Cu/Sn alloy matrix composites reinforced with β-Si3N4 whiskers (β-Si3N4w/Cu/Sn) were prepared by powder metallurgy method with the aim of improving the mechanical property. Although the β-Si3N4 whisker additions played a side effect on the densification of the composites, the mechanical property was significantly improved. The highest bending strength of β-Si3N4w/Cu/Sn reached up to 353 MPa, and the highest hardness of composites was also improved to 97.13 HRF. β-Si3N4 whiskers could induce the improved work of fracture and grain refinement of composites and thus brought about the enhancement of mechanical performance. However, excessively high β-Si3N4 whisker content was not beneficial to the high mechanical property because of the low densification and the severe aggregation of whiskers. The β-Si3N4w/Cu/Sn still had a quite high thermal conductivity. As a result, the β-Si3N4w/Cu/Sn could be a promising material applied in a severe environment.

In situ nano-TiB2 reinforced ultrafine-grained (UFG) Al composites were prepared via combined processes of flux-assisted synthesis (FAS) and asymmetrical rolling (ASR). The UFG Al composite with an ASR reduction ratio of 97% exhibits an average matrix grain size of 380 nm and an average TiB2 particulate size of 50 nm. Dislocation density in the composites is higher than that corresponding to the high purity (99.99 wt%) Al under identical processing conditions. The yield and ultimate tensile strength values of the UFG Al composites processed with an ASR reduction ratio of 97% are approximately 9 and 5 times higher relative to those of the initial coarse-grained Al, respectively. Moreover, the UFG Al composite with an ASR reduction ratio of 97% exhibits a higher elongation than that corresponding to the UFG pure Al under identical processing conditions, suggesting that nanoparticulates contribute to the overall plastic deformation when the matrix grains are refined to the UFG regime. Moreover, analysis of the strengthening behavior reveals no clear evidence that Orowan strengthening contributes significantly to the overall yield strength of the Al nanocomposites studied herein.

As a promising reinforcement of aluminum alloy, in situ formed Al3Ti particles have attracted more attention in the fabrication of aluminum matrix composites. In our research, in situ Al3Ti/7075 alloy composites were fabricated by adding K2TiF6 salt powders into molten 7075 alloy at 750 °C via casting method. The formation of in situ Al3Ti particles and their effects on the microstructure and mechanical properties of 7075 alloy, including hardness, ultimate tensile strength (UTS), and yield strength (YS), were investigated. The results showed that in situ formed Al3Ti particles were rod-like in morphology, with the average length and width of 15 µm and 5 µm, respectively. Due to the nucleating effect of Al3Ti particles, α-Al crystals of 7075 alloy transferred from dendritic to equiaxed structure in morphology, the size of which decreased obviously as well. Compared with 7075 alloy, the hardness, UTS, and YS of in situ Al3Ti/7075 alloy were improved by 14.3%, 18.1%, and 25.8%, respectively.

A multistep heat treatment process consisting of intercritical tempering between quenching and conventional tempering contributed to the development of a ferrite–martensite dual-phase structure in a Ni- and Cu-containing high-strength low-alloy steel. By using electron backscatter diffraction and scanning transmission electron microscopy, the microstructures were found to have an elongated lathlike morphology with carbide and Cu precipitates located especially at the boundaries of ferrite and martensite crystals. Atom probe tomography reveals at atomic scale the existence of solute-diluted ferrite and solute-rich martensite, and the later phase was considered to be transformed from the reverse austenite that was formed during intercritical tempering. Cu precipitation greatly correlates with the microconstituents, resulting in different distributional characteristics of Cu precipitates within these two phases and at their boundaries. It is a promising process to utilize Cu precipitation strengthening and phase transformation toughening simultaneously in alloy steels.

Thermally stable nanosized Al2O3 particles and carbon nanotubes (CNTs) are comparatively effective in simultaneous improvement of strength and ductility of wrought magnesium alloy AZ31 when incorporated in microstructure. Understanding the comparative effectiveness of these nanosized reinforcements on the high temperature deformation process of wrought AZ31 alloy is important for its potential wider automotive body application. The current study has revealed that both reinforcements are competitively effective in inducing matrix grain and intermetallic particles refinement and strengthening almost to a theoretically predicted value. Although high temperature flow stress of AZ31 was found to closely match due to incorporation of both of the nanosized reinforcements, alumina was more efficient in improving the failure strain of matrix alloy. Addition of remarkably a small amount of nanosized alumina particles or CNTs introduced huge potential in near net shape formability of AZ31 alloy at a temperature much below than the widely used 350 °C. Among the two reinforcements used in this study, alumina was found to be more efficient when compared to the effect of CNTs.

