Fcc Structure Research Articles

Phytoconstituents Assisted Biofabrication of Copper Oxide Nanoparticles and Their Antiplasmodial, and Antilarval Efficacy: A Novel Approach for the Control of Parasites

The present work aimed to biofabricate copper oxide nanoparticles (CuO NPs) using Tinospora cordifolia leaf extract. The biofabricated CuO NPs were treated against the malarial parasite of chloroquine-resistant Plasmodium falciparum (INDO) and the antilarval efficacy was evaluated against the malaria vector Anopheles stephensi and dengue vector Aedes aegypti. The prominence at 285 nm in the UV-visible spectrum helped to identify the produced CuO NPs. Based on the XRD patterns, the concentric rings correspond to reflections at 38.26° (111), 44.11° (200), 64.58° (220), and 77.34° (311). These separations are indicative of CuO's face-centered cubic (fcc) structure. The synthesized CuO NPs have FTIR spectra with band intensities of 3427, 2925, 1629, 1387, 1096, and 600 cm-1. The absorbance band at 3427 cm-1 is known to be associated with the stretching O-H due to the alcoholic group. FTIR proved that the presence of the -OH group is responsible for reducing and capping agents in the synthesis of nanoparticles (NPs). The synthesized CuO NPs were found to be polymorphic (oval, elongated, and roughly spherical) in form with a size range of 11-47 nm and an average size of 16 nm when the morphology was examined using FESEM and HRTEM. The highest antiplasmodial efficacy against the chloroquine-resistant strain of P. falciparum (INDO) was found in the synthesized CuO NPs, with LC50 values of 19.82 µg/mL, whilst HEK293 cells are the least toxic, with a CC50 value of 265.85 µg/mL, leading to a selectivity index of 13.41. However, the antiplasmodial activity of T. cordifolia leaf extract (TCLE) and copper sulfate (CS) solution showed moderate activity, with LC50 values of 52.24 and 63.88 µg/mL, respectively. The green synthesized NPs demonstrated extremely high antilarval efficacy against the larvae of An. stephensi and Ae. aegypti, with LC50 values of 4.06 and 3.69 mg/L, respectively.

Deposition characteristics of CoCrFeMnNi high-entropy alloys thin film via simulation

HEAs are composed of five or more principal elements, each of which contributes 5–35 atomic percent. Here, we investigate the CoCrFeMnNi high-entropy alloys (HEAs) thin film deposited on Ni substrate via molecular dynamics simulation. The incident atoms deposit with different incident velocity levels and compositions on different surface crystalline orientations. The surface morphology, layer coverage, structure state, lattice distortion, stress, potential, and entropy distributions of the HEAs sample are analyzed. The results reveal that the higher incident velocity results in a higher stress level and a broader high-potential zone. From 50 m/s to 200 m/s, the crystalline structure ratio improves when the incident velocity increases due to a greater penetration rate. However, improving the incident velocity from 200 m/s to 400 m/s results in a decrease in crystalline structure ratio as the excess kinetic energy causes structural damage. Because of the increase in planar density, the layer coverage value decreases gradually from orientation (001) to (110) and finally (111). From the thin film surface, potential and entropy are distributed in a gradient pattern. The potential value increases from the interface to the HEAs thin film's outer surface. While the local entropy level decreases rapidly from the top to the bottom layer. The incident atoms create a high-stress and lattice distortion in the substrate matrix. Moreover, increasing Fe content from 20 % to 60 % declines the HEAs potential rate, the FCC structure ratio, and the penetration rate between the incident and substrate atoms.

