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microstructure characterization and evaluation of mechanical properties in 2A97 aluminum-lithium alloys welded by stationary shoulder friction stir welding

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JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T 2022年 16卷 416-432页

作者： Sun, G. D. Zhou, L. Liu, Y. N. Yang, H. F. Jiang, J. T. Li, G. A. Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China Harbin Inst Technol Weihai Shandong Prov Key Lab Special Welding Technol Weihai 264209 Peoples R China Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China AVCC Beijing Inst Aeronaut Mat Beijing 100095 Peoples R China

2A97 Al-Li alloy joints with the thickness of 1.5 mm were fabricated by stationary shoulder friction stir welding (SSFSW) under rotational speeds of 600-1000 rpm and a fixed welding speed of 200 mm/min. As the rotational speeds increased, the grain sizes of the nugget zone (NZ) kept almost constant with the presence of zigzag defects. The electron back-scattered diffraction (EBSD) analysis suggested that the initial crystal orientation with near < 001 >parallel to TD and < 001 > kWD textural components exhibited weaker anisotropy induced by the severe shearing deformation. The dynamic recrystallization (DRX) mechanisms were clarified in the transition from low-angle grain boundaries (LAGBs) to high-angle grain boundaries (HAGBs). In contrast to the conventional FSW joints of Al-Li alloys, the dis-persions were indexed as Al11Cu5Mn3, Al2Cu within the grains, and Al-Cu-Mn-Zn phase at the grain boundaries in the SSFSW joints. The T-1, delta'/beta' and theta' precipitates were detected in the base metal (BM), and the theta' precipitates were dissolved in the heat affected zone (HAZ). However, those strengthening precipitates were absent in the NZ. The variation of the ultimate tensile strength first increased and then decreased with the increasing rota-tional speeds. Moreover, the joint obtained at a rotational speed of 1000 rpm exhibited the best combination of strength and ductility. The defect-free joints failed in the thermo-mechanically affected zone (TMAZ), which corresponded to the hardness minima posi-tions (HMP). However, an abnormal fracture occurred in the NZ due to the presence of weak-bonding areas and curved band structures. (c) 2021 The Authors. Published by Elsevier B.V.

关键词： Aluminum-lithium alloys SSFSW microstructure characterization Mechanical properties

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Effect of cellulose nanofiber addition on the microstructure characterization and nano-mechanical behavior of interfacial transition zones in recycled concrete

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JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T 2024年 33卷 7572-7585页

作者： Deng, Fangqian Cao, Cong Chi, Yin Xu, Lihua Wuhan Univ Sci & Technol Sch Urban Construct Wuhan 430065 Peoples R China Wuhan Univ Sch Civil Engn Wuhan 430072 Peoples R China Hubei Inst Measurement & Testing Technol Dept Mech Wuhan 430223 Peoples R China

The aggregate-matrix interfacial transition zone (ITZ) is known as the weakest link in recycled concrete. Cellulose nanofiber (CNF), as a green and renewable nano-reinforcement material, proven effective in modifying the mechanical properties of cementitious composites, is considered for incorporation into recycled concrete for the first time. This study investigates the effect of CNF addition on the microstructure characterization and nanomechanical behavior of ITZs in recycled concrete. The elastic modulus distribution and 2D microstructure topology of the old/new aggregate-matrix interfaces are characterized through statistic nanoindentation technique for different CNF dosages. The results show that the width of the new ITZ is between 40 mu m and 60 mu m, while the width of the old ITZ is between 30 mu m and 50 mu m. The old ITZ has better mechanical properties than the new ITZ, where a remarkable low elastic modulus area at the new ITZ is observed. The incorporation of an appropriate amount of CNF can significantly improve the nano-properties of the new ITZ due to the increased hydration degree of cement particles at the recycled aggregate-matrix interface. Moreover, a dense network structure around the cement hydration products is formed with improved compactness, resulting in an increase in the overall mechanical strength of the recycled aggregate concrete material. The research outcome provides a viable solution for improving the performance of concrete containing recycled aggregates and urges the green and sustainable development in concrete industry.

