Properties of entangled materials, made of fibers, depend on the number and the nature of contacts between fibers and fibers orientation. Nonsintered and sintered steel wools have been characterized by x-ray tomography to extract structural information such as fibers orientation and number of contacts before and during compression. Image analysis techniques were developed on tomography images and validated on virtual materials, generated and deformed by numerical simulation based on molecular dynamic equations. The structural parameters measured during the structural characterization were finally used to link the structure of the studied material with the measured mechanical properties. To do this link, an analytical model usually used for this kind of material was modified to describe the evolution of mechanical properties in compression.

ZnS/CdS semiconductor composites were synthesized successfully by combining a hydrothermal route with a homogeneous precipitation process. The as-prepared products were characterized by x-ray diffraction, scanning electron microscopy, and energy dispersive x-ray spectrometer. The results showed that the as-prepared products were composed of ZnS microspheres with a face-centered cubic phase and CdS nanoparticles with hexagonal phase, CdS nanoparticles were found to be assembled on the surfaces of the cubic ZnS microspheres. In addition, the ultraviolet-visible absorption spectroscopy and the room temperature photoluminescence (PL) spectroscopy of the ZnS microspheres and ZnS/CdS composites were also investigated. The PL testing indicated that the emission peak of as-prepared ZnS/CdS composites not only exhibited an obvious blue shift but also its intensity had a large enhancement compared to the pure ZnS microspheres. Furthermore, the photocatalytic degradation test showed that the as-prepared ZnS/CdS composites showed excellent photocatalytic degradation activity for methyl orange under UV irradiation. This enhanced activity may be related to the modification of CdS nanoparticles on the surfaces of ZnS microspheres.

Electrical properties of ZrO2 formed by simultaneous oxidation and nitridation of sputtered Zr thin films on Si have been systematically investigated. Various oxidation/nitridation temperatures (500, 700, 900, and 1100 °C) have been carried out in N2O ambient for an extended time of 20 min. Results indicated that the sample oxidized and nitrided at 700 °C possessed the highest effective dielectric constant of 18.22 and electrical breakdown field of 10.7 MV/cm at a current density of 10−6 A/cm2. This is attributed to the lowest effective oxide charge, interface-trap density, and total interface-trap density. The Fowler–Nordheim tunneling mechanism has been investigated for all samples and the highest value of barrier height extracted between the conduction band edges of oxide and semiconductor was 1.22 eV.

In this paper, the effect of the addition of tungsten carbide on the behavior of Fe–WC system during the mechanical alloying (MA) process has been investigated. For this purpose, raw materials containing industrial ferrotungsten and carbon black with a bit of tungsten carbide powder were milled in a high energy ball mill, and sampling was done at different times. An XRD instrument was used for estimating the probable transformation of phases and properties in the milled sample. Microstructures of specimens were studied using electron microscopy. Results showed that MA even at high milling time could not transform raw materials to other materials in a system containing ferrotungsten and carbon black. In samples with primary tungsten carbide, this was synthesized gradually at a milling time of more than 75 h, and finally, the Fe–WC composite was produced as the final product. Crystalline sizes of the synthesized carbide were in nanometer order that was confirmed by transmission electron microscopy images.

Sol–gel-derived aluminum (Al)-doped zinc oxide thin films have been deposited on silicon (Si) wafers and microslide glass substrates using the spin coating technique. The atomic ratio of Al:Zn in the films is 0.05, 0.1, 0.2, and 0.3. The films have been characterized using different techniques, i.e., x-ray diffraction, Fourier transform infrared spectroscopy, atomic force microscopy, scanning electron microscopy, UV-visible-near infrared spectrophotometry, spectroscopic ellipsometry, and the four-probe method. The films have exhibited excellent optical transmittance (∼90%). The refractive indices of the films are in the range between 1.47 and 1.53. The thickness of the films is in the range of 103–115 nm. The films have demonstrated reflectivity of about 3% at a wave length of 600 nm. The reflectivity, transmittance, refractive index, and thickness values of the films show that the films are promising candidates for utility as antireflection coatings in silicon solar cells.

High quality CdSe nanocrystals (NCs) were synthesized via a nonorganometallic precursor and extracted in different solvents. The difference in the influence of the nature of the solvent namely ethanol, N,N-dimethyl formamide (DMF), and acetonitrile on extraction of the same type of NCs was studied with respect to quality and stability of NCs. Characterization by x-ray diffraction technique, absorption–emission spectroscopy, scanning, transmission, and atomic force microscopy demonstrated the formation of NCs of good optical property and surface composition from the synthesis method used. Different polarities of the solvent strongly influence photoluminescence (PL), surface defects, concentrations of NCs extracted, particle sizes, and surface passivation. Ethanol extraction results in small-sized NCs and good particle size distribution. DMF extraction causes lesser interfacial defects and hence prevents radiative recombinations. PL quenching was observed in all the three solvents, and this necessitates further stabilization of NCs. The stability of the so-extracted NCs was evaluated for change in their properties with respect to aging. Aging substantiated the adverse effects of acetonitrile to extract the lesser surface passivated NCs leading to Ostwald ripening and island formation. The phase and structure of NCs remain unaffected with aging or by the nature of solvent used.