We investigated the persistent luminescence in europium-doped LiBaPO4. The persistent phosphors were synthesized via solid-state reaction method under mild reducing atmosphere. Its properties were investigated by x-ray diffraction, diffuse reflectance, photoluminescence, persistent luminescence, and thermoluminescence spectra. Under UV irradiation, broad-band persistent luminescence peaked at ∼470 nm was observed in the phosphors at room temperature. The effects of Eu2+ concentration on the persistent luminescence of LiBaPO4:Eu2+ were discussed. An energy level scheme was constructed to convey reasonable trapping and detrapping processes in the material.

In this paper, high-k hafnium–aluminum oxide (HAO) films were synthesized by the sol–gel technique. The effects of the ratio of Hf and Al on the properties of the HAO films were investigated thoroughly. The average optical transmittance of the HAO films was above 88% within the visible light range and Al incorporation in HfO2 can enlarge the band gap of HAO films. X-ray diffraction (XRD) results showed that Al additive can suppress the crystallization of HfO2 and the HAO films were amorphous in structure. The refractive index of HAO films can be modulated with the ratio of Hf and Al in the HAO films. The HAO films with the ratio of Hf and Al = 2:1 obtained excellent performance including the root mean square (RMS) roughness of 0.26 nm, the relative permittivity of 12.1, the leakage current density of 1.69 × 10−7 A/cm2 at 2 MV/cm, and the etching rate in dilute HF solution less than 1 nm/s.

Indium-tin-oxide (ITO) thin films were prepared by reactive magnetron sputtering; their optical constants and thickness were determined by spectral reflectometry (SR) in the wavelength range from 400 nm to 800 nm and spectroscopic ellipsometry (SE) in the wavelength range from 191 nm to 1690 nm. A comparative evaluation of the measured data from SR and SE has been made using the same single layer optical model based on the Cauchy dispersion relation. The introduction of a surface roughness layer into the optical model considerably improved the fit quality during evaluation of SE data. Vertical inhomogeneity of the ITO thin films was assessed using a multilayer optical model describing porosity gradient and the three-layer optical model suggested by Jung [Y.S. Jung, Thin Solid Films467, 36 (2004)] from the SE data.

The present study describes magnetic interactions in (Zn1–xCox)Ga2O4 (x = 0.05, 0.10, and 0.20) particles dependant on Co atoms in both tetrahedral and octahedral sites. The effects of substituted Co atoms to magnetic character are analyzed using Curie–Weiss law. The ferromagnetic character is found dominant in (Zn1–xCox)Ga2O4 semiconductors for x values lower than 0.10; in addition, a specific hysteresis with 139 ± 50 Oe coercivity is observed for 5% Co-doped ZnGa2O4. The high Co amount in tetrahedral site increased the number of antiferromagnetic couplings and the hysteresis at 300 K disappeared for (Zn0.80Co0.20)Ga2O4 particles. Furthermore, the Co+3 ions in the octahedral site decreased µeff values, per Co amounts, in the range of 4.89 ± 0.01 µB/Co to 4.44 ± 0.02 µB/Co, because of enhancing paramagnetic behaviors.

Using first principle density functional calculations, we study the formation of 2D transition metal dichalcogenides (TMDs) on TiC1−xAx, (A = S, Se, and Te) surfaces. We examine the structural misfits between chalcogen-containing TiC and different TMDs and demonstrate that the conditions for formation of TMDs are fulfilled in TiC1−xAx. We also demonstrate the influence of chalcogens on the cohesive properties and electronic structure of the carbides. We find that they react with W and form W-dichalcogenides. In the experimentally reported Ti–C–S nanocomposite coatings, the carbide grains are embedded in an amorphous carbon matrix. We discuss here the role of this matrix in the reaction. We propose that TiC1−xTex and TiC1−xSex are the favorable sources for dichalcogenide formation and suggest an alternative way to produce 2D materials in general. Furthermore, we argue that using Ti–C–Te or Ti–C–Se in nanocomposite coatings may be more advantageous for tribological applications than that of Ti–C–S.

