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Effect of build geometry and orientation on microstructure and properties of additively manufactured 316L stainless steel by laser metal deposition
摘要： The effect of build geometry and orientation on the microstructure and mechanical properties of additively manufactured AISI 316L stainless steel was studied. For this an integrated laser metal deposition system was used to build two test blocks, Block 1 and Block 2, such that Block 1 had its longest dimension parallel to the build direction while Block 2 had its longest dimension perpendicular to the build direction. Samples with different orientations with respect to the build direction were extracted from the two blocks and characterized in detail. Block 1 was found to have a coarser defect-free microstructure, while Block 2 had a finer microstructure with extensive inter-track/layer defects. The yield strengths and tensile strengths of Block 2 samples were higher than Block 1 samples, but their strain hardening capacities and ductility values were lower. These differences in microstructure and mechanical properties were shown to be an outcome of the different build rates and consequent thermal histories of the two blocks. In order to explain the variation of yield strength with sample orientation, an alternate measure for grain size called “effective grain size” was introduced, which revealed the effect of grain orientation on the mean free path for dislocation motion and hence yield/flow stress. Variation of yield strength with the effective grain size was found to follow Hall-Petch behaviour.
关键词： Anisotropy,Additive Manufacturing,Grain Size,Tensile Behaviour,Orientation
更新于2025-11-28 14:24:20
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The effect of build orientation on the microstructure and properties of selective laser melting Ti-6Al-4V for removable partial denture clasps
摘要： Statement of problem. Selective laser melting (SLM) Ti-6Al-4V has been used for removable partial dentures, but the impact of SLM Ti-6Al-4V build orientation is not evident. Purpose. The purpose of this in vitro study was to investigate the microstructure and properties of SLM Ti-6Al-4V clasps with different build orientations compared with cast Ti-6Al-4V clasps. Material and methods. Forty-eight clasps were made from Ti-6Al-4V alloys by SLM with 3 different build orientations (SLM0, SLM45, and SLM90) and cast (CAST) as a control. The microstructure was investigated by using a metallographic microscope and a confocal laser scanning microscope. The fit and surface roughness of the clasps were measured, and the physical properties were evaluated. In addition, the von Mises stresses in the clasps were calculated by finite element analysis. All specimens were then subjected to insertion and removal tests in artificial saliva to model 5 years of clinical use. After these tests, 3-point bend tests were used to analyze the fracture surface of the clasp arms, which were observed by using a scanning electron microscope. All data were statistically analyzed (a=.05). Results. The microstructure of the Ti-6Al-4V specimens was a comixture of a+b phases. In addition, growth directions of b grains were approximately parallel to the build orientation, with acicular a grains present between b grains. SLM0 and SLM45 had significantly higher roughness than SLM90. Even though the fit was inferior to that of SLM90, SLM0 and SLM45 still performed better than cast specimens (P<.05). The finite element analysis showed that the maximum von Mises stress was located on the middle part of the retainer arms and that the values of the 0.50-mm undercut clasps were much lower than the elastic limit. In addition, the decrease of retentive force in SLM90 clasps was less than that of the CAST group (P<.05). CAST clasps showed brittle fracture, whereas all SLM clasps showed ductile fracture. Conclusions. The microstructure of SLM Ti-6Al-4V affected the properties of clasps by changing the anisotropy of specimens. Among the tested groups, SLM90 clasps had the best fit, the lowest surface roughness, and the best fatigue resistance. Furthermore, SLM Ti-6Al-4V clasps could be engaged into 0.50-mm undercuts.
关键词： Selective laser melting,Ti-6Al-4V,build orientation,removable partial denture clasps,properties,microstructure
更新于2025-11-21 11:08:12
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Defect dipole evolution and its impact on the ferroelectric properties of Fe-doped KTN single crystals
摘要： The ferroelectric and piezoelectric properties of doped potassium tantalum niobate crystals with different Fe doping amounts and the adjustability of the properties are investigated. The hysteresis loops and current density curves show that the defect dipoles have an obvious effect on domain reorientation, and the effect decreases with increasing doping amount. The ferroelectric and piezoelectric properties can be adjusted via the defect dipoles, and the adjustability is reduced with increasing doping amount. A change of the doping amount leads to defect dipole structure evolution in the crystals, in which the defect dipoles transform from a polar structure to a nonpolar structure, which is the reason for the transition of the domain reorientation determined by the defect dipoles. This result has proved that introducing defects is an effective way to improve and regulate perovskite properties, and the doping amount is one of the important factors controlling the defect dipoles.
