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Showing papers on "Texture (crystalline) published in 2015"


Journal ArticleDOI
TL;DR: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder as mentioned in this paper, showing that columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions.
Abstract: The microstructural and mechanical properties of Inconel 718 were determined on the specimens manufactured by selective laser melting (SLM) of prealloyed powder. High- density (99.8%) cylindrical specimens were built with four orientations (0°, 45°, 45°×45° and 90°) in relation to the building and scanning directions. Because of directional, dendritic-cellular grain growth, microstructure of the as-built specimens was characterized by columnar grains of supersaturated solid solution with internal microsegregation of Nb and Mo, demonstrated by fractions of Laves eutectic or its divorced form in interdendritic regions. Such a heterogeneous microstructure is unsuitable for direct post-process aging and makes the alloy sensitive to subsolidus liquation during rapid heating to the homogenizing temperature. In homogenized and aged condition, the alloy received a very good set of mechanical properties in comparison with the wrought material. In heat-treated condition, like in as-built condition, weak anisotropy of properties was found, manifested by lower Young's modulus, yield strength and tensile strength of the specimens extended along the build direction in comparison to the values for the other variants of the specimens. This is attributed to the fact that the grains maintained their geometric and crystallographic texture obtained during solidification.

512 citations


Journal ArticleDOI
TL;DR: Numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components.
Abstract: Striking differences in the solidification textures of a nickel based alloy owing to changes in laser scanning pattern during additive manufacturing are examined based on theory and experimental data Understanding and controlling texture are important because it affects mechanical and chemical properties Solidification texture depends on the local heat flow directions and competitive grain growth in one of the six preferred growth directions in face centered cubic alloys Therefore, the heat flow directions are examined for various laser beam scanning patterns based on numerical modeling of heat transfer and fluid flow in three dimensions Here we show that numerical modeling can not only provide a deeper understanding of the solidification growth patterns during the additive manufacturing, it also serves as a basis for customizing solidification textures which are important for properties and performance of components

348 citations


Journal ArticleDOI
TL;DR: In this paper, selective laser melting (SLM) was used to build up IN738LC specimens with cylinder axis (loading direction) oriented either parallel to the building direction, or perpendicular to a building direction and at 45° to the laser scanning direction.
Abstract: Nickel-based IN738LC samples were built by selective laser melting (SLM). To evaluate the anisotropic mechanical behavior of IN738LC material due to layer-wise build up, specimens were built with their cylinder axis (loading direction) oriented either parallel to the building direction, or perpendicular to the building direction and at 45° to the laser scanning direction. After building up the specimens by SLM, they were investigated either under the ‘as-built’ condition or after heat treatment and compared to IN738LC cast material. The analysis of microstructural anisotropy in SLM made IN738LC specimens was done by using EBSD, EDX and X-ray texture analysis methods, and then correlated with anisotropic material behavior observed during tensile and creep testing at room temperature and 850 °C. All SLM samples possess the same general texture, with the majority of grains forming one single component of a cube texture with one of the cubic axes parallel to the building direction, and another cubic axis parallel to the laser scanning direction. The Young׳s modulus determined during tensile testing is significantly lower parallel to the building direction than perpendicular to the building direction, with the values for cast IN738LC material in between. Creep behavior of specimens with loading parallel to the building direction is superior compared to specimens with loading axis normal to the building direction. The anisotropy of Young׳s modulus was modeled based on the single crystal elastic tensor and the measured crystallographic preferred orientations, and compares well with the data from tensile tests.

326 citations


Journal ArticleDOI
TL;DR: In this paper, the Inconel 625 alloy, a widely used material in the aerospace industry, was chosen as the build material for selective laser melting (SLM), an additive manufacturing process capable of manufacturing metallic parts with complex shapes directly from computer-aided design (CAD) models.

323 citations


Journal ArticleDOI
TL;DR: In this article, electron backscattered diffraction was used to characterize unique crystal textures formed by selective laser melting of a CoCrMo alloy, and preferred crystallographic orientations were found for individual grains in the solid alloy microstructure.

