Increase Of Cu Content Research Articles

One-step solution combustion synthesis of micro-nano-scale porous Cu/CeO2 with enhanced photocatalytic properties

The Cu/CeO2 nanoporous composite material was prepared via a one-step and energy-saving method of solution combustion synthesis (SCS). The phase composition, surface morphology and optical characteristics of Cu/CeO2 were studied. The results show that the SCS products are composed of cubic fluorite CeO2 and Cu. Due to the generation and escape of gas during the synthetic reaction, the SCS CeO2 shows porous structure, in which the mesopores (diameter 10–17 nm) nest in the wall of large pores (diameter 80–300 nm). X-ray photoelectron spectroscopy (XPS) outcomes indicate that the oxygen vacancy concentration of CeO2 increases (18.97%–30.93%) with the increase of Cu concentration. The decoration of Cu greatly enhances the catalytic activity of CeO2 nanomaterials. 30 wt% Cu/CeO2 composite material shows the best photocatalytic activities for the degradation of methyl orange (MO) (95.99%), which is about 4.3 times that of CeO2 at the same time (120 min). UV-vis diffuse reflectance spectroscopy (DRS) results show that the semiconductor band gap is reduced with the addition of metallic Cu, which leads to the enhancement of photocatalytic activity. The free radical trapping experiments demonstrate that ·O2– and h+ are the main active species in the photocatalytic degradation of MO. Based on the above results, a hypothesized mechanism for enhanced photocatalysis of Cu/CeO2 nanomaterials was proposed: the porous structure provides more reactive sites and channels for mass transfer, and the presence of metallic Cu improves the oxygen vacancy concentration of CeO2 and then promotes charge-carrier separation, which helps enhance the photocatalytic performance of Cu/CeO2.

Effect of Cu Content on the Precipitation Behaviors, Mechanical and Corrosion Properties of As-Cast Ti-Cu Alloys.

Ti-Cu alloys have broad application prospects in the biomedical field due to their excellent properties. The properties of Ti-Cu alloys are strongly dependent on Cu content, microstructures, its Ti2Cu phase and its preparation process. The aim of this work is to investigate the effect of Cu content on the precipitation behaviors, mechanical and corrosion properties of the as-cast Ti-Cu alloys. The microstructures and phase evolution were characterized by SEM and TEM, and the properties were studied by tensile and electrochemical test. The results show that the volume fraction of Ti2Cu phase increases with the increase of Cu content. The Ti2Cu phase presents a variety of microscopic morphologies with different Cu content, such as rod, granular, lath and block shaped. The crystal orientation relationships between the Ti2Cu and α-Ti matrix in Ti-4Cu and Ti-10Cu alloys are (103)Ti2Cu//(0[111)α-Ti, [01]Ti2Cu//[20]α-Ti, and (103)Ti2Cu//(0002)α-Ti, [31]Ti2Cu//[110]α-Ti, respectively. The tensile strength, Vickers hardness and Young’s modulus of the Ti-Cu alloys increase with the increase of Cu content, whereas the elongation decreases. The fracture morphologies of these alloys reveal ductile, ductile-brittle hybrid, and cleavage brittle mode, respectively. The corrosion resistance of the Ti-Cu alloys in SBF solution can be described as: Ti-4Cu alloy > Ti-10Cu alloy > Ti-7Cu alloy. The volume fraction of Ti2Cu phases and the “protective barrier” provided by the fine lath Ti2Cu phases strongly affected the electrochemical performances of the alloys.

