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1
Müller, Martin, Marie Stiefel, Björn-Ivo Bachmann, Dominik Britz e Frank Mücklich. "Overview: Machine Learning for Segmentation and Classification of Complex Steel Microstructures". Metals 14, n. 5 (7 maggio 2024): 553. http://dx.doi.org/10.3390/met14050553.
Testo completoAbstract (sommario):
The foundation of materials science and engineering is the establishment of process–microstructure–property links, which in turn form the basis for materials and process development and optimization. At the heart of this is the characterization and quantification of the material’s microstructure. To date, microstructure quantification has traditionally involved a human deciding what to measure and included labor-intensive manual evaluation. Recent advancements in artificial intelligence (AI) and machine learning (ML) offer exciting new approaches to microstructural quantification, especially classification and semantic segmentation. This promises many benefits, most notably objective, reproducible, and automated analysis, but also quantification of complex microstructures that has not been possible with prior approaches. This review provides an overview of ML applications for microstructure analysis, using complex steel microstructures as examples. Special emphasis is placed on the quantity, quality, and variance of training data, as well as where the ground truth needed for ML comes from, which is usually not sufficiently discussed in the literature. In this context, correlative microscopy plays a key role, as it enables a comprehensive and scale-bridging characterization of complex microstructures, which is necessary to provide an objective and well-founded ground truth and ultimately to implement ML-based approaches.
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Robson, J. D., O. Engler, C. Sigli, A. Deschamps e W. J. Poole. "Advances in Microstructural Understanding of Wrought Aluminum Alloys". Metallurgical and Materials Transactions A 51, n. 9 (8 luglio 2020): 4377–89. http://dx.doi.org/10.1007/s11661-020-05908-9.
Testo completoAbstract (sommario):
Abstract Wrought aluminum alloys are an attractive option in the quest for lightweight, recyclable, structural materials. Modern wrought aluminum alloys depend on control of complex microstructures to obtain their properties. This requires an understanding of the coupling between alloy composition, processing, and microstructure. This paper summarizes recent work to understand microstructural evolution in such alloys, utilizing the advanced characterization techniques now available such as atom probe tomography, high-resolution electron microscopy, and synchrotron X-ray diffraction and scattering. New insights into precipitation processes, deformation behavior, and texture evolution are discussed. Recent progress in predicting microstructural evolution using computer modeling is also summarized.
3
Chen, Rong, e Xing Zhou. "Recent advances in 2D graphene reinforced metal matrix composites". Nanotechnology 33, n. 6 (15 novembre 2021): 062003. http://dx.doi.org/10.1088/1361-6528/ac2dc7.
Testo completoAbstract (sommario):
Abstract The unique combination of excellent mechanical and functional properties makes graphene an ideal component for high-performance ‘smart’ composites, which are sensitive to thermal, optical, electrical and mechanical excitations, hence being potential in application of a range of sensors. It has confirmed that the addition of graphene into metal matrix can significantly enhance the mechanical property and deliver surprising functional properties. Thus, graphene reinforced metal matrix composites (GMMCs) have long been regarded as potential prospects of nanotechnology applications. Recently, researchers mainly focused on: (i) solving the interfacial issues and realizing controllable alignment of graphene in metal matrix to achieve optimal performance; (ii) reasonable designing of the microstructures basing on usage requirement and then fabricating via efficient technique. Thus, it is necessary to figure out key roles of microstructure in fabrication process, mechanical and multi-functional properties. This review consists of four parts: (i) fabrication process. The fabrication processes are firstly divided into three kinds basing on the different bonding nature between graphene and metal matrix. (ii) Mechanical property. The microstructural characteristics of metal matrix accompanying by the incorporation of graphene and their vital effects on mechanical properties of GMMCs are systematically summarized. (iii) Functional property. The crucial effects of microstructure on electrical and thermal properties are summarized. (iv) Prospect applications and future challenges. Application and challenges basing on the research status are discussed to provide useful directions for future exploration in related fields. All these four parts are discussed with a focus on key role of microstructure characteristics, which is instructive for the microstructures design and fabrication process optimization during academic researches and potential commercial applications.
4
James, R. D. "Microstructure of Shape-Memory and Magnetostrictive Materials". Applied Mechanics Reviews 43, n. 5S (1 maggio 1990): S189—S193. http://dx.doi.org/10.1115/1.3120802.
Testo completoAbstract (sommario):
Recent advances in the analysis of microstructure is providing models and methods for treating the kinds of optimization problems that arise in the study of microstructure. The main advance has been the development of theory and methods for treating the case in which arbitrary microstructures compete for the minimum (or maximum). This contrasts for example with micromechanics in which the geometry of the microstructure is assumed, or assumed up to the choice of a few parameters, and then the optimization or stress analysis is carried out under severe geometric restrictions. Micromechanics is effective in dealing with a particular experimentally observed microstructure, but not for understanding microstructures that might be optimal in a certain sense. Much of this recent research has been fueled by critical discussions among engineering scientists, mathematicians and electron microscopists. The intent of this paper is first to summarize, in terms accessible to a broad audience, the nature of this research and then to describe applications to the improvement of shape-memory and magnetostrictive materials. The general part of the lecture will focus on three areas, effective properties of materials, optimal design of materials and phase transformation and active materials. A central role is played by the question “How does one meaningfully average a quantity whose values vary rapidly on a microstructural scale?” A second recurring theme is that the optimal microstructure is predicted to have fine structure. The latter is closely related to the failure of conditions of material stability.
5
Zheng, Hua, Kai Ming Wu, S. F. Sun e G. W. Hu. "Niobium-Alloyed Steel Treated by Quenching-Partitioning-Tempering". Applied Mechanics and Materials 528 (febbraio 2014): 149–52. http://dx.doi.org/10.4028/www.scientific.net/amm.528.149.
Testo completoAbstract (sommario):
Given the strong recent interest in quenching-partitioning-tempering processed steels, the Niobium-alloyed medium carbon steel was investigated here. The microstructural observations and hardness were analyzed by optical microscope, transmission electron microscope, X-ray diffraction and hardness test. Results show that when quenched at 210°C and partitioned at 450°C, the quenching partitioning-tempering process leads to ultra fine-grained microstructures of martensite, retained austenite and carbides. And the microstructure and hardness changed differently with the increase of partitioned time.
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Jang, Jeong Gook, e Solmoi Park. "Special Issue: “Microstructures and Durability of Cement-Based Materials”". Materials 14, n. 4 (11 febbraio 2021): 866. http://dx.doi.org/10.3390/ma14040866.
Testo completoAbstract (sommario):
Cement-based materials play an irreplaceable role in building and sustaining our society by meeting the performance demand imposed on structures and sustainability. Cement-based materials are no longer limited to derivatives of Portland cement, and appreciate a wider range of binders that come from various origins. It is therefore of utmost importance for understanding and expanding the relevant knowledge on their microstructure and likely durability performance. This Special Issue “Microstructures and Durability of Cement-Based Materials” presents recent studies reporting microstructural and durability investigation revealing the characteristics of cement-based materials.
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Lowe, Michael J. "Realistic modelling of microstructural features in numerical simulations of wave propagation in metals". Journal of the Acoustical Society of America 152, n. 4 (ottobre 2022): A293. http://dx.doi.org/10.1121/10.0016323.