226 citations


Journal ArticleDOI
TL;DR: In this article, the authors compared the microstructure and the mechanical properties of the produced specimens, directly after the manufacturing process and additionally after two diverse heat treatments subsequent to manufacturing process.
Abstract: Selective laser melting, a quite new layer-wise manufacturing process for metals, is used for processing the nickel-based superalloy IN718 The objective of this work is to compare the microstructure and the mechanical properties of the produced specimens, directly after the manufacturing process and additionally after two diverse heat treatments subsequent to the manufacturing process As the resulting microstructure and properties for specimens manufactured by selective laser melting are directional, all investigations are made for specimens oriented vertically and horizontally Optical, scanning, and transmission electron microscopy are carried out in order to characterize the microstructure explicitly For investigating the texture of the material, additional EBSD measurements are undertaken Mechanical tests include tensile testing at room temperature and at elevated temperatures and hardness measurements The investigations reveal a very good quality of the SLM-produced specimens Nonetheless, differences in the grain sizes, the orientation, and especially in the precipitation behavior could be found

221 citations


Journal ArticleDOI
TL;DR: The microstructure evolution of a typical hexagonal close-packed (HCP) material (AZ31 magnesium alloy) during friction stir welding was studied in a wide range of welding temperatures.

145 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of surface texture on friction has been investigated experimentally for a convergent-divergent bearing, operating under different lubrication regimes, and the results suggest that pockets act to increase fluid entrainment and hence reduce any asperity contact that is present.

143 citations


Journal ArticleDOI
TL;DR: In this paper, an API X70 pipeline steel was electrochemically charged with hydrogen for different durations in order to find crack nucleation and propagation sites, and the results showed that fine grain colonies with dominant ND|| orientations were prone to intergranular HIC crack propagation.

142 citations


Journal ArticleDOI
TL;DR: Direct Cu-to-Cu bonding was achieved at temperatures of 150–250 °C using a compressive stress of 100 psi (0.69 MPa) held for 10–60 min at 10−3 torr.
Abstract: Direct Cu-to-Cu bonding was achieved at temperatures of 150–250 °C using a compressive stress of 100 psi (0.69 MPa) held for 10–60 min at 10−3 torr. The key controlling parameter for direct bonding is rapid surface diffusion on (111) surface of Cu. Instead of using (111) oriented single crystal of Cu, oriented (111) texture of extremely high degree, exceeding 90%, was fabricated using the oriented nano-twin Cu. The bonded interface between two (111) surfaces forms a twist-type grain boundary. If the grain boundary has a low angle, it has a hexagonal network of screw dislocations. Such network image was obtained by plan-view transmission electron microscopy. A simple kinetic model of surface creep is presented; and the calculated and measured time of bonding is in reasonable agreement.

123 citations


Journal ArticleDOI
TL;DR: In this paper, high-crystalline thin films of MoS2 were prepared over large area by pulsed laser deposition down to a single monolayer on Al2O3, GaN, and SiC-6H substrates.
Abstract: Highly crystalline thin films of MoS2 were prepared over large area by pulsed laser deposition down to a single monolayer on Al2O3 (0001), GaN (0001), and SiC-6H (0001) substrates. X-ray diffraction and selected area electron diffraction studies show that the films are quasi-epitaxial with good out-of-plane texture. In addition, the thin films were observed to be highly crystalline with rocking curve full width half maxima of 0.01°, smooth with a RMS roughness of 0.27 nm, and uniform in thickness based on Raman spectroscopy. From transport measurements, the as-grown films were found to be p-type.

Journal ArticleDOI
TL;DR: The gas sensing results indicate that, as compared to pure SnO2, 1 wt % W-doping improves sensitivity along with better response and recovery time toward NO2 gas at operating temperatures of ∼225 °C.
Abstract: For the first time, a new facile approach based on simple and inexpensive chemical spray pyrolysis (CSP) technique is used to deposit Tungsten (W) doped nanocrystalline SnO2 thin films. The textural, optical, structural and sensing properties are investigated by GAXRD, UV spectroscopy, FESEM, AFM, and home-built sensing setup. The gas sensing results indicate that, as compared to pure SnO2, 1 wt % W-doping improves sensitivity along with better response (<2 s) and recovery time (<25 s) toward NO2 gas at operating temperatures of ∼225 °C. The optimal composition of 1 wt % W-doped films exhibit lowest crystallite size of the order of ∼8–10 nm with reduced energy band gap and large roughness values of 3.82 eV and 3.01 nm, respectively. Reduction in texture coefficient along highly dense (110) planes with concomitant increase along loosely packed (200) planes is found to have prominent effect on gas sensing properties of W-doped films.