关键词： Ferroelectric,domain orientation mechanism,defect dipoles,doping behavior
更新于2025-11-14 17:28:48
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Preparation of high-quality stress-free (001) aluminum nitride thin film using a dual Kaufman ion-beam source setup
摘要： We proposed and demonstrated a preparation method of (001) preferentially oriented stress-free AlN piezoelectric thin films. The AlN thin films were deposited by a reactive sputtering technique at substrate temperatures up to 330 °C using a dual Kaufman ion-beam source setup. We deposited the AlN on Si (100), Si (111), amorphous SiO2, and a (001) preferentially oriented Ti thin film and compared their crystallographic, optical, and piezoelectric properties. The AlN thin films deposited on the (001) preferentially oriented Ti thin films have the highest crystallographic quality. The stress-free AlN reached a high value of the piezoelectric coefficient d33 = (7.33 ± 0.08) pC·N?1. The properties of the AlN thin film prepared at such low temperatures are suitable for numerous microelectromechanical systems, piezoelectric sensors, and actuators monolithically integrated with complementary metal-oxide-semiconductor signal-processing circuits.
关键词： Ellipsometry,Aluminum nitride thin film,Optical properties,d33 piezoelectric coefficient,Kaufman ion-beam source,Ion-beam sputtering deposition,(001) preferential orientation,X-ray diffraction
更新于2025-09-23 15:23:52
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Optimal synthesis of antimony-doped cuprous oxides for photoelectrochemical applications
摘要： We investigated the influence of Sb dopant concentration on the structural, electrical, and photoelectrochemical properties of the photocathode cuprous oxide (Cu2O) thin films. The photoabsorber p-type Cu2O films were prepared by electrodeposition in ionic electrolytes including copper sulfate and antimony sulfate at 333 K and pH=10. The small amount of Sb doping contributes to the fast Cu ion transport to the substrate and ion consumption; consequently, the p-type Cu2O with high crystalline quality can be reproducibly synthesized with high electrical stability. Among the various samples, the mole fraction of c(Sb)/[c(Cu)+c(Sb)] = 0.75 mol % exhibits the best electrical resistivity and improved transparency in the infrared region, which is involved with the fast overlap of the nuclei crystals under 5 nm from the high nuclei density. Additionally, the post-thermal annealed Sb-doped Cu2O sample reveals an enhanced photocurrent of ~0.65 mA/cm2 vs. RHE (reversible hydrogen electrode) without metal catalysts.
关键词： Preferred orientation,Post annealing,Antimony doping,Photoelectrochemical cell,Cuprous oxide
更新于2025-09-23 15:23:52
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New blue phosphorescence from trifluorosulfonyl-substituted iridium complexes
摘要： For color-pure phosphorescence organic light emitting diodes (PHOLEDs), we synthesized the trifluoromethyl sulfonyl substituted ligand and two new blue Iridium complexes with perfluoro-sulfonyl group (SOCF3pic and SOCF3mpic). The both iridium complexes showed similar photophysical and thermal properties while the HOMO energy leves of two Iridium complexes slightly differnet to be -5.84 eV for SOCF3pic and -5.74 eV for SOCF3mpic, respectively. The device with the SOCF3mpic dopant exhibited higher device efficiencies of 7.17 cd/A and 3.7 % compared to that with the SOCF3pic dopant (4.03 cd/A and 2.78 %). Two-dimensional GIXD images of scattered X-ray intensity from surface to full depth for SOCF3pic-doped and SOCF3mpic-doped TCTA:4PTPS films were characterized for preferential orientation along the out-of-plane direction.