Testo completoAbstract (sommario):
Research in numerical modelling in recent years has enabled realistic simulations of wave propagation in three dimensions in large volumes of material, while including features at small scale. A critical enabler has been the growth of computer power, especially Finite Element computations on GPUs. The presentation will start with the development of modelling capability for polycrystalline materials, for which extensive recent work has created realistic simulations for wave speed and grain-scattering attenuation, representing the microstructure at grain scale. This topic has received much attention in theoretical work over several decades, so the simulations have been helpful to evaluate and understand the theoretical models and the physics of the behaviour. Subsequently, the modelling has addressed several other microstructural interests, including simulations for creep damage and fatigue damage, each of which cause reductions of wave speed; models of equivalent macro material properties for these are developed based on studies of the microstructural information. Finally, recent work will be presented on wave propagation and scattering in Titanium alloys containing Macro Textured Regions (MTRs/Macrozones); these comprise microstructures of mixed scale, for which there is interest to use ultrasound to characterise the MTRs (large scale) against a background of a smaller scale regular microstructure.
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Xi, Shangbin, e Yu Su. "Phase Field Study of the Microstructural Dynamic Evolution and Mechanical Response of NiTi Shape Memory Alloy under Mechanical Loading". Materials 14, n. 1 (2 gennaio 2021): 183. http://dx.doi.org/10.3390/ma14010183.
Testo completoAbstract (sommario):
For the purpose of investigating the microstructural evolution and the mechanical response under applied loads, a new phase field model based on the Ginzburg-Landau theory is developed by designing a free energy function with six potential wells that represent six martensite variants. Two-dimensional phase field simulations show that, in the process of a shape memory effect induced by temperature-stress, the reduction-disappearance of cubic austenite phase and nucleation-growth of monoclinic martensite multi-variants result in a poly-twined martensitic microstructure. The microstructure of martensitic de-twinning consists of different martensite multi-variants in the tension and compression, which reveals the microstructural asymmetry of nickel-titanium (NiTi) alloy in the tension and compression. Furthermore, in the process of super-elasticity induced by tensile or compressive stress, all martensite variants nucleate and expand as the applied stress gradually increases from zero. Whereas, when the applied stress reaches critical stress, only the martensite variants of applied stress-accommodating continue to expand and others fade gradually. Moreover, the twinned martensite microstructures formed in the tension and compression contain different martensite multi-variants. The study of the microstructural dynamic evolution in the phase transformation can provide a significant reference in improving properties of shape memory alloys that researchers have been exploring in recent years.
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Carter, Joseph G., e George R. Clark. "Classification and Phylogenetic Significance of Molluscan Shell Microstructure". Notes for a Short Course: Studies in Geology 13 (1985): 50–71. http://dx.doi.org/10.1017/s0271164800001093.
Testo completoAbstract (sommario):
Like most classifications of molluscan shell microstructure published during the past 25 years (e.g., MacClintock, 1967; Kobayashi, 1964, 1971; Taylor, Kennedy and Hall, 1969, 1973; Grégoire, 1972a), the present one is based largely on Bøggild's (1930) monographic work, redefined from a modern perspective of combined light and scanning electron microscopy. However, this is the first attempt to integrate shell microstructure terminology for mollusks with that employed by students of bryozoan and brachiopod shell microstructure (e.g., Williams, 1968a,b, 1970, 1973; Williams and Wright, 1970; Armstrong 1968, 1969; Sandberg, 1971, 1977; Brunton, 1972; MacKinnon, 1974, 1977; MacKinnon and Williams, 1974; Iwata, 1981, 1982). An integration of nomenclatorial schemes is desirable for purposes of interphylum comparison, and is presently needed because there is considerable overlap and inconsistency in the application of microstructural terminology even within single molluscan classes. The present synthesis of shell microstructure nomenclature is possible primarily because of the extensive data base of invertebrate shell mineralogy, microstructure and especially ultrastructure published in more than 300 references in the past 15 years. To these data, the authors have contributed original information of shell mineralogy and microstructure for scores of Recent and fossil mollusks, brachiopods and bryozoans, with a clear emphasis on bivalved mollusks. Many inadequately described microstructure terms have been reanalyzed during the course of this study, either by examining species cited in the literature, or by using closely related species. Perhaps because they are better studied, but probably for other reasons as well, the diversity of molluscan shell microstructures is considerably greater than that of brachiopods and bryozoans combined (Carter, 1979). Consequently, most of the present nomenclature is based on mollusks, and only three of the major microstructural arrangements described in this guide (crossed bladed, semi-nacreous and semi-foliated) were known first in brachiopods or bryozoans and later recognized in molluscs.
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Hanhan, Imad, e Michael D. Sangid. "Design of Low Cost Carbon Fiber Composites via Examining the Micromechanical Stress Distributions in A42 Bean-Shaped versus T650 Circular Fibers". Journal of Composites Science 5, n. 11 (7 novembre 2021): 294. http://dx.doi.org/10.3390/jcs5110294.
Testo completoAbstract (sommario):
Recent advancements have led to new polyacrylonitrile carbon fiber precursors which reduce production costs, yet lead to bean-shaped cross-sections. While these bean-shaped fibers have comparable stiffness and ultimate strength values to typical carbon fibers, their unique morphology results in varying in-plane orientations and different microstructural stress distributions under loading, which are not well understood and can limit failure strength under complex loading scenarios. Therefore, this work used finite element simulations to compare longitudinal stress distributions in A42 (bean-shaped) and T650 (circular) carbon fiber composite microstructures. Specifically, a microscopy image of an A42/P6300 microstructure was processed to instantiate a 3D model, while a Monte Carlo approach (which accounts for size and in-plane orientation distributions) was used to create statistically equivalent A42/P6300 and T650/P6300 microstructures. First, the results showed that the measured in-plane orientations of the A42 carbon fibers for the analyzed specimen had an orderly distribution with peaks at |ϕ|=0∘,180∘. Additionally, the results showed that under 1.5% elongation, the A42/P6300 microstructure reached simulated failure at approximately 2108 MPa, while the T650/P6300 microstructure did not reach failure. A single fiber model showed that this was due to the curvature of A42 fibers which was 3.18 μm−1 higher at the inner corner, yielding a matrix stress that was 7 MPa higher compared to the T650/P6300 microstructure. Overall, this analysis is valuable to engineers designing new components using lower cost carbon fiber composites, based on the micromechanical stress distributions and unique packing abilities resulting from the A42 fiber morphologies.
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Clasen, Antje, e Antonia B. Kesel. "Microstructural Surface Properties of Drifting Seeds—A Model for Non-Toxic Antifouling Solutions". Biomimetics 4, n. 2 (13 maggio 2019): 37. http://dx.doi.org/10.3390/biomimetics4020037.
Testo completoAbstract (sommario):
A major challenge in the shipping and marine industry is the biofouling on under water surfaces. So far, biocides have been the main remedy for the prevention of the adhesion of microorganisms that is also influenced by surface topography. In recent years, research projects have explored microstructured surfaces as a non-toxic antifouling strategy. In this study, physical factors of surfaces of seeds of 43 plant species were analyzed with regards to their antifouling effects. After exposure to cold water of the North Sea during the swarming periods of the barnacles larvae, the surface microstructures of seeds without fouling of barnacles were identified and compared with each other, using a scanning electron microscope (SEM). In order to validate the findings, selected microstructured surface structure properties were transferred to technical surfaces with a 2-component silicon system and subjected to the same conditions. The results of the analyses confirmed that drifting seeds with specific microstructural surface structure properties promote biofouling defense of epibionts. These results serve as a starting point for the development of non-toxic antifouling agents based on the interaction of microstructures and geometric shapes.
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Yang, Zenan, Yong Li, Xiaolu Wei, Xu Wang e Chenchong Wang. "Martensite Start Temperature Prediction through a Deep Learning Strategy Using Both Microstructure Images and Composition Data". Materials 16, n. 3 (18 gennaio 2023): 932. http://dx.doi.org/10.3390/ma16030932.