Journal ArticleDOI
TL;DR: A series of diketopyrrolopyrrole-based copolymers designed by implementing the concept of intramolecular noncovalent conformational locks through functionalization of polymer backbones with fluorine atoms or methoxy groups were synthesized and compared with their unfunctionalized analogue.
Abstract: Understanding the microstructures of semiconducting polymers is critical for improving the charge transport properties of polymer field-effect transistors (PFETs). A series of diketopyrrolopyrrole-based copolymers designed by implementing the concept of intramolecular noncovalent conformational locks through the functionalization of polymer backbones with fluorine atoms or methoxy groups were synthesized and compared with their unfunctionalized analogue. In contrast to the bimodal texture of the unfunctionalized polymer, the thin films of the polymer with fluorine atoms exhibit predominantly edge-on texture with much improved crystalline ordering. The thin films of the polymer modified with methoxy groups have a principally face-on texture. These dramatic differences in thin-film texture can be correlated with the polymers’ solubilities. Furthermore, the improved crystalline ordering of these semiconductor polymers enables the fabrication of high-performance PFETs: the hole mobility of the methoxy-modifie...

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the thermal effect of texture presence or absence on the bearing surface and found that the simulation results were in good concordance with those issued from the literature.

Journal ArticleDOI
23 Dec 2015
TL;DR: In this paper, the mechanical properties of GH4169 alloy sheet after cold rolling (at 0, 10, 30, 50% and 70%) and solid solution were investigated and the results showed increases in the yield strength (YS) (0.2%) as well as the ultimate tensile strength (UTS) (UTS) when rolling reduction was increased.
Abstract: The mechanical properties of GH4169 alloy sheet after cold rolling (at 0%, 10%, 30%, 50% and 70%) and solid solution were investigated. The textures and Taylor factors were characterized using electron backscattering diffraction (EBSD). The fractions of δ phase were measured by X-ray diffraction. The contributions of δ phase, grain size, texture, and work hardening on the mechanical properties were also discussed. The results showed increases in the yield strength (YS) (0.2%) as well as the ultimate tensile strength (UTS) of GH4169 superalloy sheet after cold rolling, when rolling reduction was increased. In contrast, following solid solution treatment, YS and UTS were increased then subsequently decreased. The changes of yield strength of GH4169 superalloy were attributed to the texture and work hardening, followed by the grain refinement and precipitation of δ phase. When the rolling reduction was below 30%, the influence of δ phase was greater than grain refinement and when the rolling reduction was larger than 50%, the controversial results occur. The precipitation of δ phase promoted the improvement of yield strength, the relationship between the fraction of δ phase and improved yield strength satisfactory fit to the following equation: σδ = 15.9Wδ + 59.7.

Journal ArticleDOI
TL;DR: In this paper, the electron beam melting (EBM) process is used to control the crystallographic texture of Inconel 718 deposits, which can be used to create complex geometric components with both site-specific microstructures and material properties.
Abstract: Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits or fully equiaxed deposits. This research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.

Journal ArticleDOI
TL;DR: The 2D Tl-Pb compound on Si(111) is believed to be the prototypical object for prospective studies of intriguing properties of the superconducting 2D system with lifted spin degeneracy, bearing in mind that its composition, atomic and electron band structures, and spin texture are already well established.
Abstract: A one-atom-layer compound made of one monolayer of Tl and one-third monolayer of Pb on a Si(111) surface having √3×√3 periodicity was found to exhibit a giant Rashba-type spin splitting of metallic surface-state bands together with two-dimensional superconducting transport properties. Temperature-dependent angle-resolved photoelectron spectroscopy revealed an enhanced electron-phonon coupling for one of the spin-split bands. In situ micro-four-point-probe conductivity measurements with and without magnetic field demonstrated that the (Tl, Pb)/Si(111) system transformed into the superconducting state at 2.25 K, followed by the Berezinskii-Kosterlitz-Thouless mechanism. The 2D Tl-Pb compound on Si(111) is believed to be the prototypical object for prospective studies of intriguing properties of the superconducting 2D system with lifted spin degeneracy, bearing in mind that its composition, atomic and electron band structures, and spin texture are already well established.

