Enhancement Of Tensile Strength Research Articles

Characteristics of bioplastics prepared from cassava starch reinforced with banana bunch cellulose at various concentrations

Human activities have led to the pollution of the environment through the accumulation of plastic waste. Since plastics are resistant to decomposition resulting negative impact on the environment, there is a pressing need for the development of bioplastics. Starch is a such of natural material that can be used made of bioplastics. However, bioplastics from starch were needed to improve starch-based bioplastics due to their brittle properties. To address this issue, researchers focused on enhancing starch-based bioplastics by incorporating cellulose, particularly derived from kepok banana bunch fibers and cassava starch variety UJ3. The production process involved adding varying concentrations of 2.5, 5, 7.5, and 10 % (wt) of kepok banana bunch cellulose. The findings indicated that increasing cellulose concentration improved the characteristics of the bioplastic materials significantly. The results showed that the addition of cellulose concentration improved the mechanical properties, water vapor absorption, and biodegradability of bioplastics. With an optimal cellulose concentration level at 7.5%, remarkable enhancements in tensile strength (from 2.92 to 6.72 MPa), reduced elongation percentage (from 20.89 to 4.06%), increased Young’s Modulus values (from 13.98 to 172.52 MPa), decreased water vapor absorption rate (from 15,93 to 11,48%), and enhanced bio-degradability rating (from 29,81 to 50,69%) were observed.

Revolutionizing protective materials: Ultrahigh peak viscosity through MOF-enhanced shear thickening fluid for advanced soft body armor

The incorporation of shear thickening fluid (STF) into aramid fabric has emerged as a compelling strategy to augment the protective attributes of aramid-based soft body armor. The peak viscosity of STF assumes a pivotal role in shaping the efficacy of this enhancement. In this study, we present an innovation in the design and synthesis of an ultrahigh peak viscosity STF using metal-organic framework (MOF)/SiO2 nanoparticles as the core constituents. The remarkable enhancement in peak viscosity of MOFs/SiO2-based STF, taking ZIF-8 as an exemplary MOFs material, is attributed to the pronounced interparticle contact friction facilitated by the rugged surface morphology of the ZIF-8/SiO2 nanoparticles. Therefore, ZIF-8/SiO2-based STF (62.5 wt.%) demonstrates a peak viscosity approximately 3938 times greater than that of conventional SiO2-based STF (62.5 wt.%). This extraordinary STF formulation has been successfully employed in aramid fabric-based soft body armor, resulting in a significantly advancement in protective performance. Compared to Kevlar fabric impregnated with SiO2-based STF (62.5 wt.%), the utilization of ZIF-8/SiO2-based STF (62.5 wt.%) results in substantial and scientifically significant improvements in key mechanical parameters. These include a notable 15.4 % increase in maximum stabbing force, a remarkable 29.5 % augmentation in maximum yarn pull-out force, a 24.3 % boost in maximum yarn tensile strength, and a 204.5 % enhancement in maximum fabric tensile strength. This research underscores the profound impact of synergizing ZIF-8 and SiO2 within the STF matrix, and significantly improves the protective abilities of SiO2-based STF-impregnated Kevlar fabrics, which provides a new route to design STF-impregnated ballistic fabric with high protective performance.

Amplifying Nanoparticle Reinforcement through Low Volume Topologically Controlled Chemical Coupling.

We present a streamlined method to covalently bond hydroxylated carbon nanotubes (CNOH) within a polyphenol matrix, all achieved through a direct, solvent-free process. Employing an extremely small concentration of CNOH (0.01% w/w) along with topologically contrasting linkers led to a maximum of 5-fold increase in modulus and a 25% enhancement in tensile strength compared to the unaltered matrix, an order of magnitude greater reinforcement (w/w) compared to state-of-the-art melt-processed nanocomposites. Through dynamic mechanical analysis, low field solid-state nuclear magnetic resonance spectroscopy, and molecular dynamics simulations, we uncovered the profound influence of linker's conformational degrees of freedom on the segmental dynamics and therefore the material's properties.

