In this study, impurity segregation and solute drag effects on grain boundary (GB) motion were investigated in a binary Al–Ni model system with an inclined Σ5 GB by direct molecular dynamics simulations. By extending the interface random walk method to impure systems, it was found that the GB mobility was significantly influenced by the segregated impurities, which generally decreased as the impurity concentration increased. Moreover, based on simulations at different temperatures and impurity concentrations, we validated that the solute drag effects can be well modeled by the theory proposed by Cahn, Lücke, and Stüwe (CLS model) more than 50 years ago, provided that proper adaptations were made. In particular, we found that in strongly segregated GB system, the boundary mobility was deeply correlated to the impurity diffusivity in the direction perpendicular to the boundary plane in the frame of the moving boundary, instead of the impurity bulk diffusivity assumed in the original CLS model and many past studies.

(Cu0.47Zr0.45Al0.08)100–xDyx (x = 0, 1, 2, 3, 4; at.%) metallic glasses with greatly enhanced glass-forming ability (GFA) and plasticity were synthesized based on microalloying technique. The structure, thermal stability, and elastic properties of the BMG samples were studied by x-ray diffraction (XRD), differential scanning calorimetry (DSC), and ultrasonic measurements, respectively. With addition of minor dysprosium (Dy), fully metallic glassy rods with diameters exceeding 20 mm could be successfully fabricated by copper mold casting. In addition, the Cu–Zr–Al–Dy BMGs exhibit good mechanical properties under a compressive deformation mode, i.e., high yield strength of 1735–1906 MPa, Young's modulus of 85–100 GPa, and distinct plastic strain up to 4.02%. The strength and plasticity show remarkable correlations with glass transition temperature and Poisson's ratio, respectively. The role of minor Dy addition in enhancement in GFA and mechanical property of the Cu-rich BMGs is also discussed.

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.

The corrosion behavior of 2099 Al–Li alloy in NaCl aqueous solutions with different concentrations (1.5, 3.5, and 5.0% in mass fraction) was investigated. Its corrosion resistance was evaluated using electrochemical measurements together with full immersion tests. The results showed that the 2099 Al–Li alloy possessed good corrosion resistance in NaCl aqueous solutions. Its corrosion rate increased with increasing chloride ion concentration. The main form of corrosion failure was pitting corrosion. The impurity containing sulfur leads to surface pitting. The oxide films that formed during the manufacturing process offer a good resistance to corrosion. They are likely to suffer separation, cracking, and drop-off when immersed in aggressive NaCl aqueous solution. The good corrosion susceptibility of the alloy may be attributed to homogeneous coherent nanoscale precipitates.

By using a two-dimensional axisymmetric finite element model, the indentation hardness has been studied with different combinations of material properties at different indentation depths. As the forward problem, the testing hardness is not only a function of material properties (E, σy, and n), indenter geometry (half apex angle, indenter shape), and friction, but also relating to the indentation depth. Based on the previous research on size effect, a model of correlation between several indentation experiment parameters (hardness H, maximum load Pm, and loading curvature C) and material properties has been derived. From simulation results, a better fitting result is obtained by the established model. Furthermore, the characteristic length h∗ in Nix/Gao model has been rewritten and discussed with material properties accordingly.

This study presents results of selective laser melting (SLM), powder metallurgy (PM), and casting technologies applied for producing Ti–TiB composites from Ti–TiB2 powder. Diffraction patterns and microstructural investigations reveal that chemical reaction occurred between Ti and TiB2 during all the three processes, leading to the formation of Ti–TiB composites. The ultimate compressive strength of SLM-processed and cast samples are 1421 and 1434 MPa, respectively, whereas the ultimate compressive strengths of PM-processed 25%, 29%, and 36% porous samples are 510, 414, and 310 MPa, respectively. The Young's moduli of porous composite samples are 70, 45, and 23 GPa for 25%, 29%, and 36% porosity levels, respectively, and are lower than those of SLM-processed (145 GPa) and cast (142 GPa) samples. Fracture analysis of the SLM-processed and cast samples shows shear fracture and microcracks across the samples, whereas failure of porous samples occurs due to porosities and weak bonds among particles.

Monotonic and cyclic tension–tension tests with an upper stress in the GPa regime have been performed on Cu–Si nanowires. The results show that the exceptional high strength of these nanomaterials is maintained or even improved upon cyclic loading. Post-mortem transmission electron microscopy gives insight in the microstructural evolution. Fatigue-induced grain growth correlates with an observed increase in compliance, the formation of dislocation networks, and an increase in tensile strength.

Groups of chloromethyl were randomly grafted to Janus composite particles and quaternization was carried out on the particles. The Janus material of titania–quaternary ammoniated poly(vinylbenzyl chloride–divinylbenzene) (TiO2–QApoly(VBC–DVB)) was investigated in detail. Results revealed that the anisotropic Janus material containing quaternary ammonium groups was synthesized successfully. The Janus material could be used as the phase transfer catalyst. The catalytic activity of the Janus material was confirmed by the esterification reaction of benzyl chloride and sodium acetate. In the presence of 0.5 wt.% (relative to benzyl chloride) of TiO2–QApoly(VBC–DVB), the esterification yield of benzyl acetate reached 87.6% when the molar ratio of sodium acetate anhydrous to benzyl chloride was 1.2. The catalyst exhibited a high activity and had no obvious loss of activity when recycled three times. Moreover, the Janus material was easily recovered by centrifugation and washed with ethanol and water.

