Journal articles on the topic 'Material characterisation: SEM/EDS/EBSD'
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1
Stephenson, Oscar, Rebecca L. Higginson, Simon Hogg, Jacob Knight, and Sarah Spindler. "Characterisation of Long Term Aging in Esshete 1250 Welds." Materials Science Forum 941 (December 2018): 589–94. http://dx.doi.org/10.4028/www.scientific.net/msf.941.589.
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In this work, two samples of service grade Esshete 1250 stainless steel, as-received and aged, were characterised to determine the microstructural differences between the parent material and weld in terms of the grain structures and the phases present using XRD, EBSD, SEM and EDS. There was no difference found in the grain structure, but the phases present in the aged weld showed that sigma phase developed during aging.
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Rößler, Christiane, Dominik Zimmer, Patrick Trimby, and Horst-Michael Ludwig. "Chemical – crystallographic characterisation of cement clinkers by EBSD-EDS analysis in the SEM." Cement and Concrete Research 154 (April 2022): 106721. http://dx.doi.org/10.1016/j.cemconres.2022.106721.
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Parish, Chad M. "Cluster Analysis of Combined EDS and EBSD Data to Solve Ambiguous Phase Identifications." Microscopy and Microanalysis 28, no. 2 (March 3, 2022): 371–82. http://dx.doi.org/10.1017/s1431927622000010.
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A common problem in analytical scanning electron microscopy (SEM) using electron backscatter diffraction (EBSD) is the differentiation of phases with distinct chemistry but the same or very similar crystal structure. X-ray energy dispersive spectroscopy (EDS) is useful to help differentiate these phases of similar crystal structures but different elemental makeups. However, open, automated, and unbiased methods of differentiating phases of similar EBSD responses based on their EDS response are lacking. This paper describes a simple data analytics-based method, using a combination of singular value decomposition and cluster analysis, to merge simultaneously acquired EDS + EBSD information and automatically determine phases from both their crystal and elemental data. I use hexagonal TiB2 ceramic contaminated with multiple crystallographically ambiguous but chemically distinct cubic phases to illustrate the method. Code, in the form of a Python 3 Jupyter Notebook, and the necessary data to replicate the analysis are provided as Supplementary material.
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Schulz, Bernhard, Dirk Sandmann, and Sabine Gilbricht. "SEM-Based Automated Mineralogy and Its Application in Geo- and Material Sciences." Minerals 10, no. 11 (November 11, 2020): 1004. http://dx.doi.org/10.3390/min10111004.
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Scanning electron microscopy based automated mineralogy (SEM-AM) is a combined analytical tool initially designed for the characterisation of ores and mineral processing products. Measurements begin with the collection of backscattered electron (BSE) images and their handling with image analysis software routines. Subsequently, energy dispersive X-ray spectra (EDS) are gained at selected points according to the BSE image adjustments. Classification of the sample EDS spectra against a list of approved reference EDS spectra completes the measurement. Different classification algorithms and four principal SEM-AM measurement routines for point counting modal analysis, particle analysis, sparse phase search and EDS spectral mapping are offered by the relevant software providers. Application of SEM-AM requires a high-quality preparation of samples. Suitable non-evaporating and electron-beam stable epoxy resin mixtures and polishing of relief-free surfaces in particles and materials with very different hardness are the main challenges. As demonstrated by case examples in this contribution, the EDS spectral mapping methods appear to have the most promising potential for novel applications in metamorphic, igneous and sedimentary petrology, ore fingerprinting, ash particle analysis, characterisation of slags, forensic sciences, archaeometry and investigations of stoneware and ceramics. SEM-AM allows the quantification of the sizes, geometries and liberation of particles with different chemical compositions within a bulk sample and without previous phase separations. In addition, a virtual filtering of bulk particle samples by application of numerous filter criteria is possible. For a complete mineral phase identification, X-ray diffraction data should accompany the EDS chemical analysis. Many of the materials which potentially could be characterised by SEM-AM consist of amorphous and glassy phases. In such cases, the generic labelling of reference EDS spectra and their subsequent target component grouping allow SEM-AM for interesting and novel studies on many kinds of solid and particulate matter which are not feasible by other analytical methods.
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Zasada, Dariusz, Wojciech Polkowski, and Robert Jasionowski. "Analysis of the Effect of the Wearing Type on Surface Structural Changes of Ni3Al-Based Intermetallic Alloy." Solid State Phenomena 225 (December 2014): 25–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.225.25.
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Results of an analysis of effect of wearing type on surface structural changes of a Ni3Al intermetallic alloy, are shown in the present paper. A microstructure evaluation was carried out by Quanta 3D FEG field emission gun scanning electron microscope (FEG SEM) equipped with an integrated EDS/WDS/EBSD system. The Ni3Al-based intermetallic alloy with an addition of boron, zirconium and chromium was examined. The investigated material had γ’ single-phase, ordered solid solution structure with 20 μm grain size. An electron backscatter diffraction (EBSD) method was applied to visualize surface structural changes upon an abrasive, a cavitational and a tribological wearing of the material.An observation of surface layer after the abrasive wear was carried out on samples examined in loose abradant by T-07 tester and according to GOST 23.2008-79 norm. An analysis of cavitational wear on changes in the near surface area of Ni3Al-based alloy was performed on an impact-jet stand. Observed structural changes were described based on results of the SEM/EBSD complex structural examination and hardness measurements. It was found, that the EBSD is an effective and sensitive method that allows estimating surface strain introduced during analyzed wearing types.
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Kejzlar, Pavel, Tomáš Pilvousek, and Michal Tregler. "Determination of DC06+ZE Sheet Crack Cause." Defect and Diffusion Forum 368 (July 2016): 121–25. http://dx.doi.org/10.4028/www.scientific.net/ddf.368.121.
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The present work deals with determination of the cause of crack occurring in a part of car body manufactured from deep-drawing sheet. UHR-SEM, EDS, EBSD and measurement of microhardness were used for evaluation of the structure, local deformation and crack formation mechanism. A material analysis discovered foreign particles in the material. These particles were identified as MgAl2O4 with BCC lattice. The occurrence of these hard particles led to local stress concentration, decrease in mechanical strength and sheet breach due to tensile stress during deformation.
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Drawin, Stefan, Virgil Malard, Anne Denquin, Jean Philippe Monchoux, and Alain Couret. "From Pre-Alloyed Rod to Gas-Atomized Powder and SPS Sintered Samples: How the Microstructure of an Nb Silicide Based Alloy Evolves." Materials Science Forum 941 (December 2018): 1264–69. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1264.
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This work investigates the evolution of the microstructure of an Nb-23Ti-20Si (at.%) based alloy, from the primary plasma-melted material that is gas-atomized towards the consolidated material (here using SPS). The nature, morphology and size of the solid solution and the various silicides are followed by SEM, EDS and EBSD. Homogenous and fine microstructures are obtained after the SPS step and are improved by a subsequent heat treatment (1500°C, 100 h). However blocky silicides, already present in the powder particles, cannot be eliminated. A better control of the primary material’s microstructure would improve the microstructure of the final material.
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Higginson, R. L., G. D. West, and M. A. E. Jepson. "The Characterisation of Oxide Scales Grown on Nickel Containing Steel Substrates Using Electron Backscatter Diffraction." Materials Science Forum 539-543 (March 2007): 4482–87. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4482.
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The oxidation of steels is critically influenced by its constituent alloying elements. These alter the classical three-phase model of the external oxide scales and in addition can introduce internal oxidised regions. This paper considers the oxidation of a number of nickel containing Fe based alloys of varying compositions, including stainless steel. These have been oxidised under different conditions to produce a number of scale morphologies, which have been characterised using two SEM based techniques; Electron Backscatter Diffraction (EBSD) and Energy Dispersive x-ray Spectroscopy (EDS). Results have shown that nickel promotes the formation of a fibrous internal scale, consisting of iron oxide particles (or iron/chromium oxide in the case of stainless steel) along grain boundary regions. Nickel is rejected from these oxide particles and consequently nickel content is enriched in neighbouring metallic areas.
