Electron Backscatter Research Articles

Effect of adding cement kiln dust on the effective geotechnical properties of sand dunes in Najran–Sharourah, Kingdom of Saudi Arabia: a laboratory study

Sand dunes are one of the most common soil types all over the world, particularly in North Africa and the Arabian Peninsula. These dunes, with their regional extensions, are considered the main natural resource for fine aggregates being used in construction purposes. To use dune sands as a road construction material, suitable treatment is necessary. Sand dunes have typically been stabilized using a cement material, however, though extremely costly and consuming a substantial amount of energy, it is not particularly effective. Therefore, this study has investigated the potentiality of adding cement kiln dust (CKD) for enhancing the strength and durability of dune sands in Najran–Sharourah, SW Saudi Arabia. Twenty-seven specimens have been mixed with 0%, 10%, 20%, and 30% CKD plus 2% cement and then examined and assessed using macro-characterization techniques. Results indicated that the strength of the sand dune samples, treated with an enhanced mixture of 30% CKD and 2% cement, improved the minimum dry density from 1.652 at 0% to 1.854 g/cm3. The soil became more qualified as a construction material. This enhanced mixture can serve as a high-quality sub-base for both flexible and rigid pavements. Besides, micro-characterization techniques, including X-ray diffraction (XRD), back-scattered electron imaging (BEI), and scanning electron microscopy (SEM) supported by energy-dispersive X-ray (EDX), were applied to identify the various phases of the treated dune sands. Finally, the implementation of adding the CKD to the dune sands geomechanical parameters has been modeled, and a series of highly reliable mathematical equations have been introduced (0.938 ≤ R2 ≤ 1.0).

Monte Carlo Simulation of Free-standing Thin Films under Low Energy Electron Bombardment: Electron Inelastic Mean Free Path (IMFP) Determination Using Elastic Peak of the Transmitted Electrons

Abstract: The electron energy spectra of transmitted scattered electrons from free-standing films are simulated using a Monte Carlo computational approach. Elastic scattering is simulated using Mott cross-sections and inelastic scattering via discrete processes determined from dielectric function data. This allows one to simulate the secondary electrons as well as the loss peaks near the elastic (zero-loss) peak. The current study suggested a directed approach for determining the electron inelastic mean free path (IMFP) of materials at low primary electron energies. The IMFP of the reference material is not necessary for the suggested technique. The suggested technique uses the ratio between the transmitted elastic peak intensity and the background intensity of backscattered electrons. Free-standing films of Si, Cu, and Au were studied with thicknesses varying from 2 to 12 nm. Primary electron energies of 1, 3, and 5 keV were applied. The results appeared very good, with the percentage error range being between 5% and 25%. We also investigated the proportion of the first and second plasmon peak intensities to the elastic peak intensity. We believe that the latter could provide a directed method of measuring the IMFP of materials. Keywords: Inelastic mean free path, Monte Carlo simulation, Geant4, Free-standing film, Zero-loss peak.

Cholesteatoma Severely Impacts the Integrity and Bone Material Quality of the Incus

Cholesteatoma can lead to progressive destruction of the auditory ossicles along with conductive hearing loss but precise data on the microstructural, cellular, and compositional aspects of affected ossicles are not available. Here, we obtained incus specimens from patients who had cholesteatoma with conductive hearing loss. Incudes were evaluated by micro-computed tomography, histomorphometry on undecalcified sections, quantitative backscattered electron imaging, and nanoindentation. Results were compared with two control groups taken from patients with chronic otitis media as well as from skeletally intact donors at autopsy. The porosity of incus specimens was higher in cholesteatoma than in chronic otitis media, along with a higher osteoclast surface per bone surface. Histomorphometric assessment revealed higher osteoid levels and osteocyte numbers in cholesteatoma incudes. Incudes affected by cholesteatoma also showed lower matrix mineralization compared with specimens from healthy controls and chronic otitis media. Furthermore, the modulus-to-hardness ratio was higher in cholesteatoma specimens compared with controls. Taken together, we demonstrated increased porosity along with increased osteoclast indices, impaired matrix mineralization, and altered biomechanical properties as distinct features of the incus in cholesteatoma. Based on our findings, a possible impact of impaired bone quality on conductive hearing loss should be further explored.

