Improvement In Strength Research Articles

Healed Subscapularis and Its Clinical Implications for Internal Rotation in Humeral Lateralized Reverse Shoulder Arthroplasty

The efficacy of subscapularis (SSC) repair in reverse shoulder arthroplasty (RSA) remains controversial. Few studies have evaluated the postoperative integrity and effect on clinical outcomes of repaired SSC; however, conflicting results regarding whether the healing of the repaired SSC influences outcomes have also been reported. Therefore, this study aimed to address the controversy by evaluating clinical outcomes in SSC repair compared to non-repair after humeral lateralized RSA, and to evaluate the significance of the integrity of the repaired SSC. This study included patients who underwent humeral lateralized RSA between 2015 and 2019 and categorized them into two groups: repaired (n=66) and non-repaired (n=36) SSCs. The clinical outcomes, such as the visual analog scale score, constant score, American Shoulder and Elbow Surgeons (ASES) score, active range of motion (aROM), activities of daily living scores consisting of active internal rotation and forward flexion (ADL score), and rotational strength, were compared. Ultrasonography was used to assess the integrity of the repaired SSC following the modified Sugaya classification and to evaluate the acromial fracture. Subgroup analysis was performed on patients with healed SSC versus non-healed SSC, versus non-repaired SSC. Overall, 102 patients were included, with a mean age of 73 ± 5 years. Both groups exhibited substantial postoperative improvements in clinical scores, active ROM, and rotational strength without significant differences. At the 2-year follow-up, 52% of patients showed healed tendons, while 44% exhibited retears in the repaired SSC group. Significant clinical improvements were noted in both groups, regardless of the SSC integrity. However, the healed SSC group exhibited significantly improved outcomes in ADL score, IR aROM, and IR strength compared to the non-healed SSC group (p=0.002, p=0.011, p<0.001). Meanwhile, compared to the non-repaired SSC group, the healed SSC group also showed significant improvements in IR aROM and IR strength (p=0.016, p=0.002), but the difference in ADL score was not statistically significant (p=0.133). Furthermore, while the SSC repair group showed a marginally higher rate of acromial fractures (9% vs. 6%, p=0.709) as evaluated through both radiography and ultrasonography, the overall rates of complications remained statistically comparable across the groups (13% vs. 11%, p=0.854). Healed SSC groups showed significantly better IR aROM, and IR strength than both non-healed and non-repaired SSC groups, highlighting SSC healing's crucial role in enhancing IR functional outcomes even with humeral lateralized RSA; hence, SSC repair should be advocated whenever possible during RSA, though further research is needed to improve its low healing rate.

Cryogenic deformation strengthening mechanisms in FeMnSiNiAl high-entropy alloys

The mechanical properties and deformation mechanisms of a newly developed Co-free FeMnSiNiAl high entropy alloy (HEA) at room and cryogenic temperatures were systematically investigated. The initial tensile deformation at room temperature was dominated by dislocation slipping, with modest strengthening from the Transformation-Induced Plasticity (TRIP) effect due to the deformation-induced FCC → HCP martensitic transformation. Subsequently, the TRIP effect was markedly enhanced during the middle and later stages of deformation, leading to an excellent combination of yield strength (σy, 315.1 MPa), ultimate tensile strength (σu, 773.4 MPa), and fracture elongations (εf, 78.3%). The strengthening by the TRIP effect was significantly enhanced at cryogenic temperatures as a result of enhanced FCC → HCP martensitic transformation. This resulted in a synergetic improvement in strength and ductility at 223 K, with σy of 363.6 MPa, σu of 832.1 MPa, and εf of 87.2%. The enhanced ductility at 223 K was linked to the FCC → HCP → BCC sequential martensitic transformation during the middle and later stages of deformation, which acted as an additional way to accommodate plastic strain and delay strain localization. However, the rapid FCC → HCP transformation at the early stage of deformation at 173 K and 77 K impeded the FCC → HCP → BCC sequential martensitic transformation during subsequent deformation stages, thus remarkably enhancing strength but reducing ductility. Our findings provide new insights into the design and development of TRIP-assisted single-phase FCC HEAs for cryogenic applications.