Enhanced thermoelectric performance of hydrothermally synthesized CuFeS2 nanostructures by controlling the Cu/Fe ratio

In this manuscript, low-cost chalcopyrite (CuFeS2) nanostructures as a potential thermoelectric material are explored. CuxFe1-xS2 (x = 0, 0.1, 0.3 & 0.5) samples were fabricated by simple hydrothermal route. X-ray diffraction pattern reveals the formation of CuFeS2 along with impurity phases of FeS, FeO, and FeS2. The presence of these unwanted impurity phases goes on decreasing while the improvement in phase purity of CuFeS2 was observed with the increase in Cu concentration. This improvement in phase purity leads to enhancement in the Seebeck coefficient from 69 to 92 μV/°C (at 25 °C) by increasing the Cu concentration. Hall measurement reveals the significant enhancement of the electrical conductivity values from 90 to 110 S/cm by increasing the Cu concentration. The enhancement in electrical conductivity was associated with the shifting of Cu/Fe stoichiometry that leads to the generation of more free carriers which leads to a high-power factor value up to 9.31 × 10−5 W/mK2. To support our results, some other supplementary measurements such as Raman spectroscopy and scanning electron microscopy were also performed.

Research on the Performance of Brass Alloy Main transformer terminal

In order to determine the material of the main transformer terminal, the electrical conductivity, mechanical properties and stress corrosion resistance of brass alloy terminal were studied by XRD, mechanical properties test and ammonia fumigation test. The results show that H59 alloy consists of (Cu, Zn) phase, Cu5Zn8 phase and CuZn phase, H70 alloy consists of (Cu, Zn) phase and dendritic Cu0.64Zn0.36 phase, H80 alloy and H90 alloy are both (Cu, Zn) phase. With the increase of Cu content, the strength of brass decreases, the conductivity increases, and the stress corrosion resistance increases. H90 alloy has excellent plasticity and toughness, excellent resistance to ammonia fumigation stress corrosion, and can be used as main transformer terminal material.

Investigating the thermoelectric power generation performance of ZnCuO: A p-type mixed-metal oxide system

Thermoelectric power generation performance of ZnCuO nanostructures is enhanced by varying the concentration of Cu atoms. This is tested by growing samples of ZnCuO by simple hydrothermal route at different Cu concentrations (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5). The X-ray diffraction (XRD) pattern shows the formation of mixed-metal oxide phases of ZnO and CuO, while the increase in Cu concentration results in generation of more stable CuO phases. Raman spectroscopy measurement is performed for all synthesized samples, which supports the XRD results. For the thermoelectric and electric conductivity behavior, Seebeck coefficient and Hall measurements are performed for all samples. Data suggest an improvement in Seebeck coefficient from 32 to 73 μV°C−1 with the increase of Cu concentration in the host crystal. Electrical conductivity data also show a similar increasing trend (19–36 Scm−1) resulting in a high power-factor value of 1.12 × 10−5 Wm−1K−2 for the sample with highest Cu concentration. This enhanced thermoelectric performance with increasing concentration of Cu atoms is due to the improvement of carrier mobility. The mobility of carriers is thought to increase because of the emergence of mixed composite phases, as verified by XRD and Raman spectroscopy measurements.

Effect of copper concentrations on microstructure, residual stress and corrosion behavior of Ni100−x-Cux alloy films processed by magnetron co-sputtering

Nickel based alloys have gained importance due to their very good mechanical properties as well as their electrochemical behavior in different environmental conditions. In this regard, thin films of nanocrystalline Ni-Cu alloys have been processed by RF / DC magnetron co-sputtering in Ar gas environment for different copper concentration (10 %, 21 %, 28 % and 39 %). Grain size determination, phase identification and residual stress measurement have been done using an X-ray diffraction technique. A compressive residual stress has been observed and the value of the compressive stress increases with an increase in the Cu concentration in the Ni100−x-Cux alloy films. The electrochemical behavior of thin films of the Ni100−x-Cux alloy has been investigated with the help of potentiodynamic polarization experiments which revealed susceptibility towards pitting corrosion. The rate of corrosion decreases from 0.92 ×10−2 to 0.26 ×10−2 mm / year with the increase in Cu concentration from 10 % to 39 %. The microstructure of thin films of the Ni100−x-Cux alloy has been investigated using a field emission scanning electron microscope (FESEM). The FESEM micrograph shows the formation of pits, and the size of pits decreases with increasing concentration of doped Cu. Experimental results also reveal that the increase in corrosion resistance can correlate with the developing residual stress in the films.

