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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]

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]

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]