Papers by Keyword: Texture

Abstract: This study reviewed the synthesis of Titania with different shapes in the presence of cetyltrimethylammonium chloride (CTAC) as the famous stabilizer for directly altering the morphology and dimensions. These CTAC stabilizers usually provide the synthesis of Titania with a narrow size distribution and mostly single-crystalline structures in high yields. Many papers on the synthesis of Titania are available. However, only a few articles focus on the synthesis of Titania using CTAC as the stabilizer. The general rule for the shape transformation of Titania by CTAC stabilizer can be easily summarized based on the literature during the last ten year from https://www.sciencedirect.com/ as the data source.

Abstract: Better use of material and energy resources is fundamental in any human activity. Finding better and more sustainable solutions might be inspired by nature herself. The natural evolution of life has shown a successful testing path of sustainable solutions that can be the inspiring starting point for engineering and manufacturing new directions of continuous improvement. This is the role that biomimicry can play. Evolution has been continuously testing this end, thriving strategies with better optimization in its yield. Keeping nature at the center of every design process will lead in the right direction. This is the role that biomimicry can play. Biomimicry or bioinspiration makes the most of the following methodologies: observing how evolution has achieved efficient strategies in any field of interest and realizing how to implement them or having a problem to solve and searching in Nature to find guidance or inspiration to succeed. Through a systematic review of some of the latest developments in manufacturing, focused on their capability to approach (mimic) natural textures; some applications are characterized and tested successfully to reduce energy consumption, improve efficiency, or reduce friction, among other potential improvements. In nature, actual surfaces present a functional texture. Natural evolution has developed textures showing real advantages for different functional purposes. Analyzing those natural surfaces can improve engineering surfaces’ qualitative and quantitative design. A correlation between scales, manufacturing processes, and natural strategies (surface features) will help map new product and engineering design areas of interest. This paper explores these correlations of natural surfaces with functional characteristics that make them sustainable and appropriate for inspiring research directions in manufacturing engineering surfaces. It mainly looks for contributions to efficient energy use in engineered solutions.

Abstract: A laser powder bed fusion (LPBF) of M789 ally steel has been carried out using an EOS M290 machine. The ideal orientations of M789 alloy were established using an electron backscatter diffraction (EBSD) technique. The analysis through ideal orientation and ODF analysis pointed out that as the heat treatment temperature is increased, the texture becomes strong. Analysis done through recrystallization map concluded that as the heat treatment temperature increases, the recrystallized grains increase which clearly explains the reason for strong texture at high temperature heat treatment. The results from this work can be used to control the texture of the M789 alloy to improve various physical and mechanical properties of the material.

Abstract: The microstructure, texture, and tensile properties of hot extruded Mg-6Zn-1Y-1Ce alloy obtained at a temperature range of 300 °C to 400 °C were studied. Electron back-scatter diffraction (EBSD) results revealed that strong basal plane texture was found along extrusion direction in the sample extruded below 340 °C due to discontinuous dynamic recrystallization (DRX) mechanism. In the sample extruded at 340 °C the average value of Schmid factor (SF) of {0001}〈11-20〉 slip system was 0.09. However, the sample extruded above 370 °C had weak basal texture under the control of continuous DRX mechanism, and the SF was well-distributed with an average value of about 0.32. The strengths of as-extruded samples decreased with increase of extrusion temperatures. In addition to fine grain strengthening, texture strengthening had a significant contribution to the high strength for the sample extruded at low temperature.

Abstract: A major challenge in forming polycrystalline aluminum alloy sheets is their strong plastic anisotropy, namely the flow stresses and plastic strains depend on the loading direction. This plastic anisotropy is due to the anisotropy of the constituent crystals and the preferred orientations that they assume in the polycrystalline material i.e. crystallographic texture. Recently, in [1] we developed a single-crystal yield criterion that involves the correct number of anisotropy coefficients such as to satisfy the intrinsic symmetries of the constituent crystals and the condition of yielding insensitivity to hydrostatic pressure. This single-crystal criterion is defined for any stress state. It is shown that a polycrystalline model that uses this single-crystal criterion in conjunction with appropriate homogenization procedures leads to an improved prediction of the plastic anisotropy in macroscopic properties under uniaxial tension and shear loadings for polycrystalline aluminum alloy 6016-T4. Moreover, results of FE simulations of cup forming operations demonstrate the predictive capabilities of this polycrystalline model.