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Wendler, Bogdan, Łukasz Kaczmarek, M. Jachowicz, and A. Rylski. "Oxidation Resistance of Nanocrystalline Microalloyed γ–TiAl Coatings under Isothermal Conditions and Thermal Fatigue." Materials Science Forum 513 (May 2006): 135–48. http://dx.doi.org/10.4028/www.scientific.net/msf.513.135.
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γ-titanium aluminide a promising structural material for automotive and aircraft applications at high temperatures suffers from poor gas corrosion resistance. It has been proved in this work by means of microthermogravimetry and SEM, EDS, EBSD and X-Ray diffraction carried out and under isothermal conditions and thermal cycling that a great improvement of the oxidation resistance of this material can be achieved due to magnetron sputtered coatings of γ-TiAl with vatious additions (Ag, Cr, Mo, Nb, Si or Ta) or their combinations. The oxidation rate of some of these coatings is four orders of magnitude smaller than that of the bare γ-TiAl substrate.
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Reshma, C., and J. Mary Gladis. "Synthesis and Characterisation of Ternary Nanocomposites as Cathode Material for Lithium-Sulphur Batteries." Materials Science Forum 830-831 (September 2015): 604–7. http://dx.doi.org/10.4028/www.scientific.net/msf.830-831.604.
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The lithium-sulphur (Li-S) system is one of the most promising candidates for high energy density applications. Sulphur has several drawbacks such as poor conductivity, large volumetric expansion upon lithiation, dissolution of the intermediate polysulfides during charge-discharge processes. The objective of the present work is to prepare a ternary composite of MWCNT/S/conducting polymer system with unique characteristics to be used as a cathode material for lithium sulphur batteries. The synthesis has been carried out in two steps. Sulphur is introduced onto the surface of MWCNT by the chemical reaction between sodium thiosulphate and hydrochloric acid. In the second step, polyindole is produced by insitu reaction from indole monomer by using FeCl3 as oxidising agent. The MWCNT and conducting polymer help to improve the conductivity of sulphur. The composite material is characterised by TGA, FTIR, SEM-EDS and XRD analysis. The polyindole formation is confirmed by using FTIR and SEM-EDS. Electrochemical studies have been performed to demonstrate MWCNT/sulphur/polymer composites as a cathode material for rechargeable lithium –sulphur batteries.
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Guan, Jing, Qing Xiang, Xiuhua Zhang, Jing Liu, and Feng Yang. "Analysis of the mechanical properties and microstructure of titanium surfaces designed by electromagnetic induction nitriding." Materials Research Express 9, no. 2 (February 1, 2022): 020010. http://dx.doi.org/10.1088/2053-1591/ac52c5.
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Abstract Nitride has high hardness and excellent wear resistance. It is frequently prepared on a material surface to improve material performance. The nitriding layer can be prepared in different ways, so the bonding strength and microstructure between the nitriding layer and the matrix differ, which will directly affect the surface mechanical properties of the material. In this study, pure titanium (TA1) was nitrided using electromagnetic induction nitriding, and the microstructure of nitriding layer was analysed using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy-electron backscatter diffraction (SEM-EBSD) and scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDS). In addition, the mechanical properties of the nitriding layer were studied using a nanoindentation and scratch tester. The experimental result shows a 20 μm induction nitriding layer composed of TiN, Ti2N and α(N)-Ti. The compound layer (Ti2N and TiN) was approximately 3 μm. The surface was contaminated with C and O elements, and evident segregation bands were found between the induction nitriding layer and matrix. The induction nitriding layer can considerably improve the wear resistance of titanium alloy, but the bonding force between the induction nitriding layer and matrix decreases owing to the segregation band.
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Kovács, Dorina, Annamária Szabó, and Alexandra Kemény. "The Role of the Material of Active Screen During the Plasma Nitriding Process." Acta Materialia Transylvanica 3, no. 1 (April 1, 2020): 20–25. http://dx.doi.org/10.33924/amt-2020-01-04.
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AbstractIn this research the effect of the active screen’s material was investigated. 42CrMo4 steel was plasma nitrided with unalloyed steel, titanium and nickel active screen at 490 and 510 °C for 4h in 75 % N2 + 25 % H2 gas mixture. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray photoelectron spectroscopy (XPS) were used for the characterisation of the surface properties. Iron-nitride was not formed on the surface with nickel screen. The evaluation of examination results showed that most of the detected nitrogen was molecular (N2) in the formed layer.
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Varughese, G., V. Rini, S. P. Suraj, and K. T. Usha. "Characterisation and Optical Studies of Copper Oxide Nanostructures Doped with Lanthanum Ions." Advances in Materials Science 14, no. 4 (December 1, 2014): 49–60. http://dx.doi.org/10.2478/adms-2014-0021.
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AbstractCopper Oxide is an extensively studied group II-VI semiconductor with optical properties. It exhibits a wide variety of morphologies in the nano regime that can be grown by tuning the growth habit of the CuO crystal. CuO nano materials with an average particle size of 15-27 nm are synthesized by chemical route. XRD, SEM, FTIR UV-Vis and EDS characterize the samples. The percentage of doping material is confirmed from the EDS spectra. The average crystal size of the prepared CuO: La nanopowder is determined by XRD. The UV absorption spectra revealed the absorption edge at wavelength 389 nm indicating the smaller size of CuO:La nano particle. The optical direct band gap energy of doped CuO nanoparticle is found to be in the range 3.149 eV. The increasing red shift with decreasing particle size suggests that the defects responsible for the intra gap states are primarily surface defect. The La doped CuO is highly effective and can significantly enhance the photo catalytic degradation.
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Cui, Di, Antaryami Mohanta, and Marc Leparoux. "Interface Control in Additive Manufacturing of Dissimilar Metals Forming Intermetallic Compounds—Fe-Ti as a Model System." Materials 13, no. 21 (October 23, 2020): 4747. http://dx.doi.org/10.3390/ma13214747.
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Laser metal deposition (LMD) has demonstrated its ability to produce complex parts and to adjust material composition within a single workpiece. It is also a suitable additive manufacturing (AM) technology for building up dissimilar metals directly. However, brittle intermetallic compounds (IMCs) are formed at the interface of the dissimilar metals fabricated by LMD. Such brittle phases often lead to material failure due to thermal expansion coefficient mismatch, thermal stress, etc. In this work, we studied a Fe-Ti system with two brittle phases, such as FeTi and Fe2Ti, as a model system. Fe was grown on top of Ti at various process parameters. The morphologies and microstructures were characterized by optical microscopy (OM) and scanning electron microscopy (SEM). No cracks along the interface between pure Ti and bottom of the solidified melt pool were observed in the cross-sectional images. Chemical composition in the fabricated parts was measured by Energy-dispersive X-ray spectroscopy (EDS). Electron backscatter diffraction (EBSD) was performed in addition to EDS to identify the crystalline phases. The Vickers hardness test was conducted in areas with different phases. The chemical composition in the melt pool region was found to be a determining factor for the occurrence of major cracks.
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Porta-Velilla, Luis, Neslihan Turan, Álvaro Cubero, Wei Shao, Hongtao Li, Germán F. de la Fuente, Elena Martínez, et al. "Highly Regular Hexagonally-Arranged Nanostructures on Ni-W Alloy Tapes upon Irradiation with Ultrashort UV Laser Pulses." Nanomaterials 12, no. 14 (July 12, 2022): 2380. http://dx.doi.org/10.3390/nano12142380.
