The purpose of this study is to experimentally investigate the interaction of inelastic deformation and microstructural changes of two Zr-based bulk metallic glasses (BMGs): Zr41.25Ti13.75Cu12.5Ni10Be22.5 (commercially designated as Vitreloy 1 or Vit1) and Zr46.75Ti8.25Cu7.5Ni10Be27.5 (Vitreloy 4, Vit4). High-temperature uniaxial compression tests were performed on the two Zr alloys at various strain rates, followed by structural characterization using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Two distinct modes of mechanically induced atomic disordering in the two alloys were observed, with Vit1 featuring clear phase separation and crystallization after deformation as observed with TEM, while Vit4 showing only structural relaxation with no crystallization. The influence of the structural changes on the mechanical behaviors of the two materials was further investigated by jump-in-strain-rate tests, and flow softening was observed in Vit4. A free volume theory was applied to explain the deformation behaviors, and the activation volumes were calculated for both alloys.

Wurtzite ZnO nanorods were grown from solution onto coarse-grain bulk polycrystalline Ag substrates to explore the nature of preferred heteroepitaxial orientations. ZnO nanorods grow copiously on grains with <111> and <001> surface normals. Two epitaxial orientations were observed: {0001} ZnO ‖ {111} Ag with <20> ZnO ‖ <10> Ag and {0001} ZnO ‖ {001} Ag with <20> ZnO ‖ <10> Ag. Both feature ZnO basal plane growth, and the specific in-plane orientation relationships both feature alignment of close-packed directions in the interface. Nanorod growth was strongly suppressed on Ag grains in most other orientations. Although strain energy minimization is often invoked to explain the {0001} ZnO ‖ {111} Ag with <20> ZnO ‖ <10> Ag orientation, associated with an almost ideal near-coincidence site lattice matching, our data suggests that strain may not be the sole, or even the most important, determinant of the preferred orientations during solution-based epitaxial growth in this system.

In the current research, we successfully prepared TiO2/Ni–Cu–Zn ferrite composite powder for magnetic photocatalyst. The core Ni–Cu–Zn ferrite powder was synthesized using the steel pickling liquor and the waste solution of electroplating as the starting materials. The shell TiO2 nanocrystal was prepared by sol-gel hydrolysis precipitation of titanium isopropoxide [Ti(OC3H7)4] on the Ni–Cu–Zn ferrite powder followed by heat treatment. From transmission electron microscopy (TEM) image, the thickness of the titania shell was found to be approximately 5 nm. The core of Ni–Cu–Zn ferrite is spherical or elliptical shape, and the particle size of the core is in the range of 70–110 nm. The magnetic Ni–Cu–Zn ferrite nanopowder is uniformly encapsulated in a titania layer forming core-shell structure of TiO2/Ni–Cu–Zn ferrite powder. The degradation efficiency for methylene blue (MB) increases with magnetic photocatalyst (TiO2/Ni–Cu–Zn ferrite powder) content. When the magnetic photocatalyst content is 0.40 g in 150 mL of MB, the photocatalytic activity reached the largest value. With a further increase in the content of magnetic photocatalyst, the degradation efficiency slightly decreased. This occurs because the ultraviolet (UV) illumination is covered by catalysts, which were suspended in the methylene blue solution and resulted in the inhibition in the photocatalytic reaction. The photocatalytic degradation result for the relationship between MB concentration and illumination revealed a pseudo first-order kinetic model of the degradation with the limiting rate constant of 1.717 mg/L·min and equilibrium adsorption constant 0.0627 L/mg. Furthermore, the Langmuir–Hinshelwood model can be used to describe the degradation reaction, which suggests that the rate-determining step is surface reaction rather than adsorption is in photocatalytic degradation.

Minor Fe additions are necessary to enhance the corrosion resistance of commercial Cu-Ni alloys. The present paper aims at optimizing the Fe content in three alloy series Cu90(Ni,Fe)10, Cu80(Ni,Fe)20, and Cu70(Ni,Fe)30 (at.%) from the viewpoint of their corrosion performance in a 3.5% NaCl solution. An Fe/Ni = 1/12 solid solubility limit line was revealed in the Cu-Ni-Fe phase diagram. Three Fe/Ni = 1/12 alloys, Cu90Ni9.23Fe0.77 (at.%) = Cu-8.6Ni-0.7Fe (wt.%), Cu80Ni18.46Fe1.54 = Cu-17.3Ni-1.4Fe, and Cu70Ni27.7Fe2.3 = Cu-26.2Ni-2.1Fe, show the best corrosion performances in their respective alloy series. The Fe/Ni = 1/12 solubility limit is explained by assuming isolated Fe-centered FeNi12 cuboctahedral clusters embedded in a Cu matrix. The three Fe/Ni = 1/12 alloys can be respectively described by cluster formulas [Fe1Ni12]Cu117, [Fe1Ni12]Cu52, and [Fe1Ni12]Cu30.3. The Fe/Ni = 1/12 rule may serve an important guideline in the industrial Cu-Ni alloy selection because above this limit, easy precipitation would negate the corrosion properties of the Cu-Ni-based alloys.