Testo completoAbstract (sommario):
In recent decades, various previous research has established empirical formulae or thermodynamic models for martensite start temperature (Ms) prediction. However, most of this research has mainly considered the effect of composition and ignored complex microstructural factors, such as morphology, that significantly affect Ms. The main limitation is that most microstructures cannot be digitized into numerical data. In order to solve this problem, a convolutional neural network model that can use both composition information and microstructure images as input was established for Ms prediction in a medium-Mn steel system in this research. Firstly, the database was established through experimenting. Then, the model was built and trained with the database. Finally, the performance of the model was systematically evaluated based on comparison with other, traditional AI models. It was proven that the new model provided in this research is more rational and accurate because it considers both composition and microstructural factors. In addition, because of the use of microstructure images for data augmentation, the deep learning had a low risk of overfitting. When the deep-learning strategy is used to deal with data that contains both numerical and image data types, obtaining the value matrix that contains interaction information of both numerical and image data through data preprocessing is probably a better approach than direct linking of the numerical data vector to the fully connected layer.
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Regier, R. W., A. Reguly, David K. Matlock, J. K. Choi e John G. Speer. "Effects of Austenite Conditioning and Transformation Temperature on the Bainitic Microstructure in Linepipe Steels". Materials Science Forum 783-786 (maggio 2014): 85–90. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.85.
Testo completoAbstract (sommario):
Low carbon bainitic steels are important in applications such as linepipe, and the details of the bainite microstructure control strength and toughness. The transformation of austenite to bainitic ferrite has been widely researched over the years, although recent use of electron backscatter diffraction techniques has provided opportunity to advance the characterization of various crystallographic aspects. In recent work, microstructures were characterized in a base steel containing 0.04 C and 1.7 Mn (wt. pct.) and two additional steels having modest carbon and manganese variations to influence the transformation behavior, with an interest in the MA (martensite-austenite) constituent and characteristics of the bainite developed at different transformation temperatures. Effects of austenite conditioning were also examined, as these steels contained an addition of 0.04 wt. pct. Nb. Microstructural details including crystallographic characteristics assessed using EBSD are presented, along with comments related to the implications of the results.
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Gargalis, Leonidas, Leonidas Karavias, Joachim S. Graff, Spyros Diplas, Elias P. Koumoulos e Evangelia K. Karaxi. "Novel Powder Feedstock towards Microstructure Engineering in Laser Powder Bed Fusion: A Case Study on Duplex/Super Duplex and Austenitic Stainless-Steel Alloys". Metals 13, n. 9 (1 settembre 2023): 1546. http://dx.doi.org/10.3390/met13091546.
Testo completoAbstract (sommario):
Additive manufacturing of Duplex Stainless Steels (DSS) and Super Duplex Stainless Steels (SDSS) has been successfully demonstrated using LPBF in recent years, however, both alloys feature an almost fully ferritic microstructure in the as-built condition due to the fast cooling rates associated with the Laser Powder Bed Fusion (LPBF) process. Blends of DSS and SDSS powders were formulated with austenitic stainless-steel 316L powder, aiming to achieve increased austenite formation during in the LPBF as-built condition to potentially minimize the post heat treatments (solution annealing and quenching). Powder characteristics were investigated and process parameters were optimized to produce near fully dense parts. Nanoindentation (NI) tests were conducted to measure, not only the local mechanical properties and correlate them with the as-built microstructure, but also to gain a deeper understanding in the deformation behavior of individual phases that cannot be studied directly by macroscopic tensile tests. Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) were employed for microstructural analysis and phase quantification. The microstructural analysis and EBSD phase maps revealed an increase in austenite in the as-built microstructures. Blend 1 resulted in a duplex microstructure consisting of 10% austenite at the XY plane and 20% austenite at the XZ plane. The austenite content increased with increasing proportion of 316L stainless steel in the powder blends. The DSS blend required a much higher volumetric energy density for the fabrication of near fully dense parts. This imposed a slower solidification and a higher melt pool homogeneity, allowing for adequate diffusion of the austenite stabilizing elements. The presented workflow and findings from this study provide valuable insights into powder mixing for the development of custom alloys for rapid material screening in LPBF.
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Snopiński, Przemysław, Marek Barlak e Katarzyna Nowakowska-Langier. "Ar+ Ion Irradiation Response of LPBF AlSi10Mg Alloy in As-Built and KOBO-Processed Conditions". Symmetry 16, n. 9 (5 settembre 2024): 1158. http://dx.doi.org/10.3390/sym16091158.
Testo completoAbstract (sommario):
In recent years, revolutionary improvements in the properties of certain FCC metals have been achieved by increasing the proportion of twin-related, highly symmetric grain boundaries. Various thermomechanical routes of grain boundary engineering (GBE) processing have been employed to enhance the fraction of low ΣCSL grain boundaries, thereby improving the radiation tolerance of many polycrystalline materials. This improvement is due to symmetric twin boundaries acting as effective sinks for defects caused by radiation, thus enhancing the material’s performance. In this study, the LPBF AlSi10Mg alloy was post-processed via the KOBO extrusion method. Subsequently, the samples were subjected to irradiation with Ar+ ions at an ion fluence of 5 × 1017 cm−2. The microstructures of the samples were thoroughly investigated using electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The results showed that KOBO processing led to the formation of an ultrafine-grained microstructure with a mean grain size of 0.8 µm. Moreover, it was revealed that the microstructure of the KOBO-processed sample exhibited an increased fraction of low-ΣCSL boundaries. Specifically, the fraction of Σ11 boundaries increased from approximately 2% to 8%. Post-irradiation microstructural analysis revealed improved radiation tolerance in the KOBO-processed sample, indicating a beneficial influence of the increased grain boundary fraction and low-ΣCSL boundary fraction on the irradiation resistance of the AlSi10Mg alloy. This research provides valuable insights for the development of customized microstructures with enhanced radiation tolerance, which has significant implications for the advancement of materials in nuclear and aerospace applications.
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Gunasegaram, Dayalan R., e Ingo Steinbach. "Modelling of Microstructure Formation in Metal Additive Manufacturing: Recent Progress, Research Gaps and Perspectives". Metals 11, n. 9 (9 settembre 2021): 1425. http://dx.doi.org/10.3390/met11091425.
Testo completoAbstract (sommario):
Microstructures encountered in the various metal additive manufacturing (AM) processes are unique because these form under rapid solidification conditions not frequently experienced elsewhere. Some of these highly nonequilibrium microstructures are subject to self-tempering or even forced to undergo recrystallisation when extra energy is supplied in the form of heat as adjacent layers are deposited. Further complexity arises from the fact that the same microstructure may be attained via more than one route—since many permutations and combinations available in terms of AM process parameters give rise to multiple phase transformation pathways. There are additional difficulties in obtaining insights into the underlying phenomena. For instance, the unstable, rapid and dynamic nature of the powder-based AM processes and the microscopic scale of the melt pool behaviour make it difficult to gather crucial information through in-situ observations of the process. Therefore, it is unsurprising that many of the mechanisms responsible for the final microstructures—including defects—found in AM parts are yet to be fully understood. Fortunately, however, computational modelling provides a means for recreating these processes in the virtual domain for testing theories—thereby discovering and rationalising the potential influences of various process parameters on microstructure formation mechanisms. In what is expected to be fertile ground for research and development for some time to come, modelling and experimental efforts that go hand in glove are likely to provide the fastest route to uncovering the unique and complex physical phenomena that determine metal AM microstructures. In this short Editorial, we summarise the status quo and identify research opportunities for modelling microstructures in AM. The vital role that will be played by machine learning (ML) models is also discussed.
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Xu, Hang, Shengjie Xu, Xun Xu, Jincheng Zhuang, Weichang Hao e Yi Du. "Recent advances in two-dimensional van der Waals magnets". Microstructures 2, n. 2 (2022): 2022011. http://dx.doi.org/10.20517/microstructures.2022.02.