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Nickel tungsten alloy tapes (Ni—5 at% W, 10 mm wide, 80 µm thick, biaxially textured) used in second-generation high temperature superconductor (2G-HTS) technology were laser-processed in air with ultraviolet ps-laser pulses (355 nm wavelength, 300 ps pulse duration, 250–800 kHz pulse repetition frequency). By employing optimized surface scan-processing strategies, various laser-generated periodic surface structures were generated on the tapes. Particularly, distinct surface microstructures and nanostructures were formed. These included sub-wavelength-sized highly-regular hexagonally-arranged nano-protrusions, wavelength-sized line-grating-like laser-induced periodic surface structures (LIPSS, ripples), and larger irregular pyramidal microstructures. The induced surface morphology was characterized in depth by electron-based techniques, including scanning electron microscopy (SEM), electron back scatter diffraction (EBSD), cross-sectional transmission electron microscopy (STEM/TEM) and energy dispersive X-ray spectrometry (EDS). The in-depth EBSD crystallographic analyses indicated a significant impact of the material initial grain orientation on the type of surface nanostructure and microstructure formed upon laser irradiation. Special emphasis was laid on high-resolution material analysis of the hexagonally-arranged nano-protrusions. Their formation mechanism is discussed on the basis of the interplay between electromagnetic scattering effects followed by hydrodynamic matter re-organization after the laser exposure. The temperature stability of the hexagonally-arranged nano-protrusion was explored in post-irradiation thermal annealing experiments, in order to qualify their suitability in 2G-HTS fabrication technology with initial steps deposition temperatures in the range of 773–873 K.
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Panagiotopoulou, C., Glykeria Kakali, Sotiris Tsivilis, T. Perraki, and Maria Perraki. "Synthesis and Characterisation of Slag Based Geopolymers." Materials Science Forum 636-637 (January 2010): 155–60. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.155.
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In the present work the geopolymerisation of blast furnace slag (GGBS) under varying conditions is being investigated. The experimental comprises the following parts: i) dissolution of slag in alkaline media and the investigation of the effect of the alkali ion (K or Na) on the dissolution of Al+3 and Si4+, ii) synthesis of slag based geopolymers and the investigation of the effect of the Si/Al ratio and the kind of alkaline ion on the development of the compressive strength and iii) characterization of geopolymers by means of XRD, FTIR and SEM/EDS measurements. As it is concluded, blast furnace slag geopolymers exhibit high compressive strength, with the maximum being 112.7±2 MPa. The Si/Al ratio of the starting material is found to affect strongly the development of the geopolymer compressive strength. The microstructure of slag–based geopolymers and the incorporation of Ca in the geopolymer matrix are also discussed.
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Dyer, Ashley, Jonathan Jones, Richard Cutts, and Mark Whittaker. "The Effect of Phase Angle on the Thermo-Mechanical Fatigue Life of a Titanium Metal Matrix Composite." Materials 12, no. 6 (March 22, 2019): 953. http://dx.doi.org/10.3390/ma12060953.
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The thermo-mechanical fatigue (TMF) behaviour of a Ti-6Al-4V matrix composite reinforced with SCS-6 silicon carbide fibres (140 μm longitudinal fibres, laid up hexagonally) has been investigated. In-phase and out-of-phase TMF cycles were utilized, cycling between 80–300 °C, with varying maximum stress. The microstructure and fracture surfaces were studied using electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), profilometry, and optical microscopy. The results have shown the damaging effect of out-of-phase cycling with crack initiation occurring earlier than in in-phase tests and crack propagation rates being accelerated in out-of-phase cycles. Fatigue crack initiation has been shown to be sensitive to crystallographic texture in the cladding material and thermo-mechanical fatigue test results can be considered according to a previously proposed conceptual framework for the interpretation of metal matrix composite fatigue.
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Sequeiros, Elsa W., Anibal Guedes, Ana Maria Pires Pinto, Manuel F. Vieira, and Filomena Viana. "Microstructure and Strength of γ-TiAl Alloy/Inconel 718 Brazed Joints." Materials Science Forum 730-732 (November 2012): 835–40. http://dx.doi.org/10.4028/www.scientific.net/msf.730-732.835.
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Intermetallics and superalloys brazing development is a current topic owing the extending use of these alloys in industrial applications. In this work a γ-TiAl alloy was joined to Inconel 718 by active metal brazing, using Incusil-ABA as filler. Joining was performed at 730 °C, 830 °C and 930 °C, with a 10 min dwelling time. The interfaces were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Electron Backscatter Diffraction (EBSD). For all processing conditions, the reaction between the base materials and the braze alloy produced multilayered interfaces. For all processing temperatures tested (Ag), (Cu), AlNi2Ti and AlCu2Ti were identified at the interface. Raising the brazing temperature increased the thickness of the interface and coarsened its microstructure. The increase of the extension of the interface was essentially due to the growth of the reaction layers formed near each base material, which were found to be mainly composed of intermetallic compounds. The mechanical behavior of the joints, at room temperature, was assessed by microhardness and shear tests. For all processing conditions the hardness decreases from periphery towards the Ag-rich centre of the joints. Brazing at 730 °C for 10 min produced the joints with the highest average shear strength (228±83 MPa). SEM and EDS analysis of the fracture surfaces revealed that fracture of joints always occurred across the interface, preferentially through the hard layer, essentially composed of AlNi2Ti, resulting from the reaction between Inconel 718 and the braze alloy.
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Malczyk, Piotr, Tilo Zienert, Florian Kerber, Christian Weigelt, Sven-Olaf Sauke, Hubertus Semrau, and Christos G. Aneziris. "Corrosion-Resistant Steel–MgO Composites as Refractory Materials for Molten Aluminum Alloys." Materials 13, no. 21 (October 23, 2020): 4737. http://dx.doi.org/10.3390/ma13214737.
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In this study, a novel metal matrix composite based on 60 vol% 316L stainless steel and 40 vol% MgO manufactured by powder metallurgy technology was developed. The corrosion resistance of the developed steel–MgO composite material against molten aluminum alloy AlSi7Mg0.3 was investigated by means of wettability tests and long-term crucible corrosion tests. The wettability tests were carried out using the sessile drop method with the capillary purification technique in a hot-stage microscope (HSM). Static corrosion tests were performed in molten aluminum alloy at 850 °C for 168 h to evaluate the impact of pre-oxidation of the composite surface on the corrosion resistance. The pre-oxidation of steel–MgO composites was carried out at 850 and 1000 °C for 24 h, based on preliminary investigations using thermogravimetry (TG) and dilatometry. The influence of the pre-oxidation on the composite structure, the corrosion resistance, and the phase formation at the interface between the steel–MgO composite and aluminum alloy was analyzed using SEM/EDS and XRD. The impact of the steel–MgO composite material on the composition of the aluminum alloy regarding the type, size, and quantity of the formed precipitations was investigated with the aid of ASPEX PSEM/AFA and SEM/EBSD. It was revealed that the pre-oxidation of the steel–MgO composite at 1000 °C induced the formation of stable MgO-FeO solid solutions on its surface, leading to a significant increase of long-term corrosion resistance against the liquid aluminum alloy.
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Charlton, T. S., M. Rouainia, A. C. Aplin, Q. J. Fisher, and L. Bowen. "Micromechanical characterisation of overburden shales in the Horn River Basin through nanoindentation." IOP Conference Series: Earth and Environmental Science 1124, no. 1 (January 1, 2023): 012087. http://dx.doi.org/10.1088/1755-1315/1124/1/012087.
