This study develops a multifunctional porous quasicrystalline (QC) material from an Al-Cu-Fe-Cr alloy for efficient adsorption and catalytic degradation of Congo Red. By optimizing alkaline leaching conditions, the material's porosity, surface chemistry, and functional performance were tailored. An Al85Cu6Fe3Cr6 (at%) alloy produced by spray forming was leached in 10 M NaOH for 0.5-48 h to selectively dissolve aluminum and expose active sites. A systematic investigation of the structural evolution and surface properties was conducted, and the adsorption capacity and catalytic behavior of the prepared alloys were also evaluated. After 30 min of controlled leaching, an optimal macroporous structure was produced with 10.9% porosity and a positive surface charge of 7.2 mV. This enhances the electrostatic adsorption of CR, achieving 70% removal within 24 h while maintaining QC phases and accessible active sites. The material also demonstrated effective catalytic activity, achieving complete azo-bond cleavage in under 10 min, favored by oxidized Fe/Cr/Cu species.

Since its discovery, Portland Cement has been a fundamental material in civil engineering, and its characteristics and properties are widely recognized. Nevertheless, new applications and uses for this material are being reported every day. Some examples rose from its intrinsic porous structure, which opens up opportunities for applications such as thermal and acoustic insulation, special filters for phase separation and water desalination, the manufacture of permeable pavements, and various other research areas requiring materials with tailored porosity. The preparation of porous cement gives it unique shapes and properties. Among the techniques which can be used for this purpose, the freeze-casting process deserves to be highlighted. In this method, an aqueous suspension with a specific concentration of solid particles is frozen. The directional water crystallization is used to form oriented pores following the temperature gradient. In this study, various proportions of water and cement, as well as different freezing rate, have been investigated to optimize this process. Specimens were evaluated in relation to their density, porosity, compressive strength, and pore structure using Archimedes tests, optical microscopy, X-ray microtomography, and mechanical testing. The results are promising: the freeze-casting process successfully oriented the porosity of the cement, and the use of liquid nitrogen as a coolant with high freezing rate resulting in increased compressive strength. Additionally, the resulting structures exhibited high accessible open porosity, which can be beneficial in many applications.

Metal particles can be welded without significant heating due to severe plastic deformation caused by high pressure torsion. This process has been used to consolidate metallic particles and incorporate ceramic materials into a metallic matrix. The present study demonstrates for the first time that this technique can also be used to incorporate pharmaceuticals into a metallic matrix. In addition, it shows that embedding pharmaceuticals in a biodegradable metal matrix enables the creation of composites with drug delivery capabilities. The results obtained here indicate the successful incorporation of ofloxacin, amphotericin B, and diclofenac sodium into a continuous magnesium matrix. The antifungal and antibacterial activities of the different composites are evaluated along with their drug release kinetics. A new class of biomaterials, biodegradable metals with integrated drug delivery functionality, is introduced in this study.

The effect of high pressure torsion processing on mechanical properties and corrosion behavior of pure magnesium and Mg-Zn, Mg-Zn-Ca, Mg-Li-Y and Mg-Y-RE alloys is investigated. Micro-tomography and SEM characterization are used to estimate corrosion rate and evaluate non-uniform corrosion features. The results show that severe plastic deformation processing improves the strength of all magnesium alloys, but deformation localization can take place in the Mg-Zn-Ca and Mg-Y-RE alloys. The occurrence of deformation localization is associated with low strain rate sensitivity in these alloys and with severe corrosion localization. Pure magnesium and Mg-Zn and Mg-Li-Y alloys display good corrosion resistance with a low corrosion rate and maintain integrity after 28 days of immersion in Hank's solution.