关键词： Recycled concrete Interfacial transition zone Nanoindentation microstructure characterization Elastic modulus

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microstructure characterization of Battery Materials Based on Voxelated Image Data: Computation of Active Surface Area and Tortuosity

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JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2024年第12期171卷 120514-120514页

作者： Daubner, S. Nestler, B. Karlsruhe Inst Technol Inst Nanotechnol INT D-76344 Eggenstein Leopoldshafen Germany Imperial Coll London Dyson Sch Design Engn London England Karlsruhe Inst Technol Inst Appl Mat IAM MMS D-76131 Karlsruhe Germany

The reliable computation of microstructure metrics such as specific surface area and tortuosity factors is key to bridge the gap between the battery microscale and fast, homogenized cell models. In this work, we present an approach to compute the surface area of phases based on pixelated image data which is both easy-to-implement and computationally efficient. The concept is inspired from the diffuse surface representation in phase-field methods. Subsequently, the approach is validated and compared with common python libraries on two benchmark cases and actual battery microstructure data. The results underline the reliability and fast computational performance of the approach. Furthermore, the concept of through-feature connectivity in pixelated image data is introduced and explored to quantify the reliability of tortuosity factor computations. Overall, this work enhances the computational tools to bridge the scale from battery microstructures to cell models and gives an overview of state-of-the-art methodology. The developed code is published to further accelerate the scientific progress in this field.

关键词： phase-field method intercalation batteries microstructure characterization Electrode Kinetics Theory and Modelling

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microstructure characterization and age hardening response of Mg-8Sn-2Al alloy with Bi, Ag addition

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MATERIALS TODAY COMMUNICATIONS 2024年 40卷

作者： Li, Wandong Zuo, Mingwei Hebei Petr Univ Technol Chengde 067000 Peoples R China

The effects of Bi and Ag addition on the microstructure and age hardening response of Mg-8Sn-2Al alloy were investigated in this study. The Mg 2 Sn phase distributed along grain boundaries was observed in as-cast Mg-8Sn2Al alloys and disappeared after solution treatment due to the Sn dissolution into alpha-Mg matrix. However, a majority of Mg 2 Sn phase disappeared and few Mg 2 Sn particles still existed in the solid solutioned Mg-8Sn-2Al alloys containing Bi element. Mg 2 Sn precipitates formed in all peak-aged alloys. And Al, Bi and Ag elements are enriched in the areas of lath-shaped and spherical Mg 2 Sn precipitates in peak-aged Mg-8Sn-2Al-1.5Bi-1Ag alloy. Bi and Ag elements can act as heterogeneous nucleation sites and restrict the growth of precipitates to improve the age hardening response of Mg-8Sn-2Al alloy. Meanwhile, the undissolved Mg 3 Bi 2 phase or early precipitated Mg 3 Bi 2 phase during ageing treatment probably change the morphology and elements distribution of Mg 2 Sn precipitates. In addition, Ag and Bi atoms play a role on grain refinement and solution strengthening in Mg-8Sn-2Al alloy. Therefore, the micro-hardness value of peak-aged Mg-8Sn-2Al-1.5Bi-1Ag alloy increased to 69.9 HV from 47.4 HV of solid solutioned Mg-8Sn-2Al alloy. The precipitation behaviour, refined second phase, grain refinement and solute atoms synergistically made contributions to the strength improvement. The roles of Bi and Ag elements on improving age hardening response and precipitates characteristics are discussed in this study, which provides an important reference for exploring aged Mg -Sn alloys.

关键词： microstructure characterization Age hardening response Mg-8Sn-2Al alloy Bi and Ag addition Precipitation behaviour

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microstructure characterization of IG110 and reactor pebble graphite using synchrotron micro X-ray diffraction 2D maps

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SURFACE AND INTERFACE ANALYSIS 2021年第1期53卷 90-99页

作者： He, Zhoutong Zhang, Can Tang, Hui Liu, Ming Marsden, Barry J. Zhou, Xingtai Chinese Acad Sci Shanghai Inst Appl Phys Shanghai 201800 Peoples R China Univ Manchester Sch MACE Nucl Graphite Res Grp Manchester M13 9LP Lancs England

Knowledge about the microstructure of nuclear graphite is critical to the understanding of its irradiation behavior in the reactor. Using micro X-ray diffraction (mu XRD) two-dimensional (2D) maps, the crystallite character of IG110 and reactor pebble graphite was characterized at the submillimeter range with a spatial resolution of about 5 mu m. Various structures in the nuclear graphite were identified by comparing the X-ray diffraction peak intensity, position, and full width at half maximum (FWHM) 2D maps. The two-peak feature of the FWHM histograms seen in pebble graphite may be related to the raw coke and natural graphite used as raw materials. With these results, it can be concluded that the mu XRD 2D map is an effective method to characterize the microstructure of nuclear graphite.