Mechanical upcycling of single-use face mask waste into high-performance composites: An ecofriendly approach with cost-benefit analysis

The COVID-19 pandemic created an unprecedented demand for PPE, with single-use face masks emerging as a critical tool in containing virus transmission. However, the extensive use and improper disposal of these single-use face masks, predominantly composed of non-biodegradable plastics, has exacerbated environmental challenges. This research presents an innovative method for mechanically upcycling PPEs used in medical sectors i.e. single use face masks. The study investigates a facile approach for reclamation of infection-free and pure polypropylene (PP) plastic from discarded single use face masks (W-PP) and blends it with various vegetable oil percentages (5, 10 and 20 %), resulting in a versatile material suitable for various applications. Melt flow index, rheological behaviour, DSC and FTIR were employed to investigate the effect of vegetable oil/radical initiator through chemical grafting on W-PP properties. The results demonstrate significant enhancements in the tensile strength and modulus of W-PP when blended with vegetable oil and a radical initiator. There was a marked increase in tensile strength (33 %) and strain (55 %) compared to untreated W-PP, rendering W-PP both robust and flexible. Furthermore, we employed this upcycled W-PP in the fabrication of glass fibre-reinforced composites, resulting in notable enhancements in both tensile strength and impact resistance. The upcycled W-PP demonstrates excellent potential for various applications, such as sheet forming and 3D printing, where the non-brittleness of plastics plays a pivotal role in manufacturing high-quality products. The cost-benefit analysis of this approach underscores the potential of upcycling PPE waste as a sustainable solution to mitigate plastic pollution and conserve valuable resources. The applications of this upcycled material span a wide range of industries, including automotive composites, packaging, and 3D printing.

Grey-Taguchi Approach for Optimizing FSW Parameters in Joining AA6262 and AA5083 Alloys

T his study concentrates on the friction stir welding (FSW) joining of dissimilar AA6262 and AA5083 plates. Four input parameters, namely tool rotational speed (TRS), welding speed (WSP), tool tilt angle (TTA), and pin depth (PDP) are chosen to analyze the output responses of tensile strength (UTS), hardness (HBN), and wear rate (WTR) in welding. The primary objective is to optimize the variables of the FSW process for AA6262 and AA5083 alloys using a combination of Taguchi and Grey Relational Analysis (GRA) methods, while also comprehending the correlations among process variables through the application of these two methods. Utilizing the Taguchi approach, L27 orthogonal array is constructed for conducting FSW experiments. After this, the multi-objective optimization challenge is streamlined into a single-objective optimization task by leveraging the grey relational degree. The significance and impact of the distinct variables are elucidated through the application of Analysis of Variance (ANOVA). Confirmation tests and predictive analysis are performed to validate the optimal variables, which are then compared against the acquired outcomes. The results highlight the welding speed as the paramount parameter, exerting substantial influence over the output responses of the welds in contrast to the other variables under examination. The application of the Grey-Taguchi methodology yields enhancements in Tensile Strength (245.23 MPa) and Hardness (99.2 Hv), while concurrently decreasing the Wear Rate (0.00456 m3/Nm). Furthermore, the Grey Relational Grade exhibits an advancement of 0.1312. These findings collectively signify an increased operational efficiency in the welding process, particularly for dissimilar alloys.

Mechanical property analysis and dry sand three-body abrasive wear behaviour of AZ31/ZrO2 composites produced by stir casting