Magnetic properties and identification of Griffiths-like phase in Mn2FeSi Heusler antiferromagnet

Materials having low magnetic moments with high spin polarization are promising for spintronic applications. Among these materials, Mn-based Heusler alloys are attractive candidates due to the antiferromagnetic alignment of Mn atoms. Theoretical calculations predict Mn2FeSi to have an inverse Heusler (XA) structure with a magnetic moment of 2 μB/f.u. However, no experimental reports exist on a phase-pure composition of this material. In this study, our first principle calculations demonstrate the effect of various types of disorder on the electronic and magnetic properties of Mn2FeSi. The B2-type disorder seems responsible for forming secondary phases in stoichiometric Mn2FeSi. We verify this by conducting theoretical calculations for different configurations of the atomic disorders permissible in a Heusler phase. We substantiate our theoretical investigation with an experimental study wherein we first stabilize the phase-pure Mn2FeSi in an inverse Heusler structure by substituting Al at the Si site. Amongst the prepared Mn2FeSi1−xAlx (x = 0, 0.1, 0.15), the compositions with x = 0 and 0.15 show a clear presence of a secondary phase, identified as the β − Mn phase with a lattice constant of 6.24 Å. Analysis of the back-scattered electron spectroscopy images and X-ray diffraction patterns confirm the formation of a pure Heusler phase in x = 0.1 composition. Magnetization measurements reveal an antiferromagnetic behavior in all compositions, with a N é el temperature of ∼ 50 K. However, deviation from Curie-Weiss law was observed for x = 0.1, suggesting competing magnetic interactions. Further investigation into the magnetic properties of this composition displays signatures of Griffiths phase, possibly caused by antisite disorder in the compound.

Stray current induced ITZ effect on chloride transport in concrete

Understanding the influence of interface transition zone (ITZ) on chloride migration characteristics in concrete under coupled stray current and high hydraulic pressure is essential to solve the durability problem of ultra-deep buried infrastructures (40 m-100 m). Herein, an advanced test system is developed and the chloride migration characteristics of deeply buried concrete is comprehensively investigated. Specimens were casted with the same aggregate volume content but different aggregate size distribution. The ITZ between aggregate and cement matrix was measured from BSE (back scattered electron imaging) images, and the ITZ thickness was measured by Vickers hardness. The silver nitrate spray was used to determine the chloride migration front, and the effective diffusion coefficient was calculated. The results showed the concentric expansion and overflow method based on BSE images were effective ways to determine ITZ porosity distribution. The significant increase of ITZ thickness and porosity on concrete reaction surface under stray current environment was observed and defined as “stray current induced ITZ effect”, which was considered to be the fundamental reason for the distinct differences in chloride migration depth and effective diffusion coefficient of specimens with different aggregate gradations.

Parametric simulation of electron backscatter diffraction patterns through generative models

Recently, discriminative machine learning models have been widely used to predict various attributes from Electron Backscatter Diffraction (EBSD) patterns. However, there has never been any generative model developed for EBSD pattern simulation. On one hand, the training of generative models is much harder than that of discriminative ones; On the other hand, numerous variables affecting EBSD pattern formation make the input space high-dimensional and its relationship with the distribution of backscattered electrons complicated. In this study, we propose a framework (EBSD-CVAE/GAN) with great flexibility and scalability to realize parametric simulation of EBSD patterns. Compared with the frequently used forward model, EBSD-CVAE/GAN can take variables more than just orientation and generate corresponding EBSD patterns in a single run. The accuracy and quality of generated patterns are systematically evaluated. The model does not only summarize a distribution of backscattered electrons at a higher level, but also mitigates data scarcity in this field.