Testo completoAbstract (sommario):
Two-dimensional (2D) magnets have evoked tremendous interest within the research community due to their fascinating features and novel mechanisms, as well as their potential applications in magnetic nanodevices. In this review, state-of-the-art research into the exploration of 2D magnets from the perspective of their magnetic interaction and order mechanisms is discussed. The properties of these magnets can be effectively modulated by varying the external parameters, such as the charge carrier doping, thickness effect, pressure and strain. The potential applications of heterostructures of these 2D magnets in terms of the interlayer coupling strength are reviewed, and the challenges and outlook for this field are proposed.
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da Silva, Elisabete Pinto, Wei Xu, Cecilia Föjer, Yvan Houbaert, Jilt Sietsma e Roumen H. Petrov. "Combined Martensite and Bainite Formation from Austenite Decomposition in HSLA Steel". Advanced Materials Research 922 (maggio 2014): 682–87. http://dx.doi.org/10.4028/www.scientific.net/amr.922.682.
Testo completoAbstract (sommario):
Recent studies have shown the possibility to induce time-dependent phase transformations during isothermal treatment between the martensite start (MS)temperature and martensite finish(Mf,)temperature, i.e. after initial martensite formation. Such treatments result in specific complex microstructures consisting of bainite, martensite and retained austenite, depending on the holding temperature and time. However, the nature of the isothermal transformations belowMSis not completely understood and issues like isothermal formation of martensite and bainite formation are still under discussion. The purpose of this study is to investigate the phase transformations from austenite, subsequent to initial martensite formation, during isothermal treatments at different temperatures of HSLA steel. The microstructure development was monitored by means of dilatometry and microstructural characterization of the transformation products by Optical Microscopy, Scanning Electron Microscope, Electron Backscatter Diffraction and X-ray diffraction. The phase transformations and complex competition and interactions between the different transformation mechanisms are discussed.
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Carneiro, Íris, e Sónia Simões. "Recent Advances in EBSD Characterization of Metals". Metals 10, n. 8 (13 agosto 2020): 1097. http://dx.doi.org/10.3390/met10081097.
Testo completoAbstract (sommario):
Electron backscatter diffraction (EBSD) has been attracting enormous interest in the microstructural characterization of metals in recent years. This characterization technique has several advantages over conventional ones, since it allows obtaining a wide range of characterization possibilities in a single method, which is not possible in others. The grain size, crystallographic orientation, texture, and grain boundary character distribution can be obtained by EBSD analysis. Despite the limited resolution of this technique (20–50 nm), EBSD is powerful, even for nanostructured materials. Through this technique, the microstructure can be characterized at different scales and levels with a high number of microstructural characteristics. It is known that the mechanical properties are strongly related to several microstructural aspects such as the size, shape, and distribution of grains, the presence of texture, grain boundaries character, and also the grain boundary plane distribution. In this context, this work aims to describe and discuss the possibilities of microstructural characterization, recent advances, the challenges in sample preparation, and the application of the EBSD in the characterization of metals.
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Chiou, W. A., C. S. Lin, P. C. Liu e M. Meshii. "EM of mechanical plated Zn coating on steel". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 880–81. http://dx.doi.org/10.1017/s0424820100172139.
Testo completoAbstract (sommario):
Zn and Fe-Zn alloy coatings on steel have been widely used for various applications due to their excellent corrosion resistance. The coatings are usually applied by electroplating or hot-dipping in molten Zn, but the mechanical plating process has also been used commercially and has been found advantageous over the conventional coating technologies in some applications with special requirements. The recent progress in investigating mechanically alloyed metals revealed interesting structural features including the formation of nanocrystalline and amorphous structures. Since the microstructures of electroplated and hot-dipped Zn coatings have been studied, and are known to be different from those of mechanically milled, the different properties of mechanically plated coating must be due to different microstructure. As no microstructural information is available in literature, this research project has been undertaken, along with a study of mechanical properties.Samples of commercially produced (Johnson Matthey Co.) fine-grained (325 mesh, or 44 (a.m) Zn (99.9%)flakes (1.1 μ m thick) were used as the coating materials.
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Roniewicz, Ewa. "The key role of skeletal microstructure in recognizing high-rank scleractinian taxa in the stratigraphical record". Paleontological Society Papers 1 (ottobre 1996): 187–206. http://dx.doi.org/10.1017/s1089332600000103.
Testo completoAbstract (sommario):
Skeleton microstructure of Recent scleractinians proves to be a valuable suprageneric taxonomical criterion, and the same has been stated with respect to Mesezoic corals where skeletonal preservation is aragonite. In paleontological practice, septal microstructure is decisive in discrimination of taxa among homeomorphic genera of different families. Similarities of microstructural features of some Recent and fossil corals encompass the genera in common taxa of higher ranks and allow for reconstruction of their presumed phylogeny.
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Huangfu, Binghan, Yujing Liu, Xiaochun Liu, Xiang Wu e Haowei Bai. "Anisotropy of Additively Manufactured Metallic Materials". Materials 17, n. 15 (24 luglio 2024): 3653. http://dx.doi.org/10.3390/ma17153653.
Testo completoAbstract (sommario):
Additive manufacturing (AM) is a technology that builds parts layer by layer. Over the past decade, metal additive manufacturing (AM) technology has developed rapidly to form a complete industry chain. AM metal parts are employed in a multitude of industries, including biomedical, aerospace, automotive, marine, and offshore. The design of components can be improved to a greater extent than is possible with existing manufacturing processes, which can result in a significant enhancement of performance. Studies on the anisotropy of additively manufactured metallic materials have been reported, and they describe the advantages and disadvantages of preparing different metallic materials using additive manufacturing processes; however, there are few in-depth and comprehensive studies that summarize the microstructural and mechanical properties of different types of additively manufactured metallic materials in the same article. This paper begins by outlining the intricate relationship between the additive manufacturing process, microstructure, and metal properties. It then explains the fundamental principles of powder bed fusion (PBF) and directed energy deposition (DED). It goes on to describe the molten pool and heat-affected zone in the additive manufacturing process and analyzes their effects on the microstructure of the formed parts. Subsequently, the mechanical properties and typical microstructures of additively manufactured titanium alloys, stainless steel, magnesium–aluminum alloys, and high-temperature alloys, along with their anisotropy, are summarized and presented. The summary indicates that the factors leading to the anisotropy of the mechanical properties of metallic AM parts are either their unique microstructural features or manufacturing defects. This anisotropy can be improved by post-heat treatment. Finally, the most recent research on the subject of metal AM anisotropy is presented.
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Olah, Arthur. "Mechanical Properties of Metal Coating Layers after Laser Heat". RECENT - REzultatele CErcetărilor Noastre Tehnice 21, n. 2 (19 novembre 2020): 72–77. http://dx.doi.org/10.31926/recent.2020.61.072.
Testo completoAbstract (sommario):
The goal of this research is to study the influence of the laser heat treatment on wearing resistance of metal coating layers. Results reveal the influence of microstructures and chemical composition of used electrodes on microhardness and wear resistance of metal coating layers. Laser heat treatment was applied after coating. Evaluation of results was made by observing the microstructures with metallographic microscopy, SEM/EDX and the mechanical properties were obtained by microhardness and wear resistance.
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Zhang, Fan, Andrew Allen, Lyle Levine, Gabrielle Long, Jan Ilavsky, Joshua Hammons e Pete Jemian. "In Situ Materials Characterization across Atomic and Microstructure Lengthscales". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 agosto 2014): C1072. http://dx.doi.org/10.1107/s205327331408927x.