An experimental study of three body abrasive wear behaviour of AZ31/15 vol.% Zirconium dioxide (ZrO2) reinforced composites prepared by stir casting has been carried out. Microstructural analysis of the developed composites was carried out and found out that the microstructure of the composites revealed a uniform distribution of ZrO2 particles with refinement in the grain size of the matrix from 70 to 20 µm. The alterations in the microstructure led to an enhancement in both hardness (68–104 HV) and tensile strength (156–236 MPa) due to Orowan strengthening, quench hardening effect and better bonding. Response surface methodology was applied to formulate the three-body abrasive wear test characteristics such as load, speed, and time. Three body abrasive test results were utilized to generate surface graphs for different combinations of wear test parameters revealed an increase in specific wear rate. The specific wear rate was observed to increase with increase in speed up to a certain level and then started to decrease. The lowest possible specific wear rate was obtained for an optimized load of 20 N and a speed of 190 ms−1. Scanning electron microscopic examination of wear-tested samples showed higher specific wear rate at higher loads with predominantly abrasion type material removal. In conclusion, this study makes a substantial contribution to the field by elucidating the complex relationships among microstructure, mechanical properties, and the three-body abrasive wear behavior of AZ31/ZrO2 composites. The determination of optimal wear conditions and the insights gained into wear mechanisms provide valuable information for designing materials, implementing engineering solutions, and advancing the creation of wear-resistant components across a range of industries.

Improved strength in nickel‑aluminum bronze/steel bimetallic component fabricated using arcing-wire arc additive manufacturing with alternating deposition strategy

To enhance microstructure and mechanical properties, arcing-wire arc additive manufacturing (AWAAM) with alternating deposition strategy was firstly employed to produce nickel‑aluminum bronze (NAB)-steel components. The implementation of alternating deposition strategy fostered the creation of interlocked microstructures, establishing robust bonds at the interface. Moreover, the convection within the melt pool during alternating deposition induced the formation of numerous precipitates, serving as a precipitation reinforcement. Simultaneously, these precipitates served as heterogeneous nucleation sites, facilitating the formation of substantial fine equiaxed crystals, resulting in grain boundary strengthening. A comprehensive examination of microstructure and mechanical properties was conducted using a variety of microscopy techniques and mechanical testing for components with and without arcing-wire. After applying arcing-wire, precise control was exerted over the melting of both matrix and wire, effectively preventing interface cracking caused by excessive melting. Moreover, with the arc heat input diminished, the temperature gradient in the melt pool decreased, leading to grain and precipitate refinement, consequently enhancing their strength. Owing to microstructural modifications, AWAAM demonstrated enhancements in ultimate tensile strength and yield strength by up to 20.1 % and 21.1 %, respectively, when compared to WAAM.

Advancements in emerging MXene-integrated nanocomposite coatings: Unraveling defect-free microstructure for superior tribological, mechanical, and anti-aging features

This study explored the enhancement potential of MXene, a novel two-dimensional material, in epoxy-based nanocomposites; which comprehensively examined the influence of MXene on epoxy's viscosity, void formation, aging resistance, mechanical properties, and anti-wear properties. MXene nanofillers, labeled as 25C and 80C, fabricated via different acid-etching methods, were incorporated into epoxy resin at varying weight percentages (0.1–2.0 wt%). Observations revealed that for both varieties of MXene, inclusion of 1.0 wt% MXene led to the mitigation of void content, whereas the incorporation of 2.0 wt% MXene yielded maximal enhancements in both tensile strength and abrasion resistance. Additionally, the integration of 1.0 and 2.0 wt% MXene displayed superior aging resistance, with around 80 % reduction in free radical formation compared to the unmodified epoxy, while maintaining its excellent mechanical properties after QUV exposure. Therefore, both MXene types significantly enhanced the performance of epoxy composites, with the 80C-MXene displaying marginally superior enhancement due to its smaller particle size and higher purity, as identified by SEM and TEM images.

Sustainable Concrete: Exploring Fresh, Mechanical, Durability, and Microstructural Properties with Recycled Fine Aggregates