Study on the influence of the properties of interfacial transition zones on the performance of recycled aggregate concrete

Applying recycled aggregate (RA) aligns with the development concept of green and environmental protection. Nevertheless, introducing RA has resulted in a complex interface structure, which will deteriorate the performance of recycled aggregate concrete(RAC). To investigate the influence of the properties of the interfacial transition zones(ITZs) on the performance of RAC, and the digital image correlation(DIC) technology was used to track the strain variation law of each interface during the failure process. The porosity and mechanical properties of the ITZs were quantitatively characterized by backscattered electron(BSE) imaging and microhardness testing. By controlling a single variable, the different ITZs of RAC were improved by targeted strengthening, including mortar and aggregate strengthening.The influence of the ITZs properties on the macroscopic properties and mesoscopic failure behavior of RAC was analyzed. The experimental results show that the mechanical properties of the ITZs were enhanced and the porosity was reduced. Strengthening treatment improved the strength of target interface, causing a change in the relative strength of the internal interface of concrete, and reducing the probability of failure of the strengthened interface. This is consistent with the results observed in SEM images, the more compact and stable the structure at the interface, the lower the probability of failure under load. A comprehensive evaluation of mortar strengthening and aggregate strengthening was carried out with the help of the linear weighted sum method, and the results showed that the mortar strengthening was more effective.

Estimating carbon content in crucible steel using image analysis

Pre-industrial crucible steel ingots, produced in both Central and South Asia, are an important class of iron-carbon alloys. Their microstructure reflects their formation from a liquid alloy at a carbon content of 1.0–2.5wt%, which is higher than most mild steels but lower than most cast irons. This article introduces a tool to quantify the carbon content of such alloys based on an operator-supervised image analysis which determines the relative proportions of austenite/pearlite and cementite, respectively, from high-contrast back-scatter electron images of unetched samples. Using examples from a recently discovered hoard of crucible steel ingots in Telangana, south-central India, we demonstrate the capabilities of the tool and test its usefulness. The main benefit is in improving accuracy and precision in metallography-based carbon content determination in such alloys by reducing the uncertainty in area estimation in complex microstructures based on visual impression alone.

Characteristics of Lunar Surface Electrons Inferred From ARTEMIS Observations: 1. Backscattered Electrons

AbstractLunar surface charging is a scientifically and practically important topic at the Moon that is largely determined by the electron currents near the surface. Among those electron populations, lunar photoelectrons (PHE) and backscattered electrons (BSE) produced by incident electrons that make up the high‐energy tail of lunar emitted electrons are not well characterized yet. Recently, Xu et al. (2021, https://doi.org/10.1029/2020je006790) reported oxygen Auger electron observations at the Moon by the Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun spacecraft, which provides a unique feature to identify lunar photoelectrons. We utilize this feature to isolate cases of emitted electrons dominated by BSE over PHE. With selected BSE cases, we characterize how the backscattering coefficient η varies with primary electron energy, which decreases with increasing energy. Our results also reveal η to be dependent on the magnetic dip angle, as a fraction of BSE re‐impact the surface in a magnetized environment. The characterization of the backscattering coefficient not only gives insights into the lunar surface properties and lunar surface charging but could also be potentially applied to other airless bodies.

Vitamin C Deficiency Deteriorates Bone Microarchitecture and Mineralization in a Sex-Specific Manner in Adult Mice.

Vitamin C (VitC) is essential for bone health, and low VitC serum levels increase the risk for skeletal fractures. If and how VitC affects bone mineralization is unclear. Using micro-computed tomography (μCT), histologic staining, as well as quantitative backscattered electron imaging (qBEI), we assessed the effects of VitC on femoral structure and microarchitecture, bone formation, and bone mineralization density distribution (BMDD) in the VitC incompetent Gulo-/- mouse model and wild-type mice. In particular, VitC-supplemented, 20-week-old mice were compared with age-matched counterparts where dietary VitC intake was excluded from week 15. VitC depletion in Gulo-/- mice severely reduced cortical thickness of the diaphyseal shaft and bone volume around the growth plate (eg, bone volume of the primary spongiosa -43%, p < 0.001). Loss of VitC also diminished the amount of newly formed bone tissue as visualized by histology and calcein labeling of the active mineralization front. BMDD analysis revealed a shift to higher calcium concentrations upon VitC supplementation, including higher average (~10% increase in female VitC deficient mice, p < 0.001) and peak calcium concentrations in the epiphyseal and metaphyseal spongiosa. These findings suggest higher bone tissue age. Importantly, loss of VitC had significantly more pronounced effects in female mice, indicating a higher sensitivity of their skeleton to VitC deficiency. Our results reveal that VitC plays a key role in bone formation rate, which directly affects mineralization. We propose that low VitC levels may contribute to the higher prevalence of bone-degenerative diseases in females and suggest leveraging this vitamin against these conditions. © 2023 American Society for Bone and Mineral Research (ASBMR).