Magnetic and dielectric properties of NiCuZn ferrite with optimized Cu content and sintered by a two-step process

Nickel-copper-zinc (NiCuZn) ferrites with high permeability and low magnetic loss have high application potential in high-frequency electronics. In this work, NiCuZn ferrite samples with different Cu contents were prepared by a two-step sintering method. First, the optimal temperatures of the two-step sintering method (1025/925 °C) were confirmed, thereafter the influence of the Cu content on the crystal structure, microstructure, magnetic and dielectric properties of NiCuZn ferrite were studied in detail. Structural characterization showed that an increase in Cu content promoted grain growth and resulted in NiCuZn ferrites with a denser microstructure and decreased porosity. However, a second phase of CuO formed once the content of Cu (x value) reached 0.16. The magnetic hysteresis loops revealed that the saturation magnetization increased as x increased and the highest value of 57.3 emu/g was obtained at x = 0.14. The dielectric property measurement showed that increasing the Cu content could improve the dielectric constant and reduce the dielectric loss. The permeability measurements showed an increase in permeability with Cu content from x = 0.10 to x = 0.14 and a decrease when x = 0.16. Consequently, a NiCuZn ferrite with an appropriate microstructure and with high permeability (μ'=855), low magnetic loss (tanδμ = 0.02), and high saturation magnetization (57.3 emu/g) could be obtained at a Cu content of x = 0.14 and sintering temperatures of 1025/925 °C in the two-step sintering method. This NiCuZn ferrite provides new guidance for developing RF frequency multilayer inductors.

Synthesis, characterization of novel ZnO/CuO nanoparticles, and the applications in photocatalytic performance for rhodamine B dye degradation.

Photocatalytic degradation of environmental pollutants is being up to date for the treatment of contaminated water. In the present study, ZnO/CuO nanomaterials were successfully fabricated by a simple sol-gel method and investigate the photo-degradation of rhodamine B (RhB). The synthesized ZnO/CuO nanoparticles were characterized by X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), thermal analysis (TGA), surface charge, and Fourier transform infrared spectroscopy (FTIR). The photo-degradation of the dye RhB was followed spectroscopically. The overall composition of ZnO/CuO material was found to be wurtzite phase, with particle size of 30 nm, and the Vis light absorption increased with an increase of Cu content. The ZnO/CuO nanomaterials were highly active leading to a photo-degradation of 10 ppm RhB reaching 98% within 180 min at 0.1 g/L catalyst dosage. The change in surface charge after degradation evaluated by ζ potential measurements and the differences in functional vibration group monitored by Fourier transform infrared spectroscopy (FTIR) indicates that the RhB adsorption on the Zn45Cu surface was insignificant. And scavenging experiments demonstrate that the RhB degradation by ZnO/CuO nanomaterials involves to some degree hydroxyl radicals.

Influences of Precursors Phase Composition on the Phase Evolution Dynamics of Bi-2223 Superconducting Tapes

Bi2Sr2Ca2Cu3O10+ (Bi-2223) precursors for the fabrication of high temperature superconducting tapes were prepared by spray pyrolysis technique followed by a calcination process. The influences of precursor powder phase composition on the phase evolution dynamics and final current capacity of Bi-2223 superconducting tapes were systematically studied. It was interesting to notice that slight increase of Cu content in chemical composition could cause obvious variations of both the phase composition and the morphology of CuO particles in precursors. Therefore, the Bi-2223 phase formation process during the sintering process of tapes could be affected, and the current capacity changed accordingly. On the other hand, during the calcination temperature optimization process, the Bi-2223 phase content in precursors changed accordingly, thus the Bi-2223 phase formation dynamics were also studied. More Bi-2223 nuclei were formed due to the pre-existed Bi-2223 grains, which worked as inhomogeneous nuclei centers. Thus, although the final Bi-2223 phase contents were similar in all the tapes, the particle size and texture structure of Bi-2223 varied greatly, which caused a dramatic decrease of critical current in Bi-2223 tapes with the formation of Bi-2223 in precursors. Therefore, it could be concluded that both the morphology of CuO particles and the Bi-2223 phase content in precursors were the factors controlling the phase evolution dynamics during Bi-2223 tape sintering process.