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Abstract The paper presents a micromechanical characterisation of Fort Simpson shale, which overlies unconventional gas-producing lithologies in the Horn River Basin, NW Canada. The Fort Simpson formation is clay-rich and microseismic data recorded during hydraulic fracturing events in the underlying reservoir has shown the formation acts as a barrier to fracture development, with a notably anisotropic seismic response. Samples were prepared from core fragments and the composition and texture of the shale was characterised using X-ray diffraction, mercury injection porosimetry and scanning electron microscopy (SEM). Nanoindentation testing was used to obtain the mechanical response of the shale microstructure, at grain-scale. The indentation was conducted on a grid pattern and samples were oriented both parallel and perpendicular to the bedding plane to assess the inherent mechanical anisotropy. Chemical analysis of the grids was also undertaken through SEM/EDS (energy dispersive X-ray spectroscopy) and the coupled chemo-mechanical data was used to characterise the material phases of the shale through a statistical clustering procedure. The results show that Fort Simpson shale broadly consists of a soft clay phase, with strongly anisotropic elastic stiffness, and stiffer but effectively isotropic grains of quartz and feldspar. A simple upscaling scheme was also applied to link the grain-scale elastic stiffness to the field-scale microseismic data.
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Silva, Marcionilo, Ana Sofia Ramos, Maria Teresa Vieira, and Sónia Simões. "Joining of Ti6Al4V to Al2O3 Using Nanomultilayers." Nanomaterials 12, no. 4 (February 21, 2022): 706. http://dx.doi.org/10.3390/nano12040706.
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Diffusion bonding of Ti6Al4V to Al2O3 using Ni/Ti reactive nanomultilayers as interlayer material was investigated. For this purpose, Ni/Ti multilayer thin films with 12, 25, and 60 nm modulation periods (bilayer thickness) were deposited by d.c. magnetron sputtering onto the base materials’ surface. The joints were processed at 750 and 800 °C with a dwell time of 60 min and under a pressure of 5 MPa. Microstructural characterization of the interfaces was conducted by scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). The mechanical characterization of the joints was performed by nanoindentation, and hardness and reduced Young’s modulus distribution maps were obtained across the interfaces. The joints processed at 800 °C using the three modulation periods were successful, showing the feasibility of using these nanolayered films to improve the diffusion bonding of dissimilar materials. Using modulation periods of 25 and 60 nm, it was also possible to reduce the bonding temperature to 750 °C and obtain a sound interface. The interfaces are mainly composed of NiTi and NiTi2 phases. The nanoindentation experiments revealed that the hardness and reduced Young’s modulus at the interfaces reflect the observed microstructure.
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Sommer, Niklas, Philipp Kluge, Florian Stredak, Sascha Eigler, Horst Hill, Thomas Niendorf, and Stefan Böhm. "Additive Manufacturing of Compositionally-Graded AISI 316L to CoCrMo Structures by Directed Energy Deposition." Crystals 11, no. 9 (August 30, 2021): 1043. http://dx.doi.org/10.3390/cryst11091043.
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In the present study, compositionally-graded structures of AISI 316L and CoCrMo alloy are manufactured by powder-based laser-beam directed energy deposition (DED-LB). Through a process-integrated adjustment of powder flow, in situ alloying of the two materials becomes feasible. Thus, a sharp and a smooth transition with a mixture of both alloys can be realized. In order to investigate the phase formation during in situ alloying, a simulation approach considering equilibrium calculations is employed. The findings reveal that a precise compositional as well as functional gradation of the two alloys is possible. Thereby, the chemical composition can be directly correlated with the specimen hardness. Moreover, phases, which are identified by equilibrium calculations, can also be observed experimentally using scanning electron microscopy (SEM) and energy-dispersive X-ray-spectroscopy (EDS). Electron backscatter diffraction (EBSD) reveals epitaxial grain growth across the sharp transition region with a pronounced <001>-texture, while the smooth transition acts as nucleus for the growth of new grains with <101>-orientation. In light of envisaged applications in the biomedical sector, the present investigation demonstrates the high potential of an AISI 316L/CoCrMo alloy material combination.
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Bergant, Zoran, Barbara Šetina Batič, Imre Felde, Roman Šturm, and Marko Sedlaček. "Tribological Properties of Solid Solution Strengthened Laser Cladded NiCrBSi/WC-12Co Metal Matrix Composite Coatings." Materials 15, no. 1 (January 4, 2022): 342. http://dx.doi.org/10.3390/ma15010342.
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NiCrBSi, WC-12Co and NiCrBSi with 30, 40 and 50 wt.% WC-12Co coatings were produced on low carbon steel by laser cladding with an Nd:YAG laser with a multi-jet coaxial cladding-nozzle. The microstructure properties after WC-12Co alloying were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), electron backscatter diffraction (EBSD) and Vickers hardness tests. The resulting microstructures consisted of a γ-Ni and Ni3B matrix, strengthened with Co and W, Ni3Si, CrB, Cr7C3, Cr23C6, WC/W2C phases. In coatings with 30, 40 and 50 wt.% WC-12Co, a solid solution, strengthened multi-matrix NiCrWCo phase formed, which yielded a higher matrix hardness. Wear tests that monitored the friction coefficients were performed with a tribometer that contained a ball-on-disc configuration, Al2O3 counter-body and reciprocal sliding mode at room temperature. The major wear mode on the NiCrBSi coatings without the WC-12Co was adhesive with a high wear rate and visible material loss by flaking, delamination and micro-ploughing. The addition of WC-12Co to the NiCrBSi coating significantly increased the wear resistance and changed the major wear mechanism from adhesion to three-body abrasion and fatigue wear.
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Sartowska, Bożena, Jerzy Piekoszewski, Lech Waliś, Marek Barlak, Irene Calliari, Katya Brunelli, Jan Senatorski, and Wojciech Starosta. "Alloying the near Surface Layer of Stainless Steel with Rare Earth Elements (REE) Using High Intensity Pulsed Plasma Beams (HIPPB)." Solid State Phenomena 186 (March 2012): 292–95. http://dx.doi.org/10.4028/www.scientific.net/ssp.186.292.
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Addition of some active elements such as yttrium, cerium, lanthanum and other rare earths elements (REE) to austenitic stainless steels helps to improve their high temperature oxidation resistance and tribological properties. The high intensity plasma pulses were used to introduce Ce and La into AISI 316L austenitic stainless steel. The plasma pulses contained both ions/atoms of Ce-La and those of the working gas. The pulse energy densities were sufficient to melt the near surface layer of the steel and introduce those elements into the surface layer. Scanning electron microscopy (SEM) as well as energy dispersion spectroscopy (EDS) was used during each one part of surface characterisation. Obtained results allowed us to make decision about directions of modified material successive investigations.
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Vasylyev, M. O., B. M. Mordyuk, S. M. Voloshko, and P. O. Gurin. "Microstructure of Co–Cr Dental Alloys Manufactured by Casting and 3D Selective Laser Melting." Progress in Physics of Metals 23, no. 2 (June 2022): 337–59. http://dx.doi.org/10.15407/ufm.23.02.337.
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The review analyses the microstructure of the commercial Co–Cr–(Mo, W) dental alloys fabricated by 3D digital selective laser melting (SLM), which is the most promising technique among the emerging additive fabrication technologies used for metal products manufacturing in dentistry. In this regard, the main goal is to compare the microstructures of the metal dental products produced by two currently used technologies, namely, conventional casting and SLM. We consider the latest research published from 2013 to 2022. The microstructures are evaluated using optical microscopy (OM), scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM–EDS), x-ray diffractometry (XRD), electron backscatter diffraction (EBSD) pattern analysis, and atomic force microscopy (AFM). The microstructure analysis allows concluding whether the SLM fabrication process is suitable for dental applications. As shown, the microstructure of the Co–Cr dental alloys depends on both the chemical composition of the samples and the parameters of the manufacturing technique used. Experimental results have proven that, in contrast to the conventional casting, the SLM-fabricated specimens display superior microstructure due to complete local melting and rapid solidification. Additionally, the SLM process minimizes residual flaws and porosity. As a result, SLM allows producing the dense material comprising homogeneous fine-grain microstructure.