Effects of Different Parts of the Okra Plant (Abelmoschus esculentus) on the Phytosynthesis of Silver Nanoparticles: Evaluation of Synthesis Conditions, Nonlinear Optical and Antibacterial Properties

In this work, stable and spherical silver nanoparticles (AgNPs) were synthesized in situ from silver salt (silver nitrate) using the aqueous extract of the okra plant (Abelmoschus esculentus) at room temperature and ambient pH conditions. The influences of different parts of the plant (such as the leaves, stems, and pods) on the chemical-reducing effectiveness of silver nitrate to silver nanoparticles were investigated. The aqueous extract of the leaves was found to be more effective in the chemical reduction of silver nanoparticles and in stabilizing them at the same time. The silver nanoparticles produced were stable and did not precipitate even after storage for 1 month. The extract of the stem was less effective in the reduction capacity followed by the extract of the pods. The results indicate that the different amounts of phytochemicals present in the leaves, stems, and pods of the okra plant are responsible for the chemical reduction and stabilizing effect. The silver nanoparticles were characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The surface plasmon resonance (SPR) peak at 460 nm confirmed the formation of silver nanoparticles. The nanoparticles were spherical with an average size of 16 nm and polycrystalline with face-centered cubic (fcc) structures. The z-scan technique was used to study the nonlinear refraction and absorption coefficients of AgNPs at wavelengths of 488 and 514 nm under C.W. mode excitation. The nonlinear refraction index and nonlinear absorption coefficients were calculated in the theoretical equations in the experimental data. The antibacterial properties of the nanoparticles were evaluated against Gram-positive and Gram-negative bacteria.

Synthesis and characterisation of Nickel oxide nanoparticles using CTAB as capping agent

This report presents the synthesis of nickel oxide nanoparticles by hydrothermal route in the presence of sodium hydroxide (NaOH) with Cetyl Trimethyl Ammonium Bromide (CTAB) used as capping agent. Nickel oxide (NiO) being a p- type semiconductor,has wide bandgap and is eco-friendly, low cost and stable material that can serve as promising material for a counter electrode in the DSSC (Dye-Sensitized Solar Cells). The use of capping agent is to control the size of nanoparticles and also prohibit the agglomeration of the synthesized material. The as synthesized nickel oxide nanoparticles (NPs) were analysed using X-ray diffraction (XRD) technique, Field Emission Scanning electron microscope (FESEM) and UV visible spectroscopy. The face-centred cubic (fcc) structure of NiO is revealed by XRD pattern. Surface morphological features associated with nickel oxide were studied by using FESEM. UV–vis spectroscopy is done to evaluate the band gap of as-synthesized material which is found to be around 2.81 eV.

Composition design to tune the mechanical behavior of a TRIP-TWIP (CrMnFeCoNi)50 Fe50-xCrx multi-principal element alloys

The utilization of the laser melting deposition (LMD) method to synthesize the (CrMnFeCoNi)50Fe50-xCrx (x = 5, 10, and 15 at.%) multi-principal elements alloys (MPEAs) are successfully demonstrated. It discovers that all (CrMnFeCoNi)50Fe45Cr5, (CrMnFeCoNi)50Fe40Cr10, and (CrMnFeCoNi)50Fe35Cr15 MPEAs retain a single-phase solid solution microstructure, and the in-situ structure transformation found in the matrix is ascribed to the reduction of the stability of FCC structure via appropriately tailoring constituent elements. (CrMnFeCoNi)50Fe45Cr5 MPEA exhibits the simultaneous enhancement in the plasticity (almost 100%) and the tensile strength (from 415 MPa to 470 MPa) resulting from the co-contribution of deformation-induced twining and tiny amounts of precipitation for M23C6 carbide at ambient temperature. Inversely, (CrMnFeCoNi)50Fe35Cr15 displays remarkable improvement in the tensile strength (∼ 600 MPa) at the sacrificing of the plasticity elongation (from 50% to 32%) originating from the contribution of strain-induced structure transformation. Here, the transformation-induced twinning and transformation-induced ductility are successfully achieved by tuning the stability of the constituent phases in the (CrMnFeCoNi)50Fe50-xCrx MPEAs. These discoveries not only distinctly distinguish the tensile strength and plasticity of the (CrMnFeCoNi)50Fe50-xCrx MPEAs from the corresponding CoCrFeMnNi MPEA, but also pave the way for designing and enhancing the comprehensive properties of MPEAs and other structural materials for engineering applications.