High-pressure torsion (HPT) processing has proved to be a powerful tool to consolidate metallic particles and fabricate nanostructured metal-matrix composites with a wide range of compositions. In this study, HPT was used to fabricate different Mg-Zn composites at room temperature, and the evolution of microstructure and mechanical properties were analyzed by x-ray diffraction, scanning and transmission electron microscopy, dynamic hardness and Vickers microhardness tests. The results show that ultrafine-grained microstructures were achieved in all composites compositions. Smaller grain sizes are observed in Mg-rich phases near areas with significant segregations of Zn. The Mg-rich phase appears to retain less deformation than the Zn-rich phase. Bending and vortex phenomena, that are usually reported in microscale for materials mixed by HPT, are observed in nanoscale in this work. There is evidence of the MgZn2 intermetallic phase with a morphology that varies with composition. Higher levels of deformation imposed by HPT leads to an increase in hardening and a decrease in strain-rate sensitivity which are attributed to the tendency to form intermetallics and Zn segregations that prevent grain boundary sliding. Moreover, a model is proposed to explain the mixing of phases in microscale and its relation to the evolution of mechanical properties. (C) 2021 Elsevier B.V. All rights reserved.

In this study, we deployed a severe mechanochemical approach to produce ultrahard Al-Nb nanocomposites. Two nanocomposites were fabricated by high-pressure torsion (HPT) at room temperature of commercially pure Al and 10 wt% Nb2O5 with distinct morphologies (extremely thin nanowires or nanorods). In addition to consolidation of powders, structural refinement and chemical mixing, HPT was applied here for inducing mechanochemical redox reactions between Al and nanostructured Nb2O5 (Nb2O5 + 10/3 Al -> 2Nb + 5/3 Al2O3). These chemical reactions released metallic niobium in its atomic form, which contributed to the dynamics of mixing between Al and Nb at the atomic scale. This strategy demonstrated to be effective for promoting the formation of supersaturated (Al-Nb) solid solution, niobium clustering, and extensive segregation of Nb at lattice defects. The effect of different nanostructured Nb2O5 morphologies on the interface structures and hardening of the produced composites was discussed. Annealing at moderate temperature (373 K for 1 h) caused an exceptional increase in hardness of similar to 54% (similar to 289 Hv) for the composite produced using Nb2O5 nanorods. This was attributed to the rearrangement of dislocations into a lower energy configuration (dislocation tangles) and an astounding segregation of Nb to this dislocation structure.

The hydrogels are advanced materials used in biomedical applications during wound healing, controlled drug release and to prepare scaffolds. In this work are prepared hydrogels of alginate/chitosan (Alg/Ch) semi-interpenetrating polymer networks (semi-IPN’s) and nanocelluloses. The hydrogels after preparation by freeze drying are namely simply as gels. The cellulose nanocrystals (CNC’s) are obtained from acid hydrolysis of bleached Eucalyptus pulps and oxidized cellulose nanocrystals (CNCT’s) prepared by (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical catalyzed reaction as known as TEMPO reaction. The cellulose nanofibers (NFC’s) are obtained from mechanical shearing of cellulose pulps and oxidized NFC’s by TEMPO-mediated reaction (NFCT’s). The nanocellulose suspension and gels are characterized by FTIR at ATR mode, TGA, XRD, TEM, SEM, X-ray computed microtomography (micro-CT) and DMTA. The addition of CNC’s, NFC’s, CNCT’s or NFCT’s in the microstructure of gels increases their dimensional stabilities. The best results are obtained when CNCT’s and NFCT’s are added. The mechanical properties and dimensional stability of Alg/Ch semi-IPN’s increase after controlled thermal post-treatment. The heating during thermal post-treatment boosts the physicochemical interactions in the microstructures of semi-IPN’s. The biological assays show biocompatibility of fibroblast cells on the substrates, and differentiation and proliferation up seven days. The optimized mechanical properties, dimensional stability and biocompatibility of the gels studied in this work are important parameters for potential biomedical applications of these biomaterials.

Severe plastic deformation by high-pressure torsion can induce solid-state reactions, including redox reactions, which can affect the mechanical properties of metal matrix composites and hybrids. The present paper shows evidence of a redox reaction between magnesium and nanostructured niobium pentoxide. These chemical reactions release metallic niobium and magnesium oxide. Accordingly, aglomerations of nanocrystalline magnesium oxide is found in the magnesium matrix and a supersaturated solid solution is formed with niobium. Hardness and indentation creep tests show a minor increase in strength and decrease in strain rate sensitivity in the processed material, compared to data for pure magnesium in the literature.

