Journal articles: 'Microstructure and Characterization'

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Lannutti, J. J. "Characterization and Control of Compact Microstructure." MRS Bulletin 22, no. 12 (December 1997): 38–44. http://dx.doi.org/10.1557/s0883769400034734.

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The microstructure and properties of a ceramic component are largely predetermined by the processes and process controls used to manufacture them. The metric for success in manufacturing is often based on gross density. For example, optimizing pressure-density response, maximizing overall density, and minimizing springback and delaminations in powder pressing all focus on characterization and control of the overall (macroscopic) state of a powder compact. Unfortunately this focus on macroscopic effects has contributed to a general neglect of the compact at the microstructural level. Process-control variables in powder compaction have been defined and discussed by many workers, but their quantitative application to predict and control compaction behavior is limited. Advances in characterization technology and computer modeling now allow us to quantitatively characterize and simulate microstructures more easily. These and other tools can help provide the scientific and technological foundation necessary to predict and control microstructure and microstructural evolution during processing.

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Lomholt, Trine C., Yoshitaka Adachi, Jeremy Peterson, Russell Steel, Karen Pantleon, and Marcel A. J. Somers. "Microstructure Characterization of Friction Stir Spot Welded TRIP Steel." Advanced Materials Research 409 (November 2011): 275–80. http://dx.doi.org/10.4028/www.scientific.net/amr.409.275.

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Transformation Induced Plasticity (TRIP) steels have not yet been successfully joined by any welding technique. It is desirable to search for a suitable welding technique that opens up for full usability of TRIP steels. In this study, the potential of joining TRIP steel with Friction Stir Spot Welding (FSSW) is investigated. The aim of the study is to investigate whether acceptable welds can be produced, and additionally, to obtain an understanding of the microstructural changes during welding. The microstructure was investigated with a combination of microscopical techniques with the aim of identifying the transformations occurring during welding. Reflected light microscopy, scanning electron microscopy, and electron backscatter diffraction were among the methods applied for detailed investigations. The microstructure adjacent to the welds can generally be subdivided in two thermo-mechanically affected zones (TMAZ), and two heat-affected zones (HAZ). The dual behavior of the microstructure in the zones is related to the two transition temperatures in steel: A1 and A3. In parts of the TMAZ the microstructure contains ultra fine-grained ferrite. This finding parallels the observation in thermo-mechanically processed steels, where severe deformation at elevated temperatures is used to produce ultra fine-grained microstructures. Several possible transformation mechanisms could in principle explain the development of ultra fine-grained ferrite, e.g. dynamic recrystallization, strain-induced ferrite transformation and dynamic recovery.

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Dong, Qin, Zhong Wei Yin, Hu Lin Li, Yang Mao, and Geng Yuan Gao. "3D Reconstruction of Microstructure for Centrifugal Casting Babbitt Lining of Bimetallic Bearing Based on Mimics." Key Engineering Materials 841 (May 2020): 94–98. http://dx.doi.org/10.4028/www.scientific.net/kem.841.94.

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Babbitt alloys are the most commonly used bearing materials for low speed diesel engines due to their excellent attributes. An understanding of microstructures in these alloys is important, especially quantifying microstructure in 3D. In this study, we used serial sectioning technique to reconstruct 3D microstructure of tin-based Babbitt lining of bimetallic bearing made by centrifugal casting based on medical software Mimics. The morphologies and volume fraction of hard phase particles and α-Sn matrix were obtained. The volume fraction of the reconstructed microstructures was verified by the area fraction of the metallographic sections, which proved a higher reliability of 3D reconstruction. The results of 3D microstructural characterization and analysis will enable a comprehensive understanding the structure–property relationships of these materials.

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Han, Xiaobing, Jie Gao, Tao Chen, Libing Qian, Houhua Xiong, and Zhiyuan Chen. "Application Progress of PALS in the Correlation of Structure and Properties for Graphene/Polymer Nanocomposites." Nanomaterials 12, no. 23 (November 24, 2022): 4161. http://dx.doi.org/10.3390/nano12234161.

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Giving a deep insight into the microstructure, and realizing the correlation between microstructure and properties is very important to the precise construction of high-performance graphene/polymer nanocomposites (GPN). For the promising application in microstructure characterization, much attention has been focused on the effective technique of positron annihilation lifetime spectroscopy (PALS). Based on the introduction of the basic principle, this review summarized the application progress of PALS in the correlation of microstructure and properties for GPN, especially for the characterization of free volume and interfacial interaction, and the correlation of these microstructures and properties.

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Baker, Ian. "Exploring the Microstructure of Ice." AM&P Technical Articles 176, no. 1 (January 1, 2018): 27–30. http://dx.doi.org/10.31399/asm.amp.2018-01.p027.

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Abstract Characterizing ice and snow is important not only for building accurate climate models, but also for activities such as relating the mechanical properties of sea ice to its microstructure so that the interaction of ice with ships and structures can be better understood. This article describes the microstructural characterization of ice. Many microstructural characterization techniques that can be applied to other materials also can be used to examine ice.

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Ott, J., A. Burghardt, D. Britz, S. Majauskaite, and F. Mücklich. "Qualitative and Quantitative Microstructural Analysis of Copper for Sintering Process Optimization in Additive Manufacturing Applications." Practical Metallography 58, no. 1 (January 1, 2021): 32–47. http://dx.doi.org/10.1515/pm-2020-0002.

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Abstract This work will present possibilities for the characterization of copper powder green bodies and sintered copper microstructures during pressureless sintering. The introduction of new parameters to microstructural characterization based on qualitative and quantitative microstructural analysis will facilitate the systematic optimization of the sintering process. As a result of the specific evaluation of the microstructure evolution, conventional isothermal sintering could be successfully replaced by multi-step temperature profiles, thus achieving sintering densities of more than 99 % by simultaneously reducing process time. This systematic optimization of the sintering process of Cu through specific microstructural analysis may now be applied to sinter-based manufacturing technologies such as Binder Jetting and Metal Powder Injection Moulding, enabling the manufacture of complex and highly conductive Cu parts for applications in electronics.

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Vurobi, Selauco, Thiago Ferreira de Andrade, and Osvaldo Mitsuyuki Cintho. "Utilization of Color Metallography in Characterization of a Modified SAE 4118H Steel Submitted to Isothermal Treatments." Materials Science Forum 805 (September 2014): 242–47. http://dx.doi.org/10.4028/www.scientific.net/msf.805.242.