Enhancing mechanical strength and microstructural properties of alkali-activated systems through nano graphene oxide dispersion and polycarboxylate ether admixture

The dispersion of graphene oxide (GO) nanoparticles in alkali-activated concrete with / without superplasticizers can help in understanding the effect it has on its mechanical strength and microstructural properties. The dispersion of GO in alkali activator fluid of 10(M) and 12(M) with / without polycarboxylate ether (PCE) admixture has been explored in this study. The alkali activator solution of 10(M) NaOH solution with PCE shows better dispersion than 12(M) NaOH solution, as higher alkalinity leads to agglomeration of GO. The study investigated the effect of incorporating PCE in GO-based alkali-activated slag (AAS) mortar with 8(M), 10(M) and 12(M) of alkaline activator solution. The mechanical strength and microstructural characteristics of conventional AAS (without both GO and PCE), GO-based AAS (without PCE) and GO-based AAS with PCE of the respective molar concentration of activator fluid are analysed. The mechanical strength of the AAS mortars has been evaluated using compressive, flexural, and splitting tensile strength testing. The micro-structural and mineralogical characteristics of the binders are evaluated using Field Emission Scanning Electron Microscopy (FESEM with EDS), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The addition of only GO (0.06 % of binder w/w) and the addition of both GO and PCE in AAS have shown up to 30 % and 40 % mechanical strength improvement with respect to conventional AAS, respectively. The effectiveness of PCE and percentages of strength improvement are higher with a lower molarity of activator fluid, and vice versa. Adding GO and PCE to the AAS system improves its hydration rate and denser microstructure, enhancing its strength.

The Effect of Traditional Strength Training on Sprint and Jump Performance in 12- to 15-Year-Old Elite Soccer Players: A 12-Month Controlled Trial.

Skratek, J, Kadlubowski, B, and Keiner, M. The effect of traditional strength training on sprint and jump performance in 12- to 15-year-old elite soccer players: a 12-month controlled trial. J Strength Cond Res 38(11): 1900-1910, 2024-The aim of the study was to evaluate the effect of traditional strength training on maximum strength (1 repetition maximum in front squat [FS] and back squat [BS]), jump (squat and countermovement jump), and linear sprint (LS) performance (5, 10, and 30 m) in elite young soccer players. A 12-month longitudinal design was chosen, and 48 elite male youth soccer players (age: 12-15 years) were included. The subjects were divided in 2 groups (a strength training group [STG] and a control group [CG]). The intervention group trained for 1 year over a competitive soccer season with additional sessions to their regular soccer practice (4 sessions per week), while the CG did not complete any additional sessions to the regular soccer training (4 sessions per week). The additional strength training (2 sessions per week [each approximately 30 minutes]) consisted of either parallel FS or BS. The squat variants switched in each session. Data were analyzed using a 2 × 3 (group × time) repeated-measures analysis of variance. The main findings of this study were that the STG resulted in significant pretest and post-test improvements in maximum strength ( d = 3.75-5.58), jump ( d = 0.84-1.14), and LS performance ( d = -0.25 to 0.44), while for the CG, smaller increases or performance decreases were measured (maximum strength: d = 1.64-2.7; jump: d = 0.12-0.31; sprint: d = 0.00-025). A significant interaction effect in all variables indicated significant ( p < 0.05) stronger performance improvements compared with the CG. Traditional strength training in elite youth soccer players is recommended to increase strength and speed-strength (jump and sprint performance) and should be considered in long-term athletic development programs.

Synthesis and Purification of Nano-sized Titanium Carbide Particles through Vacuum Carbothermal Reduction for enhanced Mechanical, Microstructural Morphology, and Tribological Properties in Friction Stir Processed A356-based Aluminum Composites

This study focused on the synthesis and purification of nano-sized titanium carbide (TiC) particles through vacuum carbothermal reduction under a hydrogen/argon atmosphere. The process involved the production of carbon-coated titanium precursors, followed by heating under vacuum conditions at 1500°C for 2.5 hours. The resulting products underwent additional treatment in either a hydrogen/argon (1:1) mixed gas or pure hydrogen gas. Experimental findings revealed that TiC powders exhibiting a single phase are obtained within a molar ratio of Ti to C ranging from 1:2 to 1:4. Adjusting the molar ratio of Ti/C in the precursors allowed for controlled variation in the particle size of the synthesized TiC powders, ranging from 50 to 80 nm. Treatment in hydrogen/argon mixed gas at 850°C for 3 hours resulted in TiC products with an impressive purity of 99.40%. The subsequent incorporation of 5% Nano-TiC-3 (Ti to C ranging from 1:3) as reinforcement into an aluminum alloy by Friction stir process technique demonstrated a remarkable 19.41% improvement in tensile strength, highlighting the efficacy of this specific reinforcement. The nano-TiC-3 reinforced composite exhibited uniform distribution without porosity. Additionally, a notable 50.81% improvement in hardness and the best wear resistance were observed for the 5% Nano-TiC-3 reinforced aluminum composite. This comprehensive study contributes valuable insights into the synthesis, purification, and application of nano-sized TiC particles, paving the way for the development of high-performance aluminum-based composites with enhanced mechanical and tribological properties.

