Phase Particles Research Articles

Anthropogenic Extremely Low Volatility Organics (ELVOCs) Govern the Growth of Molecular Clusters Over the Southern Great Plains During the Springtime

AbstractNew particle formation (NPF) often drives cloud condensation nuclei concentrations and the processes governing nucleation of molecular clusters vary substantially in different regions. The growth of these clusters from ∼2 to >10 nm diameters is often driven by the availability of extremely low volatility organic vapors (ELVOCs). Although the pathways to ELVOC formation from the oxidation of biogenic terpenes are better understood, the mechanistic pathways for ELVOC formation from oxidation of anthropogenic organics are less well understood. We integrate measurements and detailed regional model simulations to understand the processes governing NPF and secondary organic aerosol formation at the Southern Great Plain (SGP) observatory in Oklahoma and compare these with a site within the Bankhead National Forest (BNF) in Alabama, southeast USA. During our two simulated NPF event days, nucleation rates are predicted to be at least an order of magnitude higher at SGP compared to BNF largely due to lower sulfuric acid (H2SO4) concentrations at BNF. Among the different nucleation mechanisms in WRF‐Chem, we find that the dimethylamine (DMA) + H2SO4 nucleation mechanism dominates at SGP. We find that anthropogenic ELVOCs are critical for explaining the growth of particles observed at SGP. Treating organic particles as semisolid, with strong diffusion limitations for organic vapor uptake in the particle phase, brings model predictions into closer agreement with observations. We also simulate two non‐NPF event days observed at the SGP site and show that low‐level clouds reduce photochemical activity with corresponding reductions in H2SO4 and anthropogenic ELVOC concentrations, thereby explaining the lack of NPF.

Nonlinear Theory of the Growth of New Phase Particles in Supercooled Metal Melts

Nonlinear Theory of the Growth of New Phase Particles in Supercooled Metal Melts

Preparation of C-S-H seeds from waste glass powder and its effect on early performance of cement paste

This study investigates the hydrothermal synthesis of calcium silicate hydrate (C-S-H) seeds using nano-size glass powder (NGP) derived from siliceous raw materials and CaO as the calcareous precursor. The influence of varying NGP concentrations on the particle size, microstructure, and phase composition of the C-S-H seeds was systematically analyzed. The synthesized C-S-H seeds were subsequently employed as additives to evaluate their effects on the early hydration process and compressive strength development of cement paste. The results indicate that increasing the NGP concentration from 0.2 mol/L to 0.8 mol/L leads to an exponential increase in the median particle size of the C-S-H seeds from 147 nm to 1328 nm and a corresponding morphological transformation from flocculent to granular structures. Additionally, the purity of the C-S-H sample decreased from 74.8% to 54.5% as the NGP concentration increased. The addition of C-S-H seeds can increase the 12h compressive strength of cement pastes by 15.5%–53.5%. This improvement is due to the accelerated early hydration kinetics induced by the C-S-H seeds, which act as nucleation sites, thereby increasing the nucleation and growth rates by 31.4% and 53.2%, respectively.

Optimization of microstructure and mechanical properties of 7075 aluminum alloy by equal channel angular pressing technology

Abstract The equal channel angular pressing technology, as an effective technique for modifying the surface of a material, has had a significant impact on the microstructure and mechanical properties of the 7075 aluminum alloy. The study achieved the refinement of 7075 aluminum alloy grains and the homogenization of the second phase particle distribution through equal channel angular pressing technology, thereby significantly improving the strength and plasticity of the material. Through orthogonal experimental design, the effects of extrusion angle, extrusion speed, and remelting temperature on material properties were studied. The results showed that appropriate ECAP parameters could effectively regulate the microstructure of 7075 aluminum alloy, thereby optimizing its mechanical properties. Especially in the analysis of equivalent strain rate, when the extrusion angle was 50°, the position of the maximum equivalent strain rate at the forefront point remained unchanged, but the equivalent strain rate decreased to 0.107-1. In the aging hardness analysis, when the number of equal channel angular pressing passes was 3, the aging hardness of G group 7075 aluminum alloy increased to 195HV in the first 5 minutes. The equal channel angular pressing technology can optimize the internal structure of 7075 aluminum alloy and improve the material's plasticity and mechanical properties. The research provides important technical support for the application of 7075 aluminum alloy in high-end equipment manufacturing.

