Search Results (514)

Although 45 steel is widely used in the manufacture of mechanical parts, its application in harsh working conditions is limited owing to its low hardness, poor wear resistance, and corrosion resistance. Laser cladding can enhance the performance of the working surface without sacrificing substrate toughness. CoCuNiTi HEACs with different cBN additions were successfully prepared on a 45-steel substrate. The phase structure, microstructure, elemental composition, wear, and corrosion behavior of CoCuNiTi + x cBN (x = 0.0, 0.5, and 1.0 wt.%) HEACs were investigated using XRD, OM, SEM, EDS, friction and wear tester, and electrochemical workstation, respectively. The results show that all three coatings exhibit a dual-phase structure composed of FCC and BCC phases. The addition of cBN transforms the alloy phase structure from the original FCC main phase to the BCC main phase. The incorporation of cBN significantly reduces the lattice constant and cell volume of the alloy phase. The change in the alloy phase density is negatively correlated with the cell volume. CoCuNiTi + x cBN (x = 0.0, 0.5, and 1.0 wt.%) alloys have a dendritic structure. No pores were observed in the cBN-containing sample. The content of Ti in the primary phase is the highest. Co is enriched in the dendrite region, and Cu is enriched in the interdendrite region. The significant reduction in the average segregation coefficient for cBN-containing samples is attributed to the heterogeneous nucleation of the alloy melt at lower undercooling levels and the significant increase in the diffusion rate. The friction coefficient of the alloy decreases significantly with increasing cBN content. The sample with 1.0 wt.% cBN shows the best wear resistance, mainly due to the combined effects of hard particle support, solid solution strengthening, phase interface reduction, and high thermal conductivity of cBN. The sample with 1.0 wt.% cBN has the largest capacitive arc radius and charge-transfer resistance, along with the lowest annual corrosion rate, indicating optimal corrosion resistance. This is primarily related to the reduction in pore defects caused by cBN addition, hindrance of uniform penetration of the corrosive medium by dispersed cBN particles, and increased complexity of the anodic dissolution process. CoCuNiTi HEACs reinforced by cBN can simultaneously improve the wear and corrosion resistance of the surface of the 45-steel substrate, providing a feasible strategy for the design of high-performance protective coatings. Full article

In this work, the effect of partial to complete Al substitution of Si on the microstructure, retained austenite (RA) stability, and mechanical properties of cold-rolled TRIP-aided steels was investigated. Four experimental TRIP-aided steels (Fe-0.2C-1.5Mn-1.5/1.0/0.5/0Si-0/0.5/1.0/1.5Al-0.025Nb, wt.%) were designed. The results indicate that replacing Si with Al significantly increases the volume fraction of soft polygonal ferrite (from 52% to 73%) and decreases that of bainite. Although the volume fraction of RA decreases (from 15.6% to 12.4%), its average carbon content and, consequently, its mechanical stability are enhanced, which suppresses the strain-induced martensitic transformation. In terms of mechanical properties, the substitution leads to a monotonic decrease in both yield strength (from 573 MPa to 536 MPa) and ultimate tensile strength (UTS) (from 839 MPa to 648 MPa), primarily due to reduced solid-solution strengthening, coarsened ferrite grains, and a weakened TRIP effect. Conversely, the total elongation (TEL) increases from 28.3% to 32.4%, attributed to the higher fraction of ductile ferrite. Consequently, the product of tensile strength and total elongation (PSE) exhibits a slight decline. The 1.5Si-TRIP steel exhibited the most balanced mechanical properties, achieving the highest PSE of 23.7 GPa·%. Full article

High nitrogen austenitic stainless steels are an important engineering structural material. Under annealing conditions, the addition of interstitial solid solution element nitrogen can improve the yield strength and tensile strength of the alloy without reducing its plasticity. In addition, nitrogen can partly or completely replace the more expensive nickel element at a relatively cheap element cost to improve economic benefits, while maintaining or even enhancing the excellent corrosion resistance of stainless steels. However, the cracks and defects caused by high nitrogen austenitic stainless steels during hot working in high temperature ranges have always been the pain points in the engineering field. High nitrogen elements bring high temperature strength, but also narrow the hot working temperature range, the possibility of nitride precipitation and the tendency of heat induced cracking, which limit the further engineering application of high nitrogen austenitic stainless steels. It is urgent to analyze and study the hot deformation law of high nitrogen austenitic stainless steels in engineering. This article commences with an examination of the developmental trajectory of high nitrogen austenitic stainless steel, elucidates the role and strengthening mechanism of nitrogen, and delineates the factors influencing the mechanical behavior of high nitrogen austenitic stainless steel during hot working. These factors include the impact of nitrogen content and manufacturing processes, hot-working parameters, grain size distribution, and the presence of precipitated phases. This article synthesizes various studies, analyzes the causes of thermal cracking, and proposes potential solutions. Ultimately, it summarizes the practical applications and future prospects of high nitrogen austenitic stainless steel, highlighting its substantial potential. Full article