Abstract: Viscoplastic self-consistent (VPSC) modeling was used for investigating the deformation behavior of commercial EN AW-7075-T651 aluminum alloy at room temperature under quasi-static tension and compression (i) parallel, (ii) diagonal and (iii) transverse to the rolling direction. Textures of the as-received plate and of the samples after tensile and compression testing were determined using electron backscatter diffraction (EBSD). Euler angles and area fractions of the grains were used as input for calculating direction-dependent flow curves and pole figures of the deformed material. The coefficients of the integrated Voce strain hardening law were adjusted in order to fit the calculated flow curves to flow curves obtained from tensile and compression testing. Pole figures calculated with the VPSC modeling method were validated with pole figures obtained from EBSD analysis of deformed samples. VPSC modeling was successfully applied for predicting the general deformation behavior of EN AW-7075-T651 under both tension and compression. However, texture evolution during tensile testing was negligible, whereas notable texture evolution during compression testing occurred beyond a critical strain value.

Abstract: Ultrasonic Vibration-Assisted Machining (UVAM) has been investigated as one of the most suitable methods to imprint patterns on metal surfaces. Actually, UVAM, as a consequence of the superimposition of a high-frequency and small-amplitude vibration to the cutting tool motion, makes possible the generation of micro-textured surfaces. On the basis of the vibration pattern and parameters, cutting process and tool characteristics, micro-dimples of different morphology and dimension can be obtained. However, the literature review has evidenced that none of the available studies considered the influence of the cooling conditions as well as the workpiece material on the obtainable dimples geometry. To this aim an UVAM experimental campaign was carried out at varying cutting speed, workpiece material and cooling conditions. Then, the surface finish was evaluated in terms of dimples size and surface roughness. Experimental results showed that deeper dimples are obtained for materials characterized by higher elastic modulus and machined under cryogenic cooling.

Abstract: Macro-, microstructural, fine structure, phase composition, texture and complex of physical and mechanical properties in titanium alloy VT23 (Ti-5.5Al-4.7V-2.5Mo-1.1Cr-0.7Fe, wt. %) tube were studded by the macroanalysis, optical and transmission microscopy, X-ray phase analysis, durometry and microindentation methods. A close relationship between the structural-textural-phase state formed during the extrusion and the obtained level of strength, plastic, durometric properties and the contact modulus of elasticity in a hot-extruded tube has been established.

Abstract: The article investigates the effect of the strain rate on the driving force of recrystallization during hot working of the as-cast structure. For the study, we applied previously obtained experimental data of recrystallization kinetics during this stage of thermomechanical treatment. In addition, hot laboratory rolling, followed by saltpeter bath soaking, were performed in order to obtain supplemental data on grain structure size and orientations. Grain structure size was examined by optical microscopy, and its orientation was examined by X-ray texture analysis. The studies demonstrated, that overestimated recrystallization driving force not only results in erroneous kinetics estimation, but also gives excessive number of recrystallization centers and undersized grain structure. Besides, unaccounted effect of recrystallization driving force on grain size leads to distorted predictions of texture composition. In order to avoid this, it was recommended to apply an special exponential accumulated strain dependent coefficient.

Abstract: In recent years, the IC (integrated circuit) industry has developed rapidly and the chip process technology has developed in the direction of higher density. Because of its good chemical stability, tantalum is used as a sputtering coating material for the diffusion barrier in the copper interconnect process. The uniform microstructure of the tantalum target directly affects the sputtering performance. The fabrication of high-quality thin films requires the tantalum target to have fine and uniform crystal grains and random grain orientation distribution. However, due to the characteristics of tantalum, it is easy to form a microstructure with {100} (<100>//ND) orientation on the surface and {111} (<111>//ND) orientation on the core during cold working. During the fabrication of thin films, the sputtering rate varies with the thickness of the target, which affects the sputtering stability. To provide ideas for improving the uniformity of the microstructure of the tantalum target, this article reviews the preparation processes that affect the grain orientation and size of the high-purity tantalum target, including forging methods, rolling methods, recrystallization annealing, etc., analyze the law of texture evolution of tantalum and introduction the research status of cold working and recrystallization.