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Bulk metallic glasses deform irreversibly under a stress through shear-banding courses that manifest as the serrated flow behavior. The compressive deformation and dynamic serrated flow behavior of Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 bulk metallic glass samples with different aspect ratios have been investigated. The yield strength nearly remains a constant value of approximately 2 GPa, while the compressive plasticity increases obviously with decreasing aspect ratio. It is found that the serrated flows display a power-law scaling behavior at different aspect ratios. The power-law scaling behavior is discussed by controlling shear bands in BMG. In addition, a new method was proposed to study the power-law-scaling behavior. When the aspect ratio is small, the friction between the sample and the platen will play a significant role that attributes to a lateral constraint. The uniaxial stress and the lateral constraint will cause a hydrostatic pressure on the sample close to the platen. The shear bands are controlled by the different stress states, which leads to a power-law-scaling behavior in serrated flows. The investigations have a contribution to understanding the plastic-deformation mechanism of BMGs. [ABSTRACT FROM AUTHOR]

Ca 3− x Ce x Co 4− y Ni y O 9+ δ materials were prepared by the sol–gel method, and the effects of Ni, Ce co-doping on the thermoelectric properties of Ca 3 Co 4 O 9+ δ were systematically investigated from 20 K to 350 K. The thermal conductivities of co-doped specimens decreased significantly compared with that of pure Ca 3 Co 4 O 9+ δ , and the opposite trend in thermopower was observed. Ni, Ce co-doping considerably enhanced the thermoelectric responses of Ca 3 Co 4 O 9+ δ compared with those of pure and Ce single-doped Ca 3 Co 4 O 9+ δ . A maximum thermoelectric figure of merit of 0.022 was obtained from Ca 2.9 Ce 0.1 Co 3.9 Ni 0.1 O 9+ δ at 350 K. This value is approximately 9-fold higher than that obtained from Ca 3 Co 4 O 9+ δ and 1.4-fold higher than that from Ca 2.9 Ce 0.1 Co 4 O 9+ δ , which indicates good thermoelectric performance. Overall, results demonstrate that Ni, Ce co-doping effectively improves the thermoelectric properties of Ca 3 Co 4 O 9+ δ systems. [ABSTRACT FROM AUTHOR]

Compressive tests were conducted on metallic glass matrix composites at a series loading rates. It was found that mechanical properties of the composite, e.g. yielding stress and plasticity, have a week dependence on strain rates of 4.0 × 10 −4 s −1 –4.0 × 10 −1 s −1 . Four composites were tested at a constant strain rate of 2.3 × 10 s −1 to uncover the dynamic deformation behaviors. Compared with the quasi-static case, the yielding strength increased under dynamic loading rate, but the plasticity decreased significantly. On the other hand, the dynamic compressive has closely relation with the dendrite size and volume fraction. The decreasing of the dendrite size and volume fraction leaded to the dynamic yielding strength increased but the plasticity decreased. For a same composite, e.g. T1 alloy, the yielding strengths increased slightly but fracture strain decreased with increasing of dynamic strain rates. [ABSTRACT FROM AUTHOR]

• The dynamic response of the single walled and sandwich walled tubes subjected to an internal explosion was investigated. • An empirical formula was presented to predict the deformation or failure of a tube under the internal explosion. • An analytical model was proposed to describe the response of the sandwich tube under the internal blast loading. Cylindrical metallic tubes are commonly used as a protective structure to contain explosives. This study focused on the response of single walled and sandwich walled cylindrical tubes subjected to an internal explosion. Firstly, real-life detonation experiments were performed to obtain the basic deformation patterns. Finite element (FE) simulations were then conducted in ANSYS and LS-DYNA to obtain the simulated data for deformation pattern. Those simulated results were then validated against the experimentally obtained data. Next, a parametric study was performed in order to obtain the main parameters in an explosive process while keeping the failure strain of the material constant. For single-walled tubes, these were namely found to be the mass of the PE4 explosive used (M), the thickness of the tube wall (h) and the stand-off distance (R). A non-dimensional empirical formula was obtained. Then the response of sandwich-walled tube filled with the closed-cell aluminum foam under PE4 charge was investigated numerically. The numerical results revealed that the deformation or failure, and the energy absorption of the sandwich tubes were significantly affected by the PE4 charge, and also the mass ratio of the tube to the foam. As a first step, a simplified one-dimensional axisymmetric analytical model was presented where the filled foam was assumed to have an initial rigid regime, followed by a perfectly-plastic stage and locking densification (R-PP-L). Comparison with the numerical model gives a fairly good agreement. [ABSTRACT FROM AUTHOR]

Ti–5Al–5Mo–5V–1Cr–1Fe is a near β-type Ti-alloy. It has been widely used in large loading-carry structures in aircrafts due to its excellent mechanical properties. For near-β titanium alloys, DRX (dynamic recrystallization) in hot deformation process can eliminate the bimodal microstructure and refine microstructure, which helps to improve the alloy performance. So, the hot deformation behavior of Ti–5Al–5Mo–5V–1Cr–1Fe alloy was characterized in the temperature range of 750–950 °C and the initial strain rate range of 0.01–10 s −1 by the constitutive model, the critical conditions of DRX and EBSD (Electron Backscattered Diffraction) technique. The constitutive model of Ti–5Al–5Mo–5V–1Cr–1Fe alloy during hot deformation can be well described by Arrhenius hyperbolic sine function. The calculation results show that the ratio of critical strain and peak strain is about 0.64. Under the experimental conditions in this research, Ti–5Al–5Mo–5V–1Cr–1Fe alloy exhibits two soften mechanisms of (DRV) dynamic recovery and DRX. The DRX phenomenon of Ti–5Al–5Mo–5V–1Cr–1Fe alloy exists in all of hot deformation conditions. Only the extents of DRX are different. There are several nucleation mechanisms of DRX in the process of hot deformation of Ti–5Al–5Mo–5V–1Cr–1Fe alloy in this study. [ABSTRACT FROM AUTHOR]