Accurate and non-destructive evaluation of grape quality is crucial for intelligent viticulture, yet most existing approaches address cultivar classification and soluble solid content (SSC) prediction as independent tasks based on single-modality data, limiting robustness and practical applicability. This study proposes DualStream-RTNet, a unified multimodal deep learning framework that simultaneously performs grape cultivar classification and SSC prediction by integrating RGB-HSV fused images and PCA-compressed hyperspectral spectra. The dual-stream architecture enables the complementary learning of external chromatic–textural cues and internal physicochemical information, while a Transformer-enhanced fusion module strengthens global representation and cross-modal correlation. A dataset of 864 berries from five grape cultivars was used to validate the model. DualStream-RTNet achieved 93.64% classification accuracy, outperforming ResNet18 and other CNN baselines, and produced more compact and consistent confusion-matrix patterns. For SSC prediction, it consistently yielded the highest performance across cultivars, with R2p values up to 0.9693 and RMSE as low as 0.2567, surpassing the PLSR, SVR, LSTM, and Transformer regression models. These results demonstrate the superiority of the proposed framework in capturing both visual and spectral characteristics. DualStream-RTNet provides an efficient and scalable solution for comprehensive grape quality assessment, offering strong potential for real-time sorting, precision grading, and smart agricultural applications. Full article

In this study, Sn and Ni powders were incorporated into the flux core of brass brazing filler metals, with alloying achieved via in situ synthesis during brazing. The effects of Sn/Ni single and composite additions on the microstructure, melting characteristics, wettability on Q235 steel, and tensile strength of corresponding brazed joints were systematically investigated. Sn addition increased the β-phase fraction, reduced the solidus temperature, and significantly improved wettability—with a maximum unit spreading area of 4.22 mm²/mg at 20 wt.% Sn (2.85 times that of the Sn/Ni-free baseline). However, coarse β-phase grains and their transformation to brittle β′-phase at room temperature resulted in no enhancement of joint tensile strength. Ni addition expanded the α-phase region, refined grains, and induced solid solution strengthening of the α-phase matrix; joint tensile strength peaked at 501 MPa at 20 wt.% Ni (65% higher than the baseline). Excessive Ni (≥40 wt.%) deteriorated wettability due to reduced molten superheat, and 50 wt.% Ni caused α-phase over-strengthening and embrittlement, leading to a sharp strength drop to 214 MPa. The composite addition of 3 wt.% Sn + 10 wt.% Ni reconstructed the filler metal into a refined, uniform grid-like (α + β) dual-phase structure without new phase formation, realizing synergistic optimization of wettability and mechanical properties. The co-added sample exhibited optimal performance, with a unit spreading area of 4.51 mm²/mg and joint tensile strength of 584 MPa (206% and 93% higher than the baseline, respectively). This improvement was attributed to the coupling of uniform stress dispersion by the grid-like microstructure and dual-element functional complementation (Sn for wettability and β-phase strengthening; Ni for grain refinement and α-phase strengthening). This work provides a feasible alloying modification strategy for brass flux-cored brazing filler metals, and the revealed microstructure-performance regulation mechanism offers a valuable reference for developing high-performance brass brazing filler metals. Full article