By combining high-resolution transmission electron microscopy and scanning transmission electron microscopy with analytical capability, we investigated the nanostructure of a textured hematite photoanode with columnar grains obtained by the colloidal deposition of magnetite nanocrystals. This initial report describes in detail the structure and chemistry of the α-Fe2O3/SnO2:F interface by identifying semicoherent and incoherent interfaces as well as a localized interdiffusion layer of Sn and Fe at the interface (∼100 nm in length). Our study indicates that unintentional doping by tin at a high sintering temperature is not significant in enhancing hematite photoanode performance for water oxidation. The correlation of nanoscale morphology with photoelectrochemical characterization facilitated the identification of the beneficial effect of a preferential growth direction of a hematite film along the [110] axis for water-splitting efficiency.

The conventional process for preparing dry spinnable regenerated silk fibroin (RSF) aqueous solution needs not only an addition of Ca2+ but also an adjustment of pH value. In this work, an RSF dry spinning dope was prepared by using a simplified method with solely adding Ca2+. Compared with the conventional RSF solution, the simply prepared aqueous solution showed similar content of β-sheet conformation and diameter of RSF aggregates but lower viscosity. Furthermore, the posttreated RSF fiber dry-spun from this simply prepared solution showed higher crystallinity and crystalline orientation, smaller crystallite size, and better mechanical properties. It could be concluded that Ca2+ played a much more important role than pH value in improving the structures and properties of RSF spinning solution and fibers. Therefore, the step of adjusting pH value could be excluded in the process of preparing high performance RSF fibers.

Dynamic recrystallization (DRX) of 99.9999% aluminum single crystal at room temperature was examined under frictionless deformation mode. To exclude the self-heating of the specimen due to applied high strain, a microcrack that localizes the stress at a very small region was intentionally introduced by controlled local necking. For the in situ observation of DRX, a specially designed in situ microdeformation device was positioned inside an electron backscattered diffraction system chamber. Recrystallized grains showed relatively random texture and preferred growth direction. The subgrains with low-angle grain boundaries formed by dynamic recovery transformed into small grains with high-angle grain boundaries, acting as nuclei for discontinuous dynamic recrystallization and growing by further deformation. The DRX in pure aluminum can take place under frictionless tensile deformation conditions at room temperature, and the stress localization and high purity are key issues for the DRX of aluminum at room temperature.

Using a combination of high-resolution dilatometric measurements and microstructural analysis, this study investigated the bainitic transformation behavior in ultra-high strength 30CrNi3MoV steel after experiencing small deformation at 850 °C (in the nonrecrystallization austenite region). Under the influence of the small deformation in the nonrecrystallization austenite region, the bainite starting temperature (Bs) raised, the bainite finishing temperature (Bf) decreased, granular bainite was promoted to form, and intersections of differently oriented bainite laths became more common in the microstructure. The increase of Bs is owing to the stored energy in distorted austenite grain boundaries, which can serve as an extra mechanical driving force for bainitic transformation during continual cooling. The decrease of Bf can attributed to the more universal intersections of bainite laths with different orientations, which can decelerate the overall growth rate of bainite. The promoted formation of granular bainite is closely related to the increase of Bs because granular bainite usually forms at relatively high temperatures in the bainite range, above upper bainite and lower bainite.

The effect of a strong magnetic field on the solid solubility and the microsegregation during directional solidification of Al–Cu alloy at lower growth speeds (1–10 μm/s) has been investigated experimentally. Results indicate that the magnetic field causes the reduction of the grain boundary and promotes the amalgamation of the grains. Further, measurement results reveal that the magnetic field increases the solid solubility and decreases the microsegregation. It is also found that the value of the solid solubility increases as the magnetic field and the temperature gradient increase. The modification of the solid solubility and the microsegregation under the magnetic field is attributed to the thermoelectric magnetic force acting on the solid and the interdendritic thermoelectric magnetic convection. The present work may initiate a new method to enhance the solid solubility and to eliminate the microsegregation in Al-based alloys via an applied strong magnetic field during directional solidification.

The advanced quenching and partitioning (Q&P) heat treatment has been applied to 9Cr–1.8W–0.3Mo heat resistant steel. The phase transformation during Q&P is measured by a high-resolution differential dilatometer by which the accurate information can be obtained. The transmission electron microscope examination was conducted to study the microstructure evolution after Q&P, and the refined carbon-enriched martensite laths, which were produced during the second martensitic transformation, were observed. The thermodynamics of carbon partitioning was described by a paraequilibrium model according to which the partitioning of carbon from martensite into austenite can be proved. A kinetic model for the second martensitic transformation was developed with the parameters discussed in details. The retardation of onset and end temperature of the second martensitic transformation can be ascribed to the austenite stabilization caused by carbon enrichment.

Compound effects of B and Y additions on the microstructures and properties of a new type of high-strength and high-conductivity (HSHC) Cu–Mg–Te alloys are investigated on the aspects of purification and precipitation. Because of the purification function of B and Y additions, the tensile strength increased superlatively by the amplitude of 21.7% with a similar increase of elongation and the electrical conductivity of 4.2%. By comparison of the calculated decomposition pressures of B2O3 and Y2O3 at different temperatures, it can be concluded that the boron oxide is more stable than the yttrium oxide in the copper liquid, indicating the superior deoxygenization purification of the rare earth yttrium. The dispersive distribution of the Y–B compounds (YB6) was another factor for the improvement of the mechanical properties of the copper alloy. Finally, the copper alloy treated by hot rolling, cold rolling, and annealing processes in sequence exhibits HSHC with the tensile strength of 610.7 MPa and the electrical conductivity of 53.1%IACS.