The present work evaluates the segregation of alloying elements during severe plastic deformation of a magnesium alloy. A Mg-1wt% Mn-1wt% Nd alloy was processed by high-pressure torsion and the microstructure was characterized by X-ray diffraction, scanning and transmission electron microscopy. High angular annular dark field images were used to distinguish areas with segregated alloying elements. The results show that Nd readily segregates along boundaries in the early stage of deformation while Mn, which was dispersed as small particles in the starting material, undergoes slow fragmentation forming nanoparticles distributed throughout the microstructure and segregates along boundaries. The evolution of microhardness shows a rapid increase in strength at low imposed strains and saturates. It is suggested that Mn plays only a minor role in the contribution to the strength of this alloy because the slow development of nano-clusters and segregations of this element is not accompanied by changes in hardness.

Knowledge of micrometer-scale wetting layers and microporosity in rocks is crucial for a deeper understanding of immiscible fluid displacement, and especially capillary trapping. It is an established fact that the amount of capillary trapping is a result from the competition between flow via wetting layers and piston-like displacement. Despite the large amount of experimental work published, there are many open questions about fluid displacement mechanisms in complex porous media, particularly the role of microporosity in the disconnection and entrapment of the nonwetting phase. Here, we applied the state-of-the-art neutron tomography technique (with the best spatial resolution available at neutron imaging facilities) to reveal the 3D distribution of water layers and water-filled micropores in a carbonate rock. Our results revealed wetting layers with a non-uniform thickness distribution completely covering the rock surface. During imbibition at a low capillary number, a marked increase in the amount of water-filled micropores with the concomitant swelling of wetting layers were observed. This approach can be used as a platform to explore a huge range of interfacial phenomena, such as enhanced oil recovery and CO2 storage.

Interfaces can have a great influence on the behavior and properties of polymer composites. In this work, the versatile and low-cost layer-by-layer technique was used for depositing layers of poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) containing oxidized multiwalled carbon nanotubes (MWCNT-COOH) on the surface of woven glass fibers (GFs); and polypropylene composites containing the modified GFs were prepared by compression molding. The effect of this novel hybrid multilayered interface on the mechanical properties and fracture behavior of the GF reinforced polymer (GFRP) composites was systematically investigated. For that, in situ tensile tests of the composites were monitored by using the high-resolution phase-contrast tomography. We found that the GFRP composites with multilayered interface (GFRP multilayered) exhibited exceptional increase in ductility and fracture toughness (about 25 and 130%, respectively), when compared to the composites without interfacial modification (GFRP untreated). Whereas the failure characteristics of the GFRP-untreated composites were typical of fragile systems (mainly, delamination), the GFRP-multilayered exhibited additional toughening mechanisms such as crazing and fibrillation as result of the enhanced interfacial adhesion. Our results clearly indicate that the multilayered interface of PDDA/PSS/MWCNT-COOH led to a more efficient load transfer from the matrix to the GFs, culminating with the brittle-to-ductile transition in the failure mode.

The development of materials is strongly related to our capability of understanding thermal, mechanical and chemical processing on the nanoscale. Unravelling the interface structure is crucial for opening new regimes in property–performance space. Interface arrangements have been characterized by statistically limited microscopy techniques. In this work, a large-angular-range detector was used for synchrotron diffraction measurements on commercially pure Mg. Long acquisitions allowed the retrieval of preferred interface configurations through the observation of extraordinary diffraction peaks located close to the Mg 102, 200, 204 and 300 fundamental reflections. A kinematical simulation scanning possible interface structures established the correspondence of the non-bulk peaks to the interfacial organization of atoms that may be responsible for their appearance. Simulated interfaces were probed for a wide range of angular displacements with respect to the main cleavage planes. The results indicate configurations that allow the observation of X-ray diffraction, representing a long-range-ordered pattern of atomic distributions in Mg. The introduced methodology allows for nondestructive monitoring of systems that undergo processes that modify grain sizes and grain-interface orientation.