Development of microflow ultra high performance liquid chromatography-mass spectrometry metabolomic assays for analysis of mammalian biofluids

Introduction and objectivesThe application of untargeted metabolomics assays using ultra high performance liquid chromatography-mass spectrometry (UHPLC-MS) to study metabolism in biological systems including humans is rapidly increasing. In some of these studies there is a requirement to collect and analyse low sample volumes of biofluids (e.g. tear fluid) or low cell and tissue mass samples (e.g. tissue needle biopsies). The application of microflow, capillary or nano liquid chromatography (≤ 1.0 mm column internal diameter (i.d.)) theoretically should accomplish a higher assay sensitivity compared to analytical liquid chromatography (2.1–5.0 mm column internal diameter). To date, there has been limited research into microflow UHPLC-MS assays that can be applied to study samples of low volume or mass.MethodsThis paper presents three complementary UHPLC-MS assays (aqueous C18 reversed-phase, lipidomics C18 reversed-phase and Hydrophilic Interaction Liquid Chromatography (HILIC)) applying 1.0 mm internal diameter columns for untargeted metabolomics. Human plasma and urine samples were applied for the method development, with porcine plasma, urine and tear fluid used for method assessment. Data were collected and compared for columns of the same length, stationary phase and stationary phase particle size but with two different column internal diameters (2.1 mm and 1.0 mm).Results and conclusionsAll three assays showed an increase in peak areas and peak widths when applying the 1.0 mm i.d. assays. HILIC assays provide an advantage at lower sample dilutions whereas for reversed phase (RP) assays there was no benefit added. This can be seen in the validation study where a much higher number of compounds were detected in the HILIC assay. RP assays were still appropriate for small volume samples with hundreds of compounds being detected. In summary, the 1.0 mm i.d. column assays are applicable for small volume samples where dilution is required during sample preparation.

Simultaneous Measurement of Gaseous HONO and NO2− in Solutions from Aqueous Nitrate Photolysis Mediated by Organics

Field studies suggest that NO3− photolysis may play a more significant role than previously thought. In this study, we concurrently measured HONO, NO2, and NO2− in situ to gain a deeper understanding of the photogenerated HONO transfer to air and to better constrain the rate constants of NO3− photolysis. The presence of fatty acids (e.g., nonanoic acid, NA), which are naturally present in the environment, significantly increases the production of photogenerated HONO and NO2. With an increase in oxygen percentage, the release rate of photoinduced HONO slowed, while the release rate of NO2 accelerated. The measured JNO3− value averaged 1.65 × 10−5 s−1, which is two orders of magnitude higher than values reported in similar systems. The HONO transfer rate from the solutions increased from 2.3 × 10−4 s−1 to 5.6 × 10−4 s−1 as the NA concentration increased from 0.1 to 20 mM. This can be attributed to the accumulation of NO2− induced by NA at the interface. Within this interfacial region, NO2− in the solutions becomes more prone to transfer into gaseous HONO, suggesting that photogenerated NO2− hosted in atmospheric droplets may serve as a temporary reservoir of atmospheric HONO without illumination, influencing the atmospheric oxidizing capacity in the region for hours. Therefore, simultaneous measurements of both gas and particle phase photoproducts are recommended to better constrain the rate constants of NO3− photolysis, thereby enhancing the accuracy of predicting the photochemical production of HONO in the atmosphere.