Effect of a Nurse-Led Remote Guided Pelvic Floor Exercise Program on Stress Urinary Incontinence, Pelvic Floor Function and Sexual Function in Patients after Total Hysterectomy: A Retrospective Study.

Hysterectomy is associated with stress urinary incontinence (SUI), pelvic floor muscle weakness and sexual dysfunction. Pelvic floor exercises have emerged as a potential intervention for addressing these challenges, with remote guided programs offering personalised care. This retrospective study aimed to assess the effect of a nurse-led remote guided pelvic floor exercise program on in patients after total hysterectomy. A retrospective analysis was conducted on 81 patients who underwent pelvic floor exercises after total hysterectomy. The patients were divided into regular pelvic floor exercise group (n = 40) and nurse-led remote guided pelvic floor exercise group (n = 41). The severity of SUI in patients was assessed using the International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF). The strength and endurance of pelvic floor muscles were assessed using a pressure sensor before and after treatment, and sexual function was evaluated using the Female Sexual Function Index (FSFI) questionnaire. The baseline characteristics showed no significant differences between the two groups. The nurse-led remote guided pelvic floor exercise group had a significantly greater reduction in urinary incontinence severity (65.00% vs. 85.37%, χ2 = 4.516, p = 0.034) and a lower post-treatment SUI frequency (1.76 ± 0.75 vs. 2.15 ± 0.95, t = 2.059, p = 0.043). Additionally, this group showed better improvements in muscle strength and endurance (25.61 ± 5.69 vs. 23.19 ± 5.02, t = 2.036, p = 0.045) and FSFI score (29.67 ± 4.05 vs. 27.91 ± 3.83, t = 2.011, p = 0.048). The study demonstrates that a nurse-led remote guided pelvic floor exercise program is associated with significant improvements in SUI, pelvic floor muscle function and sexual well-being in patients after total hysterectomy.

Deltopectoral approach without subscapularis detachment for reverse shoulder arthroplasty. Technique and results of a safe and reproducible subscapularis-sparing approach

AimsThe importance of the subscapularis for reverse total shoulder arthroplasty (rTSA) has been demonstrated, especially for internal rotation and stability. In a deltopectoral approach, a detachment of the subscapularis is performed (tenotomy, tuberosity peeling or osteotomy) but the tendon is not always repairable at the end. When it is repaired, healing is obtained in only 40% to 76% of the cases, with potential consequences for the outcomes. The Anterior Muscle-Sparing (AMS) approach is a deltopectoral approach with preservation of the subscapularis, providing a solution to these problems. We present the surgical technique and results. MethodsIn a retrospective study, we included our first 45 cases of rTSA performed with the AMS approach for a degenerative affection of the shoulder (massive rotator cuff tear, cuff tear arthropathy, primary glenohumeral arthritis, rheumatoid arthritis), excluding traumatic and revision cases. The subscapularis was intact in all the cases. The mean age at inclusion was 74.1 years. No patients were lost at the minimum 24-month follow-up. All the patients underwent a clinical evaluation preoperatively and at the last follow-up, including Constant score, simple shoulder value (SSV), pain scale, and range of motion. An X-ray evaluation was conducted postoperatively and at the last follow-up to assess implant positioning and evolution. ResultsThere was no intraoperative complication, and the mean operative time was 62 minutes. We observed a significant improvement in Constant score (from 36 to 70, p <.001), SSV (from 33 to 81, p <.001), pain (from 6.3 to 0.7, p <.001), strength (from 0.5 to 3.5, p <.001), and most of the active mobilities. Regarding internal rotation, 95% of the patients reached level L3 or higher. Glenoid positioning was considered optimal in more than 90% of the cases (inferior tilt and low position) without any occurrence of superior tilt or high position. The osteophytes could be totally removed in 8 out of 9 cases (88.9%). Six postoperative complications (13.3%) were reported: 1 infection (2.2%), 2 cases of traumatic glenoid loosening (4.4%), 2 acromion fractures (4.4%), and 1 hematoma (2.2%). There was no instability. Eighty percent of the patients could return home, with a mean hospital stay of 1.8 days. ConclusionThe AMS approach is a safe and reproducible technique. The preservation of the subscapularis has potential benefits regarding internal rotation and stability. In the absence of tendon suture, rehabilitation can be started immediately without motion restriction, allowing for a fast recovery and return to autonomy.

