Ni-NH@CC (+, -) device exhibits excellent overall water-splitting performance with a cell voltage of 1.50 V at 10 mA cm-2 and can be operated steadily for >100 h at 100 mA cm-2. Density functional theory (DFT) calculations indicate favorable kinetics for H-adsorption at the selenotelluride heterojunction, thereby promoting the HER. This work highlights a new approach for designing a unique nanoarchitecture of MOF/hydroxide-derived selenotelluride heterojunctions for high-efficiency energy conversion applications.

High creep resistance in amorphous/crystalline dual-phase nanostructured CoCrFeNiMn high entropy alloys

Amorphous/crystalline dual-phase metallic materials received great attention owing to their synergistic combination of strength and ductility. However, the mechanisms governing creep deformation in these dual-phase materials are largely elusive. In the present letter, the creep deformation of amorphous/nanocrystalline CoCrFeNiMn high-entropy alloy (HEA) films is investigated through nanoindentation creep testing. It is suggested that dual-phase HEAs exhibit reduced creep strain compared to their monophase counterparts, and even surpass the performance of coarse-grained variants. This behavior arises from diffusion processes within the amorphous phase and the capacity for nucleation/annihilate of dislocations at amorphous/nanocrystalline interfaces. Furthermore, it is proposed that the presence of glass shell significantly influences the creep behavior of dual-phase HEAs.

Strain redistribution in stochastically perturbed single and dual-phase cellular materials under quasistatic compression

Inspired by the stochastic and dual-phase nature of spongy bone, this work examines the effect of the perturbation on the strain distribution in a single and dual-phase, surface-based cellular structure subjected to quasistatic compression. Each effect (perturbation and the introduction of a second phase) is studied in isolation, as well as in combination, using Digital Image Correlation (DIC) for the analysis of the resulting strain fields. Starting from a periodic, single-phase surface-based cellular structure, aperiodicity was introduced at three different levels, and specimens were designed with a second-phase introduced using a core–shell modeling approach. All designs were fabricated using multi-material extrusion, with ABS and TPU as the two materials used. The specimens were subjected to quasi-static compression until densification, with results showing that the addition of a second phase and aperiodicity were each found to delocalize strain, mitigate sympathetic cell collapse in continuous failure bands, thereby decreasing undulations in the stress plateau region. The dual-phase cellular structure was found to absorb more energy per unit mass and volume when normalized by the Maximum Transmitted Stress (MTS) but this trend was arrested at high levels of aperiodicity. While aperiodicity had a significant, and occasionally detrimental, effect on the behavior of the single-phase cellular structure, its effect on dual-phase cellular structures was far more muted, suggesting the benefits of adding a second-phase to aperiodic structures to improve isotropy without large sensitivities on account of local variations in the degree and nature of aperiodicity.

Unravelling the development of preferred crystallographic orientation in dual-phase amorphous/nanocrystalline Zr-V thin films

Dual-phase amorphous/nanocrystalline alloys have been proven to present enhanced properties compared to their amorphous or nanocrystalline single-phase counterparts. These dual-phase materials are typically composed of nanocrystalline cores embedded in an amorphous matrix. In contrast, a new kind of dual-phase metallic films has recently been reported in which cone-shaped crystalline regions evolve as a result of competitive growth between the amorphous and crystalline phases with increasing film thickness. Here, we demonstrate that, unlike typical dual-phase alloys, Zr-V thin films exhibiting crystalline/amorphous competitive growth develop a preferred crystallographic orientation upon growth. Relying on pole figure observations, we uncover the development of a preferred orientation of the (110) crystallographic planes in the growth direction of the film with increasing film thickness. High-resolution transmission electron microscopy analysis reveals that the crystalline regions are formed by nano-branches which grow (110)-oriented. Based on this result, together with scanning and transmission electron microscopy observations, we associate the development of the thickness-dependent preferred orientation to the impingement between cone-shaped crystalline regions. This process triggers a selective growth mechanism that favors the selection of nano-branches growing near the direction of film growth. Our results and analyses provide a step forward in understanding the growth kinetics of dual-phase alloys presenting complex microstructures.

