In this research, recrystallization behavior and COARSENING kinetics of 7075 alloy were investigated during conventional and newly modified SIMA processes. The conventional SIMA process consisted of applying 10-55% uniaxial compression strain at ambient temperature and subsequent semi-solid treatment at various temperatures and times. A new modified SIMA process was developed by introducing repetitive upsetting-extrusion (RUE) for the first time for semi-solid processing of 7075 Al alloy. Specimens of 7075 alloy were subjected to different RUE cycles at 250 ° C, and then the semi-solid treatment was carried out. Microstructural studies revealed that the recrystallization rate is accelerated, the average grain size is reduced considerably and the sphericity of solid grains is improved by the newly modified SIMA process. Lifshitz-Slyozov-Wagner (LSW) theory was used to describe the COARSENING process of the semi-solid slurries. COARSENING rate of the solid grains in the newly modified SIMA process was slower than the conventional SIMA process.

Shape or habit of crystal is controlled by physicochemical conditions of crystallization, thus quantitative measurements of crystal shape can reveal aspects of crystallization environment. In this paper, based on statistical calculations, numerical modeling software and microscopic observations. various methods of quantitative measurement of the shape of crystal have used More than 3200 plagioclase crystals in 9 thin sections of the two groups of rocks including basaltic andesite and quartz diorite were processed. Study area is located about 120 Km southeast of Birjand. The results of calculated crystals aspect ratio (Short: Intermedite: Long or S: I: L) have showed that both groups have tabular habit (I »L), but tabulation amount in the first group is to be more (I, L>2). Analysis demonstrates that microlites in the first group were formed under conditions with high undercooling, fast growth rate and environment with high advection (relative movement between the crystal and growing medium) and the high mechanical movement of magma and high chemical potential gradient had significant role on ctystal shapes. In the second group, contrastingly, low growth rate and high diffusion rate were established. Also, textural COARSENING process was affected on shift of crystal shapes from tabular to more equant forms and reduction of aspect ratio with increment of maximum length of crystals.

Multigrid methods, such as the Algebraic MultiGrid methods (AMG), are among the most efficient methods for solving discrete linear equations resulting from elliptic PDEs. In this paper, some classic AMG techniques are used for solving a typical two dimensional diffusion equation. The present work focuses on different COARSENING techniques such as the standard and aggressive COARSENING based on the RS algorithm. Results indicate that the standard COARSENING technique together with direct interpolation minimizes the CPU-time and the computational work. Regarding the memory requirement, using a variant of aggressive COARSENING with direct interpolation minimizes the size of memory usage. In addition, the setup phase time (COARSENING process) is minimum in this technique. Nevertheless, the increase in convergence factor results in higher overall time for the solution phase. Analysis of the aspect ratio of the computational cells shows that the convergence rate is affected little by this parameter. However, the COARSENING process work and the total CPU-time are slightly increased when cells with high aspect ratios are used for the numerical simulations. Overall, the standard-COARSENING method with direct interpolation is found to be appropriate for two-dimensional diffusion problems.

The high sensitivity of the morphology and final properties of co-continuous polymer blends to thermal annealing has motivated many researchers to study the evolution of their morphology during thermal annealing process. In this work, phase COARSENING of a low interfacial tension polylactic acid/polycaprolactone blend and a medium interfacial tension polylactic acid/polyethylene blend during quiescent annealing was studied in detail. To this aim, characteristic length scale of the microstructure of the polymer blends was determined at different annealing times. It was found that the phase size in both blends increased linearly by time at the early stage of the annealing and then the phase COARSENING rate gradually decreased at longer times. Finally, the phase size of the blends approached a finite size. The mechanisms involved in the observed phase COARSENING behavior were discussed in detail. Linear and exponential phase COARSENING models in the literature could not explain the observed phase COARSENING behavior in the studied blends. A new empirical model was presented which showed a very good agreement with both the obtained results in this work and the previous experimental data in the literature. The obtained results indicate the significant potential of the new model in analyzing phase COARSENING behavior of co-continuous polymer blends.

The effects of rapid induction heating on the thermal stability of a Ni3Al base alloy containing Cr, Mo, Zr and B was investigated. The alloy was produced with vacuum-arc remelting technique. Microstructural changes in the dendritic and interdendritic region during rapid heating process are clarified using scanning electron microscopy and image analyzing technique. The results of this type of heat treatment were compared with normal heat treatment. Results showed that rapid heating can accelerate the elimination speed of high zirconium phase and also the growth kinetics of γ ' precipitates but has no significant effect on the growth mechanism.