High‐pressure torsion (HPT) is a significant procedure for achieving substantial grain refinement but it may be used also to consolidate metallic particles to form bulk samples or composites where two (or more) different phases are mixed and consolidated. Herein, the consolidation of particles of the magnesium AZ91 alloy and a composite with an AZ91 matrix combined with 1% alumina powder is investigated. The results show that it is possible to fully consolidate this alloy after a large number of turns. As a consequence of the severe plastic deformation, the grain structure is significantly refined, with average grain sizes of ≈116 and ≈98 nm in the unreinforced alloy after 20 or 50 HPT turns and ≈76 nm in the composite after 50 HPT turns, respectively. This grain refinement is associated with a decrease in hardness and an increase in the strain rate sensitivity due to the onset of a grain boundary diffusion–assisted creep mechanism at room temperature. The results are consistent with the theoretical prediction of a breakdown in the Hall–Petch relationship at very small grain sizes.

The nondestructive nature of X-ray microtomography (µCT) associated with its suitable temporal resolution, obtained with the use of high energy polychromatic radiation from electron acceleration rings, allows in situ investigations of the damage evolution process during tensile loading in composite materials. In this context, the development of adequate scientific instrumentation as well as the understanding of the corresponding technology by research groups is paramount to guarantee reliability of the obtained results. In the present work, a miniaturized universal testing machine (tensile, compression and fatigue) was developed to be applied in in situ µCT experiments using synchrotron radiation with innovative technology. The equipment has a uniaxial load capacity of up to 300 N with 1 N resolution and can impose 0.01 mm resolution displacements following controlled deformation rates. In order to validate the developed equipment, tensile test results performed on sub-sized and standard annealed copper specimens were compared and in situ µCT tensile tests were performed in glass-fiber-reinforced polypropylene matrix composites at the Laboratório Nacional de Luz Síncrotron (LNLS) in Campinas (SP, Brazil). Data analysis was performed by applying image processing techniques to successive tomograms in order to monitor crack propagation in the initial stages of damage evolution. The results obtained allowed the clarification of crack propagation mechanisms in the investigated composite materials and demonstrated the viability of the equipment’s intended application.

Extremely thin Nb2O5 nanowires and Al powder were successfully consolidated at room temperature by using high-pressure torsion (HPT), producing a novel metal matrix nanocomposite with exceptional mechanical properties. It is shown that minor additions of Nb2O5 increase sharply the hardness of commercially pure Al. For instance, hardness of over 180 Hv was developed at the edge of samples with 10% nanowires and processed through 10 turns of HPT. This is markedly higher than any other value reported for pure aluminum matrix composites having this level of reinforcement phase. A detailed characterization of the interface structure using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) revealed a pronounced grain refinement of the Al matrix at the nanoscale and the occurrence of the aluminothermic reduction of the part of Nb2O5. The latter led to: (i) the formation of Al2O3 nanolayer at the Al/Nb2O5 interface and (ii) the nanosegregation of metallic Nb (with few atomic layers) along grain boundaries and dislocations. The pronounced increase in hardness is attributed to the formation of this interface nanostructure.

A magnesium/aluminium composite was produced by room temperature consolidation through high-pressure torsion (HPT) processing. Half-discs of the pure metals were placed side-by-side and subjected to different numbers of turns. The initially reduced interface between the phases gradually increased with increasing rotation. The composite displayed a significant ductility even after 10 turns. The distribution of hardness in the HPT-processed discs was bi-modal in the early stages of processing. As the number of turns increased and the thickness of the phases decreased there was a noticeable increase in hardness. The hardness values of the composite further increased after thermal treatment due to the formation of intermetallics within the interface between the magnesium and aluminium-rich phases.