Study on temperature regulation capability of asphalt mixture modified by dual phase change material used in ultra-thin overlay

ABSTRACT A dual-phase change material (DPCM) containing polyethylene glycol (PEG) 400/expanded graphite (EG) and PEG1500/EG with both high and low-temperature regulation capacities was prepared. It was added as an additive to the NovaChip-Type C asphalt mixtures. Laboratory and field temperature regulation tests were designed. The images taken by SEM showed that PEG was fully adsorbed by EG and the structure of DPCM was stable. The test results showed the DPCM has good durability in the cyclic phase change process. The modified asphalt binders with different DPCM content showed different heat storage capacity. The results of temperature regulation tests showed that the addition of DPCM effectively reduced the temperature change rate of asphalt mixtures. With 1.88% DPCM, the extremum of high temperature of asphalt mixtures reduced by 2.3°C while the extremum of low temperature increased by 2.0°C. In terms of road performance, the cracking resistance at low temperature of asphalt mixtures gradually improved with the increase of DPCM content. Meanwhile, the rutting resistance at high temperature and water damage resistance still met the requirements of the specification. The DPCM had a good effect on restraining the occurrence of road diseases caused by temperature and prolonging the service life of the road.

Enhancing Direct Eectrochemical CO2 Electrolysis By Introducing a-Site Deficiency for Dual-Phase Pr(Ca)Fe(Ni)O3-Δ Cathode

High-temperature CO2 electrolysis via solid oxide electrolysis cells (CO2-SOECs) has drawn special attention due to the high energy convention efficiency, fast electrode kinetics, and great potential in carbon cycling. However, the development of cathode materials with high catalytic activity and chemical stability for pure CO2 electrolysis is still a great challenge. In this work, A-site cation deficient dual-phase material, namely (Pr0.4Ca0.6)xFe0.8Ni0.2O3- δ (PCFN, x=1, 0.95, and 0.9), has been designed as the fuel electrode for a pure CO2-SOEC which presents superior electrochemical performance. Among all these compositions, (Pr0.4Ca0.6)0.95Fe0.8Ni0.2O3- δ (PCFN95) exhibited the lowest polarization resistance of 0.458 Ω cm2 at open circuit voltage and 800℃. The application of PCFN95 as the cathode in a single cell yields an impressive electrolysis current density of 1.76 A cm-2 at 1.5 V and 800℃, which is 76% higher than that of single cells with stoichiometric Pr0.4Ca0.6Fe0.8Ni0.2O3- δ (PCFN100) cathode. The effects of A-site deficiency on materials’ phase structure and physicochemical properties are also systematically investigated. Such an enhancement in electrochemical performance is attributed to the promotion of effective CO2 adsorption, as well as the improved electrode kinetics resulting from A-site deficiency.

Finite element analysis study: Topology optimization for the front lower arm with innovative double and complex phase materials

Suspension systems used in vehicles are an important factor affecting comfort, safety, and vehicle performance. These systems are effective in the vehicle's total weight and fuel consumption. However, while lightening the weight, it should also be ensured that the strength is within safe limits. For this purpose, dual-phase (DP) and complex-phase (CP) steel materials were used. In the study, the topology optimization of the front lower suspension arm, designed for a light commercial vehicle, was carried out with the finite element method. As a result of the topology optimization, the weight was reduced by 7.5% compared to the current design, while maintaining the safe strength values. This result will significantly contribute to reducing material costs by using dual-phase (DP) and complex-phase (CP) steel materials, reducing exhaust emissions by lightening vehicle weight, and developing more sustainable designs.