This paper reports on the wettability and aging behaviors of the silicon wafers that had been cleaned using a piranha (3:1 mixture of sulfuric acid (H 2 SO 4 , 96%) and hydrogen peroxide (H 2 O 2 , 30%), 120 °C), SC1 (1:1:5 mixture of NH 4 OH, H 2 O 2 and H 2 O, at 80 °C) or HF solution (6 parts of 40% NH 4 F and 1 part of 49% HF, at room temperature) solution, and treated with gaseous plasma. The silicon wafers cleaned using the piranha or SC1 solution were hydrophilic, and the water contact angles on the surfaces would increase along with aging time, until they reached the saturated points of around 70°. The contact angle increase rate of these wafers in a vacuum was much faster than that in the open air, because of loss of water, which was physically adsorbed on the wafer surfaces. The silicon wafers cleaned with the HF solution were hydrophobic. Their contact angle decreased in the atmosphere, while it increased in the vacuum up to 95°. Gold thin films deposited on the hydrophilic wafers were smoother than that deposited on the hydrophobic wafers, because the numerous oxygen groups formed on the hydrophilic surfaces would react with gold adatoms in the sputtering process to form a continuous thin film at the nucleation stage. The argon, nitrogen, oxygen gas plasma treatments could change the silicon wafer surfaces from hydrophobic to hydrophilic by creating a thin (around 2.5 nm) silicon dioxide film, which could be utilized to improve the roughness and adhesion of the gold thin film. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Al content is related with structural relaxation and damping capability. [•] Dynamic modulus is insensitive to the frequency especially for storage modulus. [•] Several internal-friction peaks are observed in the Al-free or Al-lean alloys. [•] The damping behavior is proposed to be strongly relied on the level of ordering. [Copyright &y& Elsevier]

Abstract: Burst sizes in different amorphous alloys are predicted by . When the diameter of tested samples is decreased, the burst size is greatly increased. And the critical diameter, corresponding to shear failure, could be predicted. The present prediction could be as a criterion to guarantee steady serrations free of failure. [Copyright &y& Elsevier]

Highlights: [•] The Z-phase CrNbN will not spontaneously change into two phases ([Cr2N]+[V2N]). [•] Increasing N can promote Z phase changing into corresponding binary compounds. [•] The mechanical stability of the Z phases with N (0.5,0.5,0.5) is lower than other Z phases. [ABSTRACT FROM AUTHOR]

• The upper and lower response bounds are obtained through a series of sequential simulations. • The proposed sequential simulation method is applicable to interval uncertainty analysis of structural or system response with multiple DOFs. • The contributive samples for the response bounds over the whole concerned domain can be identified simultaneously. • The sequential simulation strategy is demonstrated to be more efficient than the direct MC simulation for response bounds evaluation. Prediction of response bounds of structures with interval uncertainties is a major concern in interval finite element analysis. In many cases, the structural response is a variable regarding to physical parameters such as location, node, time, or other degrees of freedom. Different kinds of interval methods have been proposed and developed for response bounds analysis, which mainly include the interval arithmetic-based methods, optimization methods, perturbation methods, etc. This paper proposes a sequential simulation strategy for response bounds analysis of structures with interval uncertainties, through which we aim to find the upper and lower bounds by implementing the simulation procedure sequentially. The proposed sequential simulation strategy suggests an initial sampling and simulation, from which those contributive samples that result in the current upper or lower response bound are retained. In the subsequent simulation sequence, local samples within neighborhoods of the present contributive samples as well as a set of global samples are generated for the input interval uncertainties. With such a simulation procedure, the response bounds are expected to expand outwards sequentially until convergence. By illustration and comparison, the proposed sequential simulation strategy is proved to be more efficient than the direct simulation method for structural response bounds analysis. [ABSTRACT FROM AUTHOR]

Abstract: In-situ dendrite/metallic glass matrix composites with a composition of Ti62Zr12V13Cu4Be9 upon dynamic loading exhibit distinguishing plasticity. It is found that a positive strain-rate sensitivity of the flow stresses with the strain rates dominates in such in-situ dendrite-reinforced composites. The Johnson–Cook (J–C) plasticity model is employed to model the flow behavior, and the constitutive relationship is obtained as . The ductile dendrites accommodate plasticity, characterized by the multiplication of dislocations and lattice distortions, together with the appearance of Moiré patterns. [Copyright &y& Elsevier]

Highlights: [•] The formation enthalpy of Cr2N, CrVN, and V2N are –1.33, –2.30, and –3.10eV/f.u. respectively. [•] VCrN does not spontaneously change into two phases, Cr2N and V2N. [•] The Debye temperatures (θ D) of Cr2N, CrVN, and V2N are 132, 134, and 136K, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The crystal structure and elastic and electronic properties of γ -Fe4B were predicted using density functional theory calculations. In view of the formation energy, the phase stability increases from γ-Fe4B, γ-Fe4C to γ-Fe4N. It is confirmed that the bonds of γ-Fe4X (X=B/C/N) are complex mixtures of metallic, covalent and ionic characters. The ionicity of FeX increases from FeB, FeC to FeN in γ-Fe4X (X=B/C/N). The magnetic moments of γ-Fe4X (X=B/C/N) are mainly contributed by 3d electrons of metal atoms. For γ-Fe4B, the values of Fe Ms are 3.118 and 2.024μB for FeI and FeII, respectively. For γ-Fe4C, the values of Fe Ms are 3.135 and 1.696μB for FeI and FeII, respectively. For γ-Fe4N, the values of Fe Ms are 2.972 and 2.307μB for FeI and FeII, respectively. The Debye temperatures of γ-Fe4X (X=B/C/N) are predicted as 366, 500 and 477K. [Copyright &y& Elsevier]