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A modified SAE 4118H steel was subjected to isothermal treatments between 700 °C and 400 oC every 50 °C range, with the intention of evaluating the decomposition of austenite at constant temperature. It was varied time of stay in the isothermal treatment between 15 and 28800 seconds depending on the treatment temperature. After each isothermal treatment and standard metallographic preparation, the samples were etched with color metallography reagents for revealing the microstructure obtained. At temperatures of 700oC to 550°C the steel showed microstructure composed of ferrite and pearlite. Between 500oC and 400°C bainitic microstructure was quickly formed. The reduction of treatment temperature provided finer microstructures, which increased the hardness of steel. With the use of color metallography reagents, excellent contrast for determining the volume fraction of microstructural constituents formed isothermally was obtained, helping the study of isothermal decomposition of austenite.

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Průcha, Vojtěch, Zdeněk Jansa, Jiří Šimeček, Ondřej Žďánský, and Antonín Kříž. "Characterization of Microstructure of Hadfield Steel." Solid State Phenomena 270 (November 2017): 265–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.270.265.

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In this contribution, the preparation of metallographic sections and characterization of the microstructure of manganese Hadfield steels are discussed. The purpose of this paper is to provide information relevant to microstructural characterization of these steels. This type of steel is characterized by high resistance to abrasive wear, which is provided by surface strengthening through strain-induced martensitic transformation. Strengthening complicates the preparation of metallographic sections because the final microstructure can be influenced by the process and it can be eventually misinterpreted. Great attention must be paid to the choice of the etchant and the etching procedure. This contribution describes the entire metallographic characterization procedure, including the evaluation of grain size, micro-cleanness and presence of carbides on grain boundaries. It provides information for manufacturers and those, whose process and examine Hadfield steels with respect to their processing routes, wear resistance, non-magnetic properties and other aspects.

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Salomonsson, Kent, and Anders E. W. Jarfors. "Three-Dimensional Microstructural Characterization of Cast Iron Alloys for Numerical Analyses." Materials Science Forum 925 (June 2018): 427–35. http://dx.doi.org/10.4028/www.scientific.net/msf.925.427.

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In this paper, we aim at characterizing three different cast iron alloys and their microstructural features, namely lamellar, compacted and nodular graphite iron. The characterization of microscopic features is essential for the development of methods to optimize the behavior of cast iron alloys; e.g. maximize thermal dissipation and/or maximize ductility while maintaining strength. The variation of these properties is commonly analyzed by metallography on two-dimensional representations of the alloy. However, more precise estimates of the morphologies and material characteristics is obtained by three-dimensional reconstruction of microstructures. The use of X-ray microtomography provides an excellent tool to generate high resolution three-dimensional microstructure images. The characteristics of the graphite constituent in the microstructure, including the size, shape and connectivity, were analyzed for the different cast iron alloys. It was observed that the lamellar and compacted graphite iron alloys have relatively large connected graphite morphologies, as opposed to ductile iron where the graphite is present as nodules. The results of the characterization for the different alloys were ultimately used to generate finite element models.

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Zhang, Fan, Andrew Allen, Lyle Levine, Gabrielle Long, Jan Ilavsky, Joshua Hammons, and Pete Jemian. "In Situ Materials Characterization across Atomic and Microstructure Lengthscales." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1072. http://dx.doi.org/10.1107/s205327331408927x.

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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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Fukugauchi, Cristina Sayuri, Antonio dos Reis Faria Neto, Rosinei Batista Ribeiro, and Marcelo dos Santos Pereira. "Microstructural Characterization of Dual and Multiphase Steels Applied to Automotive Industry." Materials Science Forum 775-776 (January 2014): 146–50. http://dx.doi.org/10.4028/www.scientific.net/msf.775-776.146.

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TRIP (Transformation Induced Plasticity) and DP (Dual-Phase) steels are written in a new series of steels which present excellent mechanical properties. As for microstructure aspect, TRIP steels consist on a ferrite matrix with a second phase dispersion of other constituents, such as bainite, martensite and retained austenite, while dual-phase steels consist on martensite dispersion in a ferrite matrix. In order to identify the different microconstituents present in these materials, microstructure characterization techniques by optical microscopy (using different etchants: LePera, Heat-Tinting and Nital) and scanning electron microscopy were carried out. This being so, microstructures were correlated with mechanical properties of materials, determined by means of tensile tests. It is concluded that steels assisted by TRIP effect have a strength and elongation relation higher than the dual-phase one. With microstructure characterization, it was observed phases present in these materials microstructure.

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Santos, Dagoberto Brandão, Élida G. Neves, and Elena V. Pereloma. "Effect of Processing Route on Mechanical Behavior of C-Mn Multiphase High Strength Cold Rolled Steel." Materials Science Forum 539-543 (March 2007): 4375–80. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4375.

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The multiphase steels have complex microstructures containing polygonal ferrite, martensite, bainite, carbide and a small amount of retained austenite. This microstructure provides these steels with a high mechanical strength and good ductility. Different thermal cycles were simulated in the laboratory in order to create the microstructures with improved mechanical properties. The samples were heated to various annealing temperatures (740, 760 or 780°C), held for 300 s, and then quickly cooled to 600 or 500°C, where they were soaked for another 300 s and then submitted to the accelerated cooling process, with the rates in the range of 12-30°C/s. The microstructure was examined at the end of each processing route. The mechanical behavior evaluation was made by microhardness testing. The microstructural characterization involved optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The use of multiple regression analysis allowed the establishment of quantitative relationship between the microstructural parameters, cooling rates and mechanical properties of the steel.

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Robson, J. D., O. Engler, C. Sigli, A. Deschamps, and W. J. Poole. "Advances in Microstructural Understanding of Wrought Aluminum Alloys." Metallurgical and Materials Transactions A 51, no. 9 (July 8, 2020): 4377–89. http://dx.doi.org/10.1007/s11661-020-05908-9.

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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.

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Zhang, Feng, Yongfeng Song, Xiongbing Li, and Peijun Ni. "Long-Term Ultrasonic Benchmarking for Microstructure Characterization with Bayesian Updating." Metals 12, no. 7 (June 25, 2022): 1088. http://dx.doi.org/10.3390/met12071088.