As a new generation of structural materials, Fe-Mn-Al-C lightweight steels with low density, high strength, and excellent strength-toughness properties have shown significant application potential in fields such as transportation, aerospace, and energy equipment. In the present work, the effects of Mo alloying and annealing processes on the microstructural evolution and mechanical properties of Fe-18Mn-8Al-1C-3Cu lightweight steel are investigated. Due to the addition of Mo, the recrystallization temperature is significantly increased, and the recrystallization process is delayed. The fine and dispersed Mo₆C precipitated phases can effectively impede dislocation movements and pin the grain boundaries, hindering recrystallization and grain growth. After annealing at 900 °C, the yield and tensile strengths of the Mo-alloyed steel were enhanced, achieving 1181 MPa and 1345 MPa, respectively, while maintaining an elongation of 24%, thus exhibiting excellent comprehensive performance. Quantitative analysis of strengthening mechanisms confirmed that the strength enhancement primarily resulted from the synergistic contributions of grain refinement strengthening (~152 MPa), solid solution strengthening (44 MPa), dislocation strengthening (131.6 MPa), and Mo₆C precipitation strengthening (52.23 MPa). Through Mo alloying and annealing process optimization, a high-strength, ductile lightweight steel was successfully developed, providing theoretical foundations and technical pathways for its application in high-performance structural materials. Full article

This study examines the effect of vanadium addition on the microstructure and mechanical properties of low-cost powder metallurgy Ti-4Al-2Fe-3Cu alloys. Alloys with and without 6 wt.% V were fabricated by hot extrusion of blended elemental powders followed by vacuum heat treatment. Microstructural analysis revealed that the base alloy exhibits a coarse lamellar α/β structure, while vanadium addition promotes a refined basketweave morphology with a significantly higher β-phase fraction, increasing from 28.1% to 46.2%. Energy-dispersive spectroscopy confirmed preferential partitioning of Fe, Cu, and V into the β phase. Mechanical testing showed that the addition of 6 wt.% V markedly enhances strength, increasing yield strength and ultimate tensile strength from 1122 MPa and 1214 MPa to 1291 MPa and 1349 MPa, respectively, while maintaining comparable tensile ductility (~3.5%). The strength improvement is attributed to α-plate refinement, increased β-phase fraction, and solid-solution strengthening of the β phase. These results demonstrate that vanadium addition is an effective approach for improving the strength of low-cost PM titanium alloys without compromising ductility. Full article

This work investigated the effects of varying tungsten (W) and chromium (Cr) contents on the lattice constant, elastic properties, yield strength, and electronic structure of TiZrNb alloys via first principles and the Special Quasi-Random Structure (SQS). A modified Senkov approach, considering the local atomic environment to estimate yield strength was suggested. Analysis indicated that W and Cr decrease the lattice constant of the TiZrNb alloy. W could improve the elastic modulus of material and solid solution strengthening effect, but Cr only enhanced the bulk modulus at high levels. The alloying of W and Cr was not beneficial for enhancing the plasticity. Cr was more significant in damaging mechanical isotropy. The modified Senkov approach improved the estimation accuracy of yield strength. Electronic property analysis indicated that W and Cr could lower the Fermi level to enhance the stability of the phase. Their covalent interactions helped to enhance strength. At present, the accuracy of the theoretical predictions has improved, relative to the experimental values. This work will provide guidance for the design and optimization of TiZrNb-based alloys. Full article

This study addresses the challenge of through-hole defects in ZM6 cast magnesium alloy components by proposing an innovative repair strategy using ultrasonic-assisted Tungsten Inert Gas (U-TIG) welding. The microstructure and mechanical properties of the repaired joint were systematically characterized through optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and room-temperature tensile testing. The results indicate that, assisted by the ultrasonic energy field, the repair zone successfully reconstitutes a typical and optimized triple-phase microstructure: (1) the matrix: α-Mg solid solution (dark gray), supersaturated with Nd and Zr; (2) the strengthening phase: a eutectic Mg₁₂Nd phase (light gray), rich in Nd, distributed along grain boundaries acting as the primary strengthening component; (3) the grain refiner: dispersed Zr-rich particles (bright white spots), which effectively pin grain boundaries. Crucially, the application of ultrasound significantly refined the α-Mg grains and transformed the continuous network of the Mg₁₂Nd phase into a more fragmented and uniform dispersion. This refined microstructure synergistically integrates the strengthening mechanisms of solid solution, precipitation hardening, and grain refinement. Consequently, the repaired joint exhibits excellent mechanical properties, achieving over 90% of the base metal’s tensile strength and elongation at room temperature. This work not only validates the feasibility of U-TIG welding for repairing ZM6 alloys but also provides a solid theoretical foundation and a promising technical pathway for the in-service repair and remanufacturing of high-performance magnesium alloy components. Full article