关键词： micro X-ray diffraction 2D maps microstructure characterization molten salt reactor nuclear graphite

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Liposomal Freight and Their Advanced microstructure characterization Techniques for Food and Nutraceutical Delivery

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ACS FOOD SCIENCE & TECHNOLOGY 2024年第9期4卷 2013-2035页

作者： Aggarwal, Punita Sah, Sunil Kumar Ravichandiran, Velayutham Roy, Subhadeep Kaity, Santanu Natl Inst Pharmaceut Educ & Res NIPER Kolkata 700054 India

Liposome-based delivery technology has gained potential interest in the food sector because it is nontoxic, biocompatible, completely biodegradable, and nonimmunogenic. Numerous products have been researched to develop a safe, effective, and stable delivery system using liposomal technology. In this overview, we focus on different kinds of liposomal technology, how they are made, and how they are used to improve the safety and shelf life of foods and supplements. We also highlight several cutting-edge microstructure characterization methods that can be used to study liposomal micro- or nanodelivery systems in the food and nutraceutical industries. The regulatory approval process varies from country to country and market to market;therefore, finding the most appropriate, reliable, fast, and accurate characterization method is essential. Liposomes have low production cost, lack toxicity, and have innate versatility, representing promising new avenues for delivering food and nutraceuticals. Innovative methods are needed to characterize and standardize such food delivery systems because of the possibility of novel risks. Familiarity with the most recent developments in the characterization of liposomes could prove helpful. Moreover, these methods are not only limited to the characterization of liposomes but can also be used to describe other micro- or nanobased food and nutraceutical delivery systems.

关键词： liposomes food industry nutraceuticals lipid-based delivery system microstructure characterization

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Nondestructive microstructure characterization of Tempered Martensitic Steels Through Data Fusion

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JOURNAL OF NONDESTRUCTIVE EVALUATION, DIAGNOSTICS AND PROGNOSTICS OF ENGINEERING SYSTEMS 2022年第4期5卷 041003页

作者： Mawhin, M. A. Seuaciuc-Osorio, T. Elect Power Res Inst EPRI 1300 West WT Harris Blvd Charlotte NC 28262 USA Elect Power Res Inst EPRI Nucl Innovat 1300 West WT Harris Blvd Charlotte NC 28262 USA

Determination of the present condition of grade 91 steels commonly used in fossil plants presents an ongoing challenge for the industry. Current individual methods of nondestructive evaluations (NDEs) are challenged to reliably determine steel microstructures and are impractical for deployment over large areas such as piping systems. This work investigates the discriminatory potential of an integral assessment combining multiple NDE techniques: magnetic methods (including coercive field, incremental permeability, and Barkhausen noise), thermoelectric power, and ultrasonic methods (including attenuation, backscatter, and absorption). Using a sample inventory of manufactured representative microstructure conditions in thin-walled tubes, five of the eight microstructure conditions could be identified by data fusion. Combined magnetic methods appeared as a primary technique, as this can identify four out of the eight conditions, while the ultrasonic methods can be seen as complimentary tests to increase confidence in classification and identify a fifth condition.

关键词： nondestructive evaluation microstructure characterization magnetic material characterization thermoelectric power ultrasonic material characterization data fusion electromagnetics materials testing thermal technique ultrasonics

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Steel Material microstructure characterization using Knowledge Distillation Based Transformer Neural Networks for Data-Efficient Ultrasonic NDE System

Steel Material Microstructure Characterization using Knowled...

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IEEE International Ultrasonics Symposium (IUS)

作者： Zhang, Xin Saniie, Jafar Illinois Inst Technol Embedded Comp & Signal Proc ECASP Res Lab Dept Elect & Comp Engn Chicago IL USA

ISBN: (数字)9781665466578

ISBN: (纸本)9781665466578

Material microstructure characterization for texture recognition using ultrasonic testing has been widely used to examine the physical and structural integrity of materials. For system automation, Neural Network (NN) can be used to characterize the material texture accurately. However, training and deploying NNs requires substantial computational resources. In this study, we propose to use the knowledge distillation (KD) method and introduce a response-based teacher-student KD training framework to train NNs to find the optimal solution. In addition, a lightweight Ultrasonic microstructure characterization Transformer NN (TNN): UMCTNet, is proposed to recognize material textures using ultrasonic images. Training using the KD mechanism improves the data-efficiency of NNs by transferring knowledge from pre-trained NN models. In addition, TNN utilizes a simple network architecture with the attention mechanism resulting in reducing training and execution time. A data-efficient Ultrasonic microstructure characterization Convolutional NN: UMCCNet, is trained as the teacher model using ultrasonic images to distill the pre-trained knowledge into the UMCTNet with high accuracy and data-efficiency. To examine the results, an ultrasonic testbed platform was assembled, and Cscanning was created to acquire volumetric ultrasonic data from three different heat-treated steel blocks to train NNs. By applying the KD framework to train UMCTNet, we obtained the training and testing accuracy of 99.91% and 99.27% respectively, and the highest image throughput of 192 images/seconds on testing to characterize steel material microstructures.

