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Journal articles on the topic 'Microstructure defects'

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Author: Grafiati
Published: 30 May 2022
Last updated: 31 May 2022

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1

Chen, Xiao Hui, and Xiao Jun Liu. "Automatic Inspection of Typical Microstructure Defects Based on Image Processing Techniques." Applied Mechanics and Materials 44-47 (December 2010): 2622–26. http://dx.doi.org/10.4028/www.scientific.net/amm.44-47.2622.

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Micro-structural defects influence the performance of MEMS devices. For effective quality monitoring and assurance in mass-production of MEMS devices, it is necessary to conduct automatic defect inspection. In this paper, an approach based on image processing for automatic microstructure defect inspection is presented. In the approach, an Influence Region Template is built based on a reference microstructure image while it preserves the framework and restrains the tiny distortion of the reference, then the test microstructure image is compared with the Influencing Region Template for quality evaluation. By the approach, typical defects such as blocks in trenches or channels, transfixions between trenches or channels and missing of some part and so on, are detected and classified automatically, while some distortions which do not affect the function of the microstructures are ignored. Testing results show that the approach can conduct a high quality assurance while it can endure a given distortion tolerance of microstructures.
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2

Murr, L. E. "Microstructure-property hypermaps for shock-loaded materials." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 416–19. http://dx.doi.org/10.1017/s0424820100143675.

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Residual deformation-induced metallurgical effects or structure (microstructure)-property relationships are now generally well documented to be the result of stress or strain-induced microstructures, or microstructural changes in polycrystalline metals and alloys. In many cases, strain hardening, work hardening, or other controlling deformation mechanisms can be described by the generation, movement, and interactions of dislocations and other crystal defects which produce drag, or a range of impedances, including obstacles to dislocation motion.
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3

Wu, Fan. "Microstructure and Defect Study in Thin Film Heterostructure Materials." Nanoscience & Nanotechnology-Asia 10, no. 2 (February 25, 2020): 109–16. http://dx.doi.org/10.2174/2210681208666181008143408.

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Deformation twins and phase interface are important planar defects and microstructures that greatly influence the overall performance of a material system. In multi-layer thin-film heterostructures, their effect is more manifest due to the small dimension of thin films and their influence on the growth of multi-layer structures. This article reviews the recent progress in microstructure and defects observed in thin film heterostructures, serving as a guideline for future research in this field. The multilayer thin-film heterostructures studied here were grown by pulsed laser deposition technique. Microstructures and defects were investigated by Transmission Electron Microscopy.
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4

Selyshchev, Pavlo, and V. Sugakov. "Nanoscale Modulation of Material Properties by Means of Irradiation." Key Engineering Materials 708 (September 2016): 30–34. http://dx.doi.org/10.4028/www.scientific.net/kem.708.30.

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A theoretical approach is developed to describe creation of space-periodical modulation of microstructure by means irradiation and influence of this modulation on properties of the irradiated material. It has considered nonlinear dynamics of development of radiation-induced defects. The structure of defects drives microstructure and changes material properties. It is found that nanoscale space-periodical distribution is results of interaction of radiation-induced defects both with each other and with elements of microstructure. It is shown that homogenous defect distribution become instable and bifurcation happen with respect to development of space-periodical distribution. Thus change of microstructure and material properties become space-periodical. Period of inhomogeneity and bifurcation values of parameters have been obtained.
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5

Szpunar, Jerzy A., and Bae Kyun Kim. "High Temperature Oxidation of Steel; New Description of Structure and Properties of Oxide." Materials Science Forum 539-543 (March 2007): 223–27. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.223.

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The quality of steel sheets is strongly affected by the surface defects that can be generated during hot rolling and are often related to scales removal operation. These defects are related to rather complex high temperature oxidation processes. In order to reduce an occurrence of the defects, it is necessary to understand better the formation of iron oxides during high temperature oxidation, the structure of the interfaces with the substrate and between different oxide phases. However, due to the lack of good experimental research tools details of iron oxide microstructures were not investigated. Conventional methods, such as backscattered electron images or fractography can only provide general characteristics of microstructures like grain morphology and grain size. In this paper the microstructure, phase distribution and texture in oxide formed during high temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can be used to distinguish grains having different phase composition and orientation and can become invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide defects. The three different iron oxides phases can be distinguished and the characteristics of oxides with different oxidation histories compared The characteristics of high temperature oxidation microstructure of iron are presented with description of iron oxide defects and cracking as well as the illustration of the interfacial microstructure between the layered iron oxides.
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6

YEOM, JONG-TAEK, JEOUNG HAN KIM, JAE-KEUN HONG, NHO-KWANG PARK, and CHONG SOO LEE. "INFLUENCE OF INITIAL MICROSTRUCTURE ON HOT WORKABILITY OF Ti-6Al-4V ALLOY." International Journal of Modern Physics B 23, no. 06n07 (March 20, 2009): 808–13. http://dx.doi.org/10.1142/s0217979209060063.

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Hot workability of Ti -6 Al -4 V alloy with different initial microstructures was investigated by considering processing maps and the dynamic material deformation behavior. The emphasis has been focused on the effect of initial microstructure (equiaxed versus bimodal structure). Process maps were generated using the dynamic material model (DMM), unifying the relationships between constitutive deformation behavior, hot workability and microstructures evolution. Also, the flow instability was investigated using the various flow instability criteria and microstructural analysis. To establish the processing maps with different initial microstructures, high temperature compression tests were carried out at various temperatures and strain rates up to a true strain of 0.7. Microstructural changes occurring during the deformation were analyzed in terms of high temperature deformation mechanisms. Finally the useful instability criterion for predicting the forming defects was suggested through the compression test results with different temperatures and strain rates.
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7

Choudhury, Amitava, Snehanshu Pal, Ruchira Naskar, and Amitava Basumallick. "Computer vision approach for phase identification from steel microstructure." Engineering Computations 36, no. 6 (July 8, 2019): 1913–33. http://dx.doi.org/10.1108/ec-11-2018-0498.