Effects of bonding enhancers on shear stress and bonding strength of modified asphalt binders under different aging and moisture conditions

Insufficient bonding within pavement material causes widespread propagation of traffic-induced stresses, leading to accelerated damage accumulation and significant reduction in the service life of flexible pavements. This research aimed to examine the effects of using bonding enhancers, specifically Polyalkylene Glycol-based (PLG) and Alkylamines-based (ALM), on modified asphalt binders to improve the bonding characteristics. These additives were utilized at different concentration levels, i.e., 0.5 % and 1.0 %, based on the mass of asphalt binders, with the aim of enhancing the bonding performance between the materials within the asphalt mixture composite. The effectiveness of the modified asphalt binders was compared to the conventional ones through laboratory tests, which included shear-compression and pullout tests. These tests were conducted to assess the bonding performance of the modified asphalt binders by preparing different sets of sandwich samples using concrete cube substrates. A sodium carbonate solution was used as a medium to accelerate the effect of moisture damage on samples during the conditioning process. Additionally, the bonding performance of the asphalt binders was evaluated through a series of pullout and shear-compression tests under designated moisture and aging conditions. The dynamic shear rheological (DSR) test results of Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV)-aged binders incorporating bonding enhancers showed superior resistance to rutting and fatigue failure. Significant improvements in stress and shear strength were observed under moisture and aging conditions, highlighting improvements in the bonding performance of the modified asphalt binders. The incorporation of additives has positively contributed to the pavement performance, despite only a modest increase in bonding performance, tensile strength, and shear stress resistance.

Giant energy storage density, high efficiency and excellent stability achieved in lead-free KNN-based ceramic via a composition optimization strategy

The (1-x)K0.5Na0.5NbO3-xBi(Zn2/3Sb1/3)O3 ceramics, abbreviated as (1-x)KNN-xBZS with x values of 0.05, 0.10, 0.15, and 0.20, were prepared via solid-state reaction technique. Their structural and electrical characteristics, including dielectric and ferroelectric characteristics, were systematically examined. The achievement of an optimized phase transition-field and the broadening of the bandgap in the 0.85KNN-0.15BZS ceramics contribute to the delay of polarization and improvement in the breakdown field strength. Dielectric measurements indicate that the introduction of BZS disrupts the original large domain structure of KNN ceramics, giving rise to small domains and polar nano regions (PNRs). Specifically, the 0.85KNN-0.15BZS ceramic exhibits exceptional energy storage density (Wrec = 5.90 J/cm3) and an ultra-high energy efficiency (η = 79.9%) at an applied electric field of 570 kV/cm. Furthermore, this ceramic displays excellent frequency stability in the range of 1-100 Hz and temperature stability between 30-150 °C. The remarkable energy storage properties of (1-x)KNN-xBZS ceramics position them as highly promising materials for future pulse power capacitors and various energy storage applications.

Enhanced mechanical and thermal properties of epoxy vinyl ester nanocomposites through hybridization with functionalized graphene oxide and nanoglass flakes

This study presents the preparation of epoxy vinyl ester nanocomposites based on hybrid nanofillers, namely functionalized graphene oxide and nanoglass flakes, for outstanding mechanical, thermal, and water resistance properties. Significantly, these hybrid nanocomposites exhibited considerable improvement in tensile strength and modulus, about 39 % and 52 % greater than neat resin, respectively. DSC analysis has shown that Tg increased from 108 °C for the neat resin to 130.9 °C for the FGO/FNGF hybrid nanocomposite, which confirmed an improvement in thermal stability. Water absorption tests have shown a remarkable reduction of moisture intake. Saturation moisture content decreased from 1.35 % for the neat resin to 0.53 % for the hybrid nanocomposite due to the tortuous pathways created by the hybrid fillers. The rheological studies confirmed that better filler dispersion and interfacial bonding are achieved, which is a 34 % increase in the storage modulus with respect to neat resin. SEM studies showed homogeneous distribution of fillers with good filler-matrix adhesion in the case of the hybrid system. The studies thus confirm FGO and FNGF synergies in reinforcement of epoxy vinyl ester nanocomposites for high-performance applications in hostile environments.