New Insights into the Gold Mineralization in the Babaikundi–Birgaon Axis, North Singhbhum Mobile Belt, Eastern Indian Shield Using Magnetic, Very Low-Frequency Electromagnetic (VLF-EM), and Self-Potential Data

The North Singhbhum Mobile Belt (NSMB) in the eastern Indian shield is an excellent example of a diverse lithological domain with multiphase shear/fracture zones. It is a well-acknowledged prospective region known for various mineralizations, e.g., Cu, Au, U, and Fe. The present study was conducted in the Babaikundi–Birgaon Axis (a shear and fracture zone within NSMB) within Babaikundi village. The study suggests that anomalous zones are possibly related to gold-associated sulfide mineralization using photomicrography and geophysical methods such as magnetic, self-potential (SP), and very low-frequency (VLF) electromagnetic (EM) methods. Photomicrography on quartz samples and Scanning Electron Microscope (SEM) Backscattered-Electron (BSE) images show that gold particles are present in the quartz reef vein in Babaikundi. Magnetic data are presented in the total magnetic intensity (TMI), upward continuation, and analytical signal maps. VLF-EM data were analyzed using different processing techniques to delineate anomalous auriferous zones. Furthermore, the SP data were inverted using the Particle Swarm Optimization (PSO), Very Fast Simulated Annealing (VFSA), and Genetic Algorithm (GA) approaches for comparative study of the resultant model parameters and their suitability considering a 2D inverted resistivity section derived using VLF-EM. The photomicrography study indicates the existence of gold/ pyrite/pyrrhotite within the Babaikundi–Birgaon axis, which corresponds to a low magnetic anomaly based on a magnetic study; a high current density, a high Fraser value, and a low resistivity based on the VLF-EM study; and a negative SP value was found based on the SP study. The combined study generally supports mapping auriferous zones and demarcates the Babaikundi–Birgaon axis within the Babaikundi–Birgaon area.

Ultrasonic effects with different vibration positions on gas tungsten arc wire additive manufactured aluminum nanocomposite

Ultrasonically assisted gas tungsten arc based wire additive manufacturing (UA-GTAAM) of TiB2 nanoparticle-reinforced AA7075 aluminum metal matrix nanocomposite (MMNC) was conducted with the UA probe directly immersed in the molten pool. This work focuses on the UA effects with different probe positions on the UA-melt interactions and the resulting microstructure. In situ high-speed imaging reveals melt pool surface ripples induced by UA. More refined surface ripples, corresponding to a faster melt flow, are observed with the UA probe immersed deeper into the melt. This condition also leads to a lighter etched color under optical microscope, which is related to a more homogeneous microstructure with less eutectic phase at grain boundaries. Electron backscatter diffraction (EBSD) analysis was employed for grain orientation and nanoparticle distributions, where the lower Confidence Index (CI) served as an indicator for intragranular nanoparticle segregation. The EBSD results show a strong (110) texture in the conventional WAAM builds. High-resolution backscattered electron (BSE) imaging reveals nanoparticles tend to segregate into preferred (001) and (111) grains. UA suppresses the epitaxial growth of (110) grains and promotes a more randomly orientated microstructure. Accordingly, more (001) and (111) grains are available to accommodate nanoparticles and promote a more homogeneous dispersion.