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Ultrasonic non-destructive characterization is an appealing technique for identifying the microstructures of materials in place of destructive testing. However, the existing ultrasonic characterization techniques do not have sufficient long-term gage repeatability and reproducibility (GR&R), since benchmarking data are not updated. In this study, a hierarchical Bayesian regression model was utilized to provide a long-term ultrasonic benchmarking method for microstructure characterization, suitable for analyzing the impacts of experimental setups, human factors, and environmental factors on microstructure characterization. The priori distributions of regression parameters and hyperparameters of the hierarchical model were assumed and the Hamilton Monte Carlo (HMC) algorithm was used to calculate the posterior distributions. Characterizing the nodularity of cast iron was used as an example, and the benchmarking experiments were conducted over a 13-week transition period. The results show that updating a hierarchical model can increase its performance and robustness. The outcome of this study is expected to pave the way for the industrial uptake of ultrasonic microstructure characterization techniques by organizing a gradual transition from destructive sampling inspection to non-destructive one-hundred-percent inspection.

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Talmon, Yeshayahu. "Cryo-TEM of amphiphilic polymer and amphiphile/polymer solutions." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 876–77. http://dx.doi.org/10.1017/s0424820100150216.

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To achieve complete microstructural characterization of self-aggregating systems, one needs direct images in addition to quantitative information from non-imaging, e.g., scattering or Theological measurements, techniques. Cryo-TEM enables us to image fluid microstructures at better than one nanometer resolution, with minimal specimen preparation artifacts. Direct images are used to determine the “building blocks” of the fluid microstructure; these are used to build reliable physical models with which quantitative information from techniques such as small-angle x-ray or neutron scattering can be analyzed.To prepare vitrified specimens of microstructured fluids, we have developed the Controlled Environment Vitrification System (CEVS), that enables us to prepare samples under controlled temperature and humidity conditions, thus minimizing microstructural rearrangement due to volatile evaporation or temperature changes. The CEVS may be used to trigger on-the-grid processes to induce formation of new phases, or to study intermediate, transient structures during change of phase (“time-resolved cryo-TEM”). Recently we have developed a new CEVS, where temperature and humidity are controlled by continuous flow of a mixture of humidified and dry air streams.

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Jurado, Mayra, Gerardo Altamirano, Jorge Leobardo Acevedo, and Alvaro Aguirre. "Microstructural Characterization of the Laser Welding in a Nickel Based Superalloy." MRS Advances 4, no. 63 (2019): 3463–73. http://dx.doi.org/10.1557/adv.2019.421.

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ABSTRACTIn this research it was experimentally analyzed the effect of the parameters of the Pulsed Micro Laser Welding Process Nd:YAG on the microstructural behavior of a nickel base superalloy (IN-738). For this purpose, different laser welding tests were performed on samples subjected to different heat treatment conditions obtained from the gas turbine blades. The influence of the power and the speed welding of the applied process and heat treatment condition on the weld geometry, microstructure and mechanical properties was determined. The microstructures of the obtained welds were characterized by scanning electron microscopy and Vickers hardness tests. In general, alternatives to homogenize and rejuvenate the microstructure of the base material are proposed in order to avoid the formation and propagation of cracks. The results are discussed mainly in terms of the present phases and decomposition of carbides, which considerably affect the weldability of the IN-738 superalloy. This study provides useful information for the subsequent restoration of the 2nd step turbine blades by using of the Laser Welding Process Nd:YAG.

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Li, Hui, Zhanglong Zhao, Yongquan Ning, Hongzhen Guo, and Zekun Yao. "Characterization of Microstructural Evolution for a Near-α Titanium Alloy with Different Initial Lamellar Microstructures." Metals 8, no. 12 (December 10, 2018): 1045. http://dx.doi.org/10.3390/met8121045.

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The effects of initial lamellar thickness on microstructural evolution and deformation behaviors of a near-α Ti-5.4Al-3.7Sn-3.3Zr-0.5Mo-0.4Si alloy were investigated during isothermal compression in α + β phase field. Special attention was paid to microstructural conversion mechanisms for α lamellae with different initial thicknesses. The deformation behaviors, including flow stress, temperature sensitivity, and strain rate sensitivity, and processing maps and their dependence on initial lamellar thickness were discussed. The detailed microstructural characterizations in different domains of the developed processing maps were analyzed. The results showed that the peak efficiency of power dissipation decreased with increasing initial lamellar thickness. The interaction effects with different extents of globularization, elongating, kinking, and phase transformation of lamellar α accounted for the variation in power dissipation. The flow instability region appeared to expand more widely for thicker initial lamellar microstructures during high strain rate deformation due to flow localization and local lamellae kinking. The electron backscatter diffraction (EBSD) analyses revealed that the collaborative mechanism of continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) promoted the rapid globularization behavior for the thinnest acicular initial microstructure, whereas in case of the initial thick lamellar microstructure, CDRX leading to the fragmentation of lamellae was the dominant mechanism throughout the deformation process.

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Cheepu, Muralimohan, D. Venkateswarlu, P. Nageswara Rao, V. Muthupandi, K. Sivaprasad, and Woo Seong Che. "Microstructure Characterization of Superalloy 718 during Dissimilar Rotary Friction Welding." Materials Science Forum 969 (August 2019): 211–17. http://dx.doi.org/10.4028/www.scientific.net/msf.969.211.

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In the present study, dissimilar friction welding between super alloy 718 and carbon steel friction welded to evaluate the formation of microstructure in the weld interface and in superalloy 718. The temperature during friction welding at weld interface was recorded to determine the temperature effect on the microstructural changes on alloy 718 side. The finite element modeling of weld interface temperature, deformation and stresses were evaluated and validated with the experimental results. The microstructural observation along with the weld interface and adjacent regions are studied. The effect of friction welding on superalloy weld interface and microstructural formation were investigated under electron backscattered diffraction analysis to evaluate the grain size measurements. The effect of thermomechanical action on the microstructure was evaluated by texture analysis.

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Huo, Qinghuan. "Mechanical Performance and Microstructural Characterization of Light Alloys." Materials 16, no. 17 (August 29, 2023): 5915. http://dx.doi.org/10.3390/ma16175915.

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The present Special Issue titled “Mechanical Performance and Microstructural Characterization of Light Alloys” aims to report the close relation between mechanical performance and microstructure in light alloys, such as Al, Mg, Ti, and their alloys [...]

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Kalemba, Izabela, and Mateusz Kopyściański. "Electron Microscopy Characterization of Friction Stir Welded 5083-H111 and 7075-T651 Aluminum Alloys." Solid State Phenomena 231 (June 2015): 93–99. http://dx.doi.org/10.4028/www.scientific.net/ssp.231.93.