Abstract: First principles calculations have been performed for ε-phases Fe3X(X=B/C/N) with hexagonal close-packed Fe sublattices. The calculated equilibrium structural parameters of ε-Fe3C and ε-Fe3N are in agreement with experimental results. The crystal structure of the ε-Fe3B is predicted. In the view of the formation energy, the phase stabilities grow up from ε-Fe3B, θ-Fe3N, ε-Fe3C, θ-Fe3C, θ-Fe3B to ε-Fe3N. The bonding nature in ε-Fe3X (X=B/C/N) is described as a complex mixture of covalent, ionic and metallic characters. The average magnetic moments (Ms) of the ε-Fe3B, ε-Fe3C and ε-Fe3N are 1.53, 1.61 and 1.66μB/atom, respectively. The Ms of Fe are 2.17, 2.23 and 2.25μB in ε-Fe3B, ε-Fe3C and ε-Fe3N, respectively. The Ms of B/C/N are −0.39/−0.26/−0.08μB.The Debye temperatures of ε-Fe3X (X=B/C/N) are predicted as 427, 565 and 555K. [Copyright &y& Elsevier]

Abstract: The purpose of this experiment was to estimate the protective effects of melatonin against radiation-induced brain damages in mice induced by heavy ion beams. Kun-Ming mice were randomly divided into five groups: normal control group, irradiation control group, and three different doses of melatonin (5, 10, and 20mg/kg, i.p.) treated groups. Apart from the normal control group, the other four groups were exposed to whole-body 4.0Gy carbon ion beam irradiation (approximately 0.5Gy/min) after i.p. administration of normal saline or melatonin 1h before irradiation. The oxidative redox status of brain tissue was assessed by measurement of malondiadehyde (MDA) levels, total superoxide dismutase (T-SOD), cytosolic superoxide dismutase (Cu/ZnSOD, SOD1) and mitochondrial superoxide dismutase (MnSOD, SOD2) activities at 8h after irradiation. DNA damages were determined using the Comet assay and apoptosis and cell cycle distribution were detected by flow cytometric analyses. A dramatic dose-dependent decrease in MDA levels, tail moment, rates of tailing cells, and apoptosis, and a dose-dependent increase in T-SOD and SOD2 activities, in brain tissues in the melatonin-treated groups were detected compared with the irradiation only group. Furthermore, flow cytometric analysis demonstrated that the percentage of brain cells in the G0/G1 phase decreased significantly, while those in the S and G2/M stage increased dramatically, with mice pretreated with melatonin compared to the irradiation control group. These data indicate that melatonin has protective effects against irradiation-induced brain injury, and that its underlying protective mechanisms may relate to modulation of oxidative stress induced by heavy ionirradiation. [Copyright &y& Elsevier]

Abstract: The ingot of Fe–(18−x)at%Ga–x at%Al (3≤x≤13.5) alloys was prepared from high purity elements using a high vacuum arc melting system. The X-ray diffraction patterns indicated that the alloys were disordered bcc A2 structure. The magnetostriction of the alloys was measured and the effect of partial substitution of Ga with Al on the magnetostriction of the alloys was investigated. Fe–9at%Ga–9at%Al alloy, the optimizing magnetostrictive alloy was found in Fe–(18−x)at%Ga–x at%Al (3≤x≤13.5) alloys. The saturated magnetostriction of the directional solidification Fe–9at%Ga–9at%Al rod is up to 135ppm for 0MPa and 221ppm for 53MPa. It was found that the alloy has the high linearity of the magnetostriction curve, the low hysteresis and saturated magnetic field, which suggests the directional solidification Fe–9at%Ga–9at%Al alloy is a potential candidate for magnetostrictive actuator and transducer applications. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) flower-like Ni(OH)2 nanostructures have been successfully synthesized by a facile template-free solution process, in which F− and NH3 were used as Ni2+ coordination agents, and ammonia hydroxide solution was used as OH− supplier to accelerate the hydrolyzation of nickel complex species. The flower-like Ni(OH)2 nanostructures consisted of many intercrossed nanoflakelets with a mixed crystal structure of α- and β-Ni(OH)2. The F− and NH3 in reactive solutions played important roles in the nanostructure growth process. The Ni(II) concentration had great influence on the morphologies of Ni(OH)2 nanostructures. The possible growth mechanisms including aggregation growth, surface growth and surface dissolution were also proposed. The magnetization measurement indicated that the flower-like Ni(OH)2 nanostructures exhibited paramagnetic behavior above the critical temperature (10K) and ferromagnetic behavior below the critical temperature. [Copyright &y& Elsevier]

Abstract: Using first-principles technique, the crystal structure of cementite-type Fe3N is predicted. The average magnetic moment (Ms) of cementite-type Fe3N is also predicted as 1.4929μB/atom. The Ms of Fe3N is bigger than that of Fe3C, but smaller than that of Fe3B. Fe Ms between two different Fe sites in Fe3N are different (2.0541 and 2.0139μB), which indicates that Fe Ms are sensitive to the local short-range order in the cementite-type crystal. The Ms of B, C and N are −0.3525, −0.2474 and −0.1102μB/atom in Fe3X (X=B, C, N), respectively. The chemical bonds of Fe3X (X=B, C, N) take on metallicity, covalence, and ionicity. The ionicity of Fe3X (X=B, C, N) strengthens and the covalence of Fe–X weakens, going from Fe3B, Fe3C to Fe3N. [Copyright &y& Elsevier]