In this study, first-principles calculations were employed to systematically investigate the adsorption of Cl⁻ on Al₂Cu(110) surfaces, clean Al(111)/Al₂Cu(110) interfaces, and Fe/Si-doped interfaces, as well as the influence of strain on interfacial electronic structure and corrosion activity. When Cl⁻ is adsorbed on Al sites, the bonding between Cl and Al exhibits strong ionic characteristics with localized charge transfer, while adsorption on Cu sites is characterized by more delocalized, covalent interactions. This competition dictates the site-dependent stability of adsorption. Through geometric–electronic synergy, the interface functions as both a “Cl⁻ enrichment zone” and an “activity source,” significantly favoring Cl⁻ adsorption at high-activity anodic sites such as Al-hole and Al-bridge. Conversely, Cu-top sites maintain a high work function and an inert cathodic nature, facilitating the formation of efficient micro-galvanic couples across the interface. Moreover, Fe/Si doping further modulates the interfacial electronic landscape: Si serves as an effective strengthening element due to its low substitution energy and high stability, while Fe primarily forms a solid solution on the Al side, potentially introducing galvanic corrosion risks. Stress analysis indicates that tensile strain systematically enhances surface activity by lowering the work function, while compressive strain non-monotonically influences corrosion through a three-stage mechanism involving the “densification–cracking–plastic relaxation” of the passive film. These findings elucidate the atomistic origins of corrosion initiation at Cu–Al composite interfaces and provide a theoretical foundation for enhancing corrosion resistance through alloy design and strain engineering. Full article

This study investigates the solution and artificial aging processes of TiB₂/7050 composites. Using microscopic and mechanical tests, we systematically evaluate the material’s microstructural evolution and mechanical performance, aiming to optimize heat treatment parameters. The study shows that a solution temperature of 475 °C for 1 h is optimal for fully dissolving the second-phase particles. Regarding artificial aging, peak hardness of 246 HV is achieved at 140 °C for 16 h. Analysis of the phases and microstructure in O and T6-states shows that strengthening occurs through grain boundary hardening and precipitation hardening. The effect of TiB₂ particles on the above process was also explored. During solidification, TiB₂ particles were pushed by the advancing solid–liquid interface and primarily distributed along grain boundaries. This distribution subsequently slowed the solid solution process by reducing the contact area between the η(MgZn₂) phase and the α(Al) matrix. During aging, they enhance grain boundary precipitates (GBPs) in particle-rich regions and inhibit the formation of precipitate-free zones (PFZs), with a concentration of the η’ phase forming around the particles. Beyond a certain distance from the particles, there is a decrease in η’ phase concentration. This study is expected to contribute to advanced lightweight materials research and development, opening up new opportunities for their application in various industries. Full article

CoCuNiTi HEACs reinforced by different diamond contents were prepared on the surface of 45 steel substrate by laser cladding. Their phase composition, microstructure, elemental composition, and wear/corrosion resistance were investigated using XRD, OM, SEM, EDS, a friction and wear testing machine, and an electrochemical workstation, respectively. The results show that after adding diamond, the phase composition of the sample transforms from the original dual-phase structure of the FCC main phase and BCC to the dual-phase structure of the BCC main phase and FCC. With an increase in the diamond content, the diffraction peak intensity of the alloy phases first increases and then decreases. This behavior is related to the significant enhancement of the alloy phase crystallinity with low diamond addition and the intensified crystal lattice distortion caused by excessive diamond addition. The CoCuNiTi + x Diamond (C) (x = 0, 0.5, and 1.0 wt.%) high-entropy alloys have a dendritic structure. After the addition of diamond, no hole defects were observed in the microstructure, and the dendritic structure was significantly refined. Ti and C are enriched in the primary phase, Cu is enriched in the interdendrite regions, and Co exhibits the highest concentration in the dendrite regions. The segregation coefficients of Ni in all three alloys are relatively small. As the diamond content increases, the friction coefficient of the samples decreases significantly. The 1 wt.% diamond sample exhibits the best wear resistance, primarily owing to the combined effects of superhard phase strengthening, solid solution strengthening, and fine grain strengthening resulting from diamond addition. The sample with 0.5 wt.% diamond addition has the lowest self-corrosion current density, highest polarization resistance, and lowest annual corrosion rate, indicating the best corrosion resistance. This performance is mainly attributed to the refinement of the microstructure, reduction in defects, and formation of a dense passivation film caused by the addition of a small amount of diamond. Full article