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The microstructural characterization of butt friction stir welds of two different wrought aluminum alloys (work-hardened and heat treated) were studied. The detailed studies on the FSW process of dissimilar Al alloys are limited. In particular, the weld microstructure requires deeper characterization to better understand the phenomena occurring during mixing of dissimilar alloys.The characterization of friction stir welds was performed by scanning electron microscopy (an energy dispersive spectroscopy and an electron backscattered diffraction) and transmission electron microscopy. The dissimilar weld microstructure is complex, resembling a vortex-like structure. The microstructure of weld was highly asymmetrical with regard to the weld centerline. The research revealed a change in grain size in particular areas of the stirred zone. Recrystallization in the stirredzone occurred in particular areas in an irregular manner.

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Ceschini, Lorella, Anders E. W. Jarfors, Alessandro Morri, Andrea Morri, Fabio Rotundo, Salem Seifeddine, and Stefania Toschi. "High Temperature Tensile Behaviour of the A354 Aluminum Alloy." Materials Science Forum 794-796 (June 2014): 443–48. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.443.

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The high temperature tensile behaviour of the A354 casting aluminum alloy was investigated also evaluating the influence of secondary dendrite arm spacing (SDAS). Cast specimens were produced through a gradient solidification equipment, obtaining two different classes of SDAS, namely 20-25 µm (fine microstructure) and 40-50 µm (coarse microstructure). After hot isostatic pressing and T6 heat treatment, the samples underwent mechanical characterization both at room and high temperature (200 °C). Results of tensile tests and hardness measurements were related to the microstructural features and fractographic characterization, in order to investigate the effect of microstructure and high temperature exposure on the mechanical behaviour of the alloy.

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Li, Yan, Chuan Xin Zhai, and Chun Hua Xu. "Microstructure Characterization of Rapid Solidification Al Alloy Foil." Materials Science Forum 694 (July 2011): 847–50. http://dx.doi.org/10.4028/www.scientific.net/msf.694.847.

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The AlMn and AlMnSi foils were fabricated by rapid solidification technology. The phase transformation temperatures, microstructures and distribution of elements were characterized by Differential Scanning Calorimetry (DSC), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD) and Energy Disperse Spectroscopy (EDS) respectively. The result shows that the phases of AlMn7 nanofoil conclude Al, Al6Mn and quasicrystal phase, the crystal size is about 120nm; the phases of AlMn5Si5 nanofoil conclude Al, Al4.01MnSi0.74 and Al9Mn3Si, the crystal size is about 60nm. The phase transformation temperatures of AlMn7 and AlMn5Si5 nanofoils are 543K and over 873K, respectively. The microstructure morphology of AlMn7 nanofoil are rod, block and petal-like, but the microstructure morphology of AlMn5Si5 nanofoil is homogeneous globular.

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Liu, Lishuai, Peng Wu, Yanxun Xiang, and Fu-Zhen Xuan. "Autonomous characterization of grain size distribution using nonlinear Lamb waves based on deep learning." Journal of the Acoustical Society of America 152, no. 3 (September 2022): 1913–21. http://dx.doi.org/10.1121/10.0014289.

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Characterization of grain microstructures of metallic materials is crucial to materials science and engineering applications. Unfortunately, the universal electron microscopic methodologies can only capture two-dimensional local observations of the microstructures in a time-consuming destructive way. In this regard, the nonlinear ultrasonic technique shows the potential for efficient and nondestructive microstructure characterization due to its high sensitivity to microstructural features of materials, but is hindered by the ill-posed inverse problem for multiparameter estimation induced by the incomplete understanding of the complicated nonlinear mechanical interaction mechanism. We propose an explainable nonlinearity-aware multilevel wavelet decomposition-multichannel one-dimensional convolutional neural network to hierarchically extracts multilevel time-frequency features of the acoustic nonlinearity and automatically model latent nonlinear dynamics directly from the nonlinear ultrasonic responses. The results demonstrate that the proposed approach establishes the complex mapping between acoustic nonlinearity and microstructural features, thereby determining the lognormal distribution of grain size in metallic materials rather than only average grain size. In the meantime, the integration of the designed nonlinearity-aware network and the quantitative analysis of component importance provides an acceptable physical explainability of the deep learning approach for the nonlinear ultrasonic technique. Our study shows the promise of this technique for real-time in situ evaluation of microstructural evolution in various applications.

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Arguelles, Andrea P., Olivia Cook, Nancy Huang, Christopher M. Kube, and Allison Beese. "Ultrasonic nondestructive characterization and its role in the development and implementation of additive manufacturing processes." Journal of the Acoustical Society of America 152, no. 4 (October 2022): A93. http://dx.doi.org/10.1121/10.0015654.

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Advancements in manufacturing processes, such as metal 3D printing, are deeply reliant on our understanding of the resulting internal features and microstructures that dictate material behavior. Microstructure characterization is often relegated to techniques that require extensive sample sectioning and surface preparation, which are inherently limited to a small portion of the bulk material. In this presentation, I will show how elastic wave propagation methods (namely, ultrasonic testing) can be combined with physics-based models to extract microstructural parameters in fit-for-service parts. Example results are given for binder jet printed metals (namely, stainless steel 316 and SS316 infiltrated with bronze) where microstructure is characterized over large volumes nondestructively. These methods are correlated to both destructive metrics of microscale features and mechanical properties, which are linked to processing conditions and sample geometry. Finally, I will provide a broader outlook for the impact these techniques may have on the development and implementation of quality assurance protocols for additively manufactured parts.

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Král, Petr, Jiří Dvořák, Marie Kvapilová, Milan Svoboda, Viktor Beneš, Petr Ponížil, Ondřej Šedivý, and Vàclav Sklenička. "Quantitative Characterization of Microstructure in Copper Processed by Equal-Channel Angular Pressing." Materials Science Forum 667-669 (December 2010): 235–40. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.235.

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Experiments were conducted on extremely coarse-grained pure copper to evaluate the effect of equal-channel angular pressing (ECAP) on microstructure evolution in the as-pressed state and after creep exposure using various stereological methods. The microstructure formed by severe plastic deformation is an unusual structure which can be hardly characterized only by the mean grain size especially after low number of ECAP passes. The purpose of this paper is a detailed examination of (sub)boundaries and grain boundaries in the microstructures of the pressed material. The inhomogeneity of deformed microstructures is also evaluated. The detailed description of ECAP microstructures should contribute to the better understanding of mechanical properties of the pressed materials.

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Skowroński, Łukasz. "Optical and Microstructural Characterization of Thin Layers." Crystals 10, no. 9 (August 26, 2020): 749. http://dx.doi.org/10.3390/cryst10090749.