Abstract: A CoFe2O4/Pb(Zr0.53Ti0.47)O3 (CFO/PZT) multiferroic composite thick film assisted by polyvinylpyrrolidone (PVP) was prepared by a hybrid sol–gel processing and spin coating technique. Scanning electronic microscopy indicated a porous microstructure with a thickness of 6.2 μm. Pure PZT perovskite phase observed from x-ray diffraction suggested that the low ratio of CFO particles was deeply buried in the PZT matrix. Ferroelectric and ferromagnetic properties were observed simultaneously at room temperature as well as a lower leakage current compared with a CFO/PZT thin film. The dynamic and static magnetoelectric effects were strongly dependent on the applied DC/AC magnetic field but their values were very low. The results demonstrated the prediction that ferroelectric and ferromagnetic properties can induce a strong magnetoelectric coupling only if a dense microstructure was achieved. [Copyright &y& Elsevier]

Abstract: The structural, mechanical, electronic and magnetic properties of Fe3C with hexagonal structure and orthorhombic structure were investigated by using first-principles technique. The internal positions of atoms within the unit cell were optimized and the ground state properties such as lattice parameter, elastic constants, bulk modulus and the final enthalpy of the Fe3C in hexagonal and orthorhombic structure were calculated. The results show that the calculated equilibrium structural parameters of Fe3C are in agreement with the experimental results well, and the formation energy of Ortho-Fe3C is lower than that of Hexa-Fe3C, but the mechanical stability of Ortho-Fe3C is lower than that of Hexa-Fe3C. The density of states (DOSs) reveals that both Ortho-Fe3C and Hexa-Fe3C are strong metallic carbide. The calculated electronic structure indicates that the bonds of Fe3C are of the mixtures of metallic, covalent, and ionic properties. The average magnetic moments (Ms) of the Ortho-Fe3C and Hexa-Fe3C are 1.396 and 1.497 μ B/atom, respectively. The C atoms are oppositely polarized in the two crystals as indicated by the spin-density maps. For Ortho-Fe3C, the Fe Ms values of 1.915 and 1.990 μ B for Fe′ and Fe′′ sites were obtained, respectively. This difference on Ms between two different Fe sites in Ortho-Fe3C indicates that the Fe moments are sensitive to the local short-range order in the crystal. [Copyright &y& Elsevier]

Abstract: Tay–Sachs disease (TSD) is a progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of β-hexosaminidase A (Hex A). Deficiency of Hex A in TSD is caused by a defect of the α-subunit resulting from mutations of the HEXA gene. To date, there is no effective treatment for TSD. Animal models of genetic diseases, similar to those known to exist in humans, are valuable and essential research tools for the study of potentially effective therapies. However, there is no ideal animal model of TSD available for use in therapeutic trials. In the present study, we report an animal model (American flamingo; Phoenicopterus ruber) of TSD with Hex A deficiency occurring spontaneously in nature, with accumulation of GM2-ganglioside, deficiency of Hex A enzymatic activity, and a homozygous P469L mutation in exon 12 of the hexa gene. In addition, we have isolated the full-length cDNA sequence of the flamingo, which consists of 1581 nucleotides encoding a protein of 527 amino acids. Its coding sequence indicates approximately 71% identity at the nucleotide level and about 72.5% identity at the amino acid level with the encoding region of the human HEXA gene. This animal model, with many of the same features as TSD in humans, could represent a valuable resource for investigating therapy of TSD. [Copyright &y& Elsevier]

Abstract: Magnetic cobalt chains, self-assembled by microspheres of hexagonal-phase cobalt, have been synthesized at 100°C via a hydrothermal reduction route in the presence of cobalt chloride, the surfactant sodium dodecylsulfate (SDS) (or cetyltrimethylammonium bromide CTAB) and the complex reagent sodium tartrate. As-synthesized, the chains are 100–300μm in length and the cobalt microspheres, which consist of nanosheets with an average thickness of about 60nm, are 5–10μm in diameter. The magnetic hysteresis loops at 5K and 300K of the chains of microspheres show ferromagnetic characteristics. The morphologies of the microspheres can be controlled by adjusting the concentrations of the surfactant and the complex reagent and also the reaction temperature. [Copyright &y& Elsevier]

Abstract: Carbon/phenolic (C/PH) composites have been widely used for impact protection and energy-absorption, the proper design of which require appropriate material characterization data and stress–strain relations suitable for wide range of strain-rate conditions. Firstly, sophisticated quasi-static and medium–high strain-rate compression tests are conducted to study the mechanical behaviors of C/PH composites, and one nonlinear viscoelastic constitutive model is proposed based on the experimental results. Light gas gun tests are subsequently conducted to derive the impact Hugoniot curve and high-pressure equation of state (EOS). Finally, the proposed material model and EOS are built into a cross-format centered difference scheme to preliminarily investigate the wave effects of C/PH composites. It is established that the viscoelastic model, the equation of state along with the 1-D difference code are very effective in capturing the mechanical properties of C/PH composites over a wide range strain-rates. [Copyright &y& Elsevier]

Abstract: Nanostructured Ni(OH)2 thin films were prepared by a simple solution growth process with F− and NH3 used as Ni2+ coordination agents, and ammonia hydroxide solution used as OH− supplier to accelerate the hydrolyzation of nickel complex species. The results showed Ni(OH)2 thin films were constructed mainly with hexagonal nanorods; the F− and NH3 in reactive solutions played important roles in the film growth process; and solution pH had great influence on the morphologies of thin films, which was explained by the competition of Ni(OH)2 nucleation and growth in solutions. NiO crystallinity thin films were obtained by annealing Ni(OH)2 thin films at 400 °C for 2 h and the morphologies of the Ni(OH)2 thin films were sustained well during the annealed process. [Copyright &y& Elsevier]