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PurposeThe purpose of this paper is to develop an automated phase segmentation model from complex microstructure. The mechanical and physical properties of metals and alloys are influenced by their microstructure, and therefore the investigation of microstructure is essential. Coexistence of random or sometimes patterned distribution of different microstructural features such as phase, grains and defects makes microstructure highly complex, and accordingly identification or recognition of individual phase, grains and defects within a microstructure is difficult.Design/methodology/approachIn this perspective, computer vision and image processing techniques are effective to help in understanding and proper interpretation of microscopic image. Microstructure-based image processing mainly focuses on image segmentation, boundary detection and grain size approximation. In this paper, a new approach is presented for automated phase segmentation from 2D microstructure images. The benefit of the proposed work is to identify dominated phase from complex microstructure images. The proposed model is trained and tested with 373 different ultra-high carbon steel (UHCS) microscopic images.FindingsIn this paper, Sobel and Watershed transformation algorithms are used for identification of dominating phases, and deep learning model has been used for identification of phase class from microstructural images.Originality/valueFor the first time, the authors have implemented edge detection followed by watershed segmentation and deep learning (convolutional neural network) to identify phases of UHCS microstructure.
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8

Chen, Kunfeng, Yanlu Li, Chao Peng, Zheng Lu, Xingyun Luo, and Dongfeng Xue. "Microstructure and defect characteristics of lithium niobate with different Li concentrations." Inorganic Chemistry Frontiers 8, no. 17 (2021): 4006–13. http://dx.doi.org/10.1039/d1qi00562f.

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Li vacancies and Nb antisites are stable point defects in congruent lithium niobate. The intrinsic point defects induce the Li/Nb cation mixing, the formation of temperature-dependent defect microstructures, and disorder within the LiNbO3 lattice frame.
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9

Pataric, Aleksandra, Marija Mihailovic, Branislav Markovic, Miroslav Sokic, Andreja Radovanovic, and Branka Jordovic. "Microstructure as an essential aspect of EN AW 7075 aluminum alloy quality influenced by electromagnetic field during continuous casting process." Chemical Industry 75, no. 1 (2021): 31–37. http://dx.doi.org/10.2298/hemind201214006p.

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Microstructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA).
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10

Xu, Qing Yan, Bai Cheng Liu, Zuo Jian Liang, Jia Rong Li, Shi Zhong Liu, and Ha Llong Yuan. "Modeling of Unidirectional Growth in a Single Crystal Turbine Blade Casting." Materials Science Forum 508 (March 2006): 111–16. http://dx.doi.org/10.4028/www.scientific.net/msf.508.111.

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Single crystal superalloy turbine blade are widely used in aero-engineering. However, there are often grain defects occurring during the fabrication of blade by casting. It is important to study the formation of microstructure related defects in turbine blades. Single crystal blade sample castings of a nickel-base superalloy were produced at different withdrawal rates by the directional solidification process and investment casting. There was a difference between the microstructure morphology at the top part of the turbine blade sample castings and the one at the bottom. Higher withdrawal rates led to more differences in the microstructure and a higher probability of crystallographic defect formation such as high angle boundaries at locations with an abrupt change of the transversal section area. To further investigate the formation of grain defects, a numerical simulation technique was used to predict the crystallographic defects occurring during directional solidification. The simulation results agreed with the experimental ones.
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11

Shuai, Ge Wang, You Li, and Zheng Hua Guo. "Fabrication and Microstructure of Zn-Sn Target Material Alloy." Advanced Materials Research 785-786 (September 2013): 924–27. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.924.

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In this paper, Zn-Sn target material alloys were prepared in an electric resistance furnace. The effects of cooling condition on casting macro-defect, microstructure and segregation of ingots during solidification have been investigated by SEM and EDX analyses. The results show that the alloys casted in air-cooled and water-cooled steel moulds have not apparent casting macro-defects. The measured Sn concentration of alloys is very close to the nominal composition. The microstructures of Zn-Sn alloys are consisting of Zn-rich primary dendrite phase and divorced eutectic Sn-rich phase. The ingots solidified in water-cooled steel moulds have smaller grains than in air-cooled moulds.
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12

Marshall, A. F., K. Char, R. W. Barton, A. Kapitulnik, and S. S. Laderman. "Microstructural interaction of Y2Ba4Cu8O16 stacking faults within YBa2Cu3O7−x." Journal of Materials Research 5, no. 10 (October 1990): 2049–55. http://dx.doi.org/10.1557/jmr.1990.2049.

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A transmission electron microscopy study of a post-annealed YBa2Cu3O7−x thin film shows that extra Cu–O planes within the structure can aggregate as stacking faults to form a defect microstructure rather than forming the well-ordered Y2Ba4Cu8O16 phase. Interaction of the stacking faults with the surrounding matrix results in strain effects and microstructural variations which may hinder ordering as well as influencing superconducting properties if occurring in higher concentration. When viewed normal to the plane of the film, the boundaries of the stacking faults can be imaged as dislocation-like defects, indicating the size and shape of the stacking faults and their relationship to other defects such as twins and second phase precipitates.
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13

Ma, Yuqin, Shuangshuang Li, Jie Wang, Luyan Ju, and Xinmei Liu. "Influence of Defects on Bending Properties of 2D-T700/E44 Composites Prepared by Improved Compression Molding Process." Materials 11, no. 11 (October 30, 2018): 2132. http://dx.doi.org/10.3390/ma11112132.

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2D-T700/E44 composite materials were prepared by improved compression molding process (ICM) then microstructure and properties of the composites were analyzed and summarized by scanning electron microscope (SEM) and electronic universal testing machine. It is found that defects will occur when the process parameters are not controlled properly and the main defects of composite materials include inadequate resin impregnation, weak interlaminar binding force, fiber displacement warping, hole and brittle fracture. Moreover, there are significant differences in the infiltration microstructure, bending properties, and fracture morphology of the composite materials with different defects. When the defects of weak interlaminar binding force and brittle fracture occur, bending properties of composite materials are relatively low, and they are 220 MPa and 245 MPa, respectively, which reach 34.9% and 38.9% of the bending strength of composite material whose defects are effectively controlled. When the process parameters are reasonable and the defects of the composite materials are effectively eliminated, the bending strength can reach 630 MPa. This will lay a foundation for the preparation of 2D-T700/E44 composite materials with ideal microstructures and properties by ICM.
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14

JIANG, B., J. L. PENG, L. A. BURSILL, and H. WANG. "MICROSTRUCTURE AND PROPERTIES OF FERROELECTRIC Bi4Ti3O12 THIN FILMS." Modern Physics Letters B 13, no. 26 (November 10, 1999): 933–45. http://dx.doi.org/10.1142/s0217984999001147.

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The film morphology and defect structure of ferroelectric bismuth titanate thin films are studied by high resolution transmission electron microscopy. As-grown and RTA-processed thin films have similar defect structures, consisting of stacking faults and complex intergrowth defect structures. The as-grown specimens prepared at low temperature had smaller particle size with higher density of these defects compared to RTA-processed samples. Detailed atomic structure models for the stacking faults and intergrowth defect structures are proposed and the computer-simulated images are compared with experiment.
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15

Borisova, D., C. Schimpf, Andreas Jahn, V. Klemm, G. Schreiber, D. Šimek, and David Rafaja. "Microstructure Investigations of the Phase Boundaries in the Bridgman TRIP Steel Crystal." Solid State Phenomena 160 (February 2010): 211–16. http://dx.doi.org/10.4028/www.scientific.net/ssp.160.211.