The role of phase fraction on the deformation behavior and tensile properties of dual-phase polycrystalline Fe–Ni alloy: A molecular dynamics simulation study

An alloy containing two or more phases with significantly distinct properties may produce a unique combination of high strength and ductility. Fe–Ni alloys processed through the powder metallurgy route form dual-phase structures containing both body- and face-centered cubic phases. The detailed atomic scale microstructural evolution and deformation mechanism of such alloys have not been performed as dual-phase structure materials generate more complex deformation mechanisms than single-phase structure materials. The present study utilizes molecular dynamics simulation to compute the mechanical properties and investigate the deformation mechanism in a dual-phase Fe–Ni alloy with a variable phase fraction of body-centered cubic during a uniaxial tensile test. The results show that phase fraction affects the mechanical properties as well as the deformation behavior. Shear strain distribution and dislocation density provided an explanation for the change in the average flow stress and strengthening mechanism of the dual-phase Fe–Ni alloys. Additionally, the influence of temperature on deformation behavior is investigated. The deformation mechanism at higher temperatures is found to be dislocation slip and grain boundary sliding.

Dynamic globularization behavior of the dual-phase TiZrV medium entropy alloy during hot working

Globularization is an advantageous way to improve the formability of dual-phase materials. Dynamic globularization behavior of the TiZrV medium entropy alloy (MEA) with dual-phase was investigated at the temperature range of 500 ℃ ∼ 700 ℃ and strain rate of 0.1 s-1 ∼ 10 s-1 by the double-cone compression test. The finite element software was used to simulate the hot compression process of the double-cone specimen. Transmission electron microscope (TEM) was used to study the deformation microstructure features. The double-cone test can produce a wide strain range and corresponding deformation microstructure. The highest globularization ratio of 72.4% was obtained under the strain of about 0.88 at 500 ℃ and 10 s-1. The hot deformation mechanism map in the temperature range of 500 ℃ ∼ 700 ℃ and the strain range of 0.2 ∼ 1.2 at 10 s-1 was constructed by combining the double-cone test with finite element simulation. The hot deformation mechanism map is divided primarily into two parts. At 500 ℃, in the strain region of 0.2 ∼ 0.88, the deformation mechanism is dynamic recovery (DRV), and in the strain region of 0.88 ∼ 1.2, the deformation mechanism is dynamic recrystallization (DRX). It is considered that DRX plays a key role in dynamic globularization of the TiV phase during hot working and its production is summarized.

Effects of Ti on the solidification and crystallization behavior of nanocomposite permanent material under different cooling rates

Effects of Ti on the crystallization behavior, phase composition, microstructure and magnetic properties of Nd2Fe14B/α-Fe dual-phase nanocomposite permanent magnet materials in different states were studied, respectively. The results show that Ti could affect the solidification and crystallization behavior of dual-phase nanocomposite materials by regulating the cooling rate during the rapid solidification process. When the cooling rate is slow, part of Ti atoms enters the soft magnetic phase α-Fe, and part forms the TiFe2 phase around the hard magnetic phase. Exchange coupling is enhanced. The maximum energy product and the remanence of the alloy are 10.54 MGOe and 8.34 kGs, respectively. When the cooling rate faster, Ti can stabilize another ferromagnetic ThMn12-type phase with a low coercivity and maximum energy product, which should be avoided. When the cooling rate is fast enough to form amorphous, Ti and Fe preferentially combine to form the TiFe2 phase during crystallization, which selectively inhibits the growth of the hard magnetic phase and the precipitation of the soft magnetic phase, resulting in a significant enhancement of coercivity to 12.82 kOe. By regulating the mechanism of Ti in the solidification and crystallization process, nanocomposite permanent magnet materials with varying magnetic characteristics can be obtained, offering a flexible approach to tailoring their performance according to specific application requirements.

Characterization of an advanced bone graft material with a nanocrystalline hydroxycarbanoapatite surface and dual phase composition.