Abstract: A Ni-base single crystal superalloy was transient liquid phase (TLP) bonded using a Ni–Cr–B amorphous foil at 1230 °C for 8 h. Stress rupture tests of the TLP joint and a matrix sample were carried out at 982 °C/248 MPa and 1010 °C/248 MPa. The microstructures and fracture surfaces were studied using scanning electron microscopy (SEM). Transmission electron microscopy (TEM) investigations were performed after creep rupture testing to examine the deformation substructures. The results show that the stress rupture ductility of TLP joints is significantly decreased compared to the matrix sample. This reduction of the ductility of TLP joints can be attributed to solid solution strengthening by boron atoms, subgrain boundaries formed in the bonding zone and the concentration of creep cavities formed during the last stage of the stress rupture test. [Copyright &y& Elsevier]

Abstract: The temperature dependence of AC susceptibility has been measured as a function of AC amplitude and frequency at zero DC field in MTG-YBa2Cu2.99Li0.01O y crystals. We try to extract the critical current density near T c from the real component of AC susceptibility curves. The temperature dependence of critical current density followed J c(T)=1.548×1010 (1− T/87.3)1.38 (A/m2), which is good agreement with obtained from the traditional “loss-maximum” approach. The effective activation energy near T c is also discussed. [Copyright &y& Elsevier]

The influence of secondary Y211 phase on the oxygen diffusion in the ceramic composite of Y123 with Y211 addition has been investigated by the isothermal electric resistance relaxation. The activation energy of oxygen diffusion in the Y123 matrix of the composite is obtained as 1.13, 1.04 and 0.97 eV for the composite of Y123 with x mol Y211, x=0, 0.2, 0.4 respectively, i.e., it is decreased with the Y211 addition in the investigated composition range. [Copyright &y& Elsevier]

We have prepared Na-doped YBa2Cu3Oy (YBa1.9Na0.1Cu3Oy+40 mol% Y211) (YBNCO) and Na-free YBa2Cu3Oy (YBCO) samples by the melt-textured growth method to study the effect of doped Na ion on flux pinning. The ac susceptibility curves as well as the hysteresis loops were measured for the samples. Then the effective pinning energy (U(T,Hdc,J)), irreversibility line (Hirr(T)) and critical current density (jc(Hdc)) were determined, where T, Hdc and J are temperature, dc magnetic field and current density, respectively. We found that, with Na doping, the Hirr(T) line shifted to lower temperatures while the Jc(Hdc) and U(T,Hdc,J) became smaller. Hence Na ions play a negative role in the flux pinning of YBCO. The appearance of the second peak in the Jc(Hdc) curves and the enhancement of anisotropy in YBNCO further support this finding. [Copyright &y& Elsevier]

[Display omitted] • Zeta potential of ESP is controlled by the concentration-dependent adsorption of Ca2+ ions, and is less affected by pH of the alkaline solution. • The ESP's affinity for Ca2+ ions has helped facilitate the nucleation process of C-S-H. • ESP serves as a foreign constituent in cement paste and can provide additional sites for the deposition of C-S-H. This study demonstrated the feasibility of utilizing bio-waste eggshell powder (ESP) as a potential filler material for cement. The collected eggshells were cleaned, membrane-removed, dried and ground into powder with Blaine fineness of 5650 cm2/g. To investigate the filler effect of ESP, different ESP amounts (0, 5%, 10% and 15% by weight) were adopted to replace cement in this study. Multiple experimental methods involving zeta potential test, isothermal calorimetry, compressive strength test, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to analyze the effect of ESP on cement paste. Results showed that zeta potential of ESP is controlled by the concentration-dependent adsorption of Ca2+, and is less affected by pH of the alkaline solution. Due to ESP's affinity to Ca2+, heterogeneous nucleation effect was facilitated and more hydrates were found to form and grow on the surface of ESP. Hence, cement hydration is increased. This founding was also supported by the decoupled cumulative hydration heat curves and the microscopic observations. Through XRD and FTIR analysis, it can be inferred that calcium carbonate in the ESP can react with the aluminum phase in the cement to produce monocarboaluminate. Eventually, sustainable assessment was conducted to analyze the carbon dioxide emission. It was concluded that in this study an ESP replacement level of around 5% provides the best performance and reduces environmental pollution. [ABSTRACT FROM AUTHOR]

• The strength of CrCoNi MEA was significantly increased when maintaining a considerable elongation in CrCoNiSi 0.2 Al 0.2 MEA. • The σ + B2 precipitation strengthening structure was formed in CrCoNiSi 0.2 Al 0.2 MEA. • It is the Orowan + shearing precipitation hardening mechanisms that improved the strength and strain hardening capacity. • Orowan mechanism is more effective on improving strain-hardening capacity than shearing mechanism. [Display omitted] The CrCoNiSi x Al x (x = 0.1, 0.2) medium entropy alloys (MEAs) were designed to achieve significant improvement in strength and strain hardening via the minor addition of Si and Al elements to the CrCoNi MEA. The B2 + σ precipitation structure was formed on the CrCoNiSi 0.2 Al 0.2 MEA. Compared to CrCoNi MEA, the yield and ultimate tensile strengths of the CrCoNiSi 0.2 Al 0.2 MEA enhanced from 380 MPa to 850 MPa and 790–1287 MPa, respectively, while the uniform elongation was 23 ± 5% that outperformed various advanced steels and Al-added MEAs/HEAs. The Orowan+shearing precipitation hardening mechanisms together with the deformation twins in a face-centered cubic (FCC) matrix were identified to improve the strength and strain hardening capacity. These findings provide guidance for the development of precipitation-hardened MEAs/HEAs with strength-ductility synergy. [ABSTRACT FROM AUTHOR]