Characterization of rat vertebrae cortical bone microstructures using confocal Raman microscopy combined to tomography and electron microscopy

BackgroundThe rat vertebrae is a good model to study bone regeneration after implantation of biomaterials used to treat bone loss, a major problem in oral and dental surgery. However, the precise characterization of bone microstructures in the rat vertebrae has not been reported. Therefore, the aim of this study was to achieve the complete analysis of such bone, at different scales, in order to have a clear model of healthy bone for comparison with regenerated bone. MethodsIn order to image the cortical bone of rat caudal vertebra, confocal Raman microscopy was combined with high resolution X-ray micro computed tomography (micro-CT), with scanning electron microscopy (SEM) using backscatter electron imaging and with more conventional histology coloration techniques. SEM and Raman microscopy were done in various regions of the cortical bone corresponding to external, middle and internal areas. The spongy bone was imaged in parallel. Micro-CT was performed on the whole vertebra to monitor the network of haversian canals in the cortical bone. Osteonic canals characteristics, and relative chemical composition were analysed in several regions of interest, in cortical and spongy bone. Five rats were included in this study. ResultsOn micro-CT images, differences in intensity were observed in the cortical bone, substantiated by SEM. Chemical analysis with Raman spectra confirmed the difference in composition between the different regions of the cortical and spongy bone. PCA and k-mean cluster analysis separated these groups, except for the external and middle cortical bone. Peak intensity ratio confirmed these results with a CO3 to ν2 PO4 ratio significantly different for the internal cortical bone. Grayscale images stack extracted from micro-CT showed that global architecture of cortical bone was characterized by a dense and complex network of haversian osteonic canals, starting from the surface towards the vertebrae center. The mean diameter of the canals was 18.4 µm (SD 8.6 µm) and the mean length was 450 µm (SD 152 µm). Finally, Raman reconstructed images of the lamellar bone showed an enlargement of the lamellar layer width, both in circumferential lamellar bone and around haversian canals. ConclusionsMicro-CT and confocal Raman microscopy are good tools to complete classical analysis using optical and electron microscopy. The results and measurements presented in a rat model known for its small inter-individual differences provide the main characteristics of a mature bone. This study will allow the community working on this rat vertebrate model to have a set of characteristics, in particular on the structure of the haversian canals.

Mitigation of alkali-silica reaction in blast-furnace slag-based alkaline activated material through incorporation of alum water treatment residue

Alkaline-activated materials (AAMs) have been developed as an alternative binder for cement in an effort to reduce the carbon footprint. However, due to the high alkaline contents in AAMs, these materials, particularly ground granulated blast-furnace slag (GGBS)-based AAM, may have a high potential of detrimental alkali-silica reaction (ASR) when amorphous silica-rich aggregates are used. This study utilised alum water treatment residue (AWTR), a waste from drinking water treatment, as an additional precursor in slag-based AAM to mitigate ASR in mortars with high reactive glass aggregate. The results showed that incorporating 40% AWTR in the precursor improved the compressive strength from 47 to 64 MPa and reduced ASR-induced expansion from 0.9% to 0.2% after 28 days of the accelerated test. The characteristics of the ASR gels were analysed using backscattered electron images coupled with energy-dispersive x-ray spectroscopy. Microscopic observations revealed that the ASR products formed in two stages. In the earlier stage, amorphous ASR gels precipitated surrounding the aggregates, exerting pressure on them and the matrix, resulting in initial cracking. In the latter stage, ASR products extruded into the open cracks, and crystalline products were formed, causing additional damage to the matrix. The quantitative elemental analysis demonstrated that incorporating AWTR could slow down silica dissolution by forming an Al layer in the aggregate surface, prevent the ASR gel calcification and reduce the growth of the harmful crystalline ASR products.