Insights into corrosion resistance enhancement of nickel–phosphorus metallic glass in acid environment by the incorporation of copper

The corrosion resistance of a Ni–P metallic glass could be enhanced significantly by the addition of Cu. However, the mechanism of corrosion resistance remains unclear. In this study, Ni–Cu–P amorphous coatings with different Cu contents were chemically deposited on mild steel. The effects of the Cu content on the morphology, composition, microstructure, thermal stability and corrosion resistance of the coatings were investigated through scanning electron microscopy, energy-dispersive spectroscopy, X–ray diffraction analysis, differential scanning calorimetry, and electrochemical tests. The corrosion products on the coating in the acid corrosion medium were analyzed through X–ray photoelectron spectroscopy. The cluster size in the Ni–Cu–P amorphous coating initially decreased and then increased with an increase in Cu content. An amorphous coating with relatively smaller ordered clusters showed better corrosion resistance. In 5 wt% H2SO4 solution, the compact phosphate and hypophosphate passive film was generated on the Ni–Cu–P coating with n–type semiconductor characteristics.

Nautical Tourism in Marine Protected Areas (MPAs): Evaluating an Impact of Copper Emission from Antifouling Coating

Copper (Cu) has a narrow range between optimal concentrations as a micronutrient critical for phytoplankton growth and concentrations potentially toxic to living organisms. This sensitivity indicates an ecosystem vulnerability that threatens not only nature but also human health due to bioaccumulation. An important source of elevated Cu concentrations in coastal environments are biocides used as antifouling protection on ships. A pilot study conducted in the Marine Protected Area (MPA) of the Krka Estuary (Croatia) over a period of 16 months investigated the relationship between ship traffic and Cu concentrations. The aim was to contribute to more informed environmental management by assessing the associated risks. In the study presented here, Cu concentrations were monitored, analyzed, and correlated with vessel traffic. Observations revealed that the seasonal increase in maritime traffic caused by nautical tourism was associated with an increase in Cu concentrations of more than five times, posing a toxicity risk to the environment. In order to understand the distribution of copper emissions, a mapping of maritime traffic was carried out by counting transits, radar imagery, and drone photography. This approach has proven sufficient to identify the potential risks to the marine environment and human health, thus providing an effective assessment tool for marine stakeholders.

Effect of Cu content on electrical resistivity, mechanical properties and corrosion resistance of AlCuxNiTiZr0.75 high entropy alloy films

AlCuxNiTiZr0.75 high entropy alloy (HEA) films were deposited by magnetron sputtering with an alloy target in combination with a pure Cu metal target. The purpose of this study was to reduce electrical resistivity of the HEA films while maintaining mechanical properties and corrosion resistance by adjusting Cu content of the HEA. We found that the AlCuxNiTiZr0.75 HEA films were amorphous and displayed a homogeneous or columnar microstructure along the cross sections. The increase of Cu content changed the electronic structure of the HEA films, so that the resistivity decreased sharply to 66 μΩ·cm at x = 1.4. The hardness-to-elastic modulus ration H/E, an indicator of a material's ductility, attained the maximum value at x = 1.4. Although the corrosion current densities increased with x, they were all below 10−6 A/cm2 in 3.5 wt% NaCl solution, indicating good corrosion resistance. These findings assumably help expand industrial application of HEA films, particularly when conductivity is required for the functionality of the films.