High entropy alloy as metal additive for hybrid rocket propellant

A typical solid propellant used in rocket propulsion systems is made from polymeric fuel, crystalline liquid binder and additives. In comparison to conventional propulsion systems, hybrid propulsion is more safe, reliable and environmentally friendly. However, the hybrid systems have some drawbacks, including low fuel regression rates and low combustion efficiency. As a result, several approaches have been developed to increase the rate of solid fuel regression rate including the introduction of metal additives to the system. Nowadays, high entropy alloys (HEA) are among the most advanced materials for high-performance applications. This alloy has a potential to replace the existing metal additives in hybrid propulsion systems. The present work proposes a new composition based on Paraffin wax fuel, loaded with high entropy alloy as a metal additive for hybrid propulsion systems using the following ratio of 80:20. Therefore, this research explores the efficacy of high entropy alloys as additives for hybrid propulsion systems. Characterizations and thermal analysis of solid fuel using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis are carried out to determine the structure, thermal decomposition and energy characteristics of the solid fuel with the HEA as additive. XRD result shows that HEA in a form of solid solutions produces BCC and FCC structures. Thermal analysis of paraffin wax with the addition of HEA gives the maximum value of 136.34 J/g for the total latent heat of the mixture. It is concluded that HEA increases the energy released from the fuel by 86.92 % compared to pure paraffin wax fuel. The mixture of paraffin and HEA fuel has a prospect to be used as future rocket fuel.

Self-layering of (Ti,Al)N by interface-directed spinodal decomposition of (Ti,Al)N/TiN multilayers: First-principles and experimental investigations

Supersaturated (Ti,Al)N materials with face centered cubic (fcc) structure offer unique combinations of thermal stability and mechanical properties. However, their thermally-induced decomposition processes are crucial for extracting their full potential. Detailed experimental studies by X-ray diffraction and transmission electron microscopy reveal that the formation of the thermodynamically stable wurtzite-type w-AlN starts with 1000 °C at 100 °C lower annealing temperatures (Ta) when applying a multilayer-concept with TiN to form (Ti,Al)N/TiN multilayers. Nevertheless, the hardness of (Ti,Al)N/TiN multilayers peaks with 32.3 ± 1.0 GPa at a 100 °C higher Ta (900 °C) than the (Ti,Al)N coating, and the hardness declining trend with increasing Ta is milder. This is because the (Ti,Al)N decomposes towards a layered structure of Al-rich and Ti-rich regions, when coherently grown with fcc-TiN. Ab initio calculations highlight that Al within the (Ti,Al)N layers preferentially diffuses away from the coherent interface with the TiN layers. Thus, out of one (Ti,Al)N layer more layers form, and even upon the phase-transformation of the Al-rich layers to w-AlN, their layered structure remains. Together, the computational and experimental results suggest that the layered arrangement provides a higher resistance against dislocation glide and is beneficial for the coating integrity.

Effect of Si content and annealing temperatures on microstructure, tensile properties of FeCoCrNiMn high entropy alloys

In the present study, FeCoCrNiMnSix (x = 0, 0.1, and 0.2, molar ratio) high-entropy alloys (HEAs) were prepared via arc melting, and subsequently deformed via cold rolling and annealing (CRA). The effects of Si content and annealing temperature on the microstructural evolution and tensile properties of the alloys were systematically investigated. The results indicate that a single-phase FCC structure of coarse-grained FeCoCrNiMnSix HEAs was obtained after homogenized annealing (HOA), and the distribution of each element was uniform. When the molar ratio of Si was increased from 0 to 0.2, the strength of the HOA HEAs increased by nearly 50%, and the elongation did not decrease, largely due to solid solution strengthening and the reduction in stacking fault energy. Conversely, as Si content increased, the recrystallization ratio decreased during annealing. A heterogeneous grain structure composed of recrystallized and residual deformation regions (high density of dislocations and deformation twinning) was obtained by changing the CRA temperature and Si content. A heterogeneous grain structure of CRA HEAs with an annealing temperature of 700 ℃ and Si content of 0.2 exhibits approximately fourfold higher yield strength (733 MPa) compared to that of HOA FeCoCrNiMn HEAs (185.27 MPa). The structure’s tensile strength and ductility were measured at 959 MPa and 29.5%, respectively. The high strength was mainly attributed to the combined effect of multiple strengthening mechanisms. Heterogeneous deformation-induced strain hardening and twinning-induced plasticity provide good ductility.