Constructing Targeted Strong Nb4d-O2p-Li2s Configurations to Obtain Excellent Energy Density and Long Life for Li-Rich Cathodes.

The Li-rich Mn-based cathode materials (LMRs) deliver excellent energy density and exhibit low cost, which are considered as the most promising cathode materials for the next generation lithium-ion batteries. However, the irreversible redox reaction of the oxygen atoms directly leads to release oxygen and intensifies phase transformation. Besides, the local stress and strain will be generated due to the unit-cell volume difference between R-3m and C2/m phases, which continuously aggravates the collapse of secondary particles. Herein, the strong Nb4d-O2p-Li2s configurations at the Li1 sites of the TM-layer in the C2/m phase and secondary particles with the radial arrangement of refined primary particles are designed to inhibit oxygen release and relieve lattice stress by Nb2O5 treatment. Meanwhile, the preferential growth of the active {010} planes is presented to obtain an excellent transmission rate of Li+. As a result, the designed LMR delivers remarkable electrochemical properties with high discharge capacity and initial coulomb efficiency of 276 mAh g-1 and 85 % at 0.1 C, outstanding cycling retention rate of 81 % after 300 cycles. This novel crystal structure combining oxygen coordination regulation and micro-nano scale design provides inspiration for the design of high-performance LMRs.

Constructing Targeted Strong Nb4d−O2p−Li2s Configurations to Obtain Excellent Energy Density and Long Life for Li‐Rich Cathodes

AbstractThe Li‐rich Mn‐based cathode materials (LMRs) deliver excellent energy density and exhibit low cost, which are considered as the most promising cathode materials for the next generation lithium‐ion batteries. However, the irreversible redox reaction of the oxygen atoms directly leads to release oxygen and intensifies phase transformation. Besides, the local stress and strain will be generated due to the unit‐cell volume difference between R‐3m and C2/m phases, which continuously aggravates the collapse of secondary particles. Herein, the strong Nb4d−O2p−Li2s configurations at the Li1 sites of the TM‐layer in the C2/m phase and secondary particles with the radial arrangement of refined primary particles are designed to inhibit oxygen release and relieve lattice stress by Nb2O5 treatment. Meanwhile, the preferential growth of the active {010} planes is presented to obtain an excellent transmission rate of Li+. As a result, the designed LMR delivers remarkable electrochemical properties with high discharge capacity and initial coulomb efficiency of 276 mAh g−1 and 85 % at 0.1 C, outstanding cycling retention rate of 81 % after 300 cycles. This novel crystal structure combining oxygen coordination regulation and micro‐nano scale design provides inspiration for the design of high‐performance LMRs.

Theoretical investigation of multipulse femtosecond laser processing on silicon carbide: ablation, shielding effect, and recast formation

In this study, we propose a transient multi-physics coupling model for ultrafast laser ablation based on the material point method (MPM). By employing the continuum assumption for material, heat transfer equation and particle phase change, as well as spatial discretization of the model, we achieve simulations of various coupled physical phenomena such as material temperature, phase change, stress, and recast layer formation. In terms of time, we simulate laser processing processes with up to 1000 pulses. The model is validated by comparing with experimental results on ablation morphology, recast layer formation from melted particles, and surface oxidation. The proposed model accurately captures the multi-physics aspects of ultrafast laser ablation processes in SiC ceramics. The experimental validation confirms the model’s reliability and offers valuable insights into the underlying physical phenomena.