Refractory high-entropy alloys (RHEAs) have garnered attention for their exceptional high-temperature mechanical properties, making them suitable for aerospace and energy applications. However, balancing strength and ductility remains a challenge due to the presence of Laves phases. In this study, Al_0.5Nb_0.5TiV₂Zr_x (x = 0–2.0) alloys were prepared using vacuum arc melting, and their microstructural evolution and mechanical properties were analyzed. At room temperature, the Al_0.5Nb_0.5TiV₂Zr_0.5 alloy exhibits the highest yield strength (1658.1 MPa), which is primarily attributed to strong lattice distortion induced by Zr and moderate precipitation strengthening from Laves phases. In contrast, at higher Zr contents, excessive Laves phase precipitation promotes stress concentration, leading to a marked reduction in both strength and ductility. High-temperature compression tests revealed that the Al_0.5Nb_0.5TiV₂Zr_0.5 and Al_0.5Nb_0.5TiV₂Zr_1.5 alloys still exhibited over 50% compressive plasticity at 800 °C and 1000 °C. However, when the temperature reached 1000 °C, the instability of the Laves phase led to a reduction in the yield strength to below 160 MPa, indicating that the effect of solid-solution strengthening was no longer significant under high-temperature conditions. These findings clarify the critical role of Zr content and temperature in governing the microstructural and mechanical evolution of the Al–Nb–Ti–V–Zr system and provide a theoretical basis for achieving an optimized strength–ductility balance in RHEAs through compositional control. Full article

HfC possesses high hardness, high melting point, and excellent thermal stability, and is regarded as an important wear-resistant reinforcing phase material. In this study, the laser cladding technique was employed to fabricate CoCrFeNiTi and CoCrFeNiTi/HfC composite coatings on the surface of Q235 substrate. The influence of HfC addition on the phase structure evolution, microstructure, and wear resistance of the coatings was systematically investigated. The results showed that the addition of HfC did not alter the phase structure of the coating, which remained dominated by an FCC solid solution. However, they induced the formation of an in situ TiC strengthening phase and reduced the brittle Laves phase content, thereby optimizing the coating’s toughness. At the same time, the coating transformed from columnar to equiaxed crystals, with significantly finer grains and further improved structural uniformity. Compared with the CoCrFeNiTi coating, the CoCrFeNiTi/HfC composite coating exhibited a more stable friction coefficient, a significantly lower wear rate, and improved wear resistance by approximately 2.4 times. The performance improvement was mainly attributed to the load-bearing strengthening and crack-pinning effect of the in situ TiC, the inhibitory effect of the reduction in the Laves brittle phase on adhesive wear, and the synergistic effect of Hf, which forms a stable oxidation-protective film during friction. Full article

Decentralized graywater treatment using nature-based systems represents a sustainable, low-energy alternative to centralized wastewater technologies, particularly in water-scarce regions. This study evaluates the performance of a rain-garden-based constructed wetland implemented at Zain Park in Jerash, Jordan, for on-site graywater treatment and potential non-potable reuse. The system consists of two filtration beds with multi-layer gravel–sand media planted with ornamental vegetation to promote physical filtration, adsorption, and biologically mediated transformations. Influent and effluent samples were monitored monthly from April 2024 to January 2025 and analyzed for biodegradable and oxidizable organic fractions (BOD₅ and COD), nutrients (TN, PO₄³⁻), suspended solids, turbidity, salinity indicators, and microbial parameters (E. coli and total coliform). Average removal efficiencies reached 98% for BOD and 96% for COD, while turbidity and TSS were reduced by more than 96%, indicating effective organic degradation and particulate retention. Nutrient removal was moderate, with 40% reduction in Total Nitrogen and 74% in nitrate, reflecting partial nitrification–denitrification and plant uptake. Microbial removal was variable, with an average reduction of 0.8 log₁₀ (64.7%) for E. coli and 1.1 log₁₀ (82.6%) for total coliforms, indicating that passive filtration alone may not ensure complete pathogen attenuation. Post-treatment disinfection and substrate enhancements (aeration and plant selection) can strengthen system efficiency and support sustainable graywater reuse in water-stressed regions, contributing directly to SDG 6 (Clean Water and Sanitation), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production). These findings support the applicability of compact constructed wetland systems as decentralized wastewater treatment solutions in arid and semi-arid urban environments. Full article