Zirconium carbide (ZrC) is promising candidate materials in advanced nuclear reactors as fuel cladding and plasma facing materials. It can employ to increase ductility and fracture toughness of tungsten as prominent candidate of plasma facing materials in ITER and DEMO future fusion reactors. In this study, ZrC thin films were deposited through DC magnetron sputtering at different substrate temperatures. Argon and acetylene are respectively employed as the sputtering gas and reaction gas to produce ZrC from a Zr target. The phase and structure, crystallite size, displacement density, microstrain, and lattice’, s constant of the produced thin films were determined using X-ray diffraction (XRD) analysis. Raman spectroscopy was also used to identify various structures and chemical bonds. Furthermore, the analysis of Raman peaks associated with amorphous carbon bonds revealed that the ratio of sp3/sp2 carbon bonds increases by increasing temperature from 100°, C to 180°, C, which substantially affects the hardness of the thin films. Field Emission Scanning electron microscopy (FESEM) was used to measure the cross-sectional area and thickness of the thin films, and it was discovered that increasing temperature enhances the thickness of the thin films. The elemental analysis of ZrC thin films that was performed using X-ray energy dispersive spectroscopy (EDS) demonstrated the atoms that constitute the thin film, and their changes with temperature variations.

A numerical solution for axis-symmetrical fluid flow through a smooth constriction using the alternating direction implicit finite volume method and the fractional-step-method is presented. The wall is modelled with a smooth contraction mapped by a sinusoidal function and the flow is supposed to be axis-symmetric. A pressure boundary condition is set at the inlet and the resulting pressure gradient field drives fluid flow which is always in laminar regime. This study presents results for a non-Newtonian fluid using the Ostwaldde Waele constitutive model. Moreover, a transient network representing three different Microstructures, immersed in the fluid, is evolved by viscous dissipation and an isothermal process is considered. The time dependent Evolution of the transient network is represented by a set of kinetic equations with their respective forward and reversed constants. The numerical predictions show that, at a fixed Reynolds number, the viscous dissipation and the grade of structure restoration or breakage is influenced by constriction severity due to the energy generated during fluid flow. A 50% reduction in transversal section generates secondary flow downstream and vortex shedding, whereas a 10% and 25% constrictions presents a thin boundary layer and no secondary flow near the constricted wall.

Compositions of Al2O3+Si, SiO2+Al and Al+Si systems were prepared to study the effect of reaction bonding process on the mullite formation. The composition of each system was adopted according to mullite stoichiometery and sintered in 700-1600°C range. Results showed that the formation of reaction bonded mullite starting from Al2O3+Si mixtures, proceeded in two partially overlapping steps, the oxidation of Si to SiO2, and the reaction of SiO2 and Al2O3 to form mullite. In this system, up to 1400°C, conversion of Si to SiO2 was taken place and cristobalite formed, but mullite formation was not observed. Mullite phase started to form at 1450°C. Results indicated that complete reaction was not occurred up to 1600°C and 2 hours soaking time. XRD patterns of samples in Al+ SiO2 system showed that the reaction through sequences: (a) reduction of SiO2 by Al, (b) formation of a- Al2O3 and SiO2-rderived Si oxidation, and (c) mullite formation. X-ray diffraction patterns of heat-treated Al+Si system showed that reaction between Al and oxygen at 900°C was occurred with the reaction product being a- Al2O3 Oxidation of Si and formation of mullite were not detected in this system. SEM micrographs showed that both Al2O3+Si and SiO2+Al systems have similar Microstructures, which consisted of a- Al2O3, mullite and free Si. The Microstructures of the samples in Al+Si system consisted of a- Al2O3 free Al and Si with intermetallic Al-Si compound.

Dynamic Recrystallization (DRX) is one of the likely mechanisms for fine-graining in metals and alloys. The dynamic recrystallization (DRX) phenomena occurs in different thermo-mechanical processing (TMP) conditions for various metallic materials. DRX depends on various materials and thermo-mechanical parameters such as temperature, strain rate, strain, stress and initial Microstructure. in the present study, the restoration mechanism of the 17-7PH stainless steel has been investigated using a hot compression test under different conditions of thermo-mechanical treatment. The microstructural characteristics and the behavior of the hot deformation of the under study steel are investigated using flow curves and Microstructure images obtained from optical microscopy. The results show that the maximum and steady state stresses are significantly affected by the strain rate and the deformation temperature. So that, the flow stress increases with decrease in the deformation temperature and increase in the strain rate. Microstructural studies confirm the occurrence of DRX as a restoration mechanism in the Microstructure for the two phases of austenite and ferrite.