Carbon nanotube (CNT)-reinforced aluminum composite powders were synthesized by cryogenic milling. The effects of different milling parameters and CNT contents on the structural characteristics and mechanical properties of the resulting composite powders were studied. Detailed information on powder morphology and the dispersion and structural integrity of the CNTs is crucial for many powder consolidation methods, particularly cold spray, which is increasingly utilized to fabricate metal-based nanocomposites. While all of the produced composite powders exhibited particle sizes suitable for spray applications, it was found that with increasing CNT content, the average particle size decreased and the size distribution became narrower. The dispersion of CNTs improved with milling time and helped to maintain a small Al grain size during cryogenic milling. Although extensive milling allowed for substantial grain size reduction, the process caused notable CNT degradation, leading to a deterioration of the mechanical properties of the resulting composite.

To thoroughly understand the relationship between heat treatments and characteristics of both microstructure and corrosion behavior of Ni–Fe–Cr alloy 028, a series of heat treatments were carried out. The area fraction of precipitates increases with increasing duration of aging treatment at 900 °C. The precipitation rate is higher at 900 °C than at 850 and 950 °C. The precipitates are formed both in grains and at grain boundaries, this behavior enhances the hardness. The corrosion behavior was evaluated by potentiodynamic polarization test and electrochemical impedance spectroscopy measurement under sodium chloride solution. The results indicate that the variation of morphology, amount, and distribution of precipitates attributed to the heat treatment strongly influences the corrosion behavior of alloy 028 in the sodium chloride solution. There is a galvanic effect of Cr-rich phase in the corrosion process. The increase of corrosion rate with the aging time is attributed to the acceleration of the microgalvanic corrosion.

To establish the relationships between composition, microstructure, and properties, the influence of Al addition on microstructure and properties of Cu–Fe-based coatings by laser induction hybrid rapid cladding was studied. With increasing Al content, the main diffraction peaks of ε-Cu phase are weakened but those of α-Fe phase are strengthened, the size of Fe-rich particles generally increases but the dendrite arm spacing is further reduced, and the number of Cu-rich grains precipitated inside the Fe-rich particles increases but the size reduces. Moreover, when the amount of Al is increased, the improvement in electrochemical resistance is attributed to large amounts of fine Cu-rich grains precipitated inside the Fe-rich particles, which results in large anode–small cathode effect. The microhardness also increases with Al content and the microhardness of Cu53.5Fe36Al10C0.5 coating is approximately 2.4 times higher than that of copper alloy substrate.

A technique has been developed for determining coefficients in the power approximation of the “stress–strain” diagram by results of scratch testing with a Berkovich indenter under a normal load of 5 mN on the indenter. The procedure is based on a comparison of experimental results with the finite element simulation of the test process. The technique is intended for application on nanomechanical testing equipment enabling one to perform tests with recording of loading diagrams in terms of the “normal force – indenter displacement” coordinates. To obtain correct results, one must observe the following restrictions: indenter penetration depth > 150 nm under a loading of 5 mN with the indenter tip curvature radius R < 50 nm; indenter penetration depth > 250 nm with 50 < R < 100 nm; the tested metal must be ductile enough, for a scratch to be formed by the mechanism of plastic deformation rather than fracture.

Graphene's layered structure has opened new prospects for the exploration of properties of other monolayer-thick two-dimensional (2D) layered crystals. The emergence of these inorganic 2D atomic crystals beyond graphene promises a diverse spectrum of properties. For example, hexagonal-boron nitride (h-BN), a layered material closest in structure to graphene is an insulator, while niobium selenide (NbSe2), a transition metal dichalcogenide, is metallic, and monolayers of other transition metal dichalcogenides such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2) are direct band gap semiconductors. The rich spectrum of properties exhibited by these 2D layered material systems can potentially be engineered on-demand and creates exciting prospects for using such systems in device applications ranging from electronics, photonics, energy harvesting, flexible electronics, transparent electrodes, and sensing. A review of the structure, properties, and the emerging device applications of these materials is presented in this paper. While the layered structure of these materials makes them amenable to mechanical exfoliation for quickly unveiling their novel properties and for fabricating proof-of-concept devices, an overview of the synthesis routes that can potentially enable scalable avenues for forming these 2D atomic crystals is also discussed.