This paper discusses tensile testing of small samples of nanocrystalline Al6061-T6 alloy obtained from an unusual application of machining as a severe plastic deformation process. Ultrafine grained (UFG) shavings obtained from plane-strain cutting show higher hardness than the bulk material in agreement with existing literature. Application of restricted contact tools and extrusion-machining was explored to obtain shavings with minimum curvature to aid in tensile test specimen preparation. A novel method to prepare small tensile test specimens from these shavings has been described. During the tensile testing of UFG material, strains were measured using digital image correlation of natural speckles on the specimen. Specimens made from the UFG material had higher tensile strength and yield stress than the bulk, while ductility was lower. Lower values of Young's modulus were observed during the tensile testing of small specimens made from UFG as well as bulk material.

Silver-decorated titanium dioxide (Ag/TiO2) nanotube (NT) arrays were successfully prepared using a two-step synthesis route comprised of an anodic oxidation procedure followed by photochemical reduction using ultraviolet irradiation. The resulting Ag/TiO2 NT arrays were characterized using scanning electron microscopy, transmission electron microscopy, x-ray diffraction, and UV-vis diffusion reflectance spectrometry. The characterization results indicated that the silver decoration significantly enhanced the light absorption capability of the TiO2 NT arrays in the visible spectral range. The visible light photocatalytic activity of the subject NT arrays was investigated. The experimental results showed the photocatalytic activity of silver-decorated titanium dioxide Ag/TiO2 NT arrays to be dependent on the size of the silver particles. The improved visible light absorption can be attributed to plasmonic effects induced by particle size phenomenon. The Ag/TiO2 NT arrays exhibit promising application for photocatalytic degradation of dye solutions and pollutants in water using visible irradiation.

A systematic experimental study on the exchange bias (EB) effect in a ferromagnet/antiferromagnet bilayer system is performed both in the static (dc) and dynamic (high frequency) timescale to clarify the effects of temperature and antiferromagnetic (AFM) layer thickness on the system's stability and magnetic properties. Our system consists of NiFe/IrMn. Both parallel and perpendicular domain walls are suggested to explain the static EB and coercivity behaviors. In the microwave region, peaks, which can only be suppressed at high temperatures with strong external fields, were observed in the AFM thickness dependencies of the dynamic effective field and resonance frequency. The temperature dependence of both static and dynamic parameters suggests different values of Néel temperatures. The dynamic results show a rotatable anisotropy contribution, which has a peak value at the blocking temperature and vanishes at the dynamic Néel temperature.

The modification of near-eutectic Al–Si alloy with samarium additions (0–0.9 wt.% content) has been studied. The thermal analysis results indicated that the addition of Sm in Al–12Si alloy caused a depression of eutectic temperature (∆T E). And it was found that Sm was capable of breaking down the primary α-A1 phases, giving rise to an increment in the number of dendrites. Simultaneous primary Si refinement and eutectic modification were achieved by Sm addition. When 0.6 wt.% Sm was added to the alloy, the silicon in Al–12Si alloy was best refined and showed a fully modified, fine fibrous eutectic structure; the primary α-Al phase appears as a slightly dual dendritic-cellular nature and a pine-tree structure. Moreover, the mechanical properties were investigated by the tensile test. A good combination of ultimate tensile strength (217 MPa) and elongation (1.3%) was obtained when the addition of Sm was up to 0.6 wt.%.

Solution-processed CuInGaS2 (CIGS) thin-film solar cells are promising for large-scale commercialization due to their economic process although the efficiency still needs to be improved to compete with vacuum-based materials. Systematic studies were performed to optimize the series and shunt resistance of hydrazine-based CIGS solar cells. Optimization was achieved through compositional adjustment of copper (Cu) near the p–n junction and gallium (Ga) near the back contact. Cu adjustments optimized the shunt resistance between 4000 and 5000 Ω cm2. Ga adjustments optimized the series resistance to 2 Ω cm2. Shunt and series resistance play vital roles in the fill factor. Fill factor was hence improved upward of 0.80 with the optimization of Cu and Ga. Chemical etching was also conducted to investigate the durability of the materials and to remove small crystals near the interface. Device conversion efficiencies were improved up to 12.4%. This study provides the implications for improving the device performance of chalcogenide solar cell materials.

The fabrication of a temperature sensor based on graphene nanoplatelets (GNPs) is reported. A preheat process was carried out and the micrographs of both original and preheat-treated GNPs are observed and compared. Nonlinear temperature variation of resistance is observed and humidity interference is found to be negligible. Region of 10–60 °C (the linear region) is selected as the sensor range and further studied. High sensitivity of GNPs can be seen and the temperature coefficient of resistance (TCR) of 0.0371 is calculated, higher than that of multiwall carbon nanotubes (MWCNTs) and many other materials reported in references. Great repeatability and small hysteresis are obtained. The time constant of the GNPs film is about 5 s, much shorter than that of MWCNTs film. The result suggests that GNPs have potential applications for use in highly sensitive and fast-response temperature sensors.