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Formation of microstructure defects at the phase boundaries in TRIP steels was investigated with the aid of microstructure analysis on a TRIP steel crystal, which was grown by the Bridgman technique. The microstructure studies comprised scanning electron microscopy (SEM), X-ray diffraction (XRD), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and transmission electron microscopy with high resolution (HRTEM). Initial XRD measurements revealed that the crystals under study consist of austenite and ferrite with extremely strong preferred orientations. Subsequent XRD pole figure measurements and EBSD scans have shown that the orientation relationship between austenite and ferrite can be described by the Nishiyama-Wassermann model. For a detailed description of the microstructure of the Bridgman crystal, the orientation distribution of crystallites within the individual phases was investigated using the XRD reciprocal space mapping and the rocking curve measurements. These experiments have shown that the density of microstructure defects is much lower in ferrite than in austenite. The direct information about the defect structures at the phase boundaries between austenite and ferrite was obtained from the TEM micrographs, which revealed complicated micro-twin structures at the boundaries between the neighbouring phases. HRTEM discovered very narrow stripes of ferrite embedded in austenite that were regarded as a source of the microstructure defects in austenite.
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16

Stoltz, C., B. Mason, C. Roberts, S. Hira, and G. Strouse. "Defects and Microstructure in Crystalline Explosives." Microscopy and Microanalysis 18, S2 (July 2012): 450–51. http://dx.doi.org/10.1017/s1431927612004102.

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17

Kästner, G., D. Hesse, R. Scholz, H. Koch, F. Ludwig, M. Lorenz, and H. Kittel. "Microstructure defects in YBCO thin films." Physica C: Superconductivity 243, no. 3-4 (March 1995): 281–93. http://dx.doi.org/10.1016/0921-4534(95)00011-9.

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18

Yamashita, Tamotsu, Kenji Momose, Daisuke Muto, Yoshiki Shimodaira, Kuniaki Yamatake, Yoshihiko Miyasaka, Takayuki Sato, Hirofumi Matsuhata, and Makoto Kitabatake. "Characterization of Triangular-Defects in 4° off 4H-SiC Epitaxial Wafers by Synchrotron X-Ray Topography and by Transmission Electron Microscopy." Materials Science Forum 717-720 (May 2012): 363–66. http://dx.doi.org/10.4028/www.scientific.net/msf.717-720.363.

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We report our investigation results on triangular-defects formed on 4deg. off 4H-SiC epi- taxial wafers. Triangular-defects that had neither down-falls nor basal-plane dislocations previously reported as origins of triangular-defects at the tips of triangle were investigated by TEM. Our TEM results revealed that foreign materials contamination that were different from well-known down- -falls in size and in composition caused one of the defect formations and abnormal domain forma- tions were implied to occur and thought to relate to defect formations. We also report that several types of microstructure existed in the isosceles of defect during dislocation analyses around triangular-defects by X-ray topography.
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19

Guerchais, Raphaël, Franck Morel, and Nicolas Saintier. "The Effect of the Microstructure and Defects on Crack Initiation in 316L Stainless Steel under Multiaxial High Cycle Fatigue." Advanced Materials Research 891-892 (March 2014): 815–20. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.815.

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The aim of this study is to analyse the influence of both the microstructure and defects on the high cycle fatigue behaviour of the 316L austenitic stainless steel, using finite element simulations of polycrystalline aggregates. High cycle fatigue tests have been conducted on this steel under uniaxial (push-pull) and multiaxial (combined in-phase tension and torsion) loading conditions, with both smooth specimens and specimens containing artificial semi-spherical surface defects. 2D numerical models, using a cubic elastic constitutive model, are created to determine the degree of heterogeneity of the local stress parameters as a function of the defect size. This has been done for one microstructure using several orientation sets generated from the initial texture of the material. The grains are explicitly modelled and the anisotropic behaviour of each FCC crystal is described by the generalized Hookes law with a cubic elasticity tensor. From the simulations carried out with different defect sizes and orientation sets that are representative of the real texture of the tested material, statistical information regarding mesoscopic mechanical fields provides useful insight into the microstructural dependence of the driving forces for fatigue crack nucleation at the mesoscopic scale (or the scale of individual grains). The results in terms of the stress fields and fatigue crack initiation conditions are determined at both the mesoscopic and macroscopic scales. The results from these FE models are used along with an original probabilistic mesomechanics approach to quantify the defect size effect. The resulting predictions, which are sensitive to the microstructure, include the probability distribution of the high cycle fatigue strength.
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20

García, José, Maiara Moreno, Wei Wan, Daniel Apel, Haroldo Pinto, Matthias Meixner, Manuela Klaus, and Christoph Genzel. "In Situ Investigations on Stress and Microstructure Evolution in Polycrystalline Ti(C,N)/α-Al2O3 CVD Coatings under Thermal Cycling Loads." Crystals 11, no. 2 (February 4, 2021): 158. http://dx.doi.org/10.3390/cryst11020158.

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The stress behavior and the associated microstructure evolution of industrial Ti(C,N)/α-Al2O3 coatings subjected to thermal cycling are investigated by in situ energy dispersive synchrotron X-ray diffraction and transmission electron microscopy. Temperature-dependent stresses and changes in microstructural parameters (domain size and microstrain) are analyzed by in situ measurements at different temperatures between 25 and 800 °C, both in the heating up and cooling down step, including several thermal cycles. Transmission electron microscopy is used to evaluate defects before and after the thermal treatment. The introduction of high compressive stresses in α-Al2O3 by top-blasting is connected to a high defect density at the basal planes of the alumina layer. The stress relaxation of the alumina layer at high temperatures is associated with a successive annihilation of defects until a reversible temperature-dependent stress condition is set. Top-blasting does not change the initial microstructure and residual stress of the Ti(C,N) layer. Ti(C,N) shows a cyclic stress behavior associated with the heat treatment and an elastic deformation behavior in the temperature range investigated.
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21

Wu, J. S., C. L. Jia, K. Urban, J. H. Hao, and X. X. Xi. "Microstructure and misfit relaxation in SrTiO3/SrRuO3 bilayer films on LaAlO3(100) substrates." Journal of Materials Research 16, no. 12 (December 2001): 3443–50. http://dx.doi.org/10.1557/jmr.2001.0473.