Investigating Microstructural Evolution and Its Influence on Tribological Behaviors of In-Situ Formed VCp Reinforced Iron-Based Composites with Variable Mn Content.

In this work, we fabricated VCp-reinforced iron-based composites (VCFCs) by adjusting the amount of Mn elements and investigated how the concentration of Mn affected the microstructural characteristics of Vanadium carbide (VC) and the texture of the iron matrix, and the influence of microstructure on tribological behaviors should be investigated. We demonstrated that VC changed from thick dendrite crystals (~50 μm) to tiny equiaxed crystals (~5 μm). Furthermore, the nucleation mechanism of VC also transformed from homogeneous nucleation to heterogeneous nucleation due to the lower Gibbs free energy of TiC and the tailoring effect of the Mn elements. In addition, γ-Fe in the FCC structure gradually increased and ascribed an increase of Mn content to the lower transformation temperature of martensite. Furtherly, particulate features and phase constitution could contribute to hardness and wear resistance. Higher hardness and excellent wear resistance occurred in the 3.0 Mn sample, which had a hardness of 869 HV and a wear rate of 1.77 × 10-6 mm3/(N·m). In addition, the adhesive wear could be the main wear mechanism in the 3.0 Mn sample, while the abrasive wear could be in the 4.5 Mn sample.

Theoretical and Experimental Studies of Al-Impurity Effect on the Hydrogenation Behavior of Mg.

In this paper, we study the influence of hydrogen concentration on the binding energies in magnesium hydrides. The impact of aluminum atom addition on the hydrogenation behavior of magnesium was theoretically and experimentally defined. Doping Al into the Mg lattice allows the uniform hydrogen distribution in both the fcc and bcc Mg lattice at a low hydrogen concentration (H:Mg < 0.875) to be more energetically favorable. In addition, this leads to bcc Mg lattice formation with a uniform hydrogen distribution, which is more energetically favorable than the fcc Mg lattice when the atomic ratio H:Mg is near 0.875. In addition, compared with the pure Mg, in the Al-doped Mg, the phase transition from the hcp to the fcc structure with a uniform distribution of H atoms induces less elastic strain. Thus, the uniform hydrogen distribution is more favorable, leading to faster hydrogen absorption. Pure magnesium is characterized by cluster-like hydrogen distribution, which decreases the hydrogen diffusion rate. This leads to the accumulation of a higher hydrogen concentration in magnesium with aluminum compared with pure magnesium under the same hydrogenation regimes, which is confirmed experimentally.

First-principles study on the electronic structure, bonding, stability of Mg/6H-SiC interfaces

In order to investigate the atomic structure, electronic structure and stability of Mg/6H–SiC interfaces and explore the heterogeneous nucleation ability of SiC particles in Mg melt. The adhesion work, charge density difference and layer-projected density of states (LDOS) of Mg/6H–SiC interfaces are calculated by first-principles method. The results show that the adhesion work of C-terminated FCC structure is the largest among the six different interface structures. The interfacial electronic structures were analyzed by charge density difference, the total charge density of the C-terminated FCC interface is much greater than that of the Si-terminated HCP interface. The layer-projected DOS and Mulliken charge of the interface model reveal that the C-terminated interface is a mixed interface of polar covalent and ionic bonds, while the Si-terminated interface is mainly polar covalent bonds. The calculated interfacial energy of the Mg/6H–SiC interface is much larger than that between the α-Mg and magnesium melt, which proves that SiC particles cannot act as the nucleation sites of α-Mg.