The bone formation response of ceramic bone graft materials can be improved by modifying the material's surface and composition. A unique dual-phase ceramic bone graft material with a nanocrystalline, hydroxycarbanoapatite (HCA) surface and a calcium carbonate core (TrelCor®-Biogennix, Irvine, CA) was characterized through a variety of analytical methods. Scanning electron microscopy (SEM) of the TrelCor surface (magnification 100-100,000X) clearly demonstrated a nanosized crystalline structure covering the entire surface. The surface morphology showed a hierarchical structure that included micron-sized spherulites fully covered by plate-like nanocrystals (<60 nm in thickness). Chemical and physical characterization of the material using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy Energy Dispersive X-ray Spectroscopy (SEM-EDX) showed a surface composed of HCA. Analysis of fractured samples confirmed the dual-phase composition with the presence of a calcium carbonate core and HCA surface. An in vitro bioactivity study was conducted to evaluate whether TrelCor would form a bioactive layer when immersed in simulated body fluid. This response was compared to a known bioactive material (45S5 bioactive glass - Bioglass). Following 14-days of immersion, surface and cross-sectional analysis via SEM-EDX showed that the TrelCor material elicited a bioactive response with the formation of a bioactive layer that was qualitatively thicker than the layer that formed on Bioglass. An in vivo sheep muscle pouch model was also conducted to evaluate the ability of the material to stimulate an ectopic, cellular bone formation response. Results were compared against Bioglass and a first-generation calcium phosphate ceramic that lacked a nanocrystalline surface. Histology and histomorphometric analysis (HMA) confirmed that the TrelCor nanocrystalline HCA surface stimulated a bone formation response in muscle (avg. 11% bone area) that was significantly greater than Bioglass (3%) and the smooth surface calcium phosphate ceramic (0%).

Design and Analysis of New Type of Magnetically Controlled Reactor

In recent years, various new types of magnetic materials have emerged, especially in the field of nanotechnology. The application of material composite technology has formed a new type of dual-phase composite magnetic material. Under the control of an external magnetic field, the material can achieve functional conversion between the hard magnetic phase and the soft magnetic phase, with magnetic permeability, non-magnetic permeability, and excitation ability. In this paper, it is proposed to use this material as the basic material for the magnetic state control of the reactor core, break through the bondage of the traditional reactor core to the performance of the controllable reactor, and innovatively form a new type of reactor structure. By adding a detection and control system, according to the working state of the power grid, the function conversion of the nano adjustable magnetic material is effectively adjusted to realize the automatic adjustment of the magnetic state of the reactor. Firstly, the preparation and material properties of dual-phase composite magnetic materials were studied. The design and preparation process from magnetic powder to bulk magnet were given, and the magnetic properties were measured. Secondly, a new 380 V/100 kVar magnetically controlled reactor was designed by using dual-phase composite magnetic material to form a composite core of magnetically controlled reactor on silicon steel sheet. The simulation analysis of electromagnetic characteristics and volt-ampere characteristics was carried out to verify the correctness of the proposed scheme.

Effects of ferrite and graphite phases on scratch characteristics of nodular cast iron

In this work, we conduct micro-scratch tests of nodular cast iron with Vickers indenter under constant normal load and investigate the effects of individual phases (i.e., ferrite and graphite phases) on the scratch characteristics of nodular cast iron. Using a bimodal Gaussian model to fit the experimental data of penetration depth, residual depth, elastic recovery rate, and scratch hardness, we calculate the contribution percentages of individual phases to scratch variables. The scratch variables are independent of the scratch speed used in this work, while the penetration depth increases linearly with increasing the normal load. There exists a large difference between the contribution percentages and the volume fractions calculated from SEM images and XRD pattern. Such a large difference suggests that the bimodal Gaussian distribution analysis does not include the effect of the interaction between two phases on the scratch characteristics of dual-phase materials with significantly distinct mechanical properties and geometrical dimensions. A more refined method taking into account the interaction between two phases needs to be developed for the analysis of the scratch characteristics of dual-phase materials.