Testo completoAbstract (sommario):
Advanced materials exhibit complex, hierarchical, and multiscale microstructures that control their performance. Today, optimization of these microstructures requires iterative, ex situ studies using multiple independent instruments with different samples. To address many of the grand challenges facing the material research community, it is desirable to correlate material performance under realistic processing and operating conditions with in situ characterization of material structures across atomic and microstructural length scales. To meet this need, we have made progress in recent years in developing a suite of materials-measurement techniques that combines ultra-small angle X-ray scattering, small-angle X-ray scattering, X-ray diffraction, X-ray photon correlation spectroscopy, and X-ray imaging. When making use of high energy x rays from a third generation synchrotron source, this combined suite of techniques not only enables investigation of thick, complex materials under real operating/ processing conditions, but also allows robust structural characterization over 7 decades of structural and microstructural feature sizes, from sub-angstrom to millimeters. Depending on the scattering characteristics of the material, it can cover an unprecedented 11 decades in scattering intensity. This arrangement also allows the combination of measurement techniques be determined solely by the user's needs, allowing an unparalleled flexibility in addressing any set of microstructure, structure and dynamics material-measurement requirements. In this presentation, we will focus on various considerations required to make this combined technique possible, and use data from a series of in situ studies of aluminum alloys as examples to demonstrate the unique capability of this instrument. We will also discuss the potential impact that multi-bend achromat lattice, a concept being embraced by the worldwide synchrotron community, has on this technique.
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Svensson, Lars Erik. "Microstructure and Properties of High Strength Weld Metals". Materials Science Forum 539-543 (marzo 2007): 3937–42. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3937.
Testo completoAbstract (sommario):
The recent investigations about high strength manganese – nickel alloyed weld metals are reviewed. The mechanical properties from different alloying concepts and the associated microstructures are compared. Interesting similarities regarding the tensile and impact strength is noted, while large variations in microstructure is found.
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Cui, Puchang, Geshu Xing, Zhisheng Nong, Liang Chen, Zhonghong Lai, Yong Liu e Jingchuan Zhu. "Recent Advances on Composition-Microstructure-Properties Relationships of Precipitation Hardening Stainless Steel". Materials 15, n. 23 (27 novembre 2022): 8443. http://dx.doi.org/10.3390/ma15238443.
Testo completoAbstract (sommario):
Precipitation hardening stainless steels have attracted extensive interest due to their distinguished mechanical properties. However, it is necessary to further uncover the internal quantitative relationship from the traditional standpoint based on the statistical perspective. In this review, we summarize the latest research progress on the relationships among the composition, microstructure, and properties of precipitation hardened stainless steels. First, the influence of general chemical composition and its fluctuation on the microstructure and properties of PHSS are elaborated. Then, the microstructure and properties under a typical heat treatment regime are discussed, including the precipitation of B2-NiAl particles, Cu-rich clusters, Ni3Ti precipitates, and other co-existing precipitates in PHSS and the hierarchical microstructural features are presented. Next, the microstructure and properties after the selective laser melting fabricating process which act as an emerging technology compared to conventional manufacturing techniques are also enlightened. Thereafter, the development of multi-scale simulation and machine learning (ML) in material design is illustrated with typical examples and the great concerns in PHSS research are presented, with a focus on the precipitation techniques, effect of composition, and microstructure. Finally, promising directions for future precipitation hardening stainless steel development combined with multi-scale simulation and ML methods are prospected, offering extensive insight into the innovation of novel precipitation hardening stainless steels.
27
Malik, Affan, Danqi Qu e Hui-Chia Yu. "Smoothed Boundary Method Electrochemical Simulation Framework for Complex Electrode Microstructures". ECS Meeting Abstracts MA2022-01, n. 46 (7 luglio 2022): 1968. http://dx.doi.org/10.1149/ma2022-01461968mtgabs.
Testo completoAbstract (sommario):
Battery and fuel cell electrodes possess highly complex microstructures: tortuous interparticle space, irregular particle surfaces, and various particle sizes. Additionally, coupled physical mechanisms, such as mass transport and electron transport, heat generation, and phase transformations, simultaneously occur during the electrode’s operations. All these combined complexity makes modeling electrochemical processes with explicit considerations of electrode microstructures very challenging. As such, electrode designs are still heavily relied on experimental trial-and-error methods even though modern computational resources have grown rapidly. Furthermore, experimental technologies have become very mature to reconstruct three-dimensional (3D) microstructures. The abundant microstructure data open a window for directly simulating the physical processes in complex microstructures. This talk will introduce an innovative simulation method using a continuous function to define complex microstructures. Since the irregular complex microstructure surfaces are implicitly described, this method no longer requires meshes conformal to the complex microstructures as in the conventional simulations. Thus, it allows us to simulate detailed electrochemical phenomena in complex electrode microstructures in an unprecedented pace with ease, especially for image-based, reconstructed microstructures. We will showcase several recent simulations to demonstrate the presented method, including phase transformations in porous graphite anode, hybrid electrodes, electrochemical impedance spectroscopy, and electrochemical processes in NMC-separator-graphite full-cell. The presented method is applicable to other electrochemical systems, and can be extended to include other physical mechanisms for further studying cycling-induced phenomena such as stress, heat, and Li-plating. Figure 1
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Lacaze, Jacques, e Alain Hazotte. "Directionally Solidified Materials: Nickel-base Superalloys for Gas Turbines". Textures and Microstructures 13, n. 1 (1 gennaio 1990): 1–14. http://dx.doi.org/10.1155/tsm.13.1.
Testo completoAbstract (sommario):
From the first forged turbine blades made of iron base alloys to the present nickel base single-grain turbine blades and vanes manufactured by directional solidification, an enormous amount of research has been directed to attaining the hottest possible combustion chamber temperatures in jet engines. Temperature has been increased by about 15 K each year for the last two decades, improving the thermodynamic efficiency of the engines. The more recent developments concern the manufacturing of single-grain parts made of nickel base superalloys with large amount of the γ′ hardening phase.This paper first presents the directional solidification process used to produce single-grain parts, the formation of as-cast microstructures and the defects that can arise during solidification. In the second part the thermal treatments that are applied to the nickel base superalloys in order to enhance their mechanical properties are detailed. The effect of crystallographic orientation and of the γ/γ′ microstructure on the mechanical properties is briefly presented, as well as the. microstructural changes that can possibly arise during service.
29
Lichioiu, Iuliana. "Pack Carburizing Effect on Microstructure and Hardness of 1.7131 Steel". RECENT - REzultatele CErcetărilor Noastre Tehnice 23, n. 3 (15 dicembre 2022): 112–17. http://dx.doi.org/10.31926/recent.2022.68.112.
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Chen, Shuying, Yang Tong e Peter Liaw. "Additive Manufacturing of High-Entropy Alloys: A Review". Entropy 20, n. 12 (6 dicembre 2018): 937. http://dx.doi.org/10.3390/e20120937.
Testo completoAbstract (sommario):
Owing to the reduced defects, low cost, and high efficiency, the additive manufacturing (AM) technique has attracted increasingly attention and has been applied in high-entropy alloys (HEAs) in recent years. It was found that AM-processed HEAs possess an optimized microstructure and improved mechanical properties. However, no report has been proposed to review the application of the AM method in preparing bulk HEAs. Hence, it is necessary to introduce AM-processed HEAs in terms of applications, microstructures, mechanical properties, and challenges to provide readers with fundamental understanding. Specifically, we reviewed (1) the application of AM methods in the fabrication of HEAs and (2) the post-heat treatment effect on the microstructural evolution and mechanical properties. Compared with the casting counterparts, AM-HEAs were found to have a superior yield strength and ductility as a consequence of the fine microstructure formed during the rapid solidification in the fabrication process. The post-treatment, such as high isostatic pressing (HIP), can further enhance their properties by removing the existing fabrication defects and residual stress in the AM-HEAs. Furthermore, the mechanical properties can be tuned by either reducing the pre-heating temperature to hinder the phase partitioning or modifying the composition of the HEA to stabilize the solid-solution phase or ductile intermetallic phase in AM materials. Moreover, the processing parameters, fabrication orientation, and scanning method can be optimized to further improve the mechanical performance of the as-built-HEAs.