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The microstructure and optical properties of layers strongly depend on the method of synthesis. This Special Issue on “Optical and Microstructural Characterization of Thin Layers” is a collection of papers on the relationships between the growth conditions and specific properties of thin films.

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Barcellona, A., L. Cannizzaro, and D. Palmeri. "Microstructural Characterization of Thermo-Mechanical Treated TRIP Steels." Key Engineering Materials 344 (July 2007): 71–78. http://dx.doi.org/10.4028/www.scientific.net/kem.344.71.

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The increasing demand for the reduction of automobiles CO2 emissions for environmental preservation leads the automotive industries towards the mechanical components weight reduction. Sheet steels with multiphase microstructures exhibit favourable combinations of strength and ductility. The so called TRIP steels have a metastable microstructure that consists of a continuous ferrite matrix containing a dispersion of hard second phases martensite and bainite. These steels also contain retained austenite, at room temperature, that represents the source of the TRansformation Induced Plasticity effect. When the material is subjected to deformation step, the retained austenite transforms itself into martensite; the produced martensite delays the onset of necking resulting in a product with high total elongation, excellent formability and high crash energy absorption. In the present research the steel TRIP 800 zinc coated has been subjected to different thermo–mechanical treatments in order to evaluate the relation between microstructure of material and TRIP effects. Whit this aim the microstructural analysis has been performed and the evaluation of content of different phases has been made by means of the image analysis techniques. The relation among the strain level, the content of different phases, the thermal treatments and the work hardening properties of materials have been valued. Furthermore, it has been also highlighted the dependence of the bake hardening properties of material on the different thermo-mechanical treatments.

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Wusatowska-Sarnek, Agnieszka M., Gautam Ghosh, Gregory B. Olson, Martin J. Blackburn, and Mark Aindow. "Characterization of the microstructure and phase equilibria calculations for the powder metallurgy superalloy IN100." Journal of Materials Research 18, no. 11 (November 2003): 2653–63. http://dx.doi.org/10.1557/jmr.2003.0371.

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The microstructure of the Ni-based superalloy IN100 processed by a powder metallurgy route was evaluated to reveal the structures, volume fractions, distributions, and chemistries of the various phases present. These data were compared with those predicted by computational thermodynamics. It is shown that the microstructural parameters expected on the basis of global equilibrium conditions differ significantly from those measured experimentally. However, modification of these calculations by use of constrained and successive equilibria compensated for kinetic effects and led to accurate (or better) predictions of phase volume fractions and chemistries in this alloy. This demonstrated that such modified phase equilibria calculations could be powerful tools for modeling microstructures, even in complex multicomponent alloys processed under nonequilibrium conditions.

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Dugar, Jaka, Awais Ikram, and Franci Pušavec. "Comparative Characterization of Different Cutting Strategies for the Sintered ZnO Electroceramics." Applied Sciences 11, no. 20 (October 11, 2021): 9410. http://dx.doi.org/10.3390/app11209410.

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Sintered zinc oxide (ZnO) ceramic is a fragile and difficult-to-cut material, so finishing operations demand handling cautious and accurate surface tolerances by polishing, grinding, or machining. The conventional machining methods based on grinding and lapping offer limited productivity and high scalability; therefore, their incapacity to prepare tight tolerances usually end up with uncontrolled edge chipping and rough surfaces in the final products. This study investigates microstructural features with surface roughness in a comparative mode for conventional milling and abrasive waterjet cutting (AWJ). Edge topography and roughness maps are presented in this study to weigh the benefits of AWJ cutting over the conventional material removal methods by altering the feed rates. The porosity analysis implies that the differences during the multi-channel processing of varistors, which tend to alter the microstructure, should in turn exhibit a different response during cutting. The surface roughness, edge contours, and porosity generation due to shear forces are interpreted with the help of 3D optical and electron microscopy. The results demonstrate that the surface microstructure can have a noteworthy impact on the machining/cutting characteristics and functionality, and in addition, mechanical properties of ZnO varistors can fluctuate with non-uniform microstructures.

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Tan, Wen Liang, and Christopher R. McNeill. "X-ray diffraction of photovoltaic perovskites: Principles and applications." Applied Physics Reviews 9, no. 2 (June 2022): 021310. http://dx.doi.org/10.1063/5.0076665.

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Solar cells based on organic–inorganic hybrid perovskite materials have emerged as the most efficient next-generation thin-film solar cells within just a decade of research and show great promise for commercialization. As control of the thin-film microstructure of the perovskite layer is a key factor enabling high photovoltaic efficiency, good stability, and successful up-scaling of high-quality perovskite thin films for commercialization, a reliable and accurate characterization of the thin-film microstructure is paramount. X-ray diffraction (XRD)-based techniques, including conventional laboratory-based XRD and synchrotron-based grazing-incidence wide-angle x-ray scattering, are widely used to probe the microstructure of photovoltaic perovskite thin films. Nevertheless, it is common for these XRD experiments to be poorly executed and diffraction data to be improperly interpreted. This review focuses on principles of XRD techniques and their application for the characterization of the perovskite thin-film microstructure. Fundamentals of XRD techniques are presented with a strong emphasis on best practices in data collection and analysis. Approaches for the reliable and accurate extraction of microstructural information from diffraction data are discussed, including the need for simulating diffraction patterns. Applications of XRD techniques in characterizing perovskite thin films are demonstrated for both three-dimensional and layered hybrid perovskites, covering various microstructural aspects including phase identification and quantification, texture analysis, microstrain, and macrostrain as well as in situ and operando characterization. The additional subtleties and complexities associated with the XRD characterization of layered hybrid perovskites due to a more complex thin-film microstructure are discussed. Common mistakes and pitfalls that lead to misinterpretation of diffraction data are also highlighted.

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Chiang, S.-K. "Microstructural characterization of AIN sintered with Y2O3." Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 578–79. http://dx.doi.org/10.1017/s0424820100104959.

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Aluminum nitride's high thermal but low electrical conductivity make it a potential ceramic packaging material. Processing history, however, can have significant effects on these properties and studies aimed at correlating them to the processing and microstructure are sparse.Pure AIN cannot be readily sintered without additives. Addition of Y2O3 significantly improves its densification behavior and the results presented here concern microstructural analysis of AIN sintered with Y2O3.High-purity AIN powder (containing 1.24% oxygen impurity) with 3 or 9 weight% Y2O3 added was sintered in N2 at 1850°C for 1 hour followed by a further 3 hours at 1900°C. Samples made using this treatment were >95% dense. Specimens for microstructural investigation were prepared using standard techniques and examined using a JEOL 200 CX AEM.The general microstructure of all specimens consists of AIN grains with pockets of intergranular phase(s) located at triple points and some grain boundaries (FIG. 1).