In-situ elemental and boron isotopic variations of tourmaline from the Koktokay pegmatitic rare-metal deposit, China: Insights into external contamination and the source of the granitic pegmatite

This study presents petrochemical and boron isotope compositions of tourmalines from the fertile (No. 3) and relatively barren (No. 1, 2b) pegmatite in the Koktokay pegmatitic rare-metal deposit, to better understand the influence of external contamination on pegmatite mineralization and the source of these pegmatites. There are four types of tourmalines that have been studied: (1) tourmaline in the tourmaline-mica nest of pegmatite No. 1 (Tur-N); (2) tourmalines in the comb-like structure of pegmatite No. 1 (Tur-C1), 2b (Tur-C2), and 3 (Tur-C3), respectively. Tur-N tourmaline is heterogeneous in backscattered electron (BSE) images, Tur-C1 and Tur-C2 appear to be homogenous crystals, while Tur-C3 exhibits to have a complicated zonal structure. These tourmalines are members of the alkali group tourmalines representing mostly dravite-schorl solid solutions. Tur-N contains the lowest Ca content. There is a general increase in the contents of Mg and Ca from Tur-C1 to Tur-C3, implying that the pegmatite melt was contaminated by the host rock (metagabbro) during the emplacement. The contamination's diffusive influx of Mg, Ca, and Fe components into the pegmatite melt impelled the crystallization of tourmaline during the emplacement, which subsequently triggered the deposition of rare element minerals. The external contamination implies that the closed system of melt is extremely favorable for the enrichment and mineralization of rare elements in the pegmatitic rare-metal deposit. The boron isotopes vary slightly among the four types of tourmalines. The B-isotope composition of Tur-C3 is the heaviest (–11.63 ± 0.05 ‰ to –13.16 ± 0.05 ‰), followed by Tur-C1 (–12.29 ± 0.06 ‰ to –12.93 ± 0.05 ‰) and Tur-C2 (–12.51 ± 0.05 ‰ to –13.21 ± 0.05 ‰), Tur-N contains the lowest δ11B value (–13.20 ± 0.05 ‰ to –13.76 ± 0.05 ‰). Synthesized with the previous research results, we hold that the boron isotope of tourmaline (Tur-C3) in the comb-like structure of No. 3 pegmatite might represent the isotope composition of its initial magma, indicating that the tourmaline and associated pegmatite may derive from the melting of clastic sedimentary rock from the Habahe Group forming in Mid Ordovician to Early Devonian in the Chinese Altay orogenic belt.

Leptin receptor gene deficiency minimally affects osseointegration in rats

Metabolic syndrome represents a cluster of conditions such as obesity, hyperglycaemia, dyslipidaemia, and hypertension that can lead to type 2 diabetes mellitus and/or cardiovascular disease. Here, we investigated the influence of obesity and hyperglycaemia on osseointegration using a novel, leptin receptor-deficient animal model, the Lund MetS rat. Machined titanium implants were installed in the tibias of animals with normal leptin receptor (LepR+/+) and those harbouring congenic leptin receptor deficiency (LepR−/−) and were left to heal for 28 days. Extensive evaluation of osseointegration was performed using removal torque measurements, X-ray micro-computed tomography, quantitative backscattered electron imaging, Raman spectroscopy, gene expression analysis, qualitative histology, and histomorphometry. Here, we found comparable osseointegration potential at 28 days following implant placement in LepR−/− and LepR+/+ rats. However, the low bone volume within the implant threads, higher bone-to-implant contact, and comparable biomechanical stability of the implants point towards changed bone formation and/or remodelling in LepR−/− rats. These findings are corroborated by differences in the carbonate-to-phosphate ratio of native bone measured using Raman spectroscopy. Observations of hypermineralised cartilage islands and increased mineralisation heterogeneity in native bone confirm the delayed skeletal development of LepR−/− rats. Gene expression analyses reveal comparable patterns between LepR−/− and LepR+/+ animals, suggesting that peri-implant bone has reached equilibrium in healing and/or remodelling between the animal groups.

Bond performance between cementitious grout and normal concrete subjected to freeze–thaw damage