31
Hu, Kaiyue, Jiayu Tian, Zhifu Zhou, Daming Zhao e Xiangjiu Guan. "Direct Z-scheme photocatalytic systems based on vdW heterostructures for water splitting and CO2 reduction: fundamentals and recent advances". Microstructures 4, n. 2 (2024): 2024021. http://dx.doi.org/10.20517/microstructures.2023.76.
Testo completoAbstract (sommario):
Photocatalytic water splitting and CO2 reduction are conducive to alleviating the increasingly serious environmental problems and ever-tightening energy problems. Among various modification strategies, constructing Z-scheme heterostructures and direct Z-scheme heterostructures, in particular, by mimicking natural photosynthesis, has been widely researched for the effective separation of photogenerated electrons and holes with strong redox ability. However, a low lattice matching degree of different semiconductors often results in serious crystal defects in the composite. Fortunately, van der Waals (vdW) heterostructures constructed through interlayer weak vdW interactions provide a remedy, which not only can ensure the high quality of Z-scheme heterostructures but also preserve the original properties of individual components and induces new properties at the heterogeneous interfaces. Herein, we introduce the fundamentals of direct Z-scheme vdW heterostructure and review the last five-year progress of direct Z-scheme vdW heterostructures for photocatalytic water splitting and CO2 reduction, highlighting the characteristics and fundamental modification principles of different heterostructures, aiming to provide informative principles for the design of advanced heterostructure photocatalysts for solar energy conversion.
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Zhu, Zhenlong, e Yilong Liang. "Prediction of Residual Stress of Carburized Steel Based on Machine Learning". Applied Sciences 10, n. 21 (2 novembre 2020): 7759. http://dx.doi.org/10.3390/app10217759.
Testo completoAbstract (sommario):
In recent years, the number of machine learning applications (especially those involving deep learning) applied to predicting and discovering material properties has been increasing. This paper is based on using microstructure and carbon content to train machine learning models to predict the residual stress of carburized steel. First, a semantic segmentation model of the material organization structure (SegModel-MOS) was constructed based on the AlexNet network and initially trained on the PASCAL VOC2012 dataset. Then, the trained model was fine-tuned on an enhanced homemade dataset consisting of optical microstructures. The experimental results show that SegModel-MOS can distinguish acicular martensite, retained austenite, and lath martensite in microstructures. Finally, we used both support vector machine (SVM) and decision tree (DT) algorithms to establish a mapping relationship between the microstructure, carbon content, and residual stress to predict the residual stress of steel from its microstructure and carbon content. The experiments verified that the prediction model constructed in this study exhibits high accuracy and can directly predict residual stress without requiring any long-term measurements. Thus, the developed model provides a new approach to the study of residual stress in steel.
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Tanaka, Hiroyuki, e Jacques Locat. "A microstructural investigation of Osaka Bay clay: the impact of microfossils on its mechanical behaviour". Canadian Geotechnical Journal 36, n. 3 (25 ottobre 1999): 493–508. http://dx.doi.org/10.1139/t99-009.
Testo completoAbstract (sommario):
A recent microstructural investigation of Osaka Bay clay sediments has revealed the presence of abundant microfossils, particularly in the marine layers, which appear to influence directly the microstructural framework of the sediments and eventually its geotechnical behaviour. The microfossils act as a structural component which provides a high compressibility when most of the interaggregate pore space is closed. In addition, they can introduce some bias on the measurements of physicochemical properties.Key words: microstructure, porosimetry, Atterberg's limits, compressibility, mineralogy, microfossils.
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Sarikaya, Mehmet, Katie L. Gunnison e Ilhan A. Aksay. "Seashells as a natural model to study ceramic-polymer composites". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 agosto 1989): 558–59. http://dx.doi.org/10.1017/s0424820100154767.
Testo completoAbstract (sommario):
Interests in ceramic/polymer composites are increasing mainly because of their superior physical properties for structural and electronic applications. Naturally produced composites, such as seashells, are ideal to study the formation, microstructure, and physical properties of these composites as these materials have far superior properties with well-defined microstructures than man-made ones which require complex fabrication techniques. In this paper, a summary of a recent study on the microstructure of abalone shell (Haliotis refuscens) will be described in conjunction with its mechanical properties.A longitudinal cross-section of abalone shell displays two types of microstructures: outer prismatic layer and inner nacreous layer. Two forms of CaCO3, calcite (rhombohedral, ) and aragonite (orthorhombic, Pmcn) constitute the inorganic component of the organic/ceramic composite in the prismatic and nacreous layers, respectively. The structure and properties of the nacreous will be described here as this is the part which provides a good combination of mechanical properties for the seashell.
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Brom, Krzysztof Roman, e Krzysztof Szopa. "Morphological diversity of microstructures occurring in selected recent bivalve shells and their ecological implications". Contemporary Trends in Geoscience 5, n. 2 (1 dicembre 2016): 104–12. http://dx.doi.org/10.1515/ctg-2016-0008.
Testo completoAbstract (sommario):
Abstract Environmental adaptation of molluscs during evolution has led to form biomineral exoskeleton – shell. The main compound of their shells is calcium carbonate, which is represented by calcite and/or aragonite. The mineral part, together with the biopolymer matrix, forms many types of microstructures, which are differ in texture. Different types of internal shell microstructures are characteristic for some bivalve groups. Studied bivalve species (freshwater species – duck mussel (Anodonta anatina Linnaeus, 1758) and marine species – common cockle (Cerastoderma edule Linnaeus, 1758), lyrate Asiatic hard clam (Meretrix lyrata Sowerby II, 1851) and blue mussel (Mytilus edulis Linnaeus, 1758)) from different locations and environmental conditions, show that the internal shell microstructure with the shell morphology and thickness have critical impact to the ability to survive in changing environment and also to the probability of surviving predator attack. Moreover, more detailed studies on molluscan structures might be responsible for create mechanically resistant nanomaterials.
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Wu, Fan. "Microstructure and Defect Study in Thin Film Heterostructure Materials". Nanoscience & Nanotechnology-Asia 10, n. 2 (25 febbraio 2020): 109–16. http://dx.doi.org/10.2174/2210681208666181008143408.
Testo completoAbstract (sommario):
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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Lichioiu, Iuliana. "Evaluation of Graphite Distribution-Part Thickness Ratio in Gray Cast Irons Microstructure". RECENT - REzultatele CErcetărilor Noastre Tehnice 24, n. 3 (2023): 256–59. http://dx.doi.org/10.31926/recent.2023.71.256.
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Ma, Wenping, Zhibo Yang, Mingxia Lu, Hongshi Ma, Chengtie Wu e Hongxu Lu. "Hierarchically structured biomaterials for tissue regeneration". Microstructures 4, n. 2 (2024): 2024014. http://dx.doi.org/10.20517/microstructures.2023.61.