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Sroka, Marek, and Grzegorz Golański. "Microstructural and Mechanical Characterization of Alloys." Crystals 10, no. 10 (October 17, 2020): 945. http://dx.doi.org/10.3390/cryst10100945.

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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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Burke, M. G., and M. K. Miller. "A Comparison of Tem and Apfim to the Interpretation of Modulated Microstructures." Proceedings, annual meeting, Electron Microscopy Society of America 43 (August 1985): 70–71. http://dx.doi.org/10.1017/s042482010011742x.

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Interpretation of fine-scale microstructures containing high volume fractions of second phase is complex. In particular, microstructures developed through decomposition within low temperature miscibility gaps may be extremely fine. This paper compares the morphological interpretations of such complex microstructures by the high-resolution techniques of TEM and atom probe field-ion microscopy (APFIM).The Fe-25 at% Be alloy selected for this study was aged within the low temperature miscibility gap to form a <100> aligned two-phase microstructure. This triaxially modulated microstructure is composed of an Fe-rich ferrite phase and a B2-ordered Be-enriched phase. The microstructural characterization through conventional bright-field TEM is inadequate because of the many contributions to image contrast. The ordering reaction which accompanies spinodal decomposition in this alloy permits simplification of the image by the use of the centered dark field technique to image just one phase. A CDF image formed with a B2 superlattice reflection is shown in fig. 1. In this CDF micrograph, the the B2-ordered Be-enriched phase appears as bright regions in the darkly-imaging ferrite. By examining the specimen in a [001] orientation, the <100> nature of the modulations is evident.

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Clarke, D. R. "Critical issues in ceramic microstructures." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 640–41. http://dx.doi.org/10.1017/s0424820100165665.

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As the number and variety of ceramic materials have grown so rapidly in the last few decades, ranging from silicon nitride structural ceramics to the perovskite superconductors to the ferroelectric oxides to semiconducting sensors, the number of scientific and technical issues has also grown rapidly. Many of the basic questions relate to the role the microstructures play in determining the observed physical behavior but increasingly it is not the geometric properties of the microstructure that are of central concern but rather compositional variations and associated electrical characteristics. These require the continued development of microscopy techniques to complement the tremendous advances in microstructural understanding that have already been made possible by microscopy in the past.Since the role of microscopy is such a broad one, only a few of the most generic problems in microstructure characterization will be described in this talk. The topics selected include the characterization of intergranular films in liquid-phase sintered ceramics, the charge distribution at interfaces and the associated space charge, the epitaxial growth of oxides on oxide substrates, and the use of fluorescence imaging to identify phases and non-destructively measure local strains.

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Kulosa, Matthias, Matthias Neumann, Martin Boeff, Gerd Gaiselmann, Volker Schmidt, and Alexander Hartmaier. "A Study on Microstructural Parameters for the Characterization of Granular Porous Ceramics Using a Combination of Stochastic and Mechanical Modeling." International Journal of Applied Mechanics 09, no. 05 (July 2017): 1750069. http://dx.doi.org/10.1142/s1758825117500697.

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To correlate the mechanical properties of granular porous materials with their microstructure, typically porosity is being considered as the dominant parameter. In this work, we suggest the average coordination number, i.e., the average number of connections that each grain of the porous material has to its neighboring grains, as additional — and possibly even more fundamental — microstructural parameter. In this work, a combination of stochastic and mechanical modeling is applied to study microstructural influences on the elastic properties of porous ceramics. This is accomplished by generating quasi-two-dimensional (2D) and fully three-dimensional (3D) representative volume elements (RVEs) with tailored microstructural features by a parametric stochastic microstructure model. In the next step, the elastic properties of the RVEs are characterized by finite element analysis. The results reveal that the average coordination number exhibits a very strong correlation with the Young’s modulus of the material in both 2D and 3D RVEs. Moreover, it is seen that quasi-2D RVEs with the same average coordination number, but largely different porosities, only differ very slightly in their elastic properties such that the correlation is almost unique. This finding is substantiated and discussed in terms of the load distribution in microstructures with different porosities and average coordination numbers.

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Brahami, Abdessamad, Benattou Bouchouicha, Mokhtar Zemri, and Jamal Fajoui. "Fatigue Crack Growth Rate, Microstructure and Mechanical Properties of Diverse Range of Aluminum Alloy: a Comparison." Mechanics and Mechanical Engineering 22, no. 1 (August 12, 2020): 329–40. http://dx.doi.org/10.2478/mme-2018-0028.

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AbstractIn practice for all metallic materials, damage by fatigue usually takes in two steps, the appearance of an initial crack which then grows as a function of the present microstructure. The objective of this study is to identify the elements influencing the fatigue crack growth rate on aluminum alloys of different microstructures. Characterization tests and microstructural analysis on 2024-T3, 5083-H22, 6082-T6 and 7075-T6 shades have been carried out. Based on the experimental results obtained, AA7075-T6 has the best fatigue crack rate resistance which is explained by its behavior as well as the nature and dispersive distribution of the secondary element.

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Brahami, Abdessamad, Benattou Bouchouicha, Mokhtar Zemri, and Jamal Fajoui. "Fatigue Crack Growth Rate, Microstructure and Mechanical Properties of Diverse Range of Aluminum Alloy: A Comparison." Mechanics and Mechanical Engineering 22, no. 4 (September 2, 2020): 1453–62. http://dx.doi.org/10.2478/mme-2018-0113.

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AbstractIn practice for all metallic materials, damage by fatigue usually takes in two steps, the appearance of an initial crack which then grows as a function of the present microstructure. The objective of this study is to identify the elements influencing the fatigue crack growth rate on aluminum alloys of different microstructures. Characterization tests and microstructural analysis on 2024-T3, 5083-H22, 6082-T6 and 7075-T6 shades have been carried out. Based on the experimental results obtained, AA7075-T6 has the best fatigue crack rate resistance which is explained by its behavior as well as the nature and dispersive distribution of the secondary element.

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Li, Jian Zhang, Li Tong Zhang, Lai Fei Cheng, Yong Dong Xu, Sheng Ru Qiao, Gui Qiong Jiao, Jun Zhang, and Xin Gang Luan. "Materials Characterization in Continuous Fiber-Reinforced Ceramic Composites Served in Simulating Environment." Key Engineering Materials 351 (October 2007): 31–36. http://dx.doi.org/10.4028/www.scientific.net/kem.351.31.