All-solid-state Li–In/Li4Ti5O12 cells using Li2S–P2S5 solid electrolytes were assembled to investigate their electrochemical properties in the wide voltage range of 0–3 V (versus Li). The Li/Li4Ti5O12 cells using 1 M LiPF6 in ethylene carbonate and diethyl carbonate were fabricated for comparison with the all-solid-state cells. The capacity of the all-solid-state cell using the 70Li2S·27P2S5·3P2O5 (mol%) solid electrolyte decreased with an increase in the current density as well as the cell using the liquid electrolyte. However, the all-solid-state cell was charged and discharged even at a high current density of 10 mA/cm2. The all-solid-state cell was cycled at 1.3 mA/cm2 and retained 90% of the first reversible capacity of about 120 mAh/g after 500 cycles. The all-solid-state cell cycling at 100 °C showed the small overpotential and reversible capacity of about 120 mAh/g at 13 mA/cm2.

In this article, the shear-banding behavior in bulk metallic-glasses (BMGs) is studied using a focused ion beam (FIB)-based nanoindentation method, which involves cylindrical nanoindentation of a FIB-milled BMG microlamella and is capable of revealing the subsurface shear-band patterns down to the submicron scale. The results of the current study on a Zr-based BMG clearly show that short shear bands, with the lengths of a few hundred nanometers, could be severely kinked before growing into a longer one, which implies that structural heterogeneity plays an important role in the microplasticity of BMGs. Furthermore, through the three-dimensional finite-element simulation combined with the theoretical calculation based on the Mohr–Coulomb law, it is found that the yield strengths exhibit a large scatter as a consequence of the structural heterogeneity when microplasticity occurs in the Zr-based BMG, which is consistent with our recent findings obtained from the microcompression experiments.

Hardness of glass is known to be related to the resistance to permanent deformation. However, the mechanism of permanent deformation of glass under a sharp diamond indenter is not clear yet. One of the deformation modes of oxide glass at room temperature is permanent densification. In this study, the indentation-induced densification of soda-lime glass under diamond indenters was evaluated from the volume recovery of indentation imprint by thermal annealing. The volume change of the indentation imprint by annealing corresponds to the densified volume under the indenter. Using some kinds of diamond indenters, which have different inclined face angles, the ratios of densified volume to the total “lost” volume under the indenters were determined. With an increase in the inclined face angle, the densification contribution decreased and the shear-flow contribution increased. This indenter-shape dependence of densification in glass is discussed in terms of the stress dependence of the deformation mechanisms in glass.

High strength (Ti0.705Fe0.295)100-xSnx (0 ≤ x ≤ 6) composites have been prepared through arc melting and cold crucible casting. The microstructure consists of two phase ultrafine eutectic comprised of FeTi and β-Ti phases. The effect of Sn addition to the Ti70.5Fe29.5 eutectic is assessed in terms of microstructure variations such as eutectic spacing, morphology, cell size, lattice parameter of the phases, and the resulting mechanical properties in terms of strength and plasticity under compression. The mechanical properties (maximum strength 1939 MPa, fracture strain 13.5%) of the ternary Ti-Fe-Sn (2 ≤ x ≤ 6) are considerably improved compared to the Ti70.5Fe29.5 binary alloy (1733 MPa, 3.4%). The change in the morphology of the eutectic, the microstructure refinement, structural fluctuations, and supersaturation in the β-Ti phase, and the elastic properties of nanophases are crucial factors for improving the plastic deformability of the ultrafine eutectic alloys without presence of any additional micrometer-size toughening phase.