Testo completoAbstract (sommario):
Repairing tissue defects caused by diseases and traumas presents significant challenges in the clinic. Recent advancements in biomaterials have offered promising strategies for promoting tissue regeneration. In particular, the exploration of 3D macro and microstructures of biomaterials has proven crucial in this process. The integration of macro, micro, and nanostructures facilitates the performance of biomaterials in terms of their mechanical properties, degradation rate, and distinctive impacts on cellular activities. In this review, we summarize the recent progress in biomaterials with hierarchical structures for tissue regeneration. We explore the various methods and strategies employed in designing biomaterials with hierarchical structures of different dimensions. The improvement of physicochemical properties and bioactivities by hierarchically structured biomaterials, including the regulation of mechanical properties, degradability, and the specific functions of cell behaviors, has been highlighted. Furthermore, the current applications of hierarchically structured biomaterials for tissue regeneration are discussed. Finally, we conclude by summarizing the developments of hierarchically structured biomaterials for tissue regeneration and provide future perspectives.
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Ma Xiuquan, 马修泉, 王力波 Wang Libo, 朱政武 Zhu Zhengwu, 王春明 Wang Chunming e 米高阳 Mi Gaoyang. "厚板高功率激光切割重铸层微观组织研究". Chinese Journal of Lasers 50, n. 4 (2023): 0402015. http://dx.doi.org/10.3788/cjl220611.
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Muribwathoho, Oritonda, Velaphi Msomi e Sipokazi Mabuwa. "Metal Matrix Composite Developed with Marine Grades: A Review". Materials Science Forum 1085 (20 aprile 2023): 77–89. http://dx.doi.org/10.4028/p-jub91t.
Testo completoAbstract (sommario):
Metal matrix composites (MMCs) are now one of the most significant groups of modern engineering materials as a result of the increased attention they have received in recent years. MMCs have recently been manufactured using a variety of technical specifications and techniques, with properties such as the ability to withstand thermal stability at the lowest possible cost, reduced weight and density, increased strength and toughness, and improved wear resistance. It is crucial to homogenize the distribution of the reinforcing phase during composite processing in order to generate particulate or fibrous solid microstructures, depending on the form of the reinforcing phase of the composite. This implies that new procedures must be employed to enhance the mechanical and microstructural properties of metal products. One of the answers to the above challenges is friction stir processing (FSP). FSP improves the surface quality, ductility, formability, strength, hardness, and fatigue life of metal alloys without altering the properties of metals in bulk. This study aims to review MMCs suitable for FSP-designed marine structures and identify knowledge gaps. According to the literature, MMCs are advanced materials capable of exhibiting microstructure, increased hardness, strength, excellent damping, wear, and reduced thermal expansion, making them suitable for a wide range of applications. Although FSP is recognized as a new secondary processing approach to enhance the microstructure and properties of MMCs, few studies have reported the production of MMCs suitable for marine applications. Therefore, this opens a large gap that needs to be filled and requires further investigation of MMCs development.
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Sroka, Marek, e Grzegorz Golański. "Microstructural and Mechanical Characterization of Alloys". Crystals 10, n. 10 (17 ottobre 2020): 945. http://dx.doi.org/10.3390/cryst10100945.
Testo completoAbstract (sommario):
This Special Issue on “Microstructural and Mechanical Characterization of Alloys” features eight papers that cover the recent developments in alloys (engineering materials), methods of improvement of strength and cyclic properties of alloys, the stability of microstructure, the possible application of new (or improved) alloys, and the use of treatment for alloy improvement.
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West, A. W. "Microstructural Development in Nb-Ti Multifilamentary Superconductors During Processing". Proceedings, annual meeting, Electron Microscopy Society of America 43 (agosto 1985): 190–91. http://dx.doi.org/10.1017/s0424820100117911.
Testo completoAbstract (sommario):
The influence of the filament microstructure on the critical current density values, Jc, of Nb-Ti multifilamentary superconducting composites has been well documented. However the development of these microstructures during composite processing is still under investigation.During manufacture, the multifilamentary composite is given several heat treatments interspersed in the wire-drawing schedule. Typically, these heat treatments are for 5 to 80 hours at temperatures between 523 and 573K. A short heat treatment of approximately 3 hours at 573K is usually given to the wire at final size. Originally this heat treatment was given to soften the copper matrix, but recent work has shown that it can markedly change both the Jc value and microstructure of the composite.
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Abedi, Mohammad, Dmitry Moskovskikh, Andrey Nepapushev, Veronika Suvorova, Haitao Wang e Valentin Romanovski. "Advancements in Laser Powder Bed Fusion of Carbon Nanotubes-Reinforced AlSi10Mg Alloy: A Comprehensive Analysis of Microstructure Evolution, Properties, and Future Prospects". Metals 13, n. 9 (19 settembre 2023): 1619. http://dx.doi.org/10.3390/met13091619.
Testo completoAbstract (sommario):
Laser powder bed fusion (L-PBF) stands out as a promising approach within the realm of additive manufacturing, particularly for the synthesis of CNT-AlSi10Mg nanocomposites. This review delves into a thorough exploration of the transformation in microstructure, the impact of processing variables, and the physico-mechanical characteristics of CNT-AlSi10Mg nanocomposites crafted via the L-PBF technique. Moreover, it consolidates a substantial corpus of recent research, proffering invaluable insights into optimizing L-PBF parameters to attain the desired microstructures and enhanced properties. The review centers its attention on pivotal facets, including the dispersion and distribution of CNTs, the formation of porosity, and their subsequent influence on wear resistance, electrical and thermal conductivity, tensile strength, thermal expansion, and hardness. In line with a logical progression, this review paper endeavors to illuminate the chemical composition, traits, and phase configuration of AlSi10Mg-based parts fabricated via L-PBF, juxtaposing them with their conventionally manufactured counterparts. Emphasis has been placed on elucidating the connection between the microstructural evolution of these nanocomposites and the resultant physico-mechanical properties. Quantitative data culled from the literature indicate that L-PBF-produced parts exhibit a microhardness of 151 HV, a relative density of 99.7%, an ultimate tensile strength of 70×103 mm3N.m, and a tensile strength of 756 MPa.
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Tribula, D., e J. W. Morris. "Creep in Shear of Experimental Solder Joints". Journal of Electronic Packaging 112, n. 2 (1 giugno 1990): 87–93. http://dx.doi.org/10.1115/1.2904363.
Testo completoAbstract (sommario):
Thermal fatigue failures of solder joints in electronic devices are a great concern in the electronics industry. Since the fatigue load is often in shear the details of thermal fatigue failure in shear are of particular interest. Recent work indicates that similar failure mechanisms operate in both thermal fatigue in shear and unidirectional creep in shear. Additionally, since the operative temperatures during thermal fatigue represent high solder homologous temperatures, creep deformation is certainly involved. These factors and the relative case of conducting creep experiments encourage the study of solder joints under shear creep conditions. This work presents steady state shear creep rate vs. shear stress data for several solder compositions, including the binary eutectic alloy and Pb-Sn alloyed with small amounts of Bi, Cd, In, and Sb, in a joint configuration. These data indicate that conventional creep mechanisms operate in the temperature and shear strain rate ranges studies. Extensive microstructural information is also reported. The microstructural evolution under creep conditions indicates that the instability of the as-cast binary Pb-Sn eutectic microstructure initiates creep failure. Changes of the as-solidified microstructure with the third element addition are reported as are the microstructural responses of each of these alloys to creep deformation. The efficacy of postponing the microstructural instability with the addition of small amounts of ternary elements is discussed.
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Azevedo, G., Ronaldo Barbosa, Elena V. Pereloma e Dagoberto Brandão Santos. "Intercritical Annealing Behaviour of an Ultrafine Grained C-Mn Steel Obtained by Hot Torsion Deformation". Materials Science Forum 550 (luglio 2007): 471–76. http://dx.doi.org/10.4028/www.scientific.net/msf.550.471.