A concise strategy for enhancing the performance of bio-based polyurethane aerogels using melamine-modified sodium alginate via Aza-Michael addition reaction

Bio-based waterborne polyurethane (PU) has garnered significant attention as a sustainable alternative petroleum-derived counterpart, offering environmentally friendly alternatives. In this work, a new approach is proposed to fabricate two kinds of composite aerogels of lowly/highly melamine-modified sodium alginate (SAML/SAMH) with methacrylate-terminated PU (SAML-PU and SAMH-PU) through dynamic covalent cross-linking via Aza-Michael addition reactions. We aim to improve the poor compatibility of polysaccharide and PU associated with traditional blending methods and impart the resulting aerogels with good biodegradability, compressive strength, thermal insulation, flame-retardant, and self-healing. Comprehensive characterizations, including Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy collectively demonstrate the successful derivatization of alginate and the effective synthesis of the Aza-Michael addition copolymer involving derivate alginate and PU. Substantial improvements in compressive strength and thermal properties are realized at comparable densities. Higher compressive strength, higher decomposition temperature and lower thermal conductivity are significantly achieved for SAML-PU (0.35 MPa, 410 °C and 0.024 W/m/K at 0.13 g/cm3) and SAMH-PU (0.58 MPa, 427 °C and 0.022 W/m/K at 0.12 g/cm3) compared to pristine PU foams (0.15 MPa, 330 °C and 0.031 W/m/K at 0.15 g/cm3). Additionally, molecular simulations of the Aza-Michael addition reaction and finite element simulations of aerogel thermal-insulation properties are conducted to corroborate experimental results. Notably, the dynamic polymers of SAML-PU and SAMH-PU exhibited excellent self-healing, recycling, biodegradability, and flame-retardant attributes. The elucidated preparation methodology and the exceptional performance and versatile applications of sodium alginate-based PU aerogels suggest a promising trajectory for future research endeavors and industrial implementation.

Room- and elevated-temperature strength of as-cast Mg-Sn-Y alloys mediated by Sn and Y solubility via intrinsic stability and deformation resistance

Microstructure evolution and first-principles calculations were adopted to explore alloying elements Sn and Y proportion influence on room- and elevated-temperature mechanical properties of as-cast Mg-Sn-Y alloy in the present study. The results show that the room- and elevated-temperature compression yield strength and ultimate compression strength of Mg-1Sn-yY alloy simultaneously improves with Y addition from 0.5 wt.% to 2 wt.%. Decreasing Sn to 0.5 wt.% in Mg-1Sn-2Y alloy, Mg-0.5Sn-2Y alloy yields comparable room-temperature strength to Mg-1Sn-1.5Y alloy with similar alloying element addition. Notably, the elevated-temperature strength of Mg-0.5Sn-2Y alloy is even greater than that of counterpart Mg-1Sn-1.5Y alloy and achieves increment by ∼42 MPa at 200 °C, 48 MPa at 250 °C, and 29 MPa at 300 °C, respectively. Combined with microstructure analysis and first-principles calculations, the mechanism behind this is mainly attributed to increased Y solubility in the matrix. Sn content reduction leads to the MgSnY ternary phase (4.97%) in Mg-1Sn-1.5Y alloy being replaced by the low-content Sn3Y5 phase (2.30%) so as to high Y solid solution in the Mg-0.5Sn-2Y alloy. Raised Y solubility is more favorable to decrease cohesive energy and increase bulk modulus, shear modulus and Young’s modulus, which avails enhancing intrinsic cohesive strength and deformation resistance of alloy other than Sn solubility. Thus, improvement of cohesive strength and deformation resistance by Y solubility promotes Mg-0.5Sn-2Y alloy to endure high loading at elevated temperatures.