The growing construction industry and global population have led to increased demand for concrete, resulting in increased waste production. Recycling construction and demolition (C&D) waste as recycled fine aggregates (RFA) in concrete could help reduce waste and conserve natural resources. This research delves into the meticulous examination of particle packing density within specific cylindrical volumes under standard compacting efforts, elucidating an order of compressive strength. The study comprehensively explores various concrete properties, including workability, compressive strength, flexural strength, split tensile strength, drying shrinkage, electrical resistivity, rapid chloride penetration, and microstructural characteristics (analyzed through XRD, SEM, and EDAX). RFA particles, ranging from 0.15 to 4.75 mm, were employed as partial replacements for fine aggregates, with replacement percentages varying from 0% to 100% in increments of 25%. The empirical findings underscore that the incorporation of RFA significantly enhances concrete properties. However, it was observed that surpassing the optimum replacement percentage of 25% (RFA 25) adversely impacts the concrete’s strength and microstructure. Specifically, RFA 25 exhibited remarkable improvements, with a 14.75% increase in compressive strength, a 6.61% boost in flexural strength, and a 13.14% enhancement in split tensile strength compared to conventional concrete (RC). Furthermore, RFA 25 demonstrated a 4.16% increment in drying shrinkage, 17.65% higher electrical resistivity, and an 18.83% superior resistance to chloride penetration compared to RC. The analysis of XRD, SEM, and EDAX results elucidated that at lower replacement percentages, the pozzolanic reaction enhances strength by forming additional hydration products. Conversely, at higher replacement levels, strength diminishes.

Ultra-strong, nonfreezing, and flexible strain sensors enabled by biomass-based hydrogels through triple dynamic bond design.

Biomass-based hydrogels have displayed excellent potential in flexible strain sensors due to their adequacy, biocompatibility, nontoxic and degradability. Nevertheless, their inferior mechanical properties, particularly at cryogenic temperatures, impeded their extensive utilization. Herein, we reported a rationally designed strain sensor fabricated from a gelatin and cellulose-derived hydrogel with superior mechanical robustness, cryogenic endurance, and flexibility, owing to a triple dynamic bond strategy (TDBS), namely the synergistic reinforcement among potent hydrogen bonds, imine bonds, and sodium bonds. Beyond conventional sacrificing bonds consisting of hydrogen bonds, dynamic covalent bonds and coordinate bonds, synergetic triple dynamic bonds dominated by strong hydrogen bonds and assisted by imine and sodium bonds with higher strength can dissipate more mechanical energy endowing the hydrogel with 38-fold enhancement in tensile strength (6.4 MPa) and 39-fold improvement in toughness (2.9 MPa). We further demonstrated that this hydrogel can work as a robust and biodegradable strain sensor exhibiting remarkable flexibility, broad detection range, considerable sensitivity and excellent sensing stability. Furthermore, owing to the improved nonfreezing performance achieved from incorporating sodium salts, the sensor delivered outstanding sensing properties under subzero conditions such as -20 and -4 °C. It is anticipated that the TDBS can create diverse high-performance soft-electronics for broad applications in human-machine interfaces, energy and healthcare.

Multiple free-radical-trapping and hydrogen-bonding-enhanced polyurethane foams with long-lasting flame retardancy, aging resistance, and toughness.

Flexible polyurethane foam (FPUF) is a ubiquitous material utilized in furniture cushions, mattresses, and various technical applications. Despite the widespread use, FPUF faces challenges in maintaining long-lasting flame retardancy and aging resistance, particularly in harsh environments, while retaining mechanical robustness. Here, we present a novel approach to address these issues by enhancing FPUF through multiple free-radical-trapping and hydrogen-bonding mechanisms. A hindered amine phosphorus-containing polyol (DTAP) was designed and chemically introduced into FPUF. The distinctive synergy between hindered amine and phosphorus-containing structures enables the formation of multiple hydrogen bonds with urethane, while also effectively capturing free radicals across a broad temperature spectrum. As a result, incorporating only 5.1 wt% of DTAP led to the material successfully passing vertical burning tests and witnessing notable enhancements in tensile strength, elongation at break, and tear strength. Even after enduring accelerated thermal aging for 168 hours, the foam maintained exceptional flame retardancy and mechanical properties. This study offers novel insights into material enhancement, simultaneously achieving outstanding long-lasting flame retardancy, toughness, and anti-aging performance.

Upcycling plastic waste into fully recyclable composites through cold sintering.