Quantum dots of CdS with hexagonal phase were prepared at relatively low temperature and short time compared to the other methods reported in the literature by micro-emulsion (O/W) under ultrasound. This study was focused on the particle size distribution and the growth kinetics. The particle size distribution obtained from the optical absorption edge. It was relatively symmetrical with sonication time. In addition, an agreement was observed with the size distribution obtained from the TEM images of the sample under ultrasound. The growth kinetics was monitored by the red-shift in UV-Visible absorbance peaks. The cubed average particle radius showed an emergence of linear regions at longer times. This indicates that the increase of particle size at longer time can be attributed to the diffusion-limited COARSENING process. The rate constant for the COARSENING increases with increasing the temperature. The Arrhenius-type plot was created by using the slopes of Lifshitz-Slyozov-Wagner (LSW) curves. The activation energy was 71.72 kJ mol-1 for the ripening process. In fact, the acoustic cavitation strongly increases the diffusion of surface atoms.

Effect of continuous heating after cold deformation on the microstructural evolutions and corrosion behavior of SUS 304L metastable austenitic stainless steel was investigated. After cold rolling with the reduction in thickness of 80%, a microstructure consisting of elongated grains was obtained, in which the X-ray diffraction (XRD) analysis revealed the formation of 96 vol.% strain-induced martensite. The subsequent continuous heating up to 750 °C led to full reversion/recrystallization and the development of an ultrafine grained (UFG) microstructure with an average grain size of 0.45 µm. Continuous heating up to higher temperatures resulted in a significant grain growth, where the average grain size of samples that heated up to 850, 900, 950, and 1100 °C were obtained as 2.5 µm, 5.5 µm, 14 µm, and 45 µm, respectively. The Hall-Patch relationship of H = 155 + 106/√D was developed for the dependence of hardness on the average grain size (D). By grain refinement, corrosion current density (iCorr) increased leading to the worsening of uniform corrosion resistance. However, breakdown potential (EBr) increased by grain refinement, indicating the improved pitting resistance. The Hall-patch-type equations of iCorr = 0.0147 + 0.4458/√D and EBr = 0.1964 + 0.0695/√D were proposed for correlating the corrosion parameters to D.

In this research, based on spatial distribution and size of crystals, the role of physical processes affecting formation of the igneous rocks such as kinetics of crystallization (nucleation and growth of crystals), dynamics of magmatic systems (e.g. mixing and convection currents) and equilibrium processes such as textural COARSENING are investigated. To this end, the spatial distribution pattern (SDP) of plagioclase, amphibole and quartz crystals were quantified in the microdiorite-quartz diorites and results were combined with petrography to discuss the factors affecting plagioclase packing arrangements and physical processes operated during formation of these rocks. The study area is located in 120 Km southeast of Birjand. The 8 thin sections of rocks were processed and geometrical features e.g. length, width and centre of 3098 crystals were measured. Then, R values (a descriptive value) were measured using nearest neighbor distance method with BigR and ArcGIS software's and the data were plotted against porosity (modal abundance of other phases in igneous rocks.) Results show that crystals have clustered SDP. The degree of plagioclases clustering is different in sections with change of crystal sizes and shapes. The origin of crystal clusters is likely to involve heterogeneous nucleation, textural COARSENING and overgrowth of crystals.

A method for adaptive refinement of a triangular mesh for solution of the steady and unsteady Euler equations is presented. An upwind, finite volume based on Roe"s flux difference splitting method is used to discretize the equations. By using advancing front method an initial regular Delaunay triangulation has been made. The adaptation procedures involve mesh enrichment and mesh COARSENING to either add points in high gradient regions of the flow or remove points where they are not needed, respectively, to produce solutions of high spatial accuracy at minimal cost. Steady transonic results are shown to be of high spatial accuracy, primarily in that the shock waves are very sharply captured. Unsteady results obtained for a moving shock wave in a two-dimensional domain show the precise enrichment and COARSENING procedure. The results were obtained with large computational savings when compared to results for globally-enriched mesh with cells subdivided as many times as the finest cells of the adapted grid.

Martensitic microstructure, due to its numerous nucleation sites for austenite and its fibrous distribution, is considered as the initial microstructure in the dual-phase steel fabrication process, specifically during intermediate quenching. In the present study, the microstructural evolution of a carbon-manganese steel during intermediate quenching at three temperature ranges (upper-critical (Ac₃