Innovative solutions have been designed to meet the global demand for energy and environmental sustainability, such as enhanced hydrocarbon recovery and geo-sequestration of CO2. These processes involve the movement of immiscible fluids through permeable rocks, which is affected by the interfacial properties of rocks at the pore scale. Overcoming major challenges in these processes relies on a deeper understanding about the fundamental factors that control the rock wettability. In particular, the efficiency of oil recovery strategies depends largely on the 3D wetting pattern of reservoir rocks, which is in turn affected by the adsorption and deposition of ‘contaminant’ molecules on the pores’ surface. Here, we combined high-resolution neutron tomography (NT) and synchrotron X-ray tomography (XRT) to probe the previously unobserved 3D distribution of molecular and mineralogical heterogeneity of oil reservoir rocks at the pore scale. Retrieving the distribution of neutron attenuation coefficients by Monte Carlo simulations, 3D molecular chemical mappings with micrometer dimensions could be provided. This approach allows us to identify co-localization of mineral phases with chemically distinct hydrogen-containing molecules, providing a solid foundation for the understanding of the interfacial phenomena involved in multiphase fluid flow in permeable media.

Hydroxyapatite and bioactive glass particles were added to pure magnesium and an AZ91 magnesium alloy and then consolidated into disc-shaped samples at room temperature using high-pressure torsion (HPT). The bioactive particles appeared well-dispersed in the metal matrix after multiple turns of HPT. Full consolidation was attained using pure magnesium, but the center of the AZ91 disc failed to fully consolidate even after 50 turns. The magnesium-hydroxyapatite composite displayed an ultimate tensile strength above 150 MPa, high cell viability, and a decreasing rate of corrosion during immersion in Hank’s solution. The composites produced with bioactive glass particles exhibited the formation of calcium phosphate after 2 h of immersion in Hank’s solution and there was rapid corrosion in these materials.

Carbonate and sandstone reservoirs play an important role in oil industry as they host over 50% of the world’s hydrocarbon reserves. For an accurately assessment of porosity and pore size distribution of such complex pore-network, which affect directly the macroscopic characteristics of multiphase fluid flow, X-ray computed microtomography (micro-CT) emerges as a powerful tool. In contrast to lab-based X-ray micro-CT (XCT), synchrotron X-ray micro-CT (SXCT) images are commonly free of artefacts (i.e. beam hardening) and the unique properties of synchrotron sources enable the X-ray imaging of complex and heterogeneous materials in greater detail, with higher quality, and short acquisition time. This work reports results of cone beam computed microtomography (XCT) in comparison with synchrotron computed microtomography (SXCT) applied to very heterogeneous carbonate and sandstone reservoir rocks. We analyze the quality of the image generated in terms of detection of details and artefacts, the advantages and limitation of each technique, as well as features like contrast, sharpness, and signal-to-noise ratio (SNR). Although SXCT offers significant advantages over XCT, the latter gains in cost of operation, accessibility and user-friendliness.

Hydrogels have been studied as promising materials in different biomedical applications such as cell culture in tissue engineering or in wound healing. In this work, we synthesized different nanocellulose-alginate hydrogels containing cellulose nanocrystals, TEMPO-oxidized cellulose nanocrystals (CNCTs), cellulose nanofibers or TEMPO-oxidized cellulose nanofibers (CNFTs). The hydrogels were freeze-dried and named as gels. The nanocelluloses and the gels were characterized by different techniques such as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA), while the biological features were characterized by cytotoxicity and cell growth assays. The addition of CNCTs or CNFTs in alginate gels contributed to the formation of porous structure (diameter of pores in the range between 40 and 150 μm). TEMPO-oxidized cellulose nanofibers have proven to play a crucial role in improving the dimensional stability of the samples when compared to the pure alginate gels, mainly after a thermal post-treatment of these gels containing 50 wt % of CNFT, which significantly increased the Ca2+ crosslinking density in the gel structure. The morphological characteristics, the mechanical properties, and the non-cytotoxic behavior of the CNFT-alginate gels improved bioadhesion, growth, and proliferation of the cells onto the gels. Thus, the alginate-nanocellulose gels might find applications in tissue engineering field, as for instance, in tissue repair or wound healing applications.