EAST has currently equipped with four wide-angle infrared (IR)/visible integrated endoscope diagnostics for routinely monitoring the status of plasma facing components (PFCs) and providing temperature information to ensure safe operation of the device. However, due to the existence of various sources of vibration force during the plasma experiments, image jitter can be clearly observed from the recorded IR videos, which increases the errors of temperature extraction from region of interest (ROI) within IR images and hence reduces the accuracy of heat flux calculation. In order to solve this problem, a method based on edge detection and phase correlation has been recently developed for correcting jitter of the IR videos on EAST, which has the advantages of high robustness, none accumulated error and high efficiency. Using this method, jitter of the IR video is successfully detected and corrected. Comparison between divertor heat flux results calculated from IR videos with and without jitter correction proves that the application of the edge-based phase correlation method for jitter correction can effectively improve the accuracy of the heat flux calculation. [ABSTRACT FROM AUTHOR]

• The Lyman-Alpha-Based BES (LAB), a novel diagnostic for plasma density fluctuation measurement on tokamaks. • LAB can measure density fluctuation with a high spatial resolution of 3.3 mm, which is much higher than any of the BES diagnostics worldwide (centimeters). A 20-channel edge Lyman-Alpha-Based Beam emission spectroscopy (LAB) system, which diagnoses edge density fluctuations by measuring the Doppler-shifted Lyman-alpha line (n = 2 → 1, 121.53 nm) emitting via the interaction of neutral beams and plasma particles, is under developing on the HL-2A tokamak. The radial observation range covers the main plasma from R = 1.98 m to 2.05 m with a spatial resolution of about 0.33 cm and a temporal resolution of 1 μs. The overall design for this system is completed, including the reflective collection optics, the spectrometer with a reflective toroidal grating, the detector array, and the vacuum system. Compared with the traditional beam emission spectroscopy (BES) which measures the Balmer-alpha line (n = 3 → 2, 656.10 nm), LAB promises to achieve higher signal-to-noise measurements of smaller-scale fluctuations and therefore detect previously unobserved low-amplitude pedestal turbulence. [ABSTRACT FROM AUTHOR]

The effects of stress states and strain rates on mechanical behaviors and texture characteristics of the CoCrFeNi high-entropy alloy (HEA) were investigated via shear-tension specimens and Split-Hopkinson Tensile Bar (SHTB). The results revealed that the stress states and strain rates have an obvious influence on the mechanical properties and texture evolution. The volume fractions of textures S {123}<634> and Brass {110}<112> both increase with the decline of shear stress component under different stain rates, but their volume fractions are larger at high strain rates. The strength and elongation of the CoCrFeNi HEA are simultaneously increased at high strain rates and complex stress states. In addition, a crystal plasticity finite element model (CPFEM) with a damage factor was established to simulate the stress distribution and damage evolution at quasi-static condition. The results showed that the CPFEM can exactly predict the texture and damage characteristic of the CoCrFeNi HEA under different stress states at quasi-static deformation. Image 1 • Effect of stress states and strain rates on mechanical behavior was investigated. • The texture evolutions were analyzed at different strain rates and stress states. • A damage factor was introduced into crystal plasticity finite element model. [ABSTRACT FROM AUTHOR]

A novel CrCoNiSi x (x = 0.1, 0.2, 0.3) medium entropy alloys (MEAs) system was designed to achieve enhanced strength and ductility. The CrCoNiSi x MEAs are all single-phase face-centered cubic (FCC) structure. The recrystallization rate and average grain size obviously increase with the increase of Si. Compared to CrCoNi MEA, the ultimate tensile strength (UTS) and uniform elongation (UE) of CrCoNiSi 0.3 MEA were increased from 790 MPa to 960 MPa and 58% to 92%, respectively, and the product of UTS and total elongation (TE) increased up to 88 GPa% (46 GPa% for CoCrNi MEA), superior to most high strength-ductility alloys. The stacking-fault energy (SFE) in the Si-added MEAs decreases with Si addition, as proved by thermodynamic model. Therefore, the underlying strengthening mechanism is the reduction of SFE and increase in the lattice distortion via Si addition. More concentrated and thinner deformation twins and multiple twinning structures were observed in Si-added MEAs. Furthermore, a nanoscale diffusionless transformation from the FCC to the hexagonal close-packed (HCP) phase occurred at room-temperature tension in Si-added MEAs, which further increased the work hardening and uniform elongation. This work provides a new and significant approach to break through the strength-ductility trade-off in FCC MEAs/HEAs, especially serving as energy-absorbing materials. Unlabelled Image • The strength and ductility of CrCoNi MEA are both significantly improved by adding Si element. • CrCoNiSi 0.3 MEA exhibits outstanding product of ultimate tensile strength and total elongation, exceeding most of existing alloys tensioned at room temperature. • The recrystallization rate and the average grain size are obviously increased with the increase of Si content. • Nanoscale transformation from FCC to HCP phase occurs at ambient temperature deformation for Si-added CrCoNiSi x MEA. [ABSTRACT FROM AUTHOR]

