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The effects of recovery on the subsequent recrystallization of tantalum were investigated via two-step annealing at two temperatures. Transmission electron microscopy, electron back-scattered diffraction, and X-ray diffraction were employed to determine the respective microstructures and textures after various annealing regimes. The results show that many large grains with {111} orientations are developed when heating at 1573 K without pre-recovery, while pre-recovery can introduce a homogeneous fine microstructure and weaken the texture. This difference can be attributed to the recovery-induced change in nucleation mechanisms. Elongated grains stretch along grain boundaries or locate in the interior of deformed grains, mainly due to the heterogeneous distribution of stored energy. Dislocations characterized by submicron bands in the deformed state evolve into sub-grains during pre-recovery and grow continuously, indicating a homogeneous distribution of dislocation or stored energy after pre-recovery, which can significantly influence subsequent nucleation and grain growth. [ABSTRACT FROM AUTHOR]

Al and Ti doped ZnO thin films have been prepared by direct current magnetron cosputtering and thermal oxidation. The effects of these dopants on the microstructural, morphological and electrical properties of deposited films have been studied. The SEM demonstrated that the undoped ZnO thin film consisted of globular ZnO with particle size of ∼100 nm. Scanning electron microscopy EDX analysis confirmed that the dopant content in the ZnO–Al and ZnO–Ti thin film was 2·78 and 3·75 at-% respectively. The particle in the ZnO–Ti thin film was blocky or granular with thorns and its size was several micrometers, while the particle in ZnO–Al thin film was porous granular and the size was ∼2 μm. Resistance value testing and R/R calculation revealed that pure ZnO thin film had the highest gas sensitivity. [ABSTRACT FROM AUTHOR]

The dendrite structure of aluminum alloys can be refined with titanium, boron, and rare earth elements. The effect of a refiner on the dendrite sizes was currently neglected in the cellular automata method. The parameter setting of the cellular automata method, considering the effect of rare earth elements on the α-Al dendrite of a hypereutectic AlSi alloy, was systematically investigated. The α-Al primary phase sizes of an AlSi7Cu3Mg alloy with different Y contents are experimentally studiedю With the Y addition of up to 0.2 wt.%, the refinement effect was the most effective, and grain sizes decreased to 0.67 mm. The microstructure simulation by the cellular automata method was studied experimentally and theoretically. By the use of this model, the parameter-setting effect on the Y refinement was more consistent with physical meaning. The calculation results fit the experimental ones well, and the validity and applicability of the model were verified. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of the micro-arc oxidation (MAO) coatings modified by TiO2 on AZ91 magnesium alloys were investigated by SEM, EDS, XRD, electrochemical analysis and drop test, respectively. The modified MAO coatings were consisted of not only MgAl2O4 and MgO, which usually could be found in MAO coatings on the AZ91 alloys, but also a small quantity of Ti. With increasing the contents of TiO2 nanoparticles from 0 to 4.8 g/L in the electrolyte, the coatings thickness increased from 19 to 24 µm, and the color of the MAO coating changed from light gray to dark. The addition of TiO2 could effectively decrease the number of the pores and improve the density of the coatings. The corrosion potential of the modified coatings positively shifted about 180 mV and the corrosion current density declined and the drop time increased. The mechanism of the corrosion resistances of the modified coatings lay in the fact that TiO2 nanoparticles could increase the thickness and the density of the coatings on the AZ91 magnesium alloys. [ABSTRACT FROM AUTHOR]

Microstructure and mechanical properties of stainless steel under the Nd:YAG pulsed laser irradiation were investigated. X-ray diffraction was used to identify the phases in the laser treated layer, and the growth morphology was observed by field emission scanning electron microscope. The results showed that a homogeneous microstructure with fine grains (60–300 nm) can be attained under the applied laser energy densities (2175×103 to 3585×103 J cm–2) and after that, it was difficult to get further refinement. Mechanical properties including microhardness and sliding wear were evaluated. The results indicated that the laser surface treatment was beneficial to increase the microhardness and to decrease the sliding wear rate. [ABSTRACT FROM AUTHOR]

Influence of the system temperature on the micro-structures and dynamics of dust clusters in dusty plasmas is investigated through laboratory experiment and molecular dynamics simulation. The micro-structures, defect numbers, and pair correlation function of the dust clusters are studied for different system temperatures. The dust grains' trajectories, the mean square displacement, and the corresponding self-diffusion coefficient of the clusters are calculated for different temperatures for illustrating the phase properties of the dust clusters. The simulation results confirm that with the increase in system temperature, the micro-structures and dynamics of dust clusters are gradually changed, which qualitatively agree with experimental results. [ABSTRACT FROM AUTHOR]

Strontium titanate films were grown by standard and interval pulsed laser interval deposition on (001) strontium titanate and magnesium oxide substrates. Reflection high-energy electron diffraction (RHEED) was used to monitor the growth mode of the films. The microstructures were investigated using transmission electron microscopy. The temporal evolution of the RHEED intensity confirmed a layer-by-layer growth mode in the homoepitaxial case. In heteroepitaxy, three dimensional growth occurred. Misfit dislocations and threading dislocations were the dominant defects. The film grown using the standard deposition was relaxed; the film grown using interval deposition was under in-plane tension and showed fewer threading dislocations. [ABSTRACT FROM AUTHOR]