Effect of Cu on microstructure and corrosion behavior in 360°C lithiated aqueous solution of Zr–Cu alloys

AbstractThe effect of Cu on the microstructure and corrosion behavior in 360°C lithiated water was investigated on Zr–xCu alloys (x = 0.05, 0.2, and 1.0, wt%), with remelted pure Zr as reference material. The results revealed that the tetragonal Zr2Cu phase was induced by Cu addition higher than 0.2 wt% and its size and number density were increased with the increase of Cu content. The weight gain and oxide thickness were decreased by Cu addition, but when the Cu content increased to 1.0 wt%, they were both significantly increased and even larger than that of remelted Zr. It was supposed that structural defects, such as pores and microcracks, in the oxide film may result in such degradation in the corrosion property of Zr–1.0Cu alloy.

Studies on superparamagnetic behaviour of Ni100-xCux alloy films deposited by DC magnetron sputtering

ABSTRACT In this study, nanocrystalline Ni100-xCux alloy films have been synthesised using DC magnetron co-sputtering under argon gas atmosphere to analyse their superparamagnetic behaviour. The nanocrystalline nature and the grain size of the alloy films have been measured using grazing incidence x-ray diffraction (GIXRD) and a transmission electron microscopy (TEM). The M-H curves obtained using superconducting quantum interference device provides evidence for superparamagnetic behaviour of the nanocrystalline Ni100-xCux alloy films. For the Ni89Cu11 alloy films, the highest value (456 emu/cm3) of saturation magnetisation has been measured. Zero field cooling (ZFC) and field cooling (FC) data obtained from superconducting quantum interference device (SQUID) showed the dependence of blocking temperature, TB on Cu concentration of the investigated NiCu alloy. The blocking temperature is observed to decrease from 44 K to 33 K with increase in Cu concentration from 11 to 28 wt%.

The Preliminary Studies on the Tremendous Degradation Rate of Methylene Blue with Cu-doped α-MnO2 Photocatalyst Under UV Light Irradation

Dye contaminations have severe impacts to environment (air, soils, plants, water) due to their adverse effects. Most dyes are toxic, carcinogenic, mutagenic and resistant to bio-degradation. Photocatalysis-based advanced oxidation process (AOP) has been considered as the most effective and efficient way to treat this recalcitrant compounds. Manganese oxides are ubiquitous and environmentally friendly in natural environments and can act as semiconducting materials. Tunnel structure of manganese oxide such as α-MnO2 (cryptomelane) has been widely studied for broad applications as Fenton-based AOP. Catalytic efficiency of α-MnO2 could be further increased by doping α-MnO2 with a metal ion like the Cu ion. Although the synthesis and catalytic activity of Cu-α-MnO2 have been reported by previous studies, its photocatalytic performance using this one-pot-sol-gel approach for MB degradation has never been reported previously. Herein, Cu-doped α-MnO2 was synthesized by one-pot sol-gel method and characterized by X-ray diffraction (XRD), BET surface area and atomic absorption spectroscopy (AAS). The AAS results suggested the presence of Cu ions in α-MnO2 since the increase in doping Cu resulted in the corresponding increase in Cu content in the α-MnO2. The BET surface area indicated that the doping 10% Cu in α-MnO2 led to about two fold increase in suface area compared to undoped α-MnO2. The photo catalytic performance of Cu-α-MnO2 via UV light irradiation for the degradation of methylene blue (MB) was significantly higher that that of undoped α-MnO2 and was associated with the increased in surface area of Cu-α-MnO2 over undoped α-MnO2. The maximum degradation of MB was 97.9, 98.3, 98.7 and 99.5% achieved using α-MnO2, 1% Cu-α-MnO2, 5% Cu-α-MnO2, and 10% Cu-α MnO2 and 10% Cu-α-MnO2.