Plastics have substantial societal benefits, but their widespread use has led to a critical waste management challenge. While mechanical recycling dominates the reuse of post-consumer plastics, it is limited in efficacy, especially for composites. To address this, we propose a direct reprocessing approach that enables the creation of hybrid, long-lasting, and durable composites from difficult-to-recycle plastics. This approach utilizes cold sintering, a process that consolidates inorganic powders through fractional dissolution and precipitation at temperatures far below conventional sintering; these temperatures are compatible with plastic processing. We show that this process can create inorganic-matrix composites with significant enhancements in tensile strength and toughness over pure gypsum, which is commonly found in construction waste. These composites can be recycled multiple times through direct reprocessing with the addition of only water as a processing promoter. This approach to recycling leads to composites with orders of magnitude lower energy demand, global warming potential, and water demand, when compared against common construction products. Altogether, we demonstrate the potential for cold sintering to integrate waste into high-performance recyclable composites.

Red mud as a sustainable road construction material: An experimental investigation

In response to the pressing need for environmentally responsible waste management, this research delves into the potential applications of bauxite residue, commonly called red mud, a by-product of the Bayer process employed in aluminum extraction, within concrete-based applications. This study explores the viability of utilizing red mud to prepare construction materials for highway infrastructure. Characterization of the red mud unveiled that it poses no hazardous concerns, establishing its safety for further application. The experimental phase of the research involved the development of six distinct concrete mixtures, including a control mixture with varying proportions of red mud. Notably, including red mud, they had no adverse impact on the fresh concrete properties, with all values well within acceptable ranges. Furthermore, comprehensive microstructural analyses and leaching tests confirmed that concrete incorporating red mud adheres to safety and toxicity standards, assuaging environmental concerns. Regarding mechanical properties, laboratory tests showcased significant improvements, including a notable 14.01% increase in compressive strength, a robust 6.74% boost in flexural strength, and a 7.58% enhancement in split tensile strength following a 28-day curing period. The culmination of these findings underscores the feasibility of integrating red mud as a partial substitute for cement, up to 15%, in the construction of rigid pavement for highway applications. This approach tackles sustainable waste management and fosters eco-friendly construction materials, especially for highway projects.

Rotational stress-induced shish-kebab governs the balance of enhanced thermal conductivity and mechanical performance of high-density polyethylene (HDPE) / boron nitride (BN) composites via axial hot compression

Polymer-based composites with high BN sheets loadings have potential to improve thermal conductivity without compromising mechanical performance. In this work, a balanced enhancement in both thermal conductivity and tensile strength were achieved using rotational shear followed by axial hot compression. For neat HDPE matrix, the highly oriented shish-kebab structures induced by shear field improved tensile strength from 20.4 MPa to 80.9 MPa, compared with unsheared specimens. The in-plane thermal conductivity of sheared HDPE/BN composite was 25.0% higher than the unsheared one. Axial hot compression resulted in denser crystal and oriented fillers, leading to a 63% increase in tensile strength while simultaneously increasing thermal conductivity in both in-plane and out-plane directions. This work has utilized rotation shear and axial hot compression to manufacture HDPE/BN composites with effective two-way thermal conductivity and higher tensile strength. The excellent thermo-mechanical properties mean a longer service time and less replaced frequency of material under extreme operating conditions. The two-step methods provide a key information for the preparation of composites with balanced mechanical properties and thermal conductivity.

From Hemp Waste to Bioactive Nanofiber Composites: Deep Eutectic Solvents and Electrospinning in Upcycling Endeavors.

Natural fibers have attracted increasing interest as an alternative to produce environmentally friendly and sustainable materials. Particularly, hemp fibers have been widely used in various industrial applications due to their extremely unique properties. However, hemp can generate a large amount of agro-waste, and it results in an attractive source of biopolymers for the development of low-cost materials as an alternative to the raw materials and conventional petroleum-based plastics. In addition, deep eutectic solvents (DESs), a new type of truly green solvents, have been shown to remove gums, lignin, and other non-cellulosic components from hemp fibers. Reusing these components dissolved into the DESs to fabricate new materials directly by electrospinning is a very attractive but still unexplored endeavor. Thus, this innovative research to venture new upcycling pathways is focused on the fabrication of composite nanofibers by electrospinning of a gel-based blend of Poly(vinyl alcohol) (PVA) and hemp agro-waste (HW) dissolved into choline chloride (ChCl):Glycerol (1:2) and ChCl:Urea (1:2) DES mixtures. The results obtained revealed that the produced nanofibers displayed uniform appearance with diameters ranging from 257.7 ± 65.6 nm to 380.8 ± 134.0 nm. In addition, the mechanical properties of the electrospun composite nanofibers produced from the gel-based blends of HW dissolved in DESs and PVA (HW-DESs_PVA) were found to be superior, resulting in an enhanced tensile strength and Young's modulus. Furthermore, the incorporation of HW into the nanofibers was able to provide bioactive antioxidant and antibacterial properties. Overall, this study demonstrated a promising, more sustainable, and eco-friendly way to produce electrospun composite nanofibers using HW in a circular economy perspective.