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Dzhurinskiy, Dmitry, Abhishek Babu, Stanislav Dautov, Anil Lama, and Mayuribala Mangrulkar. "Modification of Cold-Sprayed Cu-Al-Ni-Al2O3 Composite Coatings by Friction Stir Technique to Enhance Wear Resistance Performance." Coatings 12, no. 8 (August 4, 2022): 1113. http://dx.doi.org/10.3390/coatings12081113.
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An innovative hybrid process combining two effective surface modification techniques, cold spray (CS) and friction stir processing (FSP), was proposed to refine the microstructure of Cu-Al-Ni-Al2O3 composite coating material. FSP was performed under constant rpm using extensive cooling conditions to remove heat generated during the operation. Microstructural characterizations such as optical micrography (OM), scanning electron microscopy (SEM), Electron Backscatter Diffraction (EBSD), Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were performed to evaluate the microstructural evolution of the coatings before and after FSP treatment. Mechanical characterizations such as microhardness and elastic modulus were measured using micro-depth sensing techniques. Furthermore, sliding wear tests were performed to study the wear resistance of the as-sprayed and processed coatings. The findings suggest that after FSP, there is an improvement in microstructure of the coating layers with the elimination of particle boundaries, micro-pores and micro-cracks, and processed coatings showed an improvement in mechanical properties. Furthermore, there was a slight reduction in the wear rate of the deposited CuAlNi-Al2O3 composite coatings. Among all the test coatings, friction stir processed S1 coating showed the lowest wear rate, which was an almost two times lower wear rate than its unprocessed counterparts.
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Koenig, Andreas, Julius Schmidtke, Leonie Schmohl, Sibylle Schneider-Feyrer, Martin Rosentritt, Hieronymus Hoelzig, Gert Kloess, et al. "Characterisation of the Filler Fraction in CAD/CAM Resin-Based Composites." Materials 14, no. 8 (April 15, 2021): 1986. http://dx.doi.org/10.3390/ma14081986.
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The performance of dental resin-based composites (RBCs) heavily depends on the characteristic properties of the individual filler fraction. As specific information regarding the properties of the filler fraction is often missing, the current study aims to characterize the filler fractions of several contemporary computer-aided design/computer-aided manufacturing (CAD/CAM) RBCs from a material science point of view. The filler fractions of seven commercially available CAD/CAM RBCs featuring different translucency variants were analysed using Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Micro-X-ray Computed Tomography (µXCT), Thermogravimetric Analysis (TG) and X-ray Diffractometry (XRD). All CAD/CAM RBCs investigated included midifill hybrid type filler fractions, and the size of the individual particles was clearly larger than the individual specifications of the manufacturer. The fillers in Shofu Block HC featured a sphericity of ≈0.8, while it was <0.7 in all other RBCs. All RBCs featured only X-ray amorphous phases. However, in Lava Ultimate, zircon crystals with low crystallinity were detected. In some CAD/CAM RBCs, inhomogeneities (X-ray opaque fillers or pores) with a size <80 µm were identified, but the effects were minor in relation to the total volume (<0.01 vol.%). The characteristic parameters of the filler fraction in RBCs are essential for the interpretation of the individual material’s mechanical and optical properties.
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Moreira, Aida B., Laura M. M. Ribeiro, Pedro Lacerda, Ana M. P. Pinto, and Manuel F. Vieira. "A Study on a Cast Steel Reinforced with WC–Metal Matrix Composite." Materials 15, no. 18 (September 6, 2022): 6199. http://dx.doi.org/10.3390/ma15186199.
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This study seeks to investigate the local reinforcement of low carbon cast steel specimens with WC–metal matrix composites (WC–MMCs), to obtain a new material effective in competing with hard alloy steels. For this purpose, a powder compact of tungsten carbide (WC) and iron (Fe) was prepared and placed in the mold cavity before casting. The reactions that occurred with the molten steel led to the formation of the WC–MMC and, consequently, to the local reinforcement of the steel. The microstructure of the WC–MMC reinforcement was characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). The results showed a microstructural variation throughout the depth of the reinforcement. In the surface region, most of the original WC particles retain their polygonal morphology, but towards the base metal, the dissolution of the WC particles increased with the formation of (Fe,W)6C carbides. Closer to the base metal, dendritic eutectic carbides of (Fe,W)6C and fine (Fe,W)23C6 precipitates in a matrix of martensite were formed. The mechanical properties of the reinforcement were evaluated by hardness and ball-cratering abrasion tests. The results revealed a significant increase in hardness, being three times harder than the base metal, and a decrease of 39% in the wear rate.
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Guo, X., P. He, K. Xu, X. Ch Lv, J. B. Zhang, and Y. Gu. "Microstructure investigation on the fusion zone of steel/nickel-alloy dissimilar weld joint for nozzle buttering in nuclear power industry." Welding in the World 66, no. 2 (October 9, 2021): 187–94. http://dx.doi.org/10.1007/s40194-021-01199-9.
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Abstract Microstructure of the fusion zone of steel/nickel-alloy dissimilar metal welds (DMWs) for nozzle buttering was investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and electron back-scattered microscopy (EBSD). The results showed that the dissimilar joint was complete, without welding defects. The structures of the fusion zone included the beach structure along the fusion boundary, the peninsula structures connected with the fusion boundary, and the island structures in the weld. The distribution of these three types of structures near the fusion boundary was uneven. The beach structure was formed because of the insufficient mixing and solidification of the molten liquid base material and the filler metal, with the width ranging between 0 and 150 μm. The peninsula and island structures were formed by the undercooling of the insufficiently mixed liquid base material and filler metal that entered the weld because of the convection and scouring of the weld pool. The composition of the three structures depended on the degree of mixing of the liquid base material and the filler metal, with a dilution ratio between 40 and 60%. The degree of dilution for the beach, peninsula, and island structures decreased in turn. With an increase in the dilution ratio, the initial solidification temperature of the corresponding composition increased significantly. When the dilution ratio exceeded 94.5%, the initial solidification phase transformed from the face-centered cubic γ-austenite into a body-centered cubic ferrite, with island structures solidified in the form of ferrites in the weld near the fusion boundary. The austenite grain orientations at weld side are dispersed with 75% large (> 15°) misorientation in frequency and the overall texture orientation distributes dispersedly with deviating from the < 100 > direction.
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Simões, M. F., C. Santos, and N. Lima. "The importance of structural diversity of spores in the taxonomy of Aspergillus (section Nigri)." Microscopy and Microanalysis 19, S4 (August 2013): 77–78. http://dx.doi.org/10.1017/s1431927613001001.