关键词： preferential orientation along the out-of-plane direction,blue phosphorescence,iridium complex,grazing incidence wide-angle X-ray diffraction,organic light emitting diodes
更新于2025-09-23 15:23:52
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Millimeter-Scale Growth of Single-Oriented Graphene on a Palladium Silicide Amorphous Film
摘要： It is widely accepted in condensed matter physics and material science communities that a single-oriented overlayer cannot be grown on an amorphous substrate because the disordered substrate randomizes the orientation of the seeds, leading to polycrystalline grains. In the case of two-dimensional materials such as graphene, the large-scale growth of single-oriented materials on an amorphous substrate has remained unsolved. Here, we demonstrate experimentally that the presence of uniformly oriented graphene seeds facilitates the growth of millimeter-scale single-oriented graphene with 3×4 mm2 on palladium silicide, which is an amorphous thin film, where the uniformly oriented graphene seeds were epitaxially grown. The amorphous palladium silicide film promotes the growth of the single-oriented growth of graphene by causing carbon atoms to be diffusive and mobile within and on the substrate. In contrast to these results, without the uniformly oriented seeds, the amorphous substrate leads to the growth of polycrystalline graphene grains. This millimeter-scale single-oriented growth from uniformly oriented seeds can be applied to other amorphous substrates.
关键词： silicon carbide,amorphous substrate,single orientation,graphene,palladium silicide
更新于2025-09-23 15:23:52
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Accuracy and reliability evaluation of 3D-LS for the discontinuity orientation identification with different registration/georeferencing modes
摘要： With the aid of three-dimensional laser scanning (3D-LS), a lot of geometric properties of rock discontinuities can be derived from the point cloud data. Due to the complexity of registration and georeferencing of multi-station point data, geological engineers tend to simplify processing by using single-station point data and orienting coarsely. However, there is a lack of accuracy and reliability study in the identification of discontinuity orientations with 3D-LS using different registration/georeferencing modes. In this study, the single-station scanning without registration/georeferencing was applied first to examine the accuracy and reliability of the scanner’s built-in direction system. After that, two types of automated registration/georeferencing modes were examined for the accuracy in rock mass discontinuity analysis. The results show that the dip angle measured by the scanner’s built-in directional system is reliable, accurate and can meet engineering requirements, while the dip direction measured by the scanner’s built-in directional system is unreliable and inaccurate. The dip direction is consistent but inaccurate through the semi-automated registration using natural point features and georeferencing by the scanner’s built-in directional system. Only through real-time kinematic (RTK) registration/georeferencing can the dip direction be reliable and accurate. It is observed that orientations captured by 3D-LS can be more accurate with RTK registration/georeferencing than manual survey.
关键词： orientation,3D laser scanning,rock discontinuities,georeferencing,registration
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Kiev (2018.7.2-2018.7.5)] 2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) - Referencing of U A V Images Using the Nelder-Mead Method
摘要： The paper analyses the existing methods of images coordinate referencing using approximating functions and the classical methods for restoring elements of external orientation. It reveals that those methods do not take into account the peculiarities of the images received from unmanned aerial vehicles. The paper investigates the possibility of using Nelder-Mead simplex method instead. To define the elements of external orientation the angles of external orientation were taken for the independent variables. The spatial position was calculated on the basis of angles and given reference points.
关键词： elements of external orientation,Nelder-Mead simplex algorithm,Images coordinate referencing,approximating functions,triangulation net
更新于2025-09-23 15:23:52
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[IEEE 2018 24th International Conference on Pattern Recognition (ICPR) - Beijing, China (2018.8.20-2018.8.24)] 2018 24th International Conference on Pattern Recognition (ICPR) - Scale and Orientation Aware EPI-Patch Learning for Light Field Depth Estimation
摘要： Epipolar Plane Image (EPI) implies some important depth cues for light field depth estimation. Intuitively, the EPI patches with different spatial scales and orientations may exhibit different features and result in different estimation precision. In this paper, we discuss this issue and present a scale and orientation aware EPI-Patch learning model for depth estimation. We take the multi-orientation EPI patches of each pixel as input, and design two types of network structures for adaptive scale selection and orientation fusion. One type is a scale-aware structure, which feeds one orientation patch into a multi-layer feed-forward network with long and short skip connections. The other type is a shared-weight network for fusing the multi-orientation features. We demonstrate the effectiveness of our model by experiments on 4D Light Field Benchmark.
关键词： scale-aware,orientation-aware,depth estimation,deep learning,EPI,light field
更新于2025-09-23 15:23:52