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We studied the microstructure of SrTiO3/SrRuO3 bilayer films on (001) LaAlO3 substrates by high-resolution transmission electron microscopy. At the SrRuO3/LaAlO3 interface a defect configuration of stacking faults and nanotwins bounding either Frank partial dislocations or Shockley partial dislocations and complex interaction between these planar defects were found to be the dominant means of misfit accommodation. The misfit in the SrTiO3/SrRuO3 system, however, is mainly accommodated by elastic strain. Most of the observed defects in the SrTiO3 layer can be related to the [111] planar defects in the SrRuO3 layer propagating and reaching the SrTiO3/SrRuO3 interface. Furthermore, a [110] planar defect can also be introduced in the SrTiO3 layer due to the structure change of the SrTiO3/SrRuO3 interface.
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22

Park, Sang Yeup, and Hee Gon Bang. "Effect of Sintering Atmospheres on the Microstructure Evolution of Alumina/Alumina:SiC Whisker Laminate Composites." Materials Science Forum 486-487 (June 2005): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.486-487.237.

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Alumina/Alumina: SiC laminate composites were fabricated by the pressureless sintering method. Although the laminate defect, such as channel crack, was observed under the sintering of oxidation atmosphere, laminate defects were eliminated by the sintering of non-oxidation atmospheres. Among various atmospheres, the vacuum atmosphere was effective in the elimination of laminate defects and also for homogeneous microstructure.
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23

El Hageali, Sami A., Harvey Guthrey, Steven Johnston, Jake Soto, Bruce Odekirk, Brian P. Gorman, and Mowafak Al-Jassim. "Nondestructive microstructural investigation of defects in 4H-SiC epilayers using a multiscale luminescence analysis approach." Journal of Applied Physics 131, no. 18 (May 14, 2022): 185705. http://dx.doi.org/10.1063/5.0088313.

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The development of metal oxide semiconductor field effect transistors (MOSFETs) utilizing epitaxially grown 4H-SiC has accelerated in recent years due to their favorable properties, including a high breakdown field, high saturated electron drift velocity, and good thermal conductivity. However, extended defects in epitaxial 4H-SiC can affect both device yields and operational lifetime. In this work, we demonstrate the importance of a multiscale luminescence characterization approach to studying nondestructively extended defects in epitaxial 4H-SiC semiconducting materials. Multiscale luminescence analysis reveals different aspects of excess charge carrier recombination behavior based on the scale of a particular measurement. Combining measurements of the same extended defect area at different scales tells us more about the essential nature of that defect and its microstructure. Here, we use photoluminescence imaging and cathodoluminescence spectrum imaging to investigate the recombination behavior of several different types of extended defects, including stacking faults, inclusions, and basal plane dislocations. A detailed understanding of the optoelectronic properties of extended defects in epitaxial SiC helps elucidate the microstructure of extended defects and can provide pathways to mitigate detrimental changes during device operation related to their evolution, such as the recombination enhanced dislocation glide effect that affects SiC-based MOSFETs.
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24

Horník, Jakub, Elena Čižmárová, Stanislav Krum, Jan Krčil, and Vladimír Mára. "The Influence of Microstructure on the Fracture Development in Engineering Parts." Solid State Phenomena 270 (November 2017): 74–79. http://dx.doi.org/10.4028/www.scientific.net/ssp.270.74.

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Examples of failure of mechanical parts on account of the microstructural defects or heterogeneity are described. The evaluation of defect problematic was carried out using light and scanning electron microscopy. The root detected cause of problems was in a form of coarse particles in the microstructure, intensive line spacing or banding in the material. The influence of combination of intensive stress and inappropriate orientation of parts towards the direction of forming of semi-products was often observed. A rigorous approach to the material selection and the appropriate quality control of semi-products has to be considered to prevent the risk of a failure of engineering parts.
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25

Campbell, B. J., T. R. Welberry, R. W. Broach, Hawoong Hong, and A. K. Cheetham. "Elucidation of zeolite microstructure by synchrotron X-ray diffuse scattering." Journal of Applied Crystallography 37, no. 2 (March 17, 2004): 187–92. http://dx.doi.org/10.1107/s0021889803028048.

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Single-crystal diffuse scattering measurements can now rapidly probe the three-dimensional structure of subtle defects in microporous framework materials. Diffuse scattering data from natural mordenite crystals are shown to exhibit a complex distribution of weak features which have been mapped out using a synchrotron X-ray source and a CCD detector. Comparison with computer-simulated diffuse scattering patterns yields a detailed three-dimensional columnar defect structure and reveals that roughly one third of the mordenite's columnar defects cooperate to form a block-mosaic pattern of {110} stacking faults.
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26

Čížek, Jakub, Ivan Procházka, Bohumil Smola, Ivana Stulíková, Radomír Kužel, Z. Matěj, V. Cherkaska, Rinat K. Islamgaliev, and Olya B. Kulyasova. "Microstructure and Thermal Stability of Ultra Fine Grained Mg-Based Alloys Prepared by High Pressure Torsion." Materials Science Forum 503-504 (January 2006): 149–54. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.149.

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In the present work we studied microstructure of ultra fine grained (UFG) pure Mg and UFG Mg-based alloys. The initial coarse grained samples were deformed by high pressure torsion (HPT) using pressure of 6 GPa. Such deformation leads to formation of UFG structure in the samples. The severe plastic deformation results in creation of high number of lattice defects. Therefore, we used positron annihilation spectroscopy (PAS) for defect characterizations. PAS represents a well developed non-destructive technique with high sensitivity to open volume defects like vacancies, vacancy clusters, dislocations etc. In the present work we combined PAS with TEM and XRD to obtain complete information about microstructure of the UFG samples studied. We have found that microstructure of HPT-deformed Mg contains two kinds of regions: (a) ”deformed” regions with UFG structure (grain size 100-200 nm) and high number of randomly distributed dislocations, and (b) ”recrystallized” regions with low dislocation density and grain size of few microns. It indicates some kind of dynamic recovery of microstructure already during HPT processing. On the other hand, homogenous UFG structure with grain size around 100 nm and high density of homogeneously distributed dislocations was formed in HPT-deformed Mg-9.33 wt.%Gd alloy. After characterization of the as-deformed microstructure the samples were subsequently isochronally annealed and the development of microstructure with increasing temperature and recovery of defects were investigated.
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27

Polozov, Igor, Kirill Starikov, Anatoly Popovich, and Vadim Sufiiarov. "Mitigating Inhomogeneity and Tailoring the Microstructure of Selective Laser Melted Titanium Orthorhombic Alloy by Heat Treatment, Hot Isostatic Pressing, and Multiple Laser Exposures." Materials 14, no. 17 (August 30, 2021): 4946. http://dx.doi.org/10.3390/ma14174946.