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Species of Aspergillus from section Nigri, also known as black aspergilli, are distributed worldwide and have been widely used for purposes of various types such as: biotechnological, industrial, medical, among others. They have been extensively studied for being the causing agents of biodeterioration of commodities and food.Within this section, new species have been recently described and among them Aspergillus ibericus and Aspergillus uvarum were both isolated from grapes. The polyphasic approach used in the analysis of these species, either by morphological techniques as well as by molecular methods, allowed not only their characterisation but also their consequent separation from all others in the section. Microbial taxonomy has the identification of species as one of its fundamental goals. Data such as: morphological characteristics description, physiological and biochemical properties, ecological roles, and societal risks or benefits, are key elements in any fungal identification process. But, this process is subjected to periodic changes due to frequent revisions of the taxonomic schemes, therefore becoming time consuming and more demanding and difficult, even for skilled specialists. Furthermore, each taxonomic group has specialised literature, terminology and characters. This takes place since identifications have difficulties of consensual naming, depending on the criteria used and the amount of information available when producing all data. It is increasingly becoming clear that, to better achieve a more accurate concept of species, microbial identification and authentication require a polyphasic approach to produce consistent, useful and quality data.Characterisation of morphologic and structural aspects of spores from Aspergillus strains, section Nigri, has been carried out using scanning electron microscopy (SEM) and intends to contribute to the associated data of the strains from this section.Colonies from 13 Aspergillus from section Nigri, from the Micoteca da Universidade do Minho (MUM), were grown at 25 ºC for 3 or 4 days in malt extract agar directly mounted in a sterilised SEM stub. The samples were covered with a mixture of gold and platinum (80/20%) and then examined in the SEM [NanoSEM - FEI NovaTM 200 (FEG/SEM); EDAX - Pegasus X4M (EDS/EBSD)]. A stereomicroscope (Leica MZ12.5) was used to have a clear image comparison of the size of the conidial head.Although the analysed strains presented dimensional, morphological and structural diversity, common or typical features could be inferred and related to each taxon like those represented in Fig 1.From the SEM analysis we were able to conclude that in the section Nigri of genus Aspergillus the spore wall ornamentation, and its size and shape continue to present themselves as important primary diagnostic traits for species differentiation.
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Tatli, Zafer, Adem Demir, and F. Caliskan. "Carbothermal Reduction and Nitridation of Çanakkale Origin Kaolin for SiAlON Powder Production." Materials Science Forum 554 (August 2007): 169–74. http://dx.doi.org/10.4028/www.scientific.net/msf.554.169.
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SiAlON ceramics were successfully produced in the form of powders from high purity kaolin, a hydrated aluminium silicate, Al2Si2O5(OH)4 type of clay mineral (comprises 83.85% kaolinite, 13.59% quartz, 0.88% feldspar, 1.37% others) of Canakkale-Can origin. Factors affecting SiAlON powder production were temperature, holding time, gas-flow rate and preparation methods. System optimisation was achieved following the results succeeded from numerous testing and characterisation (with XRD, SEM, EDS, BET, etc.) of each test. Changing in gas flow rate, temperature and holding time at plateau temperature had influences on the final powder yield, their morphologies and phase formation. The best conversion of kaolin clay mineral to SiAlON ceramic powder was the test run at 1475oC for 4 hour under 1 lt/min N2-flow. Product after the process was mainly of β'- Si3Al3O3N5 (z=3) powder along with small amounts of Al2O3, mullite and AlN phases. Some powder product exhibits furry type of wiskers morphology, which may be useful for using as a reinforcing material in particulate composite bodies.
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Iorga, Ovidiu, Cristiana Epure, Alexandru Marin, and Dănuț-Eugeniu Moşteanu. "Research Regarding the Properties and Combustion Performance of a Thermal Decoy Pyrotechnic Composition." International conference KNOWLEDGE-BASED ORGANIZATION 28, no. 3 (June 1, 2022): 52–57. http://dx.doi.org/10.2478/kbo-2022-0087.
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Abstract The present research focuses on the characterisation of a new formulation for thermal decoy pyrotechnic composition, as an alternative to magnesium-teflon-viton (MTV) formulations. The oxidant used in the composition is potassium perchlorate, given its good thermal stability and high percentage of available oxygen. The fuel of choice is magnalium (alloy of Al-Mg 50-50 % wt.), as an higher energy alternative to magnesium. The binder used in the composition is a blend of solvent free polyurethane and a chlorinated rubber. The main advantages of this composition are related to the high thermal stability, the ease of processing, by squeeze casting method and its good combustion performance (temperature and burn rate profile). The use of chlorinated rubber in the composition is beneficial, as a sensible increase in the burn rate and combustion temperature is observed. The morphological properties and chemical composition of the material is evidenced by SEM-EDS analysis while the burn rate and combustion temperature is recorded with a high speed thermal camera. The combustion heat and specific volume is calculated with a dedicated thermochemical code while the results are validated in experimental determinations. The presented formulation can represent a more safe and cost effective material to be used in thermal countermeasure ammunitions.
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Yuan, Shidan, Ye Ma, Xingyi Li, Zhen Ma, Hui Yang, and Liting Mu. "Fabrication and Microstructure of ZnO/HA Composite with In Situ Formation of Second-Phase ZnO." Materials 13, no. 18 (September 7, 2020): 3948. http://dx.doi.org/10.3390/ma13183948.
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Nanometer hydroxyapatite (n-HA) powders were synthesized by the chemical precipitation method, and a novel ZnO/HA composite, which consisted of second-phase particles with different sizes and distributions, was successfully fabricated. ZnO/HA composites were prepared by using powder sintering with different Zn contents and a prefabrication pressure of 150 MPa. Microstructure and local chemical composition were analyzed by a scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS), respectively. The phase composition and distribution of the composite were determined with electron back-scattered diffraction (EBSD) and an X-ray diffractometer (XRD), respectively. The experimental results of the XRD showed that the chemical precipitation method was a simple and efficient method to obtain high-purity n-HA powders. When the sintering temperature was lower than 1250 °C, the thermal stability of HA was not affected by the Zn in the sintering process. Due to sintering in an air atmosphere, the oxidation reaction of Zn took place in three stages, and ZnO as the second phase had two different sizes and distributions in the composites. The compressive strength of ZnO/HA composites, of which the highest was up to 332 MPa when the Zn content was 20%, was significantly improved compared with pure HA. The improvement in mechanical properties was mainly due to the distribution of fine ZnO particles among HA grains, which hindered the HA grain boundary migration and refinement of HA grains. As grain refinement increased the area of the grain boundary inside the material, both the grain boundary and second phase hindered crack development in different ways.
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Rogan Šmuc, Nastja, Nives Kovač, Žan Hauptman, Andrej Šmuc, Matej Dolenec, and Aleš Šoster. "A Detailed Insight into the Detrital and Diagenetic Mineralogy of Metal(oid)s: Their Origin, Distribution and Associations within Hypersaline Sediments." Minerals 11, no. 11 (October 22, 2021): 1168. http://dx.doi.org/10.3390/min11111168.
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Hypersaline environments are among the most vulnerable coastal ecosystems and are extremely noteworthy for a variety of ecological reasons. Comprehensive assessment of metal(oid) contamination in hypersaline sediments from Sečovlje (Northern Adriatic, Slovenia) was addressed by introducing the detrital and diagenetic mineralogy and geochemical properties within the solid sediment material. Close associations between Fe/Mn oxides and oxyhydroxides with As, Cr, Ni, Pb and Zn, and between organic matter with Cu, Pb and Zn were confirmed using X-ray powder diffraction, SEM-EDS and ICP emission spectrometry analysis. Possible incorporation or adsorption on the crystal lattices of clay minerals (As, Cr, Pb, Sn and Zn), halite (As) and aragonite/calcite (Cd, Cu, Pb, Sr and Zn) were also detected. All presented correlations were highlighted by various statistical analyses. The enrichment factor (EF) values showed a low degree of anthropogenic burden for As, Bi, Hg and Zn, while Cd, Cr, Cu, Ni, Pb, Sn and Sr originated from the geological background. These results emphasise that a detailed mineralogical and geochemical characterisation of solid (especially detrital and diagenetic) sediment particles is crucial in further understanding the metal(oid) translocation within the hypersaline ecosystems.
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Simić, Lidija, Rebeka Rudolf, Peter Majerič, and Ivan Anžel. "Cast Microstructure of a Complex Concentrated Noble Alloy Ag20Pd20Pt20Cu20Ni20." Materials 15, no. 14 (July 8, 2022): 4788. http://dx.doi.org/10.3390/ma15144788.