Zr-1 wt% Nb is extensively utilized as a structural material for fuel rod cladding in nuclear power plant reactors. The microstructural refinement of the cladding alloy in the hot manufacturing stage not only increase its mechanical properties but also influences the fuel rod's performance and integrity. In the present study, the hot compressive behavior and microstructural Evolution with the aim to identify the recrystallization mechanism type in Zr-1 wt% Nb was investigated. Hence, the hot compression test was conducted at different temperature range of 600-900 ◦C and strain rates of 0.001-1 s-1. At the hot deformation temperature of 600 ◦C, the compressive stress was monotonically increasing with straining due to the occurrence of the work-hardening mechanisms in the deformation process. At the high deformation temperatures of 700 ◦C and above, the compressive strength initially increased until it reached the peak stress, after which it gradually decreased and settled into the steady state region. Investigating the hot deformed Microstructures imply that significant grain refinement was obtained through the dynamic recrystallization occurrence. It was concluded that the continuous dynamic recrystallization and dynamic recovery were among the first softening mechanisms activated up to strains of 0.3 and then the discontinuous dynamic recrystallization completes the grain refinement in the Microstructure.

The present investigation was carried out to evaluate the application of Cloisite 30B organoclay (C30B) on the rheological, structural, electrical, and thermal characteristics of poly (methyl methacrylate)/multiwalled carbon nanotubes nanocomposites (PMMA/MWCNTs) fabricated by the simultaneous melt mixing. The Microstructure and the state of nanofillers dispersion were assessed by melt linear viscoelastic experiments, X-ray diffraction (XRD), and electron microscopy. The obtained results illustrated that the applied C30B nanofiller considerably altered the pattern of MWCNTs dispersion and reaggregation. The study of electrical properties of single filler and hybrid nanocomposites also showed that the percolation threshold almost remained intact with the addition of C30B ( c φ ~0. 18%), but an effective decrease in volume resistivity was observed at high MWCNTs loading levels. Finally, thermal analyses, employed as complementary experiments, confirmed that the MWCNTs dispersion was improved by the incorporation of C30B nanofillers. Upon the incorporation of nanofillers, a decrease in tanδ peak height and a small increase in Tg were observed. The Td, 5%, Td, 70%, and Tmax of the neat PMMA were 308, 342. 9 and 335. 2 ° C, respectively while for the PMMA-0. 5%MWCNTs-3%C30B, they stood at 314. 7, 380. 3 and 369. 2 ° C, respectively.

Microstructure Evolution and mechanical properties of Zn-22Al alloy after post-ECAP natural/artificial aging were investigated. A homogenization treatment was applied to the casting samples. In addition, after preparing the samples for the ECAP, secondary homogenization treatment was done and then the samples quenched in the water to form a fine grain structure. After 8 passes of ECAP, some ECAPed samples were naturally aged and some ECAPed samples were artificially aged. Natural aging after 8 passes of ECAP showed that Zn-22Al alloy has a quasi-stable Microstructure because limited grain growth occurred. Two-phase structure of Zn-22Al alloy prevented excessive grain growth after natural aging. On the other hand, artificial aging after 8 passes of ECAP caused a relatively much grain growth took place. In shorter times of artificial aging, the grain growth rate is faster due to the high surface energy of grain boundaries. On the contrary, as the time of artificial aging increased, the surface energy of grain boundaries decreased, which leads to a decrease in the grain growth rate. In addition, texture Evolution was studied after aging artificial. Therefore, the main texture of α and η phases was determined.

During the past decades, equal channel angular pressing has risen as a promising severe plastic deformation process and it is applied for the grain refinement and strengthening of metallic materials. Although the application of this process to improve the characteristics of austenitic stainless steels has been studied to some extent, little studies have considered the effect of route of the ECAP on this matter. This study aims to study the Evolution of Microstructure and the increase of hardness of stainless steel 316L during processing by two different routes of this process. For this purpose, the alloy is processed at the deformation temperature of 310 ° C using two different routes of A and Bc. Afterwards, the Microstructure Evolution of the alloy is studied using the X-ray diffraction and the scanning electron microscopy. Results show that the applied ECAP procedure, irrespective of the applied route, causes a negligible occurrence of the phase transformation while it causes a widespread occurrence of twinning. This fact is related to the elevated temperature applied for the process. Also, the process causes a considerable increase in the hardness of the alloy mainly attributed to the occurrence of twinning.