Long-term inhalation exposure: A model for phthalate accumulation in the respiratory tract

BackgroundInhalation is a major pathway for phthalates (PAEs), an endocrine disruptor, to enter the human body. The actual internal exposure amount that participates in metabolism cannot be estimated by calculating total inhalation intake. ObjectiveTo estimate the accumulation in each region of the respiratory tract after long-term exposure to PAEs in different populations. MethodsA mass transfer model was developed to simulate the long-term accumulation of PAEs in respiratory tract through inhalation. The model considered (1) mass transfer of PAEs in three phases across seven regions, (2) the effect of temperature differences on the mass transfer process. Based on this model, we simulated adult exposure to PAEs in a laboratory, identified key model parameters, and further simulated various scenarios for children, adults, and elders. ResultsPAEs are not completely cleared from the respiratory tract after 16 hours, following 8 hours of daily exposure. Under regular laboratory environment, accumulation after 30 days is 3.8 times higher than that after the first day. The distribution of PAEs between the gas and mucus phases has a greater impact on the results than between the gas and particle phases. Children are at the highest risk to Diethyl phthalate (DEP) exposure compared with adults and elders. Nearly 80 % of DEP is exhaled, with 14 % accumulating in the alveolar region after an hour. ConclusionThis model links indoor air PAEs to human internal exposure, showing that most PAEs are exhaled, while the remainder accumulates in the respiratory tract and may participate in human metabolism.

Effect of Zn on Microstructure and Wear Resistance of Sn-Based Babbitt Alloy

Tin-based Babbitt alloys are a widely used bearing bushing material which have good comprehensive properties. However, problems such as high-temperature softening and insufficient bearing capacity occur during their use, so the optimization of tin-based Babbitt alloys has become a research hotspot. In this paper, ZChSnSb11-6 alloy was mainly prepared by the gravity casting method, and different amounts of Zn were added to the alloy (the mass fraction values were 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.15 wt.%, and 0.2 wt.%, respectively). Through the hardness test, the tensile test, the friction and wear test, and the microstructure observation of the prepared alloy, the influence of Zn on the organization and properties of the ZChSnSb11-6 alloy was analyzed. The results show that the size of the SnSb hard phase changed with the increasing content of Zn. The size of the hard phase of the SnSb tended to increase first and then decrease, and the number of phase particles increased first and then decreased, resulting in changes in performance. Through comparison, it was learned that the addition of Zn can effectively improve the hardness, tensile strength, yield strength, and wear resistance of the alloy, but the elongation rate was reduced. When the Zn content was 0.1 wt.%, the hardness value of the alloy reached the maximum value, 25.82 HB, which increased by 7.3% when compared with the sample without Zn. The hardness of the Zn, 0.15 wt.%, is close to that of the Zn, 0.1 wt.%. Compared to the sample without Zn, the tensile strength and elongation of the alloy were maximized at a Zn content of 0.15 wt.%. Compared to the sample without the Zn, the tensile strength was increased by 21.29%, and the elongation rate was increased by 46%. An analysis showed that the alloy has good comprehensive mechanical properties when the Zn content is 0.15 wt.%.

Quasi-two-dimensional dispersions of Brownian particles with competitive interactions: phase behavior and structural properties.

Competing short-range attractive (SA) and long range repulsive (LR) particle interactions can be used to describe three-dimensional charge-stabilized colloid or protein dispersions at low added salt concentrations, as well as membrane proteins with interaction contributions mediated by lipid molecules. Using Langevin dynamics (LD) simulations, we determine the generalized phase diagram, cluster shapes and size distributions of a generic quasi-two-dimensional (Q2D) dispersion of spherical SALR particles confined to in-plane motion inside a bulk fluid. The SA and LR interaction parts are modelled by a generalized Lennard-Jones potential and a screened Coulomb potential, respectively. The microstructures of the detected equilibrium and non-equilibrium Q2D phases are distinctly different from those observed in three-dimensional (3D) SALR systems, by exhibiting different levels of hexagonal ordering. We discuss a thermodynamic perturbation theory prediction for the metastable binodal line of a reference system of particles with SA interactions only, which in the explored Q2D-SALR phase diagram region separates cluster from non-clustered phases. The transition from the high-temperature (small SA) dispersed fluid (DF) phase to the lower-temperature equilibrium cluster (EC) fluid phase is characterised by a low-wavenumber peak height of the static structure factor (corresponding to a thermal correlation length of about twice the particle diameter) featuring a distinctly smaller value (≈1.4) than in 3D SALR systems. With decreasing temperature (increasing SA), the cluster morphology changes from disk-like shapes in the equilibrium cluster phase, to double-stranded anisotropic hexagonal cluster segments formed in a cluster-percolated (CP) gel-like phase. This transition can be quantified by a hexagonal order parameter distribution function. The mean cluster size and coordination number of particles in the CP phase are insensitive to changes in the attraction strength.