Correlation between Precipitation and Recrystallisation during Stress Relaxation in Titanium Microalloyed Steel

This study investigated the correlation between strain-induced precipitation (SIP) and static recrystallisation (SRX) in Ti microalloyed steel during stress relaxation after controlled compression. The final compression temperature strongly influenced the order of SIP and SRX and thus the evolution of the austenite structure. Precipitation-time-temperature (PTT) curve obtained for the experimental steel exhibited an inverted “S” shape. A recrystallisation kinetics model revealed that SRX, which occurs preferentially above 940 °C, resulted in delayed subsequent SIP, thus causing deviation in the PTT curve from the typical ‘C’ shape. Below 940 °C, the fastest nose temperature for precipitation was located at 900 °C, and the precipitate was constituted by TiC particles with a NaCl-type FCC structure. The dynamic competition between SIP and SRX processes were evaluated by comparing the relative magnitude of the recrystallisation driving force and precipitation pinning force during stress relaxation, combined with the evolution of precipitate and austenitic structure. The results indicated that the plateau period occurred because of the precipitation pinning effect inhibited recrystallisation-induced austenite softening. However, the non-uniform distribution of SIP restricted the mobility of the boundaries to a portion of the austenite grains, resulting in abnormal grain growth during the plateau period.

Microstructure evolution and compressive property variation of AlxCoCrFeNi high entropy alloys produced by directional solidification

The AlxCoCrFeNi (molar radio, x = 0.3, 0.6, 0.9 and 1.2) high entropy alloys (HEAs) were directionally solidified at the withdrawal rate of 150 μm/s. The effects of Al content on microstructure evolution, element segregation as well as compressive property were investigated. It was found that the increase of Al content resulted in the formation of BCC crystal structure. Meanwhile, the microstructure of AlxCoCrFeNi HEAs transformed from dendrite to equiaxed dendrite. The Al0.3CoCrFeNi HEA formed a single FCC solid solution phase, the Al0.6CoCrFeNi HEA consisted of CoFeCr-enriched FCC solid solution phase + NiAl-enriched BCC solid solution phase, the Al0.9CoCrFeNi and Al1.2CoCrFeNi HEAs were composed of NiAl-enriched B2 solid solution phase + CoFeCr-enriched BCC solid solution phase. Morphology of solid-liquid interface was coarse dendrite or typical dendrite. As the Al content increased, the compressive strain of directionally solidified AlxCoCrFeNi HEAs decreased from 21.26% to 18.05%, and the ultimate compressive strength increased first and then decreased. The improvement of strength results from crystal structure transition and solution strengthening. As the Al contents increased from 0.6 to 0.9, the crystal structure of AlxCoCrFeNi HEAs transformed from CoFeCr-enriched FCC structure + NiAl-enriched BCC structure to CoFeCr-enriched BCCstructure + NiAl-enriched B2 structure. The strain of Al0.3CoCrFeNi HEA was higher than others, and Al0.9CoCrFeNi HEA exhibited the maximum ultimate compressive strength of 2114.57 MPa.

Composition formula of Al-TMs high-entropy alloys derived by cluster-plus-glue-atoms model and its experimental verification

High-entropy alloys (HEAs) are based on solid solutions which characterized by chemical short-range ordering (CSRO), but there is no accurate structural tool to address CSRO characteristic, which obstacles precise composition design for HEAs. In this study, based on the cluster-plus-glue-atoms model, the composition law of Al-TMs (TMs, transition metals) HEAs with BCC and FCC structures was revealed. In BCC structure, with five elements in equi-atomic ratio, the composition formula of Al-TMs HEAs can be expressed by a cluster formula [Al-M14]Al3, and in non equi-atomic ratio can be expressed by [Al-M14]Al, where M is the average atom of the TMs. But in FCC structure, both Al-TMs HEAs with five elements in equi-atomic and non equi-atomic ratios can be expressed by a cluster formula [Al-M12]Al. To confirm the effectiveness of cluster formula for Al-TMs, two alloys were designed, [Al-Ti4V3Nb4Mo3]Mo and [Al-Ti3V3Nb4Mo4]Al. Results show that the [Al-Ti3V3Nb4Mo4]Al alloy has both higher strength and higher plastic deformation at room temperature. Besides, [Al-Ti3V3Nb4Mo4]Al alloy shows slower soften effect at 800 °C, contributed to its higher strength. By substituting Ta for some of Mo, the strength of [Al-Ti3V3Nb4Mo3Ta]Al at room temperature and high temperature drastically decreases, suggesting that Ta element deteriorates the properties of Al-TMs alloys.