The initiation and detonation properties of explosives are often empirically correlated to density, surface area, and particle size. Although these correlations are sometimes used successfully to predict the performance of bulk samples, the data are spatially averaged, which unfortunately muddles information critical to understanding fundamental processes. Density and surface area are essentially an indirect measure of porosity, which is arguably a more appropriate metric in many applications. We report the direct characterization of porosity in polycrystalline molecular crystal explosives by focused ion beam nanotomography, a technique that is typically reserved for robust materials such as ceramics and metals. The resulting three-dimensional microstructural data are incredibly rich, promising a substantial advance in our ability to unravel the processes governing initiation and detonation of molecular crystal explosives. In a larger context, this work demonstrates that focused ion beam nanotomography may be successfully extended to the investigation of nanoscale porosity in other molecular crystal or polymer materials.

Porous SnO2/multiwalled carbon nanotube (CNT) thin film composites as anode material for Li-ion batteries were prepared using the electrostatic spray deposition (ESD) technique. The morphologies of the samples were found to be affected mainly by deposition temperatures. Electrochemical test cells were assembled using the as-prepared samples without any conductive additive or binder. The influence of deposition temperature and CNT content on the electrochemical performance of the anodes was investigated. Compared to pure tin oxide and pure CNT, the composite anode materials showed better discharge capacity and cyclability. Among the composites, the sample deposited at 250 °C with 30 wt% CNT content was found to show better energy capacity. This can be ascribed to the porous nature of the anodes and the improvement in the conductivity by the addition of CNTs.

In this study, we produced an Al matrix composite material reinforced by Al-Cu-Fe particles of the icosahedral phase. The composite material was prepared using a hot isostatic pressure technique at T = 673 K and P = 180 MPa. The mechanical properties were investigated by compression tests performed at constant strain rate over the temperature range 290–823 K. The results show a vigorous strengthening effect resulting from the reinforcement particles. Strengthening is attributed to two main contributions arising from load transfer between the Al matrix and the reinforcement particles and from plastic deformation of the Al grains. The present results are compared with those obtained in a previous work on an Al-based composite reinforced by Al-Cu-Fe particles of the ω-tetragonal phase.

Zr65Al7.5Ni10Cu12.5Nb5 glass was found to exhibit a large plastic compressive strain of over 10% and the property was suggested to be due to deformation-induced nanocrystallization. A transmission electron microscopic observation, however, only revealed obscure ordered clusters with a size of ˜2 nm in the fracture surface of a deformed sample, instead of well-identified crystals as previously reported for the Zr–Al–Ni–Cu–Pd system. This phenomenon is suggested to correlate with the higher viscosity of supercooled liquid and the slower grain growth of icosahedral phase during primary crystallization in the Zr65Al7.5Ni10Cu12.5Nb5 compared to those in the Zr65Al7.5Ni10Cu12.5Pd5 alloy. The role of the deformation-induced nanoclusters on the enhanced compressive plasticity was discussed.

Photocatalytic activity of different morphologies of tungsten oxide was investigated before and after platinum loading. Different shape particles of tungsten oxide were synthesized using peroxo tungstic acid solution as a basic precursor and different methods. The prepared materials were composed of nanoparticles, nanorods, and nanosheets that formed different morphologies. The results of photodegradation with isopropyl alcohol (IPA) under visible light showed that the samples composed of nanostructures with an average lateral thickness of 20 to 47 nm were more active than one composed of broad nanosheets with a thickness of 60 nm. The samples were loaded with a platinum cocatalyst. The results of photocatalytic evaluation of loaded samples showed that the photooxidation reaction of samples with a smaller feature was accelerated with a higher rate rather than one with broad nanosheets. We conclude that although loading of a cocatalyst promoted the photocatalytic activity, it is not capable of compensating for the morphology influence on the photocatalytic activity.

The phase equilibria at 200 °C, 250 °C, 300 °C, and 400 °C and the phase transformation of the Sn-Au-Bi system were investigated by using the electron probe micro-analyzer (EPMA) and differential scanning calorimeter (DSC), respectively. It is found that there is a new ternary intermetallic compound with a possible AuSn structure (called the ϕ phase in the present work), which has a limited solubility of Au in the Au-rich portion, and the ϕ phase decomposes peritectically at about 313 °C. Based on the experimental data reported in the previous papers and new experimental data determined by the present work, thermodynamic assessments of the Sn-Au-Bi system were carried out by the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the Gibbs free energy of each phase were optimized, and reasonable agreement between the calculated results and experimental data was obtained in the Sn-Au-Bi ternary system.