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Materials characterization is a crucial issue in the development and application of new materials. Materials characterization aims to mine and acquire characteristic information and their evolution in the materials. It mainly includes three important topics which are microstructural characterization, properties characterization, and environmental degradation. In this paper, characterization techniques about these topics were discussed for C/SiC composites and a characterization system was preliminarily established. All these characterization research and their results further the better understanding of the relationship between microstructure and properties and of the failure mechanisms in the C/SiC composites.

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Cui, Ning, Qianqian Wu, Jin Wang, Binjiang Lv, and Fantao Kong. "The Directional Solidification, Microstructural Characterization and Deformation Behavior of β-Solidifying TiAl Alloy." Materials 12, no. 8 (April 12, 2019): 1203. http://dx.doi.org/10.3390/ma12081203.

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A β-solidifying Ti–43Al–2Cr–2Mn–0.2Y alloy was directionally solidified by the optical floating zone melting method. The microstructure is mainly characterized by γ/α2 lamellae with specific orientations, which exhibits straight boundaries. The β phase is randomly distributed in the lamellar microstructure, indicating that the β phase cannot be directionally solidified. The directional solidification of γ/α2 lamellae was not affected by the precipitation of the β phase. Hot compression tests show that the deformation behavior of the β-containing lamellar microstructure also exhibits the anisotropic characteristic. The deformation resistance of the lamellae is lowest when the loading axis is aligned 45° to the lamellar interface. Microstructural observation shows that the decomposition of the lamellar microstructure tends to begin around the β phase, which benefits from the promotion of a soft β phase in the deformation. Moreover, the deformation mechanism of the lamellar microstructure was also studied. The bulging of the γ phase boundaries, the decomposition of α2 lamellae and the disappearance of γ/γ interfaces were considered as the main coarsening mechanisms of the lamellar microstructure.

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Chen, Y. L. "Microstructure of high-energy product Fe-Nd-B magnequench ribbons." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 826–27. http://dx.doi.org/10.1017/s0424820100145479.

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Melt-spun Fe-Nd-B MAGNEQUENCH® ribbons have been produced by Croat et al. with energy products in excess of 10 MG.Oe using a relatively narrow window of composition and quenching speed. The hard magnetic phase has subsequently been identified as the Nd2Fe14B compound which has a very high anisotropy field. The microstructure of the MAGNEQUENCH® ribbon which has a maximum energy product of 14.1 MG•0e was found to consist of equiaxed Nd2Fe14B grains surrounded by a very thin intergranular film. This paper presents the results of some of our earlv work on the microstructural characterization of high energy product MAGNEQUENCH® ribbons having nominal compositions of Nd13Fe82.6B4.4 and Nd15Fe79.9B5.1. The purpose of this investigation was to characterize the microstructures of various MAGNEQUENCH® ribbons for correlation with their magnetic properties.

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Go Roa, Stewart M., Eduardo Magdaluyo Jr., and Wojciech Gierlotka. "Microstructural Characterization and Properties of Sn-Ag-Cu (SAC) Compound Induced by Zn Alloying." Nano Hybrids and Composites 16 (June 2017): 33–36. http://dx.doi.org/10.4028/www.scientific.net/nhc.16.33.

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The microstructural properties and intermetallic (IMC) formation of Sn-Ag-Cu (SAC) through varying amounts of zinc were examined in this study while having tin held at constant composition. Samples were prepared and heated in a furnace for 168 hours to achieve complete solidification and homogenization. Results showed relatively fine microstructure primarily containing Sn dendrites, eutectic, and pro-eutectic phases. Microstructures for each alloy was similar for which majority of them formed copper-based IMCs and Sn dendrites. The alloy (0.7Sn-0.15Ag-0.1Cu-0.05Zn) containing minimal amount of zinc with high amount of Ag resulted to high Vickers hardness number. Structural analysis showed that these group of alloys composed mainly of β-Sn, Cu6Sn5, and Ag3Sn.

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Francisco, Fernanda Regina, Joao Roberto Moro, Evaldo Jose Corat, R. A. Campos, and Osmar Bagnato. "Effect of Heat Treatment on Microstructure and Mechanical Property of Diamonds Substrates Brazed with Active Filler Metal." Defect and Diffusion Forum 353 (May 2014): 254–58. http://dx.doi.org/10.4028/www.scientific.net/ddf.353.254.

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This study aims to identify the effects caused by diffusion through heat treatment in diamonds, brazed components with metals and its effects on mechanical properties and microstructure. It will be used diamond films produced by CVD process, brazed by active filler metals with metallic substrate, using a high vacuum furnace at MAT / LNLS / CNPEM; the samples were heat treated in the atmosphere furnace at MAT too. The characterizations are carried out by hardness testing, vacuum sealing equipment at the MAT / LNLS / CNPEM facilities, and chemical and microstructural characterization will be performed using the scanning electron microscopes and EDS at LNNano / CNPEM.

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Chauhan, Vinay S., Joshua Ferrigno, Saqeeb Adnan, Janne Pakarinen, Lingfeng He, David H. Hurley, and Marat Khafizov. "Comprehensive characterization of irradiation induced defects in ceria: Impact of point defects on vibrational and optical properties." Journal of Applied Physics 132, no. 8 (August 28, 2022): 085105. http://dx.doi.org/10.1063/5.0099189.

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Validation of multiscale microstructure evolution models can be improved when standard microstructure characterization tools are coupled with methods sensitive to individual point defects. We demonstrate how electronic and vibrational properties of defects revealed by optical absorption and Raman spectroscopies can be used to compliment transmission electron microscopy (TEM) and x-ray diffraction (XRD) in the characterization of microstructure evolution in ceria under non-equilibrium conditions. Experimental manifestation of non-equilibrium conditions was realized by exposing cerium dioxide (CeO2) to energetic protons at elevated temperature. Two sintered polycrystalline CeO2 samples were bombarded with protons accelerated to a few MeVs. These irradiation conditions produced a microstructure with resolvable extended defects and a significant concentration of point defects. A rate theory (RT) model was parametrized using the results of TEM, XRD, and thermal conductivity measurements to infer point defect concentrations. An abundance of cerium sublattice defects suggested by the RT model is supported by Raman spectroscopy measurements, which show peak shift and broadening of the intrinsic T2g peak and emergence of new defect peaks. Additionally, spectroscopic ellipsometry measurements performed in lieu of optical absorption reveals the presence of Ce3+ ions associated with oxygen vacancies. This work lays the foundation for a coupled approach that considers a multimodal characterization of microstructures to guide and validate complex defect evolution models.