The present work adopts an extended multi-level crystal plasticity finite element method (CPFEM) framework coupled with an improved artificial neural network (ANN) algorithm to predict the quasi-static and dynamic uniaxial tensile mechanical response, twinning and texture characteristic in NiCoCrFe high-entropy alloy. Firstly, a Split-Hopkinson tensile bar setup is utilized to achieve high strain rates, and the initial microstructure and texture data used in CPFEM is characterized by electron backscattered diffraction. The experimental results show the effect of twins on strain hardening is more obvious with the increase of strain rates. Next, a developed dislocation-density based hardening law taking into account rate and temperature sensitive property is firstly extended by calculating the slip/twin activation stresses through thermal activation mechanism, Hall-Petch resistance, forest dislocation drag and slip-twin interactions. The simulations reveal some underlying defect mechanisms using the temporal evolution of microstructure and macro response over a wide range of strain rates. Then, an advantageous ANN model combined with the Genetic algorithm (GA) optimized is applied to exploit potential law of massive experimental and CPFEM data and serve engineering applications efficiently. The verification results capture well the features of strain rate sensitivity with CPFEM and experimental data sources. Finally, the predictive ability of two models is further demonstrated by validating the uniaxial tension of NiCoCrFe HEA. It is clear that the improved idea (an ANN model through GA optimization) is more efficient than the physical mechanism based CPFEM model. Image 1 • A multi-level crystal plasticity model is extended to describe the quasi-static and dynamic behaviors of NiCoCrFe alloy. • The model features a dislocation density-based hardening law and a lattice reorientation method due to slip and twin. • An efficient artificial neural network model based genetic algorithm optimization is proposed for FCC HEA. • Strain-rate-sensitive mechanical testing and microstructural data set are used to validate both models. • Micro- and macro-behaviors are well captured by both the proposed modeling schemes. [ABSTRACT FROM AUTHOR]

The mechanical properties and strain-rate strengthening mechanism of single-phase TiZrHfNbTaMo x (x = 0.25, 0.5, and 0.75) refractory high entropy alloys (RHEAs) upon dynamic loading are investigated. Dynamic compression with varying strain rates of 2100–6000 s−1 at room temperature are performed by the split-Hopkinson pressure bar (SHPB), and the dynamic yielding strength is about 1.3 times of the quasi-static one. Positive strain-rate sensitivity (SRS) on the yielding strength is available, and the work-hardening is weakened but the yielding strength is improved with increasing strain rates due to the adiabatic heating upon dynamic loadings and the dislocation movement resistance, respectively. Considering the adiabatic temperature rise converted by plastic deformation work at high strain rates, the flow behavior is characterized by employing the modified Johnson-Cook model. A semi-empirical Zerilli-Armstrong constitutive model is proposed to predict yielding strengths at various strain rate. Image 1 • Dynamic impact tests of three compression-plastic refractory high-entropy alloys. • High strain rate sensitivity due to severe lattice distortion of high-entropy alloys. • Dislocations were the major carrier of plasticity for BCC RHEAs under impact loading. • Yield strength and flow stress model, were fitted by Johnson-Cook and Zerilli-Armstrong model, respectively. • The yield strength and fracture strain of this work were compared with some recent reported RHEAs at room temperature. [ABSTRACT FROM AUTHOR]

Origami structures, whose mechanical properties can be tuned by programing the crease network, have been sought in application including DNA origami nanorobots and deployable space structures. However, the existing researches mainly placed on the cylindrical origami tubes or the periodic cellular metamaterials, which are based on the stacking of individual 3D origami units. Here, we present a novel mechanical metamaterial, which can be constructed via using the curved-crease origami (CCO), with tunable Poisson's ratio and stiffness. We further analytically and experimentally demonstrate that the Poisson's ratio of these structures exhibits some new properties by altering the length to width ratio of the structures. In addition, we verify the tunable stiffness of the CCO-based metamaterials by changing the patterns of these structures. Our approach can be used to design and construct the next generation of the CCO-based metamaterials with tunable mechanical properties for engineering applications. [ABSTRACT FROM AUTHOR]

Dual-phase Al 0.6 CoCrFeNi high-entropy alloys (HEAs) with heterogeneous structure are obtained by cold rolling and annealing. Tensile experiments show that this alloy exhibits excellent combinations of yield strength, tensile strength and tensile elongation at room (298 K) and cryogenic (77 K) temperatures. Through the thermodynamic formula, the stacking fault energy of face-centered cube (fcc) phases in Al 0.6 CoCrFeNi alloys are calculated to be 49.33 mJ/m2 and 28.69 mJ/m2 at 298 K and 77 K, respectively. Combining with EBSD (electron backscattering diffraction) and TEM (transmission electron microscopy), it is concluded that the deformation of dual-phase Al 0.6 CoCrFeNi alloys with heterogeneous structure at 298 K is mainly dominated by the dislocation slip in fcc plus bcc (body-centered cube) phases, and the deformation mode at 77 K can be divided into two stages: (1) when the true strain is between 0 and 3.8%, the plasticity is mainly caused by dislocation slip of fcc and bcc phases; (2) when the true strain is between 3.8% and samples fracture, the plasticity is mainly induced by deformation twins in fcc phase and dislocation slip in bcc phase. • Al 0.6 CoCrFeNi HEAs with heterogeneous structure have a combination of high strength and good plasticity. • The SFE of the fcc phase in Al 0.6 CoCrFeNi is calculated to be 49.33 mJ/m2 and 28.69 mJ/m2 at 298 K and 77 K, respectively. • Based on the critical stress formula, deformation twins prevail when true train is over 3.8% at 77 K. • Nanoscale deformation twins induced by 77 K loading realize the excellent strength-ductility combination. [ABSTRACT FROM AUTHOR]