The evolution of Cr-rich precipitates in Cu-0.25Cr-0.03Ti alloy induced by trace Ti element

In this paper, the prepared Cu-0.25Cr alloy and Cu-0.25Cr-0.03Ti alloy strips were treated with aging at 490 °C for different holding time. The electrical conductivity and the yield strength of the alloy were tested. The morphology, size, spacing and phase structure of Cr-rich precipitates in the copper matrix were observed by TEM. The results show that the evolution rule of Cr-rich precipitates in Cu-0.25Cr alloy is as follows: supersaturated solid solution→G. P region (Cr atom-rich region)→ Cr-rich precipitates with fcc structure→Cr-rich precipitates with ordered bcc structure. The precipitates of peak aged Cu-0.25Cr alloy consist of fcc Cr-rich precipitates and ordered bcc Cr-rich precipitates. The electrical conductivity and the yield strength is 93.5%IACS and 178 MPa, respectively. The strengthening mechanism is mainly attributed to the synergistic effect of dislocation shear and dislocation bypass. Compared with Cu-0.25Cr alloy, the yield strength of Cu-0.25Cr-0.03Ti alloy at peak aging state increases by 31.5%, while the electrical conductivity remains at 82.4%IACS. The great increase in strength is mainly attributed to the refinement of bcc Cr-rich precipitates by adding trace Ti element. The addition of Ti promotes the nucleation of Cr-rich precipitates and refines the Cr-rich precipitates of bcc structure. The interaction mechanism is that there is a strong mutual attraction between Ti and Cr atoms, which promotes the formation of clusters between Ti and Cr. This research results can provide a theoretical basis for the development of copper alloy for high-performance electrical connectors in aerospace, new energy vehicles and other fields.

Mechanical properties and impact energy release characteristics of Al0.5NbZrTi1.5Ta0.8Ce0.85 high-entropy alloy

To explore the potential of high-entropy alloys (HEAs) as energetic structural materials (ESMs), Al0.5NbZrTi1.5Ta0.8Ce0.85 high-entropy alloys were prepared by vacuum arc melting. XRD and TEM indicated the coexistence of BCC and FCC structures. SEM images illustrated element segregation in HEA. HEA exhibited excellent mechanical properties and impact energy release characteristics. When the strain rate increased from 10–3 s−1 to 4500 s−1, the yield strength increased by 56.2% from 909 MPa to 1420 MPa. Under impact, the threshold of strain rate of HEA was about 1200 s−1. Ballistic gun tests were performed to investigate the penetration behaviour and energy release characteristics. Al0.5NbZrTi1.5Ta0.8Ce0.85 could penetrate 6 mm A3 plate at the speed of 712 m s−1 and ignite the cotton behind the target, combining excellent mechanical properties and impact energy release characteristics.

Effect of Bilayer Thickness and Bias Potential on the Structure and Properties of (TiZr/Nb)N Multilayer Coatings as a Result of Arc-PVD Deposition.

This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, ε-NbN with a hexagonal structure, as well as with a small volume fraction of the ε-Ti2N and β-Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of ε-NbN and β-Nb2N nitrides. In all investigated systems obtained at -100 V and -200 V bias potentials, ε-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure.