Biocompatible, robust, waterproof and breathable PDMS-based PU fibrous membranes for potential application in wound dressing

Wound dressings, an effective tool for repairing injured skin and protecting it from secondary damage, have been widely manufactured. However, the design of wound dressings with waterproofness, breathability, mechanical robustness, and excellent biocompatibility remains a challenge due to the imbalance between the multiple desirable properties. Herein, a strategy is proposed to fabricate biocompatible membranes via a facile one-step electrospinning method. Polydimethylsiloxane-based polyurethane is effectively prepared to form durable hydrophobic surfaces, resulting in a high degree of hydrophobicity (141.0° water contact angle). The porous structure is enhanced by adjusting the solution concentration and heat treatment temperature, resulting in an optimal water vapor transmission rate of 8.2 kg·m−2·h−1. Additionally, the membrane exhibits a hydrostatic pressure of 52.3 kPa, which is approximately 14.1 times greater than that of PU fibrous membrane, and an enhanced tensile strength of 6.60 MPa. Moreover, the membrane can be utilized in a wide temperature range from − 123 °C to 160 °C due to its low glass transition temperature and exceptional thermal stability. Significantly, both in vitro and in vivo studies confirmed the remarkable biocompatibility and minimal toxicity to normal cells and mice skin. Our work presents a new approach to designing waterproof and breathable biomaterials with high mechanical strength, thereby enhancing their performance and functionality in the biomedical field, particularly in wound dressing applications.

Improved mechanical and frictional properties of hypereutectic Al-Si alloy by modifying Si phase with La addition

Hypereutectic Al-Si alloys play an important role in the automotive industry and wear-resistance field. In this study, B390 hypereutectic Al-Si alloys with different La additions (0, 0.2, 0.4, 0.6 wt%) are solidified under permanent magnet stirring. The beneficial effects of La addition on the B390 alloy are investigated by XRD, DSC, SEM, EPMA, hardness tester, tensile tester and wear tester. Experimental results indicate that as the La addition increases from 0 to 0.4 wt%, the Si phase evolves from coarse needle-like to fine coral-like particles, and the mean size decreases from 18.6 µm to 4.7 µm. Moreover, the introduction of La to B390 alloy would result in an enhancement in tensile strength from 115.7 MPa to 162.1 MPa, and an increase in the Rockwell hardness from 58.5HRB to 66.4HRB. In addition, the average friction coefficient of the alloy decreases from 0.55 to 0.48 with the increasing La addition from 0 to 0.4 wt%, indicating an obvious improvement in frictional properties. It is noted that adding 0.6 wt%La cannot further improve the Si phase or enhance its properties of the B390 alloy in comparison to the addition of 0.4 wt%La. These results confirm that a suitable La addition is feasible and economical to improve materials performance of hypereutectic Al-Si alloy.