Exploring effects of supplementary cementitious materials on setting time, strength, and microscale properties of mortar

The concept of sustainability has become a crucial concern for safeguarding the planet. The current research has focused on developing affordable and eco-friendly mortar by using industrial wastes. This study explores the use of fly ash (FA) and ground granulated blast furnace slag (GGBFS), byproducts of steelmaking and coal burning, in mortar production. It examines their impacts on the compressive strength and setting times, when utilizing varying proportions of the materials. The study also evaluates water requirements for the workability, thus demonstrating the sustainability of these waste products in construction. The cementitious materials were employed in finely ground form and were replaced with further tertiary mixes including both supplements at 10%, 30%, and 50% of each. The mixtures were allowed to cure for 7, 14, and 28 days by immersion in water. The results showed improvements in the compressive strength of mortar samples incorporating FA and GGBFS at various curing ages. However, the water requirement and workability of mortar samples were altered as a result of utilizing these supplementary cementitious materials (SCMs). These findings will serve as a standard for environmentally responsible mortar using GGBFS and/or FA as SCMs.

Synergistic Effects of Concurrent Aerobic and Strength Training on Fitness in Children and Adolescents: A Multivariate and Network Meta-Analysis.

The decline in fitness levels among children and adolescents underscores the urgent need for effective exercise interventions. Aerobic endurance training (ET) and resistance training (RT) are vital for physical development in this demographic. This study employs multivariate and network meta-analysis (NMA) to assess the impact of concurrent training (CT), which integrates both ET and RT, on youth physical fitness. The objective is to identify the distinct advantages of CT over either ET or RT alone, emphasizing demographic and training-specific variables. A systematic literature review of publications from 1980 onward was conducted through ISI Web of Science, PubMed/MEDLINE, and SPORTDiscus databases, adhering to the PICOS criteria for study selection. Data were analyzed using univariate, multivariate, and network meta-analyses in Stata 17.0, focusing on cardiorespiratory fitness and muscular strength. The methodological quality and risk of bias were evaluated using the PEDro scale and Egger's test, along with sensitivity analyses and meta-regression to explore heterogeneity and publication bias. This analysis included 36 studies with 2658 participants (mean age: 14.32 ± 2.29 years) from an initial 11 074 publications, indicating low bias risk (PEDro scores ≥ 6). Univariate meta-analysis showed no significant differences in maximal oxygen uptake (VO2max) between CT and ET (standardized mean difference [SMD] = 0.01; 95% confidence interval [CI]: -0.23 to 0.25; p = 0.93). In contrast, CT significantly improved countermovement jump (CMJ) compared to RT alone (SMD = 0.19; 95% CI: 0.01-0.36; p = 0.04). Multivariate analysis confirmed notable enhancements in endurance and explosiveness for CT compared to ET or RT. NMA indicated significant improvements in lower limb strength, CMJ, and VO2max across interventions compared to controls, with the consecutive resistance training followed by ET (CRE) group yielding the most significant CMJ improvement (SMD = 0.27; 95% CI: 0.07-0.47). Isolated RT showed the highest lower limb strength improvement (SUCRA score 80.1%), while CRE excelled in CMJ advancements (SUCRA score 93.4%), and the CRED group (alternating ET and RT) led in VO2max improvements (SUCRA score 81.6%). Furthermore, high-intensity interval training (HIIT) significantly enhanced VO2max compared to team sports. This meta-analysis emphasizes the effectiveness of CT in improving muscle power and VO2max in children and adolescents, surpassing isolated ET or RT, and advocates for integrating ET and RT to optimize physical performance. Future research should explore the mechanisms underlying these enhancements. Trial Registration: PROSPERO registration number CRD42022368452.