Journal ArticleDOI
TL;DR: In this article, the effect of Ca addition on the mechanical properties and texture characteristics of Mg sheets was evaluated in hot extrusion for the purpose of evaluating their effect on texture and mechanical properties, and the reduction of c/a ratio and decrease of SFE may be responsible for the texture weakening of Ca-containing alloys.
Abstract: Five Mg alloys, Mg–2Zn, Mg–0.5RE, Mg–0.5Ca, Mg–2Zn–0.5Ca and Mg–2Zn–0.5RE (wt%), were subjected to hot extrusion for the purpose of evaluating the effect of Ca addition on the mechanical properties and texture characteristics of Mg sheets. Ca addition to pure Mg and Mg–Zn alloys contributes to the texture weakening of extruded sheets. The ductility increase through the addition of Ca to Mg is related to the texture weakening of extruded Ca-containing alloys. The enhancement of extrusion temperature leads to a broader spread of basal poles toward TD, but a strengthened texture intensity. The reduction of c/a ratio and the decrease of SFE may be responsible for the texture weakening of Ca-containing alloys.

Journal ArticleDOI
TL;DR: In this article, the Mg-3.0Zn-0.2Ca (wt.%) alloy has been extruded at temperature range of 25-300°C and the resulting microstructure, texture and mechanical properties are systematically investigated.

Journal ArticleDOI
TL;DR: In this paper, multidirectional forging was applied to severely deform the homogenized coarse-grained Mg-Gd-Y-Nd-Zr alloy under decreasing temperature condition, and the microstructure, texture and tensile properties of the MDFed alloy were investigated.

Journal ArticleDOI
TL;DR: An ultra-high strength and high ductility Mg-8.2Gd-3.8Y-1.4Zr alloy sheet was fabricated by vertical direct chill casting, extrusion, hot rolling and peak-ageing treatment as mentioned in this paper.
Abstract: An ultra-high strength and high ductility Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr Mg alloy sheet was fabricated by vertical direct chill casting, extrusion, hot rolling and peak-ageing treatment. The peak-aged sheet shows tensile yield strength of 416 MPa, ultimate tensile strength of 505 MPa and superior elongation to failure of 12.8% at ambient temperature. The remarkable improvement of strength is ascribed to the fine β′ phase precipitated within the grains, grains with strong basal texture and the dispersed long period stacking ordered (LPSO) phases located at the grain boundaries.

Journal ArticleDOI
23 Jun 2015-ACS Nano
TL;DR: The developed fine-tuning of crystal orientation having a huge impact on the photoefficiency would induce further improvement of thin hematite films mainly if cation doping will be combined with the controllable texture.
Abstract: Hematite, α-Fe2O3, is considered as one of the most promising materials for sustainable hydrogen production via photoelectrochemical water splitting with a theoretical solar-to-hydrogen efficiency of 17%. However, the poor electrical conductivity of hematite is a substantial limitation reducing its efficiency in real experimental conditions. Despite of computing models suggesting that the electrical conductivity is extremely anisotropic, revealing up to 4 orders of magnitude higher electron transport with conduction along the (110) hematite crystal plane, synthetic approaches allowing the sole growth in that direction have not been reported yet. Here, we present a strategy for controlling the crystal orientation of very thin hematite films by adjusting energy of ion flux during advanced pulsed reactive magnetron sputtering technique. The texture and effect of the deposition mode on the film properties were monitored by XRD, conversion electron Mossbauer spectroscopy, XPS, SEM, AFM, PEC water splitting, IPCE, transient photocurrent measurements, and Mott-Schottky analysis. The precise control of the synthetic conditions allowed to fabricate hematite photoanodes exhibiting fully textured structures along (110) and (104) crystal planes with huge differences in photocurrents of 0.65 and 0.02 mA cm(-2) (both at 1.55 V versus RHE), respectively. The photocurrent registered for fully textured (110) film is among record values reported for thin planar films. Moreover, the developed fine-tuning of crystal orientation having a huge impact on the photoefficiency would induce further improvement of thin hematite films mainly if cation doping will be combined with the controllable texture.

Journal ArticleDOI
TL;DR: In this paper, a non-destructive in-situ measurement of 3D microstructure evolution of 99.995 % pure polycrystalline copper during tensile loading using synchrotron radiation is presented.