Owing to the increasing application of cementitious grout in strengthening projects in cold regions, the freeze–thaw durability of the bond between cementitious grout and concrete has attracted attention. This study investigates the bond performance of a cementitious grout–normal concrete interface after FTCs through splitting tensile and slant shear tests at different angles. The microstructure of the cementitious grout–concrete interface is observed via backscattered electron (BSE) microscopy. The results show that FTCs rapidly reduce the splitting bond strength and slant shear bond strength of the interface. After 240 FTCs, the splitting and slant shear bond strengths decrease by 40.7%–72.4% and 46.1%–57.3%, respectively. An increase in substrate strength significantly enhances the interfacial bond strength, particularly the slant shear bond strength. Freeze–thaw damage to the substrate reduces the interfacial bond strength and frost resistance. The slant shear strength increases significantly with the slant shear angle. The effects of FTCs on the interfacial shear strength parameters are reflected through a rapid decrease in cohesion, whereas the interface internal friction angle remains relatively unaffected. Empirical formulas for calculating the interface bond strength are obtained from experimental data and validated. The BSE images show that cracks begin to appear at the cementitious grout–normal concrete interface as the number of FTCs increases, thereby decreasing the interfacial bond strength.

Comparison between image based and tabular data-based inclusion class categorization

Abstract Non-metallic inclusions (NMI) have a significant impact on the final properties of steel products. As of today, the scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS) serves as the state of art characterization tool to study NMIs in steel. The automated 2D analysis method with the SEM-EDS allows for a comprehensive analysis of all the inclusions observed within a selected area of the sample. The drawback of this method is the time taken to complete the analysis. Therefore, machine learning methods have been introduced which can potentially replace the usage of EDS for obtaining chemical information of the inclusion by making quick categorizations of the inclusion classes and types. The machine learning methods can be developed by either training it directly with labeled backscattered electron (BSE) images or by tabular data consisting of image features input such as morphology and mean gray value obtained from the BSE images. The current paper compares both these methods using two steel grades. The advantages and the disadvantages have been documented. The paper will also compare the usage of shallow and deep learning methods to classify the steels and discuss the outlook of the existing machine learning methods to efficiently categorize the NMIs in steel.

Exploring the interfacial structure and crystallinity for direct growth of Mn3Sn(0001) on sapphire (0001) by molecular beam epitaxy

The Kagome antiferromagnet Mn3Sn has garnered a lot of attention due to the presence of interesting properties such as anomalous Hall effects and Nernst effects. Until now, few papers have been reported to grow using molecular beam epitaxy with a buffer layer or on other substrates. In this paper, we discuss the synthesis of crystalline Mn3Sn layers, prepared on Al2O3 (0001) without a buffer layer using molecular beam epitaxy. The growth is monitored in-situ using reflection high energy electron diffraction and measured ex-situ using X-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. The samples were deposited at 524 ± 5 °C, with an Mn: Sn atomic flux ratio of 3.2:1 for 90 min. Orientation relationships between the Mn3Sn films and the sapphire substrates are determined from in-plane and out-of-plane measurements. Our analysis indicates that the resulting film is predominantly c−plane oriented. Lastly, the samples prepared in this way were found to be discontiguous, showing a 3-dimensional morphology. According to first-principles calculations, the Mn3Sn exhibits a displaced Kagome structure in the very first stages of growth, for 2 ML and 4 ML growth on Al2O3 (0001). This result is corroborated by calculating the surface formation energies and explains the observed RHEED patterns.

Experimental-Computational Investigation of the Elastic Modulus of Mortar under Sulfate Attack.

External sulfate attack is an important factor causing a decrease in the mechanical properties of cement-based materials. In this paper, a computational prediction model of elastic modulus, considering the characteristics of sulfate corrosion from outside to inside and the influence of the interface transition zone (ITZ), was established to predict the elastic modulus of mortar under the external sulfate attack. Firstly, the backscattered electron (BSE) images of mortar and the algorithm of image threshold segmenting were used to determine a reasonable thickness of corroded ITZ. Secondly, the nanoindentation test was adopted to acquire the microscopic elastic parameters of phases (sand, cement, and ITZ) in corroded mortar. Moreover, the mortar mix proportion and Lu and Torquato's model were adopted to calculate the volume fractions of phases. Finally, a computational prediction model of elastic modulus of mortar under sulfate attack was proposed with homogenization methods. The results indicate that the thickness of corroded ITZ is 20 mm, and the error values of elastic modulus between the theoretical prediction results and the experimental results are within 8%, indicating that the macroscopic elastic modulus of corroded mortar can be precisely predicted by the computational prediction model of elastic modulus.