Gelatin-serum plasma film incorporated with curcumin for improvement of antioxidant and antibacterial properties for fresh pork packaging application

In this study, a novel active packaging film based on gelatin and serum plasma (GT/SM) with varying amounts of curcumin (CUR) was prepared. Curcumin, a strong antibacterial and antioxidant agent, was incorporated into the film to investigate its efficacy on physical/structural characteristics and bacterial inhibition in packaged pork. The results demonstrated significant enhancements in tensile strength (43.95–61.99 MPa), elongation at break (49.46–73.31%), swelling capacity (49.57–68.82%), solubility index (40.80–59.82%), and moisture content (13.85–16.37%). The films exhibited improved opacity (2.70–14.85 mm−1) and water vapor barrier characteristics (5.20–1.46 × 10−11 g−1 s −1 Pa−1). The antioxidant and antibacterial capacities were also increased, exhibiting enhanced preservation potential for fresh pork. Curcumin was uniformly distributed throughout the GT/SM matrix, according to scanning electron microscopy (SEM) results. Using solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS), over 55 volatile aroma components were identified in fresh pork loin, including ketones, acids, alcohols, hydrocarbons, aldehydes, and esters. This study offers a novel strategy for active packaging that extends the shelf life of fresh pork loins while ensuring the safety and quality of food.

Coarse-grained molecular dynamics study on submicron structuring of calcium silicate hydrate with enhanced tensile modulus and strength

Potential of cement-based materials for energy harvesting is encoded in their elusive mesoporous structure, and understanding the sub-micron structure of calcium silicate hydrate (C–S–H), a major binding phase of cement, is an important yet challenging task. Nanoscale C–S–H is ductile, while macroscopic performance is brittle, suggesting a gap in the transition of material properties from the nano-to the macro-scale, and a chance in finetuning the submicron (∼100 nm) structure to effectively deliver the atomistic properties to the bulk performance. The refined sub-micron structure of C–S–H can enhance the strength and modulus of concrete, thus providing a base material with better mechanical properties and durability. Here, two critical structural features of C–S–H, including agglomeration of globules and stacking of layers, are modeled by spherical and oblate ellipsoidal units, respectively. Coarse-grained modeling and peridynamics simulations find that the packing of ellipsoidal units is better than that of spherical units, from the perspectives of size distribution, morphology, fractality of pores and tensile properties. The analyses on the mesoporous structure shows that the ellipsoid-packing is more homogeneous than the sphere-packing model, and it yields a refined structure with enhancement in tensile modulus and strength. The submicron finetuning enhancement of C–S–H can be realized through different physical and chemical approaches, like inducing lateral growth of silicate chains by chemical additives, scaffolding materials, and conditioned hydration. This coarse-grained simulation work gives novel insights and fundamental strategies for toughening the cement matrix through delivering ductile nanoscale performance of C–S–H to macroscale cementitious materials, and provides superior performance for concrete in existing and new structures.

Co50Cr20Ni20Fe5Mn5 high entropy alloy: Overcoming the strength-ductility trade-off of Cantor alloy

In this study, we aimed to design and investigate a non-equiatomic high strength and ductile high entropy alloy (HEA) by controlling the FCC phase stability. A new Co-rich Co50Cr20Ni20Fe5Mn5 HEA was synthesized by vacuum arc remelting and processed through homogenization, cold rolling, and recrystallization. The alloy’s phase composition, mechanical properties, and plastic deformation behavior were characterized using X-ray diffraction (XRD), tensile testing, and Transmission Electron Microscopy (TEM) analysis. The tensile properties of the alloy were compared with those of the conventional Co20Cr20Ni20Fe20Mn20 HEA produced and processed using the same technique and route. The results showed that reducing the Fe and Mn concentrations while increasing the Co concentration reduced the FCC phase’s stability, leading to the occurrence of partial FCC to HCP phase transformation upon cooling from high temperature and TWIP-TRIP effects during tensile deformation. The Co50Cr20Ni20Fe5Mn5 HEA exhibited improved mechanical properties, including higher yield strength (502 MPa), ultimate tensile strength (1002 MPa), and total elongation (50%) compared to the reference Cantor HEA (405 MPa, 766 MPa, and 40%, respectively). The principal strengthening mechanisms contributing to the increased yield strength with higher Co concentration were identified as initial HCP phase strengthening and grain boundary strengthening. The enhancement in ultimate tensile strength and ductility is attributed to the TWIP-TRIP effects during the tensile deformation of the Co50Cr20Ni20Fe5Mn5 HEA.