Bimodal grain structure, phase transformation, and mechanical properties of a Mg-Gd-Y-Zn-Zr alloy during hot extrusion

In this study, we investigated the evolution of grain structures and second phases of a Mg-9.5Gd-4Y–2Zn-0.3Zr alloy during two-stage deformation that took place in the metal during hot extrusion, as well as their effects on its mechanical properties. We found that the alloy exhibited a bimodal grain structure consisting of equiaxed dynamic recrystallized (DRXed) grains and elongated unDRXed grains. As the extrusion process progressed, DRX occurred on a large scale, resulting in an increase in the proportion of DRXed grains from 17.8% to 93.2%, and a reduction in average grain size from 80.3 μm to 9.41 μm. The grain orientation also underwent a transition from a single orientation of an extrusion direction (ED) parallel to <0001> (i.e. ED//<0001>) to mixed orientations of ED//<01–10> and ED//<0001>. The primary mechanism of dynamic recrystallization (DRX) during extrusion involved particle-stimulated nucleation (PSN) accompanied by both continuous and discontinuous DRX. The Mg-9.5Gd-4Y–2Zn-0.3Zr alloy mainly contained intergranular 18R-long period stacking order (LPSO) phases and intragranular 14H-LPSO. As the extrusion process progressed, 18R-LPSO changed from blocky to lamellar to accommodate deformation, and β-Mg5(Gd,Y) phase particles dynamically precipitated along DRXed grain boundaries. The 14H-LPSO phase was found to be primarily distributed within coarse unDRXed grains. As deformation via extrusion progressed, the quantity of 14H-LPSO gradually decreased. Ultimately, with the gradual dissolution of Mg5(Gd,Y), 14H-LPSO reprecipitated within the recrystallized grain boundaries. As the extrusion process progressed, both the yield strength (YS) and elongation (EL) increased from 132.6 MPa to 287.6 MPa and from 10.8% to 15.5%, respectively. This was mainly attributed to the significant reduction in grain size and second phase size.

Advanced Spray-Dried Inhalable Microparticles/Nanoparticles of an Innovative Mitophagy Activator for Targeted Lung Delivery: Design, Comprehensive Characterization, Human Lung Cell Culture, and In Vitro Aerosol Dispersion Performance.

Urolithin A (UA) has demonstrated the ability to stimulate mitophagy and enhance mitochondrial and cellular health in skeletal muscles in humans after oral administration. It is hypothesized that targeted delivery of UA as inhaled dry powders to the lungs will enhance mitochondrial health through mitochondrial biogenesis. This study aimed to engineer inhalable excipient-free powders of UA as dry powder inhalers (DPIs) for targeted pulmonary delivery. The particles were designed by particle engineering from dilute organic solutions of UA using the state-of-the-art spray drying technology in a closed mode. Comprehensive physicochemical characterization and advanced microscopy techniques were conducted to examine phase behavior, molecular properties, and particle properties, which are necessary for the rational design of advanced pulmonary inhalation aerosols. Molecular fingerprinting was conducted by using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and Raman spectroscopy. Chemical imaging and mapping were conducted using confocal Raman microscopy (CRM) and IR microscopy. The advanced spray-dried (SD) excipient-free powders were successfully produced at different spraying pump feed rates and exhibited favorable molecular and particle properties. The excipient-free SD powders exhibited outstanding in vitro aerosol dispersion performance with an FDI-approved human DPI device (Neohaler) and correlated with the spray drying pump rate. In vitro, cell viability of various human pulmonary cells from different lung regions demonstrated biocompatibility and safety at different doses of UA. The transepithelial electrical resistance (TEER) assay shows that UA maintains cell membrane integrity and barrier tightness, indicating its potential for safe and effective localized drug delivery without long-term adverse effects. These results demonstrated that UA has favorable physicochemical and in vitro properties for inhalation and can be successfully engineered into excipient-free inhalable microparticles/nanoparticles as DPIs.