Tungsten oxide (WO3) nanostructures receive sustained interest for a wide variety of applications, and especially for its usage as a photocatalyst. It is therefore important to find suitable methods allowing for its easy and inexpensive large scale production. Tungstite (WO3·H2O) nanoparticles were synthesized using a simple and inexpensive low temperature and low pressure hydrothermal (HT) method. The precursor solution used for the HT process was prepared by adding hydrochloric acid to diluted sodium tungstate solutions (Na2WO4·2H2O) at temperatures below 5 °C and then dissolved using oxalic acid. This HT process yielded tungstite (WO3·H2O) nanoparticles with the orthorhombic structure. A heat treatment at temperatures at or above 300 °C resulted in a phase transformation to monoclinic WO3, while preserving the nanoparticles morphology. The production of WO3 nanoparticles using this method is therefore a three step process: protonation of tungstate ions, crystallization of tungstite, and phase transformation to WO3. Furthermore, this process can be tailored. For example, we show that WO3 can be doped with cesium and that nanorods can also be obtained. The products were characterized using powder x-ray diffraction, transmission electron microscopy (including electron energy-loss spectroscopy and electron diffraction), and x-ray photoelectron spectroscopy.

Injectable bone grafts with strength exceeding that of trabecular bone could improve the clinical management of a number of orthopedic conditions. Ceramic/polymer composites have been investigated as weight-bearing bone grafts, but they are typically weaker than trabecular bone due to poor interfacial bonding. We hypothesized that entrapment of surface-initiated poly(ε-caprolactone) (PCL) chains on 45S5 bioactive glass (BG) particles within an in situ-formed polymer network would enhance the mechanical properties of reactive BG/polymer composites. When the surface-initiated PCL molecular weight exceeded the molecular weight between crosslinks of the network, the compressive strength of the composites increased 6- to 10-fold. The torsional strength of the composites exceeded that of human trabecular bone by a factor of two. When injected into femoral condyle defects in rats, the composites supported new bone formation at 8 weeks. The initial bone-like strength of BG/polymer composites and their ability to remodel in vivo highlight their potential for development as injectable grafts for repair of weight-bearing bone defects.

Zn3(VO4)2 nanorods with visible light-driven photocatalytic activity were prepared by hydrothermal reaction and characterized by x-ray diffraction, Fourier transform infrared, scanning electron microscopy, x-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, and Brunauer–Emmett–Teller surface area and pore size analyzer. The Zn3(VO4)2 nanorods consisted of rods with a thickness of approximately 30 nm, length in the range 400–600 nm, and width in the range 150–250 nm. The photocatalytic degradation activities for methylene blue (MB) and 4-nitrophenol (4-NP) over the Zn3(VO4)2 nanorods were studied in detail. The photocatalytic activity of the as-prepared photocatalyst for MB and 4-NP in visible light under the same conditions was about 3.5 times and 2.5 times higher than that of N–TiO2, respectively. The main active species in the photodegradation come from •OH, and the photogenerated electrons also partly involved in the photocatalytic degradation process, in which the •OH radicals formed were in proportional to the light illumination time obeying zero-order reaction rate kinetics.

The infrared emissivity properties of carbon fibers with different treatments were investigated in the wave length range 6–15 μm from 1273 to 1873 K. The heat treatment affected the infrared emissivity of carbon fibers through the microstructure evolution. The Raman investigation about the microstructure indicated that the increase of the graphitization degree in carbon fibers degenerated the infrared emissivity of carbon fibers, especially under high temperatures. For the coated carbon fibers, the infrared emissivity properties were decreased for carbon fibers coated pyrolytic carbon (PyC) due to the lamellar structure of PyC and increased for carbon fibers deposited carbon nanotubes (CNTs) owing to the skeleton-like structure of CNTs. The study also illustrated that the PyC coating thickness from 0.5 to 1.0 μm had few effects on the infrared emissivity properties of carbon fibers.

The media advertizes that soon everybody can manufacture models and parts of all kinds via computer-aided design –computer-aided manufacturing by additive manufacturing (AM) technologies. That can boost the do-it-yourself activities enormously. But it can also revolutionize the industries: Most conventional technologies of manufacture are profitable only in big lots of production. For single specimens and small lots of production, they are too expensive. But with AM, one or a few original or spare parts can be produced at low cost. However, to succeed in the market, the AM products must become competitive. They must have reproducibility of an exact shape, even in tiny details, a perfect surface and, above all, sufficient mechanical strength. This article deals with three-dimensional ink-jet printing with monomer inks and polymer powders. Since powder beds are always porous, the main aim was to fill the pores permanently with high amounts of the ink polymer. A new polymer powder that rapidly dissolves in monomer inks is reported.