An investigation of kinetics of release of nitrogen from uranium melt were carried out under pressure of less than 0.01Pa via electron beam cold hearth refining. The results indicated that electron beam smelting was an effective purifacation method to reduce nitrogen, the nitrogen decreased sharply to be 10% of initial after 60 min refining. The nitrogen removal rate is first order with respect to nitrogen content in the melt, and the release process is controlled by nitrogen transfer in liquid diffusion layer. The mass transfer coefficient was determined, and the values were estimated to be 0.82 × 10−5 m s−1 and 1.40 × 10−5 m s−1 at 1940 °C and 2320 °C, respectively. The release of denitrogenation increased with melt temperature, and apparent activation energy of the release was calculated to be 68 kJ mol−1 from Arrhenius type equation. • Electron beam smelt refining can reduce nitrogen impurity in uranium sharply. • The nitrogen removal rate is first order with nitrogen content in melt, and it is controlled by nitrogen transfer in liquid diffusion layer. • Derived properties considered include apparent rate coefficient, activation energy and half-life of denitrogenization reaction. [ABSTRACT FROM AUTHOR]

The shear-tension deformation behaviors of CoCrFeNi high-entropy alloy (HEA) were investigated by introducing five groups of different inclined notches, and mainly focus on mechanical response and texture evolution. The results show that CoCrFeNi HEA exhibits significant structural sensitivity and high notch strength ratio (NSR), and the stress concentration factor K t of specimens and stress distribution at the notch roots were acquired by finite element method (FEM). In addition, the notch strengthening effect of HEA is more obvious with the increase of shear stress component. When the shear stress component increases, the E {111}<110>, F {111}<112> and γ-fiber textures are the main texture components after deformation. The evolution characteristics of Cu-type and Brass-type textures under the shear-tension stress states are significantly different from those under the rolled state. Moreover, complex stress states have no obvious effect on Cu texture under shear-tension deformation, but a large one on CuT texture. Image 1 • The mechanical behaviors of CoCrFeNi HEA were performed by five different notches. • The CoCrFeNi HEA shows more obvious notch effect with higher shear stress. • The detailed texture evolutions were analyzed under shear-tension deformation. [ABSTRACT FROM AUTHOR]

Solution treatment is a very important method to modify the microstructure and mechanical properties of additive-manufactured nickel-based superalloy. This study mainly investigated the effect of solution temperature on static recrystallization and ductility of Inconel 625 superalloy fabricated by directed energy deposition (DED). The microstructural results showed that static recrystallization occurred after solution treatment, and as the solution temperature increased, the recrystallization volume fraction in the alloy gradually increased. When the solution temperature reached 1200 °C, static recrystallization occurred more completely. The tensile results indicated that the elongation and strain hardening exponent of Inconel 625 improved with the solution temperature increased, while the yield strength decreased. The deformation behaviors during the tensile process of different samples were obtained by digital image correlation (DIC), and the results showed that the uniform plastic deformation ability was strengthened with the solution temperature increased. In addition, due to the decrease of dislocation density, the yield strength decreased, too. Besides, the increase of strain hardening exponent delayed the appearance of the necking and the dissolution of the Laves phase caused the ductility increasing. [ABSTRACT FROM AUTHOR]

The yielding, deformation and fracture behavior for the Widmanstätten structure of Ti–8Al–1Mo–1V alloy upon high speed impact were studied through characterization and discussion. Seven strain rates ranging from 870 s−1 to 3300 s−1 were applied. The results show that: The yield strength of Widmanstätten structure shows two distinct changing stages among the whole range of strain rates. Under the strain rates below 2250 s−1, Widmanstätten structure exhibits positive strain rate sensitivity. Surprisingly, under the strain rates from 2250 s−1 to 3300 s−1, it shows negative strain rate sensitivity. The increasing importance of twinning in the initiation of plastic deformation with higher strain rate is deemed as the reason causing this phenomenon. The dynamic compression behavior of Widmanstätten structure is described by J-C model, which shows unstable prediction performance. Adiabatic shearing band starts forming under the strain rates above 1950 s−1, from which the fracture behavior of Widmanstätten structure is analyzed. An interesting phenomenon is that the adiabatic shearing band thicknesses at different locations of specimen can be obviously different. This is attributed to the relative orientation of α lamellae to the biggest shear stress plane. Saw-tooth chips start forming at the two end faces of specimen under the strain rates above 2500 s−1, and its formation mechanism is thoroughly discussed. Adiabatic shearing band after post annealing was characterized by EBSD, which shows recrystallized grains with gradient diameters. In addition, it is found that the Burgers orientation relationship of the microstructure outside adiabatic shearing band was generally retained during the dynamic loading and post-annealing process. • Widmanstätten structure exhibits negative strain rate sensitivity above 2250 s−1. • Twinning is deemed as the reason causing NSRS. • ASB thickness varies with the relative orientation of α lamellae to shear plane. • Saw-tooth chips start forming under the strain rates above 2500 s−1. [ABSTRACT FROM AUTHOR]

Al 0.3 CoCrFeNi high-entropy alloys (HEAs) with B2 ordered phase mainly precipitated at grain boundaries are obtained by cold rolling, annealing and aging treatment. Tensile experiments show that both CRSA (annealed at 1100 °C for 1 h) and CRSA-600-24 (annealed at 1100 °C for 1 h and subsequently aging treatment at 600 °C for 24 h) samples have excellent combinations of yield strength, tensile strength and tensile elongation at room temperature, and more importantly, simultaneous enhancements in strength and ductility at liquid nitrogen (77 K) are attained for the latter condition. Analyses reveal that after aging treatment, the precipitation of B2 phase with ultrafine-grained or even nanoscale sizes, as well as moderate grain refinement, yields the significant increase in tensile strength and fascinating tensile plasticity. By transmission electron microscopy (TEM) characterization, it is found that the deformation mode dominated by dislocation glide at room temperature is transformed to that combined with dislocation glide plus nanoscale twinning at 77 K. Moreover, the twinning-induced work hardening renders the onset of necking instability to a higher strain/stress value, which therefore improves the strength and ductility simultaneously. [ABSTRACT FROM AUTHOR]