Enhancing 3D printing performance of O/W emulsions with asparagus fibre

Asparagus fibre recovered from agricultural waste stream can be valorised as a natural ingredient for fibre enrichment in food products. This study investigated the effects of asparagus fibre on the 3D printing performance of oil-in-water (O/W) emulsions as edible inks. Emulsion gels were prepared by either varying the fibre concentration in the aqueous phase or varying the volume fraction of the oil phase. Printability, rheological properties, and microstructure of the samples were systematically evaluated. Our results show increasing fibre concentration (up to 9.9 %w/w) significantly improved 3D printing performance of the inks, which was attributed to their enhanced rheological properties. Interestingly, reducing the oil volume fraction from 72 to 66 %v/v (i.e., fibre concentration was kept at 9.9 %w/w) did not detrimentally influence the 3D printing quality. Microstructural analysis of the emulsions revealed that increasing fibre concentration led to smaller size and different surface morphology of the oil droplets. Fibre particles in the aqueous phase may hinder oil droplet movement, stabilizing emulsions during 3D printing. Our findings give new insights into the development of edible 3D-printed food products via fibre enrichment and oil reduction.

Research on the microstructure, mechanical and fatigue performance of 7075/6061 dissimilar aluminum alloy fusion welding joint treated by nanoparticle and post-weld heat treatment

The microstructure and mechanical properties of 7075/6061 high-strength dissimilar aluminum alloy fusion welds, after TiC nanoparticle-assisted welding and heat treatment, were discussed, and their fatigue performance was analyzed. The results indicate that the significant increase in hardness at the weld zone with T6 treatment compared to T5 is due to the solution treatment providing supersaturated solid solution for subsequent aging precipitation. T5 treatment causes the precipitation in the heat affected zones, thereby increasing the hardness of these regions. The joints exhibit excellent yield strength and tensile strength after heat treatment, with the elongation performance being optimal in T6 state. The fatigue performance of dissimilar aluminum alloy joints treated with nanoparticle and heat treatment is superior to the joints with single riveting. Porosity defects and microcracks generated during welding are prone to stress concentration, with interconnected pores and easily propagating cracks forming fatigue sources for pores and cracks. The crack propagation behavior is influenced by the pinning effect of TiC nanoparticles at the grain boundaries, and the second phase particles hinder crack propagation along the grain boundaries, forcing cracks to extend towards the 6061 side or the HAZ of the lower strength 6061 matrix. It demonstrates that the method of combining nanoparticle-assisted melt inert-gas welding and T6 heat treatment improves the fatigue life of 7075/6061 dissimilar aluminum alloy joints.

Research on energy utilization of electron beam melting for silicon purification

As a key material for solar photovoltaic power generation, the purity of silicon plays a crucial role in the photovoltaic conversion efficiency and performance. The electron beam melting (EBM), which is irreplaceable metallurgical methods, has been widely used for silicon purification. However, high energy consumption result in relatively high cost, which limits its widespread application in melting industry. This study was centered on the energy distribution that proposes a new approach to reducing energy consumption during EBM. The scanning form of electron beam is most important factor concerning energy consumption. Different scanning forms can affect the characteristics of molten pool which is closely correlated with the purification process. In this study, efficient and energy-saving preparation processes of EBM are being explored through the numerical model and experimental. The relationship of energy distribution form and purification efficiency is studied. The research results indicate that electron beam scanning under uniform distribution can achieve more uniform temperature and flow field distribution in the molten pool, which has a higher energy utilization rate during silicon purification by EBM. The mathematical model established in this study can effectively predict the energy consumption level under different melting parameters, providing important reference for the optimization and energy conservation of EBM process for other materials. In addition, evaporation characteristics of volatile impurity, migration of the second phase particles in the melt, controlling of melt pool characteristics and the crystal growth control all can be conducted based on this study.