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Titanium orthorhombic alloys based on intermetallic Ti2AlNb-phase are attractive materials for lightweight high-temperature applications. However, conventional manufacturing of Ti2AlNb-based alloys is costly and labor-consuming. Additive Manufacturing is an attractive way of producing parts from Ti2AlNb-based alloys. High-temperature substrate preheating during Selective Laser Melting is required to obtain crack-free intermetallic alloys. Due to the nature of substrate preheating, the temperature profile along the build height might be uneven leading to inhomogeneous microstructure and defects. The microstructural homogeneity of the alloy along the build direction was evaluated. The feasibility of mitigating the microstructural inhomogeneity was investigated by fabricating Ti2AlNb-alloy samples with graded microstructure and subjecting them to annealing. Hot isostatic pressing allowed us to achieve a homogeneous microstructure, eliminate residual micro defects, and improve mechanical properties with tensile strength reaching 1027 MPa and 860 MPa at room temperature and 650 °C, correspondingly. Annealing of the microstructurally graded alloy at 1050 °C allowed us to obtain a homogeneous B2 + O microstructure with a uniform microhardness distribution. The results of the study showed that the microstructural inhomogeneity of the titanium orthorhombic alloy obtained by SLM can be mitigated by annealing or hot isostatic pressing. Additionally, it was shown that by applying multiple-laser exposure for processing each layer it is possible to locally tailor the phase volume and morphology and achieve microstructure and properties similar to the Ti2AlNb-alloy obtained at higher preheating temperatures.
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Ji, Peihong, Chuanlei Zhang, Yanhui Kong, Huiyu Liu, Jia Guo, Longsheng Shi, Hui Yang, Zhongwei Gu, and Yang Liu. "Collagen Film with Bionic Layered Structure and High Light Transmittance for Personalized Corneal Repair Fabricated by Controlled Solvent Evaporation Technique." Journal of Functional Biomaterials 13, no. 2 (May 2, 2022): 52. http://dx.doi.org/10.3390/jfb13020052.

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Corneal blindness is a common phenomenon, and corneal transplantation is an effective treatment for corneal defects. However, there is usually a mismatch between the corneal repair material and the degree of the patient’s corneal defect. Therefore, patients with different corneal defects need suitable corneal repair materials with a specific microstructure for personalized treatment. In this research, collagen films with bionic structures were fabricated through ethanol evaporation technique by regulating the volume ratios of collagen solution: ethanol = 10:0(Col)/9:1(CC91)/8:2(CC82)/CC73(CC73). Under various preparation conditions, the obtained collagen films contain layered structures of different density. SEM photos show that the CC73 film with a dense layer arrangement has a microstructure similar to that of the corneal epithelial layer, whereas the Col film has a loose layered structure similar to that of the corneal stroma layer. Four kinds of collagen films showed different optical properties and water absorption ability. A more ordered arrangement of internal layer structure leads to better mechanical properties of the collagen film. In view of this, we think that these collagen films with different microstructures and different interlayer spacing may have huge potential applications for personalized corneal repair.
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Jiang, Yong, Lan Er Wu, and Zhen Kun Huang. "Microstructure Observation and Analysis of Sintered SiC Ceramics by SEM." Key Engineering Materials 544 (March 2013): 200–204. http://dx.doi.org/10.4028/www.scientific.net/kem.544.200.

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Comparison of microstructures between LPSed and SSSed SiC ceramics were made. Several kinds of structure defects for LPSed SiC were emphasized to discuss. They related with whole flow path of processing, compositional design of powder mixture, spray granulation of powder mixture, milling, shaping, and sintering control. All could affect the microstructure and mechanical property of resultant ceramics.
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Ben Ahmed, Amal, Ahmad Bahloul, Mohamed Iben Houria, Anouar Nasr, and Raouf Fathallah. "Multiaxial fatigue life estimation of defective aluminum alloy considering the microstructural heterogeneities effect." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 9 (August 16, 2018): 1830–42. http://dx.doi.org/10.1177/1464420718792024.

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The Al–Si–Mg high-cycle fatigue behavior is mainly affected by the microstructural heterogeneities and the presence of casting defects. This attempt aims to develop an analytical approach based on the evaluation of the highly stressed volume caused by local porosities and defined as the affected area methodology. The proposed approach is able to predict the aluminum alloy fatigue response by considering the effect of microstructure described by the secondary dendrite arm spacing and its correlation with the defect size effect. A representative elementary volume model is implemented to evaluate the stress distribution in the vicinity of the defect and to determine its impact on the high-cycle fatigue resistance. Work hardening due to cyclic loading is considered by applying the Lemaitre–Chaboche model. The Kitagawa–Takahashi diagrams corresponding to different microstructures and for two loading ratios: R σ = 0 and R σ = −1 were simulated based on the AA method. Simulations were compared to the experimental results carried out on cast aluminium alloy A356 with T6 post heat-treatment. The results show clearly that the proposed approach provides a good estimation of the A356-T6 fatigue limit and exhibits good ability in simulating the Kitagawa–Takahashi diagrams for fine and coarse microstructures.
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Vranec, Peter, Slavka Hockicková, Alicia Mašlejová, Mária Demčáková, Lucia Hrabčáková, Pavol Zubko, Peter Kalmár, and Atila Drotár. "Rarely Occurring Defects on Tinplates." Defect and Diffusion Forum 405 (November 2020): 234–39. http://dx.doi.org/10.4028/www.scientific.net/ddf.405.234.

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This paper deals with rarely occurring defect on the surface of the tinplates produced in the conditions of U. S. Steel Košice, s.r.o. at the cleaning section of the continuous annealing line (CAL), which was caused by burnt. Random occurrence of such surface imperfections was observed within the short period of time (two months) for various continuous annealed tinplate grades, i.e. TH415, TH435 or TH550 with the thickness of the materials in the interval of 0.172 – 0.240 mm. Surface defects caused by burnt (thermal attack) manifested in different ways. Their appearance on the sheet surface was spot with regular or irregular circle shape, as well as line with the length of up to 2 mm oriented not directly in the rolling direction. By observing of the imperfections in scanning electron microscope (SEM) it was found that the surface of the steel substrate was always compact in the defective areas with clearly visible rolling lines. Foreign material, EDS analysis of which revealed that its chemical composition was on the basis of Fe and Cr, was deposited on the surface of the base material. The appearance of the foreign material shape indicated that it was in the liquid state at the time of incidence on the steel substrate surface. Metallographic analysis from the longitudinal metallographic sections through the defective areas revealed that the substrate under the spot defect with regular circle shape had thermally influenced microstructure. Similar manifestations of the microstructure influence were observed for the line defects. In the case of the spot defect with irregular shape, the microstructure of the material was not influenced, what indicated that the particle of liquid metal was solidified at the time of incidence on the plate surface. After revising technical conditions of the cleaning section of CAL, this type of imperfection was suppressed.
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32

Chen, S. J., U. Dahmen, and D. G. Howitt. "In-Situ Observations of the Effect of Electron Irradiation on the Defect Microstructure of Alumina." Microscopy and Microanalysis 3, S2 (August 1997): 601–2. http://dx.doi.org/10.1017/s1431927600009892.