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Penelle, Richard, and Thierry Baudin. "Multiscale Approach to Texture-Microstructure Coupling." Materials Science Forum 509 (March 2006): 1–10. http://dx.doi.org/10.4028/www.scientific.net/msf.509.1.

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Materials exhibit microstructures and textures that influence their use and properties. Xray and neutron diffraction allow characterization of the bulk texture, whereas Electron Backscattered Diffraction (EBSD) permits determination of the local texture. In many cases Transmission Electron Microscopy (TEM) remains necessary to characterize the substructure and the local texture for highly deformed materials. Depending on the scale considered, all these complementary techniques permit the coupling of texture and microstructure so that it becomes possible to control microstructure and its evolution during a processing route. Some examples in titanium aluminides, (α + β) titanium alloys and an Fe-Ni alloy will illustrate this challenge.

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Maeshima, Takashi, Keiichiro Oh-Ishi, Hiroaki Kadoura, and Masashi Hara. "Microstructure Characterization of AlSi10Mg Fabricated by Selective Laser Melting Process." Materials Science Forum 941 (December 2018): 1437–42. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1437.

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Multi-scale microstructure observation and three dimensional finite element thermal analysis of AlSi10Mg alloy fabricated by selective laser melting (SLM) process were demonstrated in order to understand the microstructure formation process during SLM fabrication. The unique hierarchically microstructures were observed: (1) the “fish scale” microstructure corresponding to a part of molten pool consists of columnar and equiaxed grains and (2) these grains contain a substructure of α-Al surrounded by Si particles. It is revealed that a supersaturated Si concentration due to the predicted rapid cooling rate on the order of 106 oC/s. In addition, the base temperature during the fabrication increases gradually with some peak temperature of each laser path as the laser scan has proceeded on a powder layer. Although the thermal changes cause no melting of the AlSi10Mg except directly fused region by selective laser so called molten pool, those are capable of causing precipitation and/or clustering.

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Tuzun, Mert Yagiz, Mustafa Alp Yalcin, Kemal Davut, and Volkan Kilicli. "Nondestructive microstructural characterization of austempered ductile iron." Materials Testing 65, no. 3 (March 1, 2023): 453–65. http://dx.doi.org/10.1515/mt-2022-0265.

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Abstract Austempered ductile iron (ADI) has been preferred in a wide range of applications due its unique combination of high strength, good ductility, wear resistance and fracture toughness together with lower cost and lower density compared to steels. Magnetic Barkhausen noise (MBN) measurement offers a better alternative to traditional characterization techniques by being fast and non-destructive. A simple linear regression using only one single independent variable cannot correlate the MBN with the microstructure of ADI, since its microstructure is multi-component. Multiple linear regression analysis (MLRA) was used to build a model that uses the characteristic features of microstructural constituents as input parameters to predict the MBN. For that purpose, Cu-Ni-Mo alloyed ductile iron samples austempered between 325 and 400 °C and for 45–180 min duration were used. The results show that MBN is most sensitive to the size and shape of acicular ferrite and retained austenite. Moreover, MBN is almost insensitive to the size, morphology and volume fraction of graphite particles. This indicates that retained austenite pins the domain walls more effectively than the graphite particles. Considering the results MLRA, MBN technique can be used to characterize the ausferritic microstructure of ADI.

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Han, Bao Jun. "Microstructure Characterization of Hot Deformed Fe-32%Ni Alloy." Advanced Materials Research 230-232 (May 2011): 154–58. http://dx.doi.org/10.4028/www.scientific.net/amr.230-232.154.

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Hot deformation behavior and microstructure evolution of Fe-32%Ni alloy were investigated when compressed at the temperature of 1000°C and a strain rate of 2×10-3s-1. The microstructures were analyzed using optical microscope (OM), electron back scatter diffraction (EBSD) and transmission electron microscope (TEM). The results show that the generation and development of dynamic recrystallization (DRX) can obviously refine the grains of Fe-32Ni% alloy and the DRX reached dynamic equilibrium when the strain was high. According to the TEM observations, the DRX microstructure can be categorized into three kinds: grains with low dislocation density, which are DRX nucleations; grains with low dislocation density around the grain boundary and high dislocation density in its interior which means that grains with dislocation density gradient and which are DRX grains in growth; grains with high dislocation density, which are fully work-hardened DRX grains.

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Pfeiffer, Björn, Johannes Maier, Jonas Arlt, and Carsten Nowak. "In Situ Atom Probe Deintercalation of Lithium-Manganese-Oxide." Microscopy and Microanalysis 23, no. 2 (January 30, 2017): 314–20. http://dx.doi.org/10.1017/s1431927616012691.

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AbstractAtom probe tomography is routinely used for the characterization of materials microstructures, usually assuming that the microstructure is unaltered by the analysis. When analyzing ionic conductors, however, gradients in the chemical potential and the electric field penetrating dielectric atom probe specimens can cause significant ionic mobility. Although ionic mobility is undesirable when aiming for materials characterization, it offers a strategy to manipulate materials directly in situ in the atom probe. Here, we present experimental results on the analysis of the ionic conductor lithium-manganese-oxide with different atom probe techniques. We demonstrate that, at a temperature of 30 K, characterization of the materials microstructure is possible without measurable Li mobility. Also, we show that at 298 K the material can be deintercalated, in situ in the atom probe, without changing the manganese-oxide host structure. Combining in situ atom probe deintercalation and subsequent conventional characterization, we demonstrate a new methodological approach to study ionic conductors even in early stages of deintercalation.

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Réti, Tamás, Agnes Csizmazia, and Imre Felde. "On the Topological Characterization of 3-D Polyhedral Microstrutures." Materials Science Forum 537-538 (February 2007): 563–70. http://dx.doi.org/10.4028/www.scientific.net/msf.537-538.563.

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To characterize topologically the polycrystalline microstructure of single-phase alloys computer simulations are performed on 3-dimensional cellular models. These infinite periodic cellular systems are constructed from a finite set of space filling convex polyhedra (grains). It is shown that the appropriately selected topological shape factors can be successfully used for the quantitative characterization of computer-simulated microstructures of various types.

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Carneiro, Íris, and Sónia Simões. "Recent Advances in EBSD Characterization of Metals." Metals 10, no. 8 (August 13, 2020): 1097. http://dx.doi.org/10.3390/met10081097.

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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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Journal articles on the topic 'Microstructure and Characterization'

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