关键词： Data-Efficient Ultrasonic NDE System Knowledge Distillation Transformer Neural Network Convolutional Neural Network microstructure characterization

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Non-Negligible Effect of Additives in the Application of Successive Self-Nucleation and Annealing Fractionation for microstructure characterization of Matrix Resin in Additive-Containing Samples

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ACS APPLIED POLYMER MATERIALS 2021年第9期3卷 4634-4644页

作者： Yue, Yang Sha, Xuan Wang, Fushan Gao, Yan Zhang, Liangliang Zhu, Yuguo Wang, Xinxin Feng, Jiachun Fudan Univ Dept Macromol Sci State Key Lab Mol Engn Polymers Shanghai 200433 Peoples R China China Natl Petr Corp CNPC Lanzhou Petrochem Corp Lanzhou 730060 Peoples R China

Successive self-nucleation and annealing (SSA) is a convenient and versatile thermal fractionation technique that has been extensively used to characterize the chain microstructure of semicrystalline polymers. In practical applications, commercial products containing various additives are frequently tested by SSA to analyze the resin structure. In this case, whether the presence of additives affects the SSA result of matrix resin is worth considering. In this work, four additives including two nucleating agents (beta-NA and alpha-NA), a lubricant, and an acid scavenger were purposefully added into the same polypropylene random copolymer (PPR) matrix resin, and SSA fractionation results of PPR with and without these additives were comparatively studied. It was found that SSA results of PPR containing diverse additives and pristine PPR are different. The results of small-angle X-ray scattering monitoring of the melting process of the "standard" crystal proved that additives altered the thermal stability of the ordered structure in the polymer upon heating. It is the variation in thermal stability that led to the change in the ideal self-nucleation temperature determined by the self-nucleation experiment, which is a crucial reason why different additives affected the SSA results of the same matrix resin. This work reminds that in the practical application of SSA to characterize the chain microstructure of the resin matrix for samples containing additives, the influence of additives cannot be ignored.

关键词： successive self-nucleation and annealing fractionation microstructure characterization additive matrix resin polypropylene random copolymer

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Estimation of fretting fatigue lifetime in heterogeneous material based on microstructure characterization and multi-scale homogenization

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THEORETICAL AND APPLIED FRACTURE MECHANICS 2023年第1期126卷

作者： Wang, Can Li, Lingxiao Zinovev, Aleksandr Terentyev, Dmitry Wang, Dagang Wahab, Magd Abdel Univ Ghent Fac Engn & Architecture Dept Elect Energy Met Mech Constructions & Syst Soete Lab B-9052 Ghent Belgium Zhengzhou Univ Sch Mech & Power Engn Zhengzhou 450001 Henan Peoples R China SCK CEN Inst Nucl Mat Sci Struct Mat Grp B-2400 Mol Belgium China Univ Min & Technol Sch Mechatron Engn Xuzhou 221116 Peoples R China

Fretting fatigue is a complex phenomenon that is affected by multiaxial stress and contact problems. In the contact surface, due to the cyclic load, a relatively small displacement is generated, and the stress concentration is established as well. To assess the fretting fatigue endurance complimentary to experimental efforts, the Finite Element Method (FEM) has become a useful tool combined with theoretical approaches. Meanwhile, most (if not all) of commercially available structural materials can be regarded as heterogeneous materials due to the existence of secondary phases and some fabrication defects and porosity. Therefore, to further understand the mechanism of fretting fatigue, knowledge of the material's microstructure is important. In this study, several microstructure characterization techniques are applied to characterize precipitates and micro-voids in aluminium alloy AA2024-T3. These techniques are Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS). To account for the precipitates, the homogenization method is adopted in this study. Additionally, a 3D structure non-destructive reconstruction technique is applied to obtain accurate information on micro-voids. The fretting fatigue lifetime is estimated by using the critical plane approach combined with the theory of critical distance. The numerical results are compared with experimental data showing a good agreement. The influence of micro-voids on the fretting fatigue endurance is studied and discussed as well.

关键词： Fretting fatigue Heterogeneous microstructure characterization Homogenization method Precipitates Micro-voids TCD method

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