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The interaction of radiation produced point defects with a dislocation microstructure at high temperature is of considerable interest and careful high voltage microscopy experiments can provide valuable insight into the mechanisms. Veyssière and Westmacott carried out in-situ experiments monitoring the partial dislocation climbs in Ni3Al induced by thermal vacancies as well as by Frenkel pairs produced during irradiation.1 We report here the results of some preliminary experiments we performed on alumina (A12O3) single crystals with high dislocation densities to study the modification of the microstructure by electron irradiation at high temperature.The dislocation microstructures were produced by shock wave deformation using a high-velocity impact technique. The technique is capable of producing a very high density of defects consisting primarily of basal twins, and slips on the basal, pyramidal and rhombohedral planes in alumina. The dislocations are all of glide type, mostly forming shear bands. A typical microstructure prior to irradiation is shown in figure la.
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33

Zhu, Yu Man, A. J. Morton, and Jian Feng Nie. "Characterization of Intermetallic Phases and Planar Defects in Mg-Y-Zn Alloys." Materials Science Forum 561-565 (October 2007): 151–54. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.151.

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The structure of intermetallic phases and planar defects in the as-cast and the solutiontreated microstructures of a Mg-8Y-2Zn-0.6Zr (wt%) alloy are characterized using transmission electron microscopy. The alloy was produced by permanent mould casting and solution treated at 500 °C. It is found that the intermetallic particles in the as-cast microstructure have a monoclinic structure. An appreciable amount of intermetallic particles is still retained along grain boundaries after solution treatments for up to 60 hrs. However, the structure of the retained intermetallic particles changes gradually from monoclinic to hexagonal during the solution treatments. Some planar defects are also detected in the as-cast and the solution-treated (1 hr) microstructures. These defects have characteristic features of stacking faults.
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34

Blinn, Bastian, Florian Krebs, Maximilian Ley, Christopher Gläßner, Marek Smaga, Jan C. Aurich, Roman Teutsch, and Tilmann Beck. "Influence of the Chemical Composition of the Used Powder on the Fatigue Behavior of Additively Manufactured Materials." Metals 9, no. 12 (November 29, 2019): 1285. http://dx.doi.org/10.3390/met9121285.

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To exploit the whole potential of Additive Manufacturing (AM), a sound knowledge about the mechanical and especially cyclic properties of AM materials as well as their dependency on the process parameters is indispensable. In the presented work, the influence of chemical composition of the used powder on the fatigue behavior of Selectively Laser Melted (SLM) and Laser Deposition Welded (LDW) specimens made of austenitic stainless steel AISI 316L was investigated. Therefore, in each manufacturing process two variations of chemical composition of the used powder were utilized. For qualitative characterization of the materials cyclic deformation behavior, load increase tests (LITs) were performed and further used for the physically based lifetime calculation method (PhyBaLLIT), enabling an efficient determination of stress (S)–number of cycles to failure (Nf) curves (S–Nf), which show excellent correlation to additionally performed constant amplitude tests (CATs). Moreover, instrumented cyclic indentation tests (PhyBaLCHT) were utilized to characterize the materials’ defect tolerance in a comparably short time. All material variants exhibit a high influence of microstructural defects on the fatigue properties. Consequently, for the SLM process a higher fatigue lifetime at lower stress amplitudes could be observed for the batch with a higher defect tolerance, resulting from a more pronounced deformation induced austenite–α’-martensite transformation. In correspondence to that, the batch of LDW material with an increased defect tolerance exhibit a higher fatigue strength. However, the differences in defect tolerance between the LDW batches is only slightly influenced by phase transformation and seems to be mainly governed by differences in hardening potential of the austenitic microstructure. Furthermore, a significantly higher fatigue strength could be observed for SLM material in relation to LDW specimens, because of a refined microstructure and smaller microstructural defects of SLM specimens.
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35

Hall, Ernest L., and Ami E. Berkowitz. "Microstructural defects in γ-Fe2O3 particles." Journal of Materials Research 1, no. 6 (December 1986): 836–44. http://dx.doi.org/10.1557/jmr.1986.0836.

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The microstructure of three different types of γ-Fe2O3 particles were examined using transmission electron microscopy. These included pure γ-Fe2O3, γ-Fe2O3 that had been surface modified using Co, and γ-Fe2O3 that had been doped with Co. The major internal microstructural defects found in the particles in all of the samples were pores and antiphase boundaries. Some particles also had a very high density of dislocations and low-angle boundaries. In general, the particles could be described as single crystals with symmetric cross section. The structure is based on a tetragonal unit cell, and each particle is divided into antiphase domains in which the c axis is oriented at 90°with respect to adjoining domains. The particles often exhibited very irregular shapes. No effect of Co modification was seen on the internal or surface structure of the particles. The Co-doped particles were found to be smaller in size and contained a lower density of internal defects. The effect of the microstructural defects and morphological irregularities in these particles on magnetic behavior is discussed.
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36

Furuhara, Tadashi, and Tadashi Maki. "Microstructure control with heterogeneous nucleation on defects." Materia Japan 39, no. 5 (2000): 417–21. http://dx.doi.org/10.2320/materia.39.417.

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37

Rafaja, David, Mikhaylo Barchuk, Christian Roeder, and Jens Kortus. "Interplay of microstructure defects in GaN layers." Acta Crystallographica Section A Foundations and Advances 71, a1 (August 23, 2015): s160. http://dx.doi.org/10.1107/s2053273315097685.

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38

Zhu, Y., L. Wu, V. Volkov, Q. Li, G. Gu, A. R. Moodenbaugh, M. Malac, M. Suenaga, and J. Tranquada. "Microstructure and structural defects in MgB2 superconductor." Physica C: Superconductivity 356, no. 4 (August 2001): 239–53. http://dx.doi.org/10.1016/s0921-4534(01)00700-6.

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39

Kaae, J. L., P. K. Gantzel, J. Chin, and W. P. West. "Microstructures of diamond formed by plasma-assisted chemical vapor deposition." Journal of Materials Research 5, no. 7 (July 1990): 1480–89. http://dx.doi.org/10.1557/jmr.1990.1480.