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A complex concentrated noble alloy (CCNA) of equiatomic composition (Ag20Pd20Pt20Cu20Ni20–20 at. %) was studied as a potential high—performance material. The equiatomic composition was used so that this alloy could be classified in the subgroup of high—entropy alloys (HEA). The alloy was prepared by induction melting at atmospheric pressure, using high purity elements. The degree of metastability of the cast state was estimated on the basis of changes in the microstructure during annealing at high temperatures in a protective atmosphere of argon. Characterisation of the metallographically prepared samples was performed using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), differential scanning calorimetry (DSC), and X–ray diffraction (XRD). Observation shows that the microstructure of the CCNA is in a very metastable state and multiphase, consisting of a continuous base of dendritic solidification—a matrix with an interdendritic region without other microstructural components and complex spheres. A model of the probable flow of metastable solidification of the studied alloy was proposed, based on the separation of L—melts into L1 (rich in Ni) and L2 (rich in Ag). The phenomenon of liquid phase separation in the considered CCNA is based on the monotectic reaction in the Ag−Ni system.
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Monajati, Hossein, Mariem Zoghlami, Amevi Tongne, and Mohammad Jahazi. "Assessing Microstructure-Local Mechanical Properties in Friction Stir Welded 6082-T6 Aluminum Alloy." Metals 10, no. 9 (September 16, 2020): 1244. http://dx.doi.org/10.3390/met10091244.
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The severe deformation and temperature paths in the stir zone, also called weld nugget, of friction stir welded joints result, at very local levels, in significant microstructural variations, such as major differences in grain size or precipitation. One of the most common features of friction stir welds is the presence of successive material layers, known as onion rings; however, little data is available on the mechanical properties of the different regions of the weld nugget, and particularly within the onion ring bands. Such information becomes very important for the integrity of large size friction stir welded structures. In the present study, a comprehensive characterization of onion rings produced during friction stir welding of a 6082-aluminum alloy was carried out. Advanced techniques such as in-situ SEM nanoindentation, EBSD, and high-resolution EDS were used to validate and compare the characteristics of the different bands in the onion rings. The analyses consisted of quantifying variations in grain size, precipitate composition and distribution, crystallographic orientations, and mechanical properties in each band. Furthermore, the tensile strengths of different regions of the weld nugget were evaluated using shear punch testing and correlated with those for the onion ring region in order to determine the impact of the presence of onion rings on weld nugget mechanical properties. The main difference between the alternate bands in the onion ring was found to be due to the difference in their grain size, misorientation, and precipitate content. It was also observed that the bands originate from the base metal and stir zone successively due to the nature of the stirring process, which pulls BM into SZ. Comparison of the shear punch testing results in different regions of the nugget revealed that, in spite of having local differences in the hardness of alternate bands in the onion ring, the presence of onion rings has no significant impact on the deterioration of the mechanical properties of the weld nugget.
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Nghipulile, Titus, Thomas Ehongo Moongo, Godfrey Dzinomwa, Sandile Nkwanyana, Benjamin Mapani, and Jaquiline Tatenda Kurasha. "Evaluation of the Relationship between the Milling Breakage Parameters and Mineralogical Data: A Case Study of Three Copper Ores from a Multi-Mineralised Deposit." Minerals 12, no. 10 (October 6, 2022): 1263. http://dx.doi.org/10.3390/min12101263.
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The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and related the breakage parameters to the mineral composition data. Five mono-size fractions between 1000 µm and 212 µm were dry milled for short grinding times in the laboratory ball mill in order to obtain data for predicting breakage rate parameters. The analytical and mineralogical characterisation of the ores were performed using X-ray fluorescence (XRF) analysis, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, optical microscopy analysis and X-ray diffractometer (XRD). The mineralogy data showed that quartz was the abundant gangue mineral (average for each ore was above 60% (w/w)), followed by K-feldspar minerals (orthoclase and microcline) which constituted between 4% (w/w) and 6% (w/w) and the remainder are the minor calcite and dolomite minerals which are also in the host rock. The experimental milling kinetics parameters and mineralogical data were used to assess the robustness of the heterogeneous (two-component) and homogeneous (single-component) first-order rate breakage models. The mineral composition data were used for setting up the predictions of breakage parameters in the two-component and single-component first-order breakage models. The experimental data fitted better on the two-component breakage model than the single-component breakage model. These results highlighted the influence of two groups of minerals (generally classed as valuable and gangue minerals). The breakage data showed that the selection function for the hard component (the gangue minerals) has a dominant contribution to the overall selection function of the ores, with SiA correlating fairly well with experimental Si. The parameter a in the Austin empirical breakage model was relatively similar (approximately 1) for all three ores, which confirms similar milling conditions to which the ores were subjected to. The data suggests that there is a relationship between breakage parameter α (material-specific parameter) in the Austin empirical breakage model and brittleness index βi (calculated from the mineralogical composition of the gangue phase). No clear trends could be deduced from the cumulative breakage distributions of the three ores. This highlights the complexity of developing relationships between the mineralogical composition data and breakage distributions of the ores which are extracted from the same deposit and with comparable gangue composition.
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Nayak, U. Pranav, Florian Schäfer, Frank Mücklich, and María Agustina Guitar. "Wear Induced Sub-surface Deformation Characteristics of a 26 Wt% Cr White Cast Iron Subjected to a Destabilization Heat Treatment." Tribology Letters 71, no. 1 (December 4, 2022). http://dx.doi.org/10.1007/s11249-022-01683-3.
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AbstractIn the present work, the sub-surface microstructure of a heat treated and worn 26 wt% Cr white cast iron was investigated to gain better insight into the tribological behaviour of the material. The samples were destabilized at 980 °C for 0 (Q_0), 30 (Q_30) and 90 (Q_90) minutes followed by air cooling, and later subjected to dry-sliding linear reciprocating wear tests. The microstructural characterization of the area under the wear track was carried out using a combination of SEM, EDS and EBSD. Additionally, nanoindentation (NI) measurements were used to corroborate the mechanical behaviour with the microstructural observations. EBSD and NI measurements indicated that the matrix area underneath the wear track in Q_0 had undergone significant plastic deformation resulting in a drastic increase in hardness, whereas no such phenomena was observed in the Q_90. This was attributable to the relatively high amount of retained austenite in the former and a predominately martensitic matrix in the latter. Moreover, the large M7C3 eutectic carbides were less cracked in the destabilized samples compared to the as-cast sample owing to the presence of martensite and dispersed secondary carbides, leading to an increased matrix load-bearing capacity. These factors led to the destabilized samples showing a lower wear rate compared to the as-cast sample, and the Q_0 showing the best wear resistance amongst all the samples.
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Di Benedetto, Francesco, Andrea Giaccherini, Maurizio Romanelli, Giordano Montegrossi, Elena Belluso, Silvana Capella, Alfonso Zoleo, et al. "A study of radicals in industrial raw cristobalite powders." Physics and Chemistry of Minerals 48, no. 2 (February 2021). http://dx.doi.org/10.1007/s00269-020-01127-1.
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AbstractWe report the results of an experimental multianalytical characterisation of industrial cristobalite powders, used as raw materials for artificial stone production. Cristobalite is considered a serious threat to human health. The study was carried out through X-ray diffraction (XRD), scanning electron microscopy with energy dispersive microanalysis (SEM/EDS), continuous-wave (cw) and pulse electron paramagnetic resonance (EPR) spectroscopy. Our results point out a sub-micrometric size of the structural coherence in cristobalite, associated with numerous stacking defects. Moreover, the material was found characterised by the presence of superoxide radicals, whose persistence appears conceivably long. Radicals in a material synthesized through a high-temperature treatment were generated during the grinding step in the industrial production of cristobalite. During this process, in fact, both superoxide generation and structural defectivity are induced. Indeed, cristobalite powders already result activated by a radical population, before any kind of process in artificial stone production.