Optical and electrical properties of NiO and Cu-doped NiO thin films synthesized by spray pyrolysis

Spray pyrolysis technique was employed to synthesize NiO and NiO:Cu thin films (0.1–25% Cu) on soda-lime glass substrate. Optical properties, as well as electrical resistivity of these films, were investigated. UV–Visible spectrophotometer was employed to measure the optical properties. The absorption edge of the films was located within the UV range i.e. λ = 280–380 nm. The average reflectance of the films was 16.9% in the range λ = 280–900 nm. On increasing the Cu/Ni ratio, the optical band gap decreased whereas the refractive index and Urbach energy increased. Quantitatively, the measured average value of the refractive index and the value calculated from the Reddy-Ahammed empirical formula, which connects refractive index with optical band gap, were in good agreement. Optical conductivity was found to be in the range 10 14 –10 15 s −1 while the dielectric loss was rather very low; it points to the good optical response of the films. The average oscillator energy as well as dispersion energy evaluated from Wemple–DiDomenico model decreased rapidly to begin with as Cu/Ni ratio was increased up to 5% but later on decreased rather slowly. Optical band gap values calculated by the Wemple-DiDomenico model and by Tauc relation agreed very well. The PL spectra of all the films displayed an intense peak at 403 nm and two secondary peaks at 426 nm and 365 nm. The PL intensity of each peak decreased monotonically with an increase in Cu content in NiO:Cu thin film from 0 to 3%. However, it remained almost independent of Cu content in the range of 4–25%. With an increase in Cu/Ni ratio, electrical resistivity and carrier mobility decreased whereas carrier concentration increased. • Optical band gap of NiO:Cu thin films (0–25% Cu) was in the range 3.57–3.21 eV. • Refractive index (2.15–2.42) increased on doping and average reflectance was 16.9%. • Optical band gap calculated by Tauc relation and Wemple-DiDomenico model agree well. • PL spectra of all the films displayed three peaks at 403, 426, and 365 nm. • Intensity of each PL peak decreased up to 3% Cu and then remained nearly constant.

Influence of PtCu/C Catalysts Composition on Electrochemical Characteristics of Polymer Electrolyte Fuel Cell and Properties of Proton Exchange Membrane

The present work aimed to investigate the influence of “weakly bound“ copper dissolution from the surface of bimetallic PtCux/C catalysts on the properties of proton exchange membrane and the membrane electrode assembly (MEA) in general. A number of PtCux/C materials have been obtained by the simultaneous reduction in copper and platinum precursors in the course of liquid-phase synthesis with a varying ratio of metals from PtCu2.0/C to PtCu0.3/C. All bimetallic PtCux/C electrocatalysts after the activation stage exhibit high activity in the oxygen electroreduction reaction. The PtCux/C catalysts in “as prepared” state were tested in MEA. The increase in Cu content in PtCux/C catalysts led to a decrease in current density of MEA while its resistance was almost independent of the Cu fraction in the catalyst. The membrane saturation degree by Cu2+-ions after MEA testing did not exceed 40%, even in the case of the PtCu2.0/C material. The main reason for the degradation of membrane electrode assembly with PtCux/C materials is the transport limitation caused by the contamination of Nafion in three catalytic layer by “weakly bound” copper ions.

Increasing Temperature Alters the Effects of Extracellular Copper on Thalassiosira Pseudonana Physiology and Transcription