Journal ArticleDOI
TL;DR: The interfacial spin mixing conductance is significantly enhanced in structures where both cobalt and iridium have fcc(111) structure in comparison to those where the cobalt layer has subtly different hcp(0001) texture at the interface.
Abstract: Enhancement of Gilbert damping in polycrystalline cobalt thin-film multilayers of various thicknesses, overlayered with copper or iridium, was studied in order to understand the role of local interface structure in spin pumping. X-ray diffraction indicates that cobalt films less than 6 nm thick have strong fcc(111) texture while thicker films are dominated by hcp(0001) structure. The intrinsic damping for cobalt thicknesses above 6 nm is weakly dependent on cobalt thickness for both overlayer materials, and below 6 nm the iridium overlayers show higher damping enhancement compared to copper overlayers, as expected due to spin pumping. The interfacial spin mixing conductance is significantly enhanced in structures where both cobalt and iridium have fcc(111) structure in comparison to those where the cobalt layer has subtly different hcp(0001) texture at the interface.

Journal ArticleDOI
TL;DR: This work explores how drainage due to gravity or due to an external flow can be prevented through the use of chemical patterning, which involves a small area of the overall surface being chemically treated to be preferentially wetted by the external fluid rather than the infused liquid.
Abstract: Liquid-infused surfaces display advantageous properties that are normally associated with conventional gas-cushioned superhydrophobic surfaces. However, the surfaces can lose their novel properties if the infused liquid drains from the surface. We explore how drainage due to gravity or due to an external flow can be prevented through the use of chemical patterning. A small area of the overall surface is chemically treated to be preferentially wetted by the external fluid rather than the infused liquid. These sacrificial regions disrupt the continuity of the infused liquid, thereby preventing the liquid from draining from the texture. If the regions are patterned with the correct periodicity, drainage can be prevented entirely. The chemical patterns are created using spray-coating or deep-UV exposure, two facile techniques that are scalable to generate large-scale failure-resistant surfaces.

Journal ArticleDOI
TL;DR: In this article, the role of strain gradient and deformation compatibility in the plasticity of magnesium alloys was studied in three-point bending with in-situ electron backscatter diffraction (EBSD) observations, and the results indicate that strain gradients in macro-scale from tension to compression can lead to a graded microstructure and texture evolution in the samples during bending.

Journal ArticleDOI
TL;DR: In this paper, the mechanical responses and deformation mechanisms of AZ31 Mg alloy sheets were studied under dynamic (tension and compression) and simple shear deformations along different in-plane loading directions.

Journal ArticleDOI
TL;DR: In this article, the effect of the shape and size of the texture on the tool rake face on the impact of tool feature parameters on the cutting forces has been analyzed and the maximum reduction of 28 % was predicted in the effective coefficient of friction compared to the non-textured surface.
Abstract: Literature survey showed that the micro-textures on the tool rake face can help in reduction in friction at chip-tool interface and therefore, reduction in the cutting forces. Consequently, the current work is based on FE simulation of hard turning of bearing steel (AISI52100). Four types of micro-textures have been considered on the tool rake face: non-texture, perpendicular, parallel, and rectangle. Johnson-Cook (J-C) material constitutive law has been considered for the workpiece with temperature-dependent material properties. Experimental work has been performed at cutting conditions: type, parallel; edge distance, 0.195 mm; pitch size, 0.110 mm; and height of the texture, 0.049 mm to validate the current machining model. Parametric study of effect of tool feature parameters on the cutting forces has been performed. Based on the current model, it is observed that the perpendicular shape showed the minimum cutting force. The maximum reduction of 28 % was predicted in the effective coefficient of friction compared to the non-textured surface. Additionally, effect of size of the texture (edge distance, pitch size, texture height) and the friction factor at tool-chip interface on the process responses is predicted. The perpendicular texture at an edge distance of 100 μm, pitch size of 100 μm, and texture height of 50 μm showed the most effective shape and size for the minimum cutting forces and effective friction. It is simulated that the chip flow angle can be governed by the shape/size of the texture on the tool rake face. It is expected that the current model can further be helpful in the characterization of other hard materials and complex texture shape/size.

Journal ArticleDOI
TL;DR: In this article, a detailed study of the characterization of laser-surface textured titanium alloy (Ti-6Al-4V) with line and dimple geometry developed by using an ArF excimer laser operating at a wavelength of 193nm with a pulse length of 5 nns is undertaken.

Journal ArticleDOI
Bin Wang1, Bo-bo Lei1, Jia-xiang Zhu1, Quan Feng1, Liang Wang1, Wu Deng1 
TL;DR: Friction stir welded AA5052-O and AA6061-T6 dissimilar joint has a more obvious impact on microstructure and texture evolution compared to single material welding due to differences in physical and chemical parameters between two aluminum alloys as mentioned in this paper.