Microstructure and corrosion properties of AlxCuFeNiCoCr(x = 0.5, 1.0, 1.5, 2.0) high entropy alloys with Al content

Al x CoCrFeNiCu (x = 0.5, 1.0, 1.5, 2.0) high entropy alloy was prepared by powder metallurgy method.The effect of Al content x on microstructure and corrosion properties of high entropy alloy was systematically studied. The results show that the high entropy alloy has a simple crystal structure and the distribution of components is uniform. The increase of Al content promotes the formation of the BCC structural phase. When the Al mole content is less than 1.0, the main phase is FCC and the dendrite is FCC2 and the interdendritic is FCC1. When the Al mole content is higher than 1.0, the main phase is BCC and the second phase is FCC1. The electrochemical corrosion properties of Al 1.0 CoCrFeNiCu high entropy alloy is good, and the corrosion mainly starts in the form of spot corrosion. In general, the alloy has poor resistance to nitric acid corrosion , and FCC structural phase has better resistance to nitric acid corrosion than BCC structural phase. • The increase of Al content promotes the formation of BCC structural phase in Al x CoCrFeNiCu high entropy alloy. • FCC second phase particles exist in Al x CoCrFeNiCu high entropy alloy and change with the increase of Al content. • Al 1.0 CoCrFeNiCu high entropy alloy has the best electrochemical corrosion performance. • Al x CoCrFeNiCu high entropy alloy FCC structure shows better resistance to nitric acid corrosion than BCC structure phase.

Interstitial-driven local chemical order enables ultrastrong face-centered cubic multicomponent alloys

Multicomponent alloys of the Fe-Mn-Co-Cr-Ni family with face-centered cubic (fcc) structure exhibit many excellent properties. However, they usually show limited yield strength, which cannot meet the demand for practical applications. Here, we report a universal strategy for designing ultrastrong and ductile fcc multicomponent alloys, by introducing interstitial-driven local chemical order (LCO) through simple thermomechanical processing. In a prototype FeMnCoCrN multicomponent alloy processed by partial-recrystallization annealing, a high-density of fine laths containing interstitial-driven LCO domains (with both short- and medium-range orders) are predominant. Those laths evolve from planar dislocation slip bands promoted by the intrinsic short-range order of the alloy under prior cold deformation. Owing to the hardening effect of the LCO-laths, an ultra-high yield strength of 1.34 GPa is achieved, while deformation twinning contributes to a uniform elongation of 13.9%. This design strategy, which is also successfully verified in a multicomponent austenitic steel, provides a new paradigm for developing high-performance fcc materials at low cost.

Highly porous FeNi 3D foams produced by one-step electrodeposition: Electrochemical stability and mechanical properties

Highly porous iron‑nickel foams, including the first-ever reported pure iron foam, were prepared by the dynamic hydrogen bubble template electrodeposition method and studied regarding their electrochemical stability and mechanical properties. Changes on the morphology, microstructure, and electrochemical resistance of the foams were investigated as a function of the Fe:Ni ratio by scanning electron microscopy (SEM), d.c. polarization and electrochemical impedance spectroscopy (EIS). Tensile and bending tests were carried out to evaluate the mechanical behavior of the prepared foams. Both crystalline structure and morphology are affected by the increase of Ni content, evolving from a highly porous foam with a body-centered cubic (bcc) structure to a denser material with open pores and face-centered cubic (fcc) structure. Polarization curves reveal an ennoblement of the corrosion potential as the nickel content increases. The impedance response revealed a dependence on the foam porosity. An increased number of pores was found more detrimental to the mechanical properties of the foams, as fractures seem to propagate, preferentially by cracks due to connecting pores. As result, foams with higher Ni contents displayed better mechanical performance for both tensile and bending assays. Results show that this innovative and powerfull technique enables to design iron foams with the adequate properties required for industrial applications. • Fe and FeNi nanofoams are prepared by Dynamic Hydrogen Bubble Template Electrodeposition. • Pure iron foam is obtained for the first time. • Foams morphology change for higher Ni contents. • Faradaic resistance depends on both %Fe and the pore availability. • Improved mechanical resistance is observed for the less porous foams.