We evaluate Vickers hardness and true instrumented indentation test (IIT) hardness of 24 metals over a wide range of mechanical properties using just IIT parameters by taking into account the real contact morphology beneath the Vickers indenter. Correlating the conventional Vickers hardness, indentation contact morphology, and IIT parameters for the 24 metals reveals relationships between contact depths and apparent material properties. We report the conventional Vickers and true IIT hardnesses measured only from IIT contact depths; these agree well with directly measured hardnesses within ±6% for Vickers hardness and ±10% for true IIT hardness.

Solid solutions 0.7Bi1−xLax (Fe0.9Cr0.1) O3–0.1BaTiO3–0.2PbTiO3 (BLxFOC-BT-PT, with x = 0, 0.03, 0.05, 0.07) solid solutions were prepared by the traditional ceramic process. X-ray diffraction results reveal that all samples show pure pseudocubic perovskites structure. The lattice parameter of the solid solutions increases linearly with the La content, indicating that La ions have entered crystal lattices to form a solid solution. The Curie temperature of the solid solutions decreases with the La content. Room-temperature polarization–electric field (P–E) curves indicate that the samples with x = 0.03 and 0.05 exhibit saturated P–E loops. Piezoelectric constant d33 of the solid solutions increases firstly and then decreases. Magnetizations of the solid solutions decrease with the La content. The evidence of weak ferromagnetism and saturated ferroelectric hysteresis loops in BLxFOC–BT–PT system at room temperature makes it a good candidate for multiferroic applications.

The very high strengths that have been reported for nanoporous gold may be related to strain gradients within the deforming porous microstructure. We present a mechanism-based model for the strength of nanoporous foams that is derived from conventional models for the deformation of macroscopic foams and now includes the influence of strain gradients. This model predicts that the strength of the ligaments within the nanoporous gold is proportional to the ligament diameter raised to the power −0.5. We have used the model to analyze experimental data for the strength of nanoporous gold and find excellent agreement with published data.

C-doped, Mo-doped, and (Mo, C)-codoped TiO2 photocatalysts were prepared by a sol-gel process. The photocatalytic activity was evaluated by the photocatalytic degradation of methyl orange (MO) under simulated solar irradiation. Results indicated that both monodoped and codoped TiO2 exhibited better visible light absorption behavior and narrower energy gap than pure TiO2, and codoped TiO2 showed a slightly higher adsorption property in the dark because of higher Brunauer–Emmett–Teller-specific surface area. The photocatalytic activity of monodoped TiO2 was also enhanced, and the (0.04% Mo, C)-codoped sample had the best photocatalytic activity for degrading MO among all of the samples. The reason can be ascribed to the synergistic effect due to Mo and C doping. Furthermore, the transfer pathways of photoinduced carriers and photocatalytic reaction mechanism of (Mo, C)-codoped TiO2 was first investigated.

Ultra fine CuO nanoparticles in the range of 2 ± 0.2 nm were synthesized by the supercritical hydrothermal method in a batch reactor. It was demonstrated that elevating the pH of the Cu2+ precursor solution to around 6 (neutral condition) not only does not lead to excessive agglomeration of the particles, but also reduces particle size and in general promotes their nanoscale characteristics. Prepared nanoparticles were immobilized in the biopolymeric matrix of barium alginate and calcined at different temperatures resulting in microspherical granules of high porosity and elevated mechanical strength. The fabricated samples were characterized using x-ray diffractometry (XRD), transmission and scanning electron microscopy (TEM and SEM), nitrogen adsorption analysis (BET), mechanical testing, and temperature programmed reduction (TPR). It was found that topochemical models based on a nucleation growth mechanism fail in proper fitting of the TPR data. Instead, a generalized Sestak model in which different physicochemical mechanisms such as the mass action law are taken into account gives a satisfactory regression of the kinetics behavior.

Conical indentation methods to determine residual stress are proposed by examining the finite element solutions based on the incremental plasticity theory. We first note that hardness depends on the magnitude and sign of residual stress and material properties and can change by up to 20% over a specific range of elastic tensile and compressive residual stress, although some prior indentation studies reported that hardness is hardly affected by residual stress. By analyzing the characteristics of conical indentation, we then select some normalized indentation parameters, which are free from the effect of indenter tip rounding. Adopting dimensional analysis, we present practical conical indentation methods for the evaluation of elastic/plastic equi- and nonequi-biaxial residual stresses. The validity of developed approaches is confirmed by applying them to the experimental evaluation of four-point bending stress.