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Grewal, H. S., H. S. Arora, H. Singh, Anupam Agrawal, and S. Mukherjee. "Improving Erosion Resistance of Hydroturbine Steel Using Friction Stir Processing." Journal of Tribology 136, no. 4 (June 6, 2014). http://dx.doi.org/10.1115/1.4027622.
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In the present work, the slurry erosion behavior of friction stir processed (FSPed) hydroturbine steel (CA6NM) was investigated. For comparison, the erosion performance of unprocessed CA6NM steel was evaluated under similar conditions. Friction stir processing (FSP) is a microstructural refinement tool which is useful in enhancing the bulk and surface properties of materials. An in-depth characterization of both steels was done using an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), the electron backscatter diffraction (EBSD) technique, and micro- and nano-indentation techniques. The FSP of the steel helped in reducing the erosion rates by 50% to 60%, depending upon the impingement angle. The improved performance of the FSPed steel in comparison to unprocessed steel was attributed to microstructural refinement, which increased the hardness and yield strength. At an oblique impingement angle, plowing, along with microcutting, was observed to be the dominant erosion mechanism. At a normal impingement angle, the material removal process was controlled by the platelet mechanism of erosion. A modified form of the mathematical model for predicting the erosion rates of the ductile materials, proposed by authors earlier, was also presented. This modified model based upon the theory of plasticity was able to predict the erosion rates with an accuracy of ±20%.
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Öhlin, Oscar, Guocai Chai, and Raveendra Siriki. "Structural Stability of Sandvik 3R60™ After 240 131 Hours Ageing and Creep Test at 700 °C." Transactions of the Indian National Academy of Engineering, November 26, 2021. http://dx.doi.org/10.1007/s41403-021-00298-9.
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AbstractSandvik 3R60™ is an AISI 316/316L type of stainless steel. In this paper, the structural stability of the material under long-term ageing or creep test has been studied. The material had been creep tested with a stress of 45 MPa at 700 °C. The predicted rupture time for the creep specimen was about 100,000 h; however, the specimen broke first after 240,131 h. The oxidation behavior and structural stability in both aged and creep-tested samples were studied using SEM/EDS, EBSD and ECCI techniques. Thin oxide layers near the sample surface are mainly spinel oxides and eskolaite (Cr2O3). Sigma phase, χ-phase, Eta phase, M23C6 and Cr2N have been observed in the matrix of the samples. In the crept sample, the amount of sigma phase has increased, so has Eta phase and χ-phase as well. Thermo-Calc evaluation can reasonably predict precipitation of sigma phase, Eta phase and M23C6, but not χ-phase and Cr2N phases. Creep crack initiation behavior has been studied. It is mainly noticed to start at surface oxide layer or coarse sigma particles at grain boundary or triple point. Additionally, it is also observed that the presence of a thin Cr2O3 layer between the oxide and matrix along with discontinuous sigma phase distribution at grain boundary that will reduce the risk for creep crack initiation. Further, the crack propagation behavior has also been discussed.
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Quiñones, Javier, Ángel González de la Huebra, and Aurora Martínez Esparza. "Coprecipitation Experiments Using Simulated Spent Fuel Solutions in the Presence of Metallic Iron in Synthetic Bentonitic-Granitic Water Under Oxidising Conditions." MRS Proceedings 824 (2004). http://dx.doi.org/10.1557/proc-824-cc8.9.
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AbstractThis paper presents the results obtained from coprecipitation experiments of uranyl solutions in the presence of metallic iron and/or its alteration phases in synthetic bentonitic-granitic composition water. Experiments were done under oxidising conditions at room temperature. The pH range covered was 7.4 – 8.8. Changes in the uranium concentrations and the characterisation of the secondary phases formed in the experiments were done using XRD and SEM-EDS and are presented herein.Final uranium concentration values were in the range of 2·10−5 – 5·10−4 mol (kg of H2O)−1. In all cases, results from these experiments did not show evidence of a clear effect due to the presence of iron (metallic or previously corroded) on the uranium concentration. These data were similar to those obtained by coprecipitation in similar conditions but in absence of iron material. Boltwoodite was observed [K2(UO2)2(SiO3)2(OH)2·3H2O] in iron surface materials and characterized in all experiments. Based on the experimental data obtained (uranium concentration in solution and bulk solid phase characterisation) we propose the following surface-mediated reaction:2 K+ + 2 H4SiO4 + 2 UO2+2 + 3 H2O ⇔ K2(UO2)2(SiO3)2(OH)2·3H2O + 6 H+
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Samandi, M., M. Bate, R. Donnan, and S. Miyake. "Microwave Induced Plasma (MIP) Brazing of Silicon Nitride to Stainless Steel." MRS Proceedings 430 (1996). http://dx.doi.org/10.1557/proc-430-113.
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AbstractIn an attempt to accelerate the process of joining of metals to ceramics, a new rapid brazing technology has been developed. In this process, referred to as Microwave Induced Plasma (MIP) brazing, a microwave plasma is used to rapidly heat the ceramic and metal to the melting temperature of the reactive braze material. The heating rate obtained by MIP could be many times faster than those achieved by conventional resistive heating in a tube furnace. The fast heating rate has no detrimental effect on the joint quality and in fact results in the formation of a thick interfacial film suggesting significant interdiffusion between the braze and ceramic, possibly stimulated by the microwave radiation. In this paper the experimental arrangement of the MIP system is described. The unique capability of the MIP heating is demonstrated by successful joining of hot pressed silicon nitride to stainless steel using reactive metal brazing. The results of microstructural characterisation of the joints carried out by SEM and EDS will also be presented.
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Faisal, Nadimul Haque, Nazmi Sellami, Federico Venturi, Tanvir Hussain, Tapas Mallick, Firdaus Muhammad-Sukki, Alex Bishop, Hari Upadhyaya, Nirmal Kumar Katiyar, and Saurav Goel. "Large-scale manufacturing route to metamaterial coatings using thermal spray techniques and their response to solar radiation." Emergent Materials, July 4, 2021. http://dx.doi.org/10.1007/s42247-021-00252-z.
Full textAbstract:
AbstractMetamaterials, an artificial periodic two- or three-dimensional configuration, can change propagation characteristics of electromagnetic waves (i.e., reflection, transmission, absorption). The current challenges in the field of metamaterial coatings are their manufacturing in a large-scale and large-length scale. There is a clear need to enhance process technologies and scalability of these. Thermal spraying is a method used to deposit small- to large-scale coatings where the sprayed layer is typically formed by the successive impact of fully or partially molten particles of a material exposed to various process conditions. This work aims to investigate the feasibility to manufacture large scale metamaterial coatings using the thermal spray technique and examine their response to solar radiation. Two types of coatings namely, Cr2O3 and TiO2, were deposited onto various substrates (e.g., steel, aluminium, glass, indium tin oxide (ITO)–coated glass) with a fine wire mesh (143 µm and 1 mm aperture sizes) as the masking sheet to manipulate the surface pattern using suspension high-velocity oxy-fuel thermal spraying (S-HVOF) and atmospheric plasma-sprayed (APS) methods, respectively. Post deposition, their responses subjected to electromagnetic wave (between 250 and 2500 nm or ultraviolet (UV)-visible (Vis)-infrared (IR) region) were characterised. The additional microstructural characterisation was performed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), three-dimensional profilometry, and optical spectroscopy. It is demonstrated that through novel application of thermal spray techniques, large-scale manufacturing of metamaterial coating is possible, and such material can affect electromagnetic wave propagation. Comparison between Cr2O3 and TiO2 coatings on aluminium substrates showed reduced three orders of reduced reflectance for Cr2O3 coatings (for 1-mm aperture size) throughout the spectrum. It was concluded that for a similar bandgap, Cr2O3 coatings on aluminium substrate will yield improved optical performance than TiO2 coating, and hence more useful to fabricate opto-electronic devices. Graphical abstract