Modeling of Dual-Phase Composite Magnetic Material and Its Application in Transformers

Dual-phase composite magnetic materials have magnetic and permanent magnetic properties. They can realize the dual-phase conversion of soft magnetic and permanent magnetic composites with a small amount of excitation energy. They have the advantages of good control and conversion characteristics and save energy, and they have a wide range of application scenarios in regard to power equipment. In this paper, the magnetization modeling of dual-phase composite magnetic materials is carried out based on micromagnetic theory, and a specific mathematical expression is given. Secondly, the preparation process of the dual-phase composite magnetic material is studied, the dual-phase composite magnetic material is prepared, and the demagnetization curve of the dual-phase composite magnetic material is measured. Finally, the application of dual-phase composite magnetic materials in power equipment is carried out. Using the soft magnetic and permanent magnetic characteristics of dual-phase composite magnetic materials, their impact on DC bias suppression in transformers is assessed. Magnetic circuit reluctance theory is used to develop the structure and electromagnetic design of a transformer. A transformer prototype with DC bias suppression ability based on dual-phase composite magnetic materials is manufactured, and simulation and experimental research are carried out. The simulation and experimental results verify the correctness of the proposed scheme. Although this scheme requires a more complex core structure, the energy-saving effect is remarkable without changing the transformer’s neutral grounding. The indicators meet the actual requirements of the project.

Constructing Heterointerfaces in Dual-Phase High-Entropy Oxides to Boost O2 Activation and SO2 Resistance for Mercury Removal in Flue Gas.

The low O2 activation ability at low temperatures and SO2 poisoning are challenges for metal oxide catalysts in the application of Hg0 removal in flue gas. A novel high-entropy fluorite oxide (MgAlMnCo)CeO2 (Co-HEO) with the second phase of spinel is synthesized by the microwave hydrothermal method for the first time. A high efficiency of Hg0 removal (close to 100%) is achieved by Co-HEO catalytic oxidation at temperatures as low as 100 °C and in the atmosphere of 145 μg m-3 Hg0 at a high GHSV (gas hourly space velocity) of 95,000 h-1. According to O2-TPD and in situ FT-IR, this extremely superior catalytic oxidation performance at low temperatures originates from the activation ability of Co-HEO to transform O2 into superoxide and peroxide, which is promoted by point defects induced from the spinel/fluorite heterointerfaces. Meanwhile, SO2 resistance of Co-HEO for Hg0 removal is also improved up to 2000 ppm due to the high-entropy-stabilized structure, construction of heterointerfaces, and synergistic effect of the multicomponents for inhibiting the oxidation of SO2 to surface sulfate. The design strategy of the dual-phase high-entropy material launches a new route for metal oxides in the application of catalytic oxidation and SO2 resistance.

Cobalt ferrite induced enhancement in the thermoelectric properties of zinc oxide composites

Thermoelectric (TE) material devices can be treated as an initiative to reduce global warming by scavenging waste heat and recycling it into useful electrical energy. In dual-phase materials, the energy filtering mechanism serves a significant role to enhance power factor by controlled electrical conductivity and Seebeck coefficient in connection with carrier concentration and carrier mobility. Here we performed the preparation of Cobalt Ferrite (CF) using mechanical alloying and the cf@zno composites via solid state reaction technique by varying stoichiometric weight between CF and ZnO. The magnetic, electric, and optical properties of the samples exposed the influence of CF on the TE properties of ZnO matrix. The cf7.5wt%@zno sample shows greater carrier mobility and moderate carrier concentration results the improved electrical conductivity value 4235 Sm−1 and hence achieved highest power factor 439 μWm−1K−2.

Sintering and electrical properties of Mn–Co–Fe–Zn–Ni–O high-entropy ceramics for NTC thermistors