Testo completoAbstract (sommario):
Several studies concerning ferrite grain refinement have been developed in recent the last years due to the recognised influence of such microstructures on steels properties. This work was focused on the evaluation of the microstructure and mechanical properties of an ultrafine grained CMn steel obtained by hot torsion deformation and intercritical annealing. After 5 min soaking at 900 and 1200°C, the samples of low carbon steel were quenched and then reheated. Hot torsion deformation was conducted at temperatures of 700 or 740°C. The torsion schedule consisted of 7 isothermal passes leading to a total true strain of ≈1 and generating an ultrafine and inhomogeneous microstructure with grain sizes of the order of 1-m, formed by strain-induced dynamic transformation (SIDT). The samples were heated up to 800oC and held for 1, 2 and 3 h. A more homogeneous microstructure and ferrite grain size were obtained after annealing The microhardness tests showed the reduction in hardness with the increase in annealing time. They also highlighted the effects of the ferrite grain size and the volume fractions of the microstructure constituents.
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Raabe, Dierk, Binhan Sun, Alisson Kwiatkowski Da Silva, Baptiste Gault, Hung-Wei Yen, Karo Sedighiani, Prithiv Thoudden Sukumar et al. "Current Challenges and Opportunities in Microstructure-Related Properties of Advanced High-Strength Steels". Metallurgical and Materials Transactions A 51, n. 11 (5 settembre 2020): 5517–86. http://dx.doi.org/10.1007/s11661-020-05947-2.
Testo completoAbstract (sommario):
Abstract This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, formable steels that are designed mainly as sheet products for the transportation sector. AHSS have often very complex and hierarchical microstructures consisting of ferrite, austenite, bainite, or martensite matrix or of duplex or even multiphase mixtures of these constituents, sometimes enriched with precipitates. This complexity makes it challenging to establish reliable and mechanism-based microstructure–property relationships. A number of excellent studies already exist about the different types of AHSS (such as dual-phase steels, complex phase steels, transformation-induced plasticity steels, twinning-induced plasticity steels, bainitic steels, quenching and partitioning steels, press hardening steels, etc.) and several overviews appeared in which their engineering features related to mechanical properties and forming were discussed. This article reviews recent progress in the understanding of microstructures and alloy design in this field, placing particular attention on the deformation and strain hardening mechanisms of Mn-containing steels that utilize complex dislocation substructures, nanoscale precipitation patterns, deformation-driven transformation, and twinning effects. Recent developments on microalloyed nanoprecipitation hardened and press hardening steels are also reviewed. Besides providing a critical discussion of their microstructures and properties, vital features such as their resistance to hydrogen embrittlement and damage formation are also evaluated. We also present latest progress in advanced characterization and modeling techniques applied to AHSS. Finally, emerging topics such as machine learning, through-process simulation, and additive manufacturing of AHSS are discussed. The aim of this viewpoint is to identify similarities in the deformation and damage mechanisms among these various types of advanced steels and to use these observations for their further development and maturation.
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Guo, Changqing, e Houbing Huang. "Design of super-elastic freestanding ferroelectric thin films guided by phase-field simulations". Microstructures 2, n. 4 (2022): 21. http://dx.doi.org/10.20517/microstructures.2022.20.
Testo completoAbstract (sommario):
Understanding the dynamic behavior of domain structures is critical to the design and application of super-elastic freestanding ferroelectric thin films. Phase-field simulations represent a powerful tool for observing, exploring and revealing the domain-switching behavior and phase transitions in ferroelectric materials at the mesoscopic scale. This review summarizes the recent theoretical progress regarding phase-field methods in freestanding ferroelectric thin films and novel buckling-induced wrinkled and helical structures. Furthermore, the strong coupling relationship between strain and ferroelectric polarization in super-elastic ferroelectric nanostructures is confirmed and discussed, resulting in new design strategies for the strain engineering of freestanding ferroelectric thin film systems. Finally, to further promote the innovative development and application of freestanding ferroelectric thin film systems, this review provides a summary and outlook on the theoretical modeling of freestanding ferroelectric thin films.
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Golvaskar, Mandar, Sammy A. Ojo e Manigandan Kannan. "Recent Advancements in Material Waste Recycling: Conventional, Direct Conversion, and Additive Manufacturing Techniques". Recycling 9, n. 3 (21 maggio 2024): 43. http://dx.doi.org/10.3390/recycling9030043.
Testo completoAbstract (sommario):
To improve the microstructure and mechanical properties of fundamental materials including aluminum, stainless steel, superalloys, and titanium alloys, traditional manufacturing techniques have for years been utilized in critical sectors including the aerospace and nuclear industries. However, additive manufacturing has become an efficient and effective means for fabricating these materials with superior mechanical attributes, making it easier to develop complex parts with relative ease compared to conventional processes. The waste generated in additive manufacturing processes are usually in the form of powders, while that of conventional processes come in the form of chips. The current study focuses on the features and uses of various typical recycling methods for traditional and additive manufacturing that are presently utilized to recycle material waste from both processes. Additionally, the main factors impacting the microstructural features and density of the chip-unified components are discussed. Moreover, it recommends a novel approach for recycling chips, while improving the process of development, bonding quality of the chips, microstructure, overall mechanical properties, and fostering sustainable and environmentally friendly engineering.
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Chougale, Sanket, Dirk Romeis e Marina Saphiannikova. "Magneto-Mechanical Enhancement of Elastic Moduli in Magnetoactive Elastomers with Anisotropic Microstructures". Materials 15, n. 2 (15 gennaio 2022): 645. http://dx.doi.org/10.3390/ma15020645.
Testo completoAbstract (sommario):
Magnetoactive elastomers (MAEs) have gained significant attention in recent years due to their wide range of engineering applications. This paper investigates the important interplay between the particle microstructure and the sample shape of MAEs. A simple analytical expression is derived based on geometrical arguments to describe the particle distribution inside MAEs. In particular, smeared microstructures are considered instead of a discrete particle distribution. As a consequence of considering structured particle arrangements, the elastic free energy is anisotropic. It is formulated with the help of the rule of mixtures. We show that the enhancement of elastic moduli arises not only from the induced dipole–dipole interactions in the presence of an external magnetic field but also considerably from the change in the particle microstructure.
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Zhou, Xi, Yongna Zhang, Jun Yang, Jialu Li, Shi Luo e Dapeng Wei. "Flexible and Highly Sensitive Pressure Sensors Based on Microstructured Carbon Nanowalls Electrodes". Nanomaterials 9, n. 4 (1 aprile 2019): 496. http://dx.doi.org/10.3390/nano9040496.
Testo completoAbstract (sommario):
Wearable pressure sensors have attracted widespread attention in recent years because of their great potential in human healthcare applications such as physiological signals monitoring. A desirable pressure sensor should possess the advantages of high sensitivity, a simple manufacturing process, and good stability. Here, we present a highly sensitive, simply fabricated wearable resistive pressure sensor based on three-dimensional microstructured carbon nanowalls (CNWs) embedded in a polydimethylsiloxane (PDMS) substrate. The method of using unpolished silicon wafers as templates provides an easy approach to fabricate the irregular microstructure of CNWs/PDMS electrodes, which plays a significant role in increasing the sensitivity and stability of resistive pressure sensors. The sensitivity of the CNWs/PDMS pressure sensor with irregular microstructures is as high as 6.64 kPa−1 in the low-pressure regime, and remains fairly high (0.15 kPa−1) in the high-pressure regime (~10 kPa). Both the relatively short response time of ~30 ms and good reproducibility over 1000 cycles of pressure loading and unloading tests illustrate the high performance of the proposed device. Our pressure sensor exhibits a superior minimal limit of detection of 0.6 Pa, which shows promising potential in detecting human physiological signals such as heart rate. Moreover, it can be turned into an 8 × 8 pixels array to map spatial pressure distribution and realize array sensing imaging.