Grain size hardening versus texture softening: Mechanical anisotropy of an AZ31B magnesium alloy processed by equal-channel angular pressing

Microstructural evolution of hexagonally close-packed (hcp) alloys subjected to severe plastic deformation differs from that of alloys with cubic crystal structure. While grain refinement is the main objective in conventional ECAP texture changes in hcp materials can result in lower strength but improved ductility depending on the deformation direction. This paper addresses the question of how the processes of grain size hardening and texture softening contribute to the highly anisotropic mechanical behavior of a severely deformed AZ31B magnesium alloy. ECAP is performed at different temperatures starting at 250 °C for the first 4 passes and subsequently reduced to 200 °C (C5, C6) and 150 °C (C7, C8). The mechanical properties of the resulting material conditions are investigated with tensile tests in four different deformation directions. While the yield strength increases up to 280 MPa in the transverse direction (TD), an opposite trend of low strength and good ductility can be observed for deformation in the extrusion (ED) and normal directions (ND). Additional microstructural investigations using EBSD show that the grain size is reduced by 95% during ECAP. Moreover, texture measurements using XRD reveal a strong fiber texture, with a high number of basal planes parallel to the shear plane of ECAP deformation, which results in a significantly improved ductility and lower strength in ED and ND. The results are discussed in the light of the competition between grain size hardening and texture softening. They highlight the potential of ECAP for the improvement of strength and ductility for magnesium alloys.

Effects of Hf addition on the microstructure and properties of Cu-Sn-P alloy

In this paper, the effects of Hf addition on the mechanical properties, electrical conductivity and microstructure of Cu-Sn-P alloy were investigated. The results show that the Hf addition can enhance the mechanical properties and electrical conductivity of Cu-Sn-P alloy. The alloy with 0.05 wt.% Hf exhibits the best comprehensive performance with yield strength of 625 MPa, tensile strength of 661 MPa and electrical conductivity of 16.8 %IACS. Compared with the Cu-Sn-P alloy without Hf addition, the yield strength and tensile strength are increased by 8.4% and 7.8%, and the electrical conductivity is increased by 24.4%. The increase in the strength of Hf-added alloy can be attributed to the synergistic effect of multiple strengthening mechanisms, including fine grain strengthening, twin strengthening, dislocation strengthening, precipitation strengthening and Σ3n (n = 1, 2, 3) grain boundary strengthening. Moreover, the Hf-P precipitates can be observed in the Hf-added alloy. According to the amount of Hf addition, these precipitates can manifest as the fine HfP2 phase and the coarse HfP phase. The formation of Hf-P precipitates contributes to the precipitation strengthening and the purification of Cu matrix, thus contributing to the improvement of strength and conductivity.

Enhancing the mechanical and environmental performance of solidified soil using construction waste and glass micro-powder

The rapid accumulation of construction waste and waste glass, coupled with their environmental hazards, has highlighted the need for sustainable waste management strategies. This study explores the potential of using construction waste (CW) and glass micro-powder (GMP) as innovative additives in soil stabilization, providing both mechanical and environmental benefits. This research focuses on enhancing the compressive strength, tensile strength, and heavy metal stabilization of solidified soils while reducing carbon emissions. Experimental methodologies involved the systematic preparation of soil samples stabilized with various proportions of CW and GMP. Microstructural analyses were conducted using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to understand the formation of cementitious products, including calcium silicate hydrate (C-S-H) and calcium aluminate hydrate (C-A-H), which play a pivotal role in the strength improvement of stabilized soils. This study found that the optimal formulation of 30 % CW and 15 % GMP improved compressive strength by 56.8 %, from 7.25 MPa to 11.38 MPa, while reducing porosity by 57 % and increasing tensile strength by 85 %. In terms of environmental performance, the combination of CW and GMP enhanced the soil's ability to immobilize heavy metals, with 80 % sequestration efficiency, significantly contributing to soil remediation. These findings underscore the practical engineering significance of utilizing CW and GMP for sustainable soil stabilization, providing a greener alternative to traditional binders and promoting resource efficiency in the construction industry.

Enhanced biopolymer composites through micro-integrated lignin and anhydride modified nonwoven bast fiber

The growing need for sustainable materials in various industries has driven research towards eco-friendly biopolymer composites. In this study, lignin microfillers were integrated into PHBV/modified bast fiber matrices, offering a promising solution for sustainable material innovation with improved performance and functionality. Nonwoven bast fiber mats were initially treated with propionic, succinic, and maleic anhydrides, evaluated through weight gain analysis, chemical characterization, thermal stability, and wettability assessments. These modified bast fibers were then reinforced with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biopolymer at 30 % loading using specialized molding techniques. The resulting biocomposites were subjected to comprehensive characterization, including moisture related properties, mechanical strength, thermal behavior, and fracturographical properties. In a final stage, lignin microparticles (LMPs) as biofillers were integrated at 1 %, 3 %, 5 %, and 7 % concentrations to enhance biocomposite properties. Experimental findings highlighted succinylated bast fibers as offering the greatest improvements in mechanical strength, thermal stability, and morphological integrity among the modified fibers. At an optimal 5 % lignin microfiller content, the biocomposites exhibited superior wettability and improved stiffness. However, excessive lignin loading led to particle agglomeration, diminishing overall performance. Fracturographical analysis provided insights into the fracture behavior of the biocomposites, highlighting the cohesive and interfacial characteristics of the materials under stress conditions. This research highlights the efficacy of sequential modification strategies in developing high-performance sustainable materials tailored for diverse industrial applications.