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The microstructures of five different diamond films formed by plasma-assisted chemical vapor deposition have been studied by transmission electron microscopy. The films were selected for study based on differences in their surface morphologies. The preferred orientations inferred from the symmetries of the crystals observed on the surfaces of these films were consistent with those measured by x-ray diffraction. A general characteristic of all of the diamond film microstructures was stacking faults and microtwins on {111} planes, but the densities and the distributions of the defects varied widely among the films. The observations of microstructure indicate that when a crystal grows so that {100} facets are formed, stacking faults and microtwins are confined to regions near its boundaries, and when a crystal grows so that {111} facets are formed, stacking faults and microtwins are distributed throughout its volume. Under some deposition conditions the defects are confined to bands in the crystal, and coincidence of these defect bands with small steps on the crystal facets suggests that the steps may be caused by the intersection of the bands with the surface.
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40

Moli-Sanchez, L., F. Martin, E. Leunis, J. Chêne, and M. Wery. "Hydrogen Transport in 34CrMo4 Martensitic Steel: Influence of Microstructural Defects on H Diffusion." Defect and Diffusion Forum 323-325 (April 2012): 485–90. http://dx.doi.org/10.4028/www.scientific.net/ddf.323-325.485.

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The electrochemical permeation technique was used to evaluate the effect of the microstructure on hydrogen diffusivity and hydrogen trapping at room temperature in martensitic steels. A detailed study of the electrochemical permeation technique was first performed in order to identify the boundary conditions of a permeation test in the selected experimental set-up. The validity of the apparent diffusion coefficient derived from this test is also discussed. A 34CrMo4 quenched steel has been selected and designed at three tempering temperatures (200°C, 540°C and 680°C) in order to obtain three different microstructures. According to permeation measurements, H diffusion strongly depends on the microstructure. The material tempered at 540°C exhibits the smallest diffusion coefficient and the largest fraction of reversible traps at room temperature.
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41

Réti, Tamás, Mihály Réger, Ágnes Csizmazia, and Imre Czinege. "Modeling of Distribution of Visible and Non-Visible Graphite Nodules Embedded in the Surface Layer of Ductile Cast Iron." Materials Science Forum 659 (September 2010): 453–58. http://dx.doi.org/10.4028/www.scientific.net/msf.659.453.

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The graphite nodule count and size distribution are important structural parameters in the quantitative characterization of the microstructure of ductile cast irons. In several cases, it is observed that local surface damages (cracks or microchip formations) are generated by the final manufacturing process (superfinishing operation), and these defects are originated basically from the hidden (invisible) graphite nodules located directly below surface. Based on measured data obtained by an image analyzer, a stereological model and a simulation algorithm have been developed to analyse the correspondances between the graphite morphology and the defect formation. This method makes it possible to establish a correlation between the microstructure parameters and the occurrence of local surface defects on ductile cast iron components.
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42

Maamoun, Ahmed, Yi Xue, Mohamed Elbestawi, and Stephen Veldhuis. "The Effect of Selective Laser Melting Process Parameters on the Microstructure and Mechanical Properties of Al6061 and AlSi10Mg Alloys." Materials 12, no. 1 (December 20, 2018): 12. http://dx.doi.org/10.3390/ma12010012.

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Additive manufacturing (AM) offers customization of the microstructures and mechanical properties of fabricated components according to the material selected and process parameters applied. Selective laser melting (SLM) is a commonly-used technique for processing high strength aluminum alloys. The selection of SLM process parameters could control the microstructure of parts and their mechanical properties. However, the process parameters limit and defects obtained inside the as-built parts present obstacles to customized part production. This study investigates the influence of SLM process parameters on the quality of as-built Al6061 and AlSi10Mg parts according to the mutual connection between the microstructure characteristics and mechanical properties. The microstructure of both materials was characterized for different parts processed over a wide range of SLM process parameters. The optimized SLM parameters were investigated to eliminate internal microstructure defects. The behavior of the mechanical properties of parts was presented through regression models generated from the design of experiment (DOE) analysis for the results of hardness, ultimate tensile strength, and yield strength. A comparison between the results obtained and those reported in the literature is presented to illustrate the influence of process parameters, build environment, and powder characteristics on the quality of parts produced. The results obtained from this study could help to customize the part’s quality by satisfying their design requirements in addition to reducing as-built defects which, in turn, would reduce the amount of the post-processing needed.
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43

Zhou, Shi Meng, Zhi Wei Wang, and Yu Ren. "Effects of Microstructure and Shock Prestrain on the Dynamic Mechanical Behavior of Ti-6Al-4V Alloy." Key Engineering Materials 837 (April 2020): 51–57. http://dx.doi.org/10.4028/www.scientific.net/kem.837.51.

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Ti–6Al–4V alloy (Ti64) with different microstructures was first preshocked at ~6–13 GPa and then compression reloaded at 4×103s-1 to investigate the effect of microstructure and shock prestrain on the dynamic mechanical behavior of this alloy. The strengthening effect caused by shock prestrain is weaker than that introduced by the uniaxial stress compression during dynamic reloading process regardless of microstructure type and impact stress amplitude. However, the shock-induced enhancement ratio is higher in Ti64 having bimodal microstructures or the lamellar microstructure with wide α-platelets. These mechanical behaviors exhibited by postshock materials are closely related to the shock-induced microstructure evolution. Dislocations more tend to nucleate and interact in large-sized α phases such as equiaxed primary α and wide α-platelets. The generation of high-density micro-defects during the propagation of shock waves results in the improvement of strength but degradation of ductility of Ti64 during dynamic reloading process.
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44

Lewis, Jennifer A., and Waltraud M. Kriven. "Microstructure-Property Relationships in Macro-Defect-Free Cement." MRS Bulletin 18, no. 3 (March 1993): 72–77. http://dx.doi.org/10.1557/s0883769400043943.