In this work, the dual-phase structure Mn–Co–Fe–Zn–Ni–O high-entropy negative temperature coefficient (NTC) ceramics were synthesized by a solid-phase reaction method. The ceramics are mainly composed of the cubic spinel phase and the rock salt phase. Electron microscopic images revealed the typical morphology and the homogeneous distribution of all elements. The results confirmed that the microstructure and electrical properties of the high-entropy ceramics are closely related to the sintering temperature. As the sintering temperature increased, the content of the rock salt phase gradually improved, meanwhile, the higher resistivity of samples was achieved. Notably, it was found that an appropriate proportion of the rock salt phase could significantly enhance the aging stability of ceramics. The aging drift of the samples sintered at 1175 °C was only 0.632 %. In addition, the ratio of the two phases was adjusted by adding NiO. The ρ25 and B25/50 of the materials can be tuned in the range of 22.25 kΩ cm∼24.19 kΩ cm and 4047 K–4145 K, respectively. Regulating the phase ratio of dual-phase materials is a novel strategy for designing NTC ceramic materials with excellent characteristics. This work provides an idea for future research on high-entropy NTC thermistor ceramics.

Design, synthesis, and influencing factors of medium-/high-entropy Y2(ZrTiGeHfSnSi)2O7 with a pyrochlore structure

A set of medium-/high-entropy pyrochlore oxides (M-HEPOs) with different compositions were designed and synthesized. The phase compositions of the prepared materials were determined through X-ray diffraction and Raman spectroscopy. Among the 24 designed samples, two high-entropy and six medium-entropy samples formed single-phase pyrochlore materials, two medium-entropy samples formed dual-phase pyrochlore materials, and the others formed multiphase materials dominated by the pyrochlore phase. The factors affecting the formation of single-phase pyrochlore structure were studied. The results revealed that size disorder is a major element determining the formation of single-phase pyrochlore, whereas mixing entropy has minimal effect. It is anticipated that this study will provide significant insights into the effects of size disorder and mixing entropy on the formation of M-HEPOs.

Lanthanide element variation in rare earth doped ceria – FeCo2O4 dual phase oxygen transport membranes

The increased interest in dual-phase membrane materials for oxygen separation leads to the continuous optimization of their composition. Rare-earth doped ceria is a promising candidate as the ion-conducting phase in the membrane. Spinel-structured FeCo2O4 was investigated as an electronic conducting phase forming an additional electronic conducting perovskite-structured phase during sintering when combined with Ce1−xLnxO2−δ. The influence of rare-earth lanthanide elements, i.e., Gd and Sm, as well as their concentration, i.e. x = 0.1 and 0.2, on the final phase composition and microstructure as well as its related functional properties in particular oxygen permeation is analyzed. 20 mol.% doping of either Gd or Sm reveals a multi-phase microstructure after sintering. Moreover, segregation of Gd/Sm, iron, and cobalt is found at the ceria-ceria grain boundaries in Ce0.8Sm0.2O2−δ- and Ce0.9Gd0.1O2−δ-based composites. In contrast, 10 mol.% Gd–doping leads to a dual-phase membrane material without the formation of any other phase. In all cases, the percolation threshold is reached at approx. 20 vol% of the electron-conducting phase in the system leading to similar maximum permeation rates determined by the ionic conductivity of the ceria phase.

Thermal performance of an innovative double-skin ventilated façade with multistep-encapsulated PCM integration

The simultaneous occurrence of nighttime insulation requirements and daytime overheating risks in a single day is a concern of buildings that is often overlooked. This study introduces a novel approach utilizing a dual-phase change materials (DPCM) layer in a double-skin ventilated glazing façade (DSPVGF) to store and release energy through photothermal conversion. This technology facilitates heat removal during the day via a ventilation layer and the reduces long-wave radiation through a vacuum glass layer. The thermal performance of DSPVGF is evaluated under a temperate continental climate characterized by significant diurnal temperature variations. Emphasis is placed on considering the net solar energy gain of DSPVGF. The results demonstrate that DSPVGF outperforms ventilated façades utilizing air or PCM, exhibiting the lowest heat transfer rate of 30.03 W. Optimal DSPVGF configurations for climates with substantial temperature fluctuations are identified, including a DPCM melting temperature of 28 °C and 16 °C, a thickness of 36 mm, and multistep placement by turn according to a height-to-width ratio of 200D. Daytime ventilation with a flow velocity of 1.09 m·s−1 is confirmed as the most effective passive cooling strategy.