Anti-dispersion, rheological, and mechanical properties of GBFS/FA geopolymer for underwater engineering applications

Cementitious materials used in underwater engineering primarily face challenges such as water infiltration, chloride ion penetration, and sulfate attack. Therefore, the use of fast curing, strong corrosion resistance, and high-performance geopolymers is critical in underwater engineering. In this study, NaOH was selected as the activator, with granulated blast furnace slag (GBFS) and fly ash (FA) serving as precursors. The effects of hydroxypropyl methylcellulose (HPMC) content, alkali content, and the GBFS/FA ratio on the anti-dispersion, rheological, and mechanical properties of the geopolymers were systematically investigated. The results indicated that when the Na₂O content was below 5 wt%, increasing the HPMC enhanced the anti-dispersion properties of the geopolymer paste. However, in a highly alkaline environment (Na2O≥7 wt%), HPMC did not enhance the anti-dispersion properties of the paste. Infrared spectrum analysis suggested that the degradation of HPMC chemical bonds was responsible for the loss of underwater anti-dispersion properties in the geopolymer paste. The workability of the paste was negatively impacted by the thickening effect of HPMC. As the HPMC content increased, both the yield stress and plastic viscosity of the paste rose. FA enhanced the paste's workability, increasing its flowability by 13.36 %. At a constant alkali content, the rheological behavior of the paste was significantly affected by the HPMC content and the GBFS/FA ratio. The Bingham and modified Bingham (MB) models were employed to fit the rheological curve of the geopolymer paste, yielding satisfactory results. While GBFS contributed to the improvement of early strength, FA had a contrary effect. HPMC could delay the hydration process, increase the porosity of geopolymers, and reduce the strength of the samples. Underwater pouring further exacerbated the porosity, negatively affecting the geopolymer's strength. This study offers valuable insights for the application of geopolymers in underwater engineering.

Microstructural evolution and high strain rate deformation response of SLM-printed CoCrFeMnNi after annealing and deep-cryogenic treatment

This study examines the microstructural evolution and high strain rate deformation response of Selective Laser Melted (SLM) CoCrFeMnNi high-entropy alloys (HEAs) after annealing and deep cryogenic treatment. Annealing treatment has traditionally improved the ductility of SLM materials. However, in this work, a significant improvement in strength was observed in the annealed SLM CoCrFeMnNi after high strain rate deformation testing. TEM/HRTEM investigations revealed the formation of refined oxides, generated from the processing chamber environment and constituent powder feedstock. These oxides were homogenously distributed within microstructure, reinforcing its structural integrity. Initial microstructural analysis of the as-printed samples showed Mn2O3 oxides sparsely distributed within a cellular dislocation structure and significant Mn segregation. Unique grain growth with a less prominent cellular dislocation structure was observed in the annealed specimen. Deep cryogenic treatment induced oriented cellular structures with higher dislocation density and rounded oxides that were 56 % smaller. High strain rate impact tests (up to 6500 s-1) demonstrated that the as-printed sample was sensitive to the strain rate and reached a yield strength of ∼920 MPa at 6000 s−1 and a strain deformation of ∼55 % making it desirable for high strain rate applications. Remarkably, up to 22 % higher strength and ∼10 % greater ductility were achieved after annealing. The strengthening mechanisms in the samples and their contributions to the overall material strength were thoroughly analyzed. It was determined that a substantial portion of the strength in the annealed samples was due to the contributions of the precipitates within the alloy. The observed increase in strength was primarily attributed to the presence of two distinct nano-precipitates in the annealed specimens. However, there was no change in ductility after the deep cryogenic treatment but ∼10 % higher yield strength values at equivalent strain rates also attributed to the increased dislocation density.