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The term “macro-defect-free” refers to the absence of relatively large voids (or defects) that are normally present in conventional cement pastes due to entrapped air or inadequate mixing. A decade ago, Birchall and co-workers developed a novel processing method that avoids the formation of these strength-limiting defects. This method, outlined schematically in Figure 1, consists of mixing hydraulic cement powder, a water-soluble polymer, and a minimal amount of water under high shear to produce a macro-defect-free (MDF) cement composite. Several cement/polymer systems can be processed by this flexible technique, although the calcium aluminate cement/polyvinyl alcohol-acetate (PVA) copolymer system is most common: MDF cements display unique properties relative to conventional cement pastes. For example, the flexural strength of MDF cement is more than 200 MPa as compared to values on the order of 10 MPa for conventional pastes. One can view MDF cements as a type of “inorganic plastic.” As is the case with plastic processing, fillers such as alumina, silicon carbide, or metal powders can be added to MDF cement to modify its performance properties (e.g., abrasion resistance, thermal or electrical conductivity, and hardness). The combined attractiveness of inexpensive raw materials and flexible, low-temperature processing has generated great interest in this new class of advanced cement-based materials.
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45

Berteaux, Olivier, Roger Valle, Monique Raffestin, Marc Thomas, and G. Henaff. "An Investigation of Fracture Origins in Heat-Treated Ti49Al47Cr2Nb2 Powder Compacts." Materials Science Forum 638-642 (January 2010): 1422–27. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1422.

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The fatigue behaviour of a powder-metallurgy (PM) + heat-treated Ti49Al47Cr2Nb2 alloy is investigated using detailed SEM characterization. Based on the results of comparative static and cyclic loadings at RT, the fracture origins for the different test specimens is investigated. Conventional fractographic analyses revealed that internal structural defects inherent to powder metallurgy such as compaction defects, porosities and non-metallic inclusions can promote crack initiation. However, the fracture surface of test specimens is markedly affected by the microstructure, which is indicative of the microstructure dependence on crack initiation and propagation. In sub-transus heat treatment conditions, the detrimental effect of structural defects is illustrated by clear crack initiation sites onto the fracture surfaces. In super-transus conditions, crack propagation from defects can be blunted due to crack deflection, branching through lamellar interfaces, thus leading to lower defect sensitivity. Correlation of the results of these microfractographic examinations with the stress-strain curves corresponding to the various specimens allows identifying the role of such structural defects on the static and cyclic deformation behaviours. Finally, implications of such dependencies will be assessed relative to the requirements for aerospace gas turbine applications.
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46

Muntifering, Brittany, Rémi Dingreville, Khalid Hattar, and Jianmin Qu. "Electron Beam Effects during In-Situ Annealing of Self-Ion Irradiated Nanocrystalline Nickel." MRS Proceedings 1809 (2015): 13–18. http://dx.doi.org/10.1557/opl.2015.499.

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ABSTRACTTransmission electron microscopy (TEM) is a valuable methodology for investigating radiation-induced microstructural changes and elucidating the underlying mechanisms involved in the aging and degradation of nuclear reactor materials. However, the use of electrons for imaging may result in several inadvertent effects that can potentially change the microstructure and mechanisms active in the material being investigated. In this study, in situ TEM characterization is performed on nanocrystalline nickel samples under self-ion irradiation and post irradiation annealing. During annealing, voids are formed around 200 °C only in the area illuminated by the electron beam. Based on diffraction patterns analyses, it is hypothesized that the electron beam enhanced the growth of a NiO layer resulting in a decrease of vacancy mobility during annealing. The electron beam used to investigate self-ion irradiation ultimately significantly affected the type of defects formed and the final defect microstructure.
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47

Borsato, Thomas, Paolo Ferro, Filippo Berto, and Carlo Carollo. "Effect of Solidification Time on Microstructural, Mechanical and Fatigue Properties of Solution Strengthened Ferritic Ductile Iron." Metals 9, no. 1 (December 28, 2018): 24. http://dx.doi.org/10.3390/met9010024.

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Microstructural, mechanical, and fatigue properties of solution strengthened ferritic ductile iron have been evaluated as functions of different solidification times. Three types of cast samples with increasing thickness have been produced in a green sand automatic molding line. Microstructural analyses have been performed in order to evaluate the graphite nodules parameter and matrix structure. Tensile and fatigue tests have been carried out using specimens taken from specific zones, with increasing solidification time, inside each cast sample. Finally, the fatigue fracture surfaces have been observed using a scanning electron microscope (SEM). The results showed that solidification time has a significant effect on the microstructure and mechanical properties of solution strengthened ferritic ductile iron. In particular, it has been found that with increasing solidification times, the microstructure becomes coarser and the presence of defects increases. Moreover, the lower the cooling rate, the lower the tensile and fatigue properties measured. Since in an overall casting geometry, same thicknesses may be characterized by different microstructures and mechanical properties induced by different solidification times, it is thought that the proposed methodology will be useful in the future to estimate the fatigue strength of cast iron castings through the numerical calculation of the solidification time.
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48

Coduri, M., M. Scavini, M. Pani, M. M. Carnasciali, H. Klein, and C. Artini. "From nano to microcrystals: effects of different synthetic pathways on the defect architecture in heavily Gd-doped ceria." Physical Chemistry Chemical Physics 19, no. 18 (2017): 11612–30. http://dx.doi.org/10.1039/c6cp08173h.

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The evolution of the defect structure and microstructure of heavily Gd-doped ceria for different synthetic pathways is investigated to explore the way defects interact with each other in a composition range known to effectively hamper the application of the material as electrolyte.
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49

Carvalho, R. G., M. S. Pires, A. J. S. Fernandes, F. J. Oliveira, T. Monteiro, R. F. Silva, and F. M. Costa. "Microstructure of Mullite-zirconia Fibres Grown by Directional Solidification." Microscopy and Microanalysis 18, S5 (August 2012): 103–4. http://dx.doi.org/10.1017/s1431927612013177.

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Recently, much attention has been given to directional solidified eutectic (DSE) materials for functional and structural applications. DSE materials take advantage from their microstructural features. Typically, DSE are dense homogeneous materials composed by fine microstructures without grain boundaries (GBs). Since impurities and defects typically concentrate at GBs, their deleterious effects on the mechanical, thermal and electrical properties can thus be minimized.
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50

Musin, F. F., A. Y. Medvedev, and B. O. Bolshakov. "Linear Friction Welding of a Commercial Aluminum Alloy." Materials Science Forum 870 (September 2016): 608–13. http://dx.doi.org/10.4028/www.scientific.net/msf.870.608.

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The mechanical properties and microstructure of a solid-phase compound produced by linear friction welding (LFW) of commercial Al-4.4%Cu-0.5%Mg-0.4%Mn-0.5%Ag alloy have been studied. The samples of Al-Cu-Mg-Ag alloy were produced by ingot metallurgy and subjected to thermomechanical treatment to get different initial microstructures. It has been shown that the LFW of two rectangular-shaped samples with different microstructures enabled forming a well-done welding joint without macroscopic defects. The LFW samples have shown high mechanical properties. Strength has reached 452 MPa, and plasticity has become not less 15%. The microstructure transformation in the welding joint during plastic deformation and deformation heating at LFW is discussed.
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