Copper (Cu) is essential for many physiological processes in phytoplankton, including electron-transfer reactions and high-affinity Fe transport systems. However, at high concentrations, Cu can have a toxic effect on phytoplankton. Phytoplankton’s tolerance to certain toxicants in marine ecosystems cannot always be solely attributed to the presence of compounds, as various environmental factors including temperature can also indirectly influence their effects on organisms. In this study, we investigated the effects of different Cu concentrations (0, 19.6, 160, 800, and 8000 nM) on the growth and physiological changes in the centric diatom Thalassiosira pseudonana (CCMP 1335) when simultaneously applied with temperature cultivation of 20 °C and 25 °C. At low (0 nM) and high (8000 nM) Cu concentrations, the growth rate of T. pseudonana was inhibited, though an increase in temperature lessened this inhibition. There were no significant changes in the POC:PON ratio during all of the treatments. However, increasing the temperature significantly decreased the POC: POP, PON: POP and BSi: POP ratios of T. pseudonana. The intracellular Cu content of T. pseudonana varied from 0.13 to 13.28 fg cell−1 in response to increases in ambient Cu concentrations. Lastly, an increase in the Cu concentration decreased the transcriptional expression of CTR (copper transporter), 3Hfcp (photosynthetic protein), and Sit1 (silica shell formation) encoding genes. In conclusion, our results indicated that T. pseudonana can adapt to physiological processes and molecular mechanisms in response to varying Cu concentrations and ambient temperatures.

Efficiency of antioxidant system in barrel medic (

Iron (Fe) deficiency leads to an overproduction of reactive oxygen species (ROS) in plants that activate their antioxidant systems to control oxidative burst. In this study, contrasting Medicago truncatula genotypes, A17 and TN8.20 (tolerant) and TN1.11 (sensitive), were grown under Fe deficiency. The superoxide dismutase (SOD: EC1.15.1.1) activity, their isoforms’ coding genes, the copper chaperone expression patterns, and leaf phenolic contents were analysed. Our results showed that Fe deficiency decreases the photosynthetic capacity and plant biomass production with a prominent effect on TN1.11 genotype. The tolerance of A17 and TN8.20 was correlated with a maintenance of Fe content and the photosynthetic apparatus and an increase of Cu concentration compared with the sensitive genotype. We revealed a significant increase of H2O2 in Fe-deficient plants, mainly in TN1.11 sensitive genotype. TN8.20 and A17 tolerance were concomitant with a significant increase of SOD activities (SOD, Cu/Zn-SOD, and Mn-SOD) under Fe deficiency. This increment was correlated to an induction of the copper chaperone gene expression level, as well as an accumulation of isoquercitin phenolic compound. Our study provides new insights into the orchestration of SOD’s isoforms activities, the expression of the copper chaperone, FeSOD, Cu/ZnSOD genes, and the leaf phenolic compounds accumulation that allows Medicago truncatula to overcome Fe deficiency.

The in-situ β phase reinforced Ti/Zr-based bulk metallic glass matrix composite by selective laser melting

In this study, in-situ β phase reinforced Ti/Zr-based BMGCs without toxic element Be, (Ti0.65Zr0.35-yNby)100-xCux (x = 5, 10, y = 0.05, 0.1, at. %), were prepared via selective laser melting (SLM). The effect of Cu and Nb contents on phase formation, microstructure, and compressive mechanical properties were studied, and the microcrack formation mechanism in the deposits with lower Cu content (5 at. %) was also investigated. With the increase of Cu content from 5 to 10 at. %, the volume fraction of β phase decreased, while the volume fraction of amorphous phase and (Ti, Zr)2Cu phase increased. Meanwhile, the amorphous phase presented a more continuous network-shaped morphology. Compared with the content of Cu element, the variation of Nb content had a minor effect on the phase precipitation and microstructure evolution. With the increase of Nb content, β phase became more stable, which may cause the increase of compression fracture strain. In addition, the microstructure with a good connectivity of β phase in the center zone of the molten pool had a higher deformation capacity than that in the edge zone of molten pool, where β phase was isolated by the amorphous phase network. There are some solidification microcracks existing in Cu5Nb4.75 and Cu5Nb9.5 deposits. Because of a higher |dT/d(fS1/2)| near fS1/2 = 1, the liquid phase cannot feed the liquid channel between β phases in time, liquid film is ruptured, and solidification crack forms.