Exceptional elevated-temperature properties of a Laves phase-strengthened CoNiCrFe high-entropy alloy

This work reported a Laves phase-strengthened high-entropy alloy, featured by high-density Laves phase particles uniformly distributed within a face-centered cubic matrix. The pinning effect from these fine Laves phase particles on matrix grain growth and dislocation gliding results in extraordinary microstructure stability and mechanical properties. Additionally, the alloy demonstrates superior oxidation resistance, attributed to the formation of a Cr/Si-rich oxide film and beneficial effects from the Laves phase.

Damage sensing in multi-functional nanocomposite polymer bonded energetics with embedded multi-walled carbon nanotube sensing networks

Abstract This experimental investigation evaluates the strain and damage sensing abilities of multi-walled carbon nanotube (MWCNT) networks embedded in the binder phase of polymer-bonded energetics (PBEs). PBEs are a special class of particulate composite materials that consist of energetic crystals bound by a polymer matrix, wherein the polymer matrix serves to maintain the composite’s shape and form. The structural health monitoring (SHM) approach presented in this work exploits the piezoresistive properties of the distributed MWCNT networks. Major challenges faced during such implementation include the low binder concentrations of PBEs, the presence of conductive/non-conductive particulate phases, the high degree of heterogeneity in the PBE microstructure, and achieving the optimal MWCNT dispersion. In this study, ammonium perchlorate (AP) crystals as the oxidizer, Aluminum grains as the metallic fuel, and Polydimethylsiloxane (PDMS) as the binder are used as the constituents for fabricating PBEs. To study the effect of each constituent on the MWCNT network’s SHM abilities, various materials systems are comprehensively studied: MWCNT/PDMS materials are first evaluated to study the binder’s electromechanical response, followed by AP/MWCNT/PDMS to assess the impact of AP addition, and finally, AP/AL/MWCNT/PDMS to evaluate the impact of adding conductive aluminum grains. Compression samples (ASTM D695) were fabricated and subjected to monotonic compression. Electrical resistance is recorded in conjunction with the mechanical test via an LCR meter. Gauge factors relating to the change in normalized resistance to applied strain are calculated to quantify the electromechanical response. MWCNT dispersions and mechanical failure modes are analyzed via scanning electron microscopy imaging of the fracture surfaces. Correlations between the electrical behavior in response to the mechanical behavior are presented, and possible mechanisms that influence the electromechanical behavior are discussed. The results presented herein demonstrate the successful ability of MWCNT networks as SHM sensors capable of real-time strain and damage assessment of PBEs.

Micro-alloying of Sm with rolling for synergetic corrosion resistance and mechanical properties of Mg-Al-Sn-Ca-Mn alloys

Micro Sm alloying coupling with four-pass rotary rolling is conducted to synergize the corrosion resistance and mechanical properties of Mg-Al-Sn-Ca-Mn alloys. Micro Sm alloying weakens the galvanic corrosion. Rolling process refines the grains, intensifies the basal texture and promotes dispersed second phase particles, thereby contributing to forming a uniform and protective corrosion product film, and enhancing the mechanical strength and ductility. As a result, rolled Mg-Al-Sn-Ca-Mn-Sm alloy exhibits a synergy of mechanical properties and corrosion resistance, i.e., an UTS of 271 MPa, YS of 204 MPa, elongation to failure of 18 %, and a low corrosion rate of 0.85 mm y−1.