Journal of Materials Science最新文献

This study systematically investigates the influence of Mn element on the stability and anisotropic behavior of the Al₈Mn₅ phase in AZ80 magnesium alloy by combining first-principles calculations, thermodynamic simulations, and experimental validation. The microstructure evolution was further verified using JMatPro phase diagram simulations and metallographic experiments. The results indicate that the Al₈Mn₅ phase possesses high structural stability and toughness (B/G=1.76). Furthermore, this phase exhibits significant anisotropy in elastic modulus, shear modulus, and strain energy density. Experimental studies show that with increasing Mn content (0.15~0.35 wt.%), the precipitation amount of the Al₈Mn₅ phase in the alloy increases. Its dispersed distribution effectively refines the grains, reducing the grain size from 215 to 96 μm, and suppresses the formation of the network-like β-Mg₁₇Al₁₂ phase. This research elucidates the stability and toughening essence of the Al₈Mn₅ phase from the atomic–electronic scale and verifies its role in microstructure regulation through macroscopic experiments, providing a solid theoretical and experimental basis for optimizing the comprehensive properties of AZ80 alloy through Mn microalloying.

Cementing is a key link in oil exploitation, and its operation quality directly affects the sealing performance and long-term service stability of oil wells. Under the influence of downhole pressure fluctuation, complex geological conditions and brittleness of cement paste, microcracks are easy to occur in cement sheath. The incorporation of self-healing materials is the key technology to solve the cracking of cement sheath. This paper reviews the research progress of cement paste self-healing in recent years, focusing on the analysis of a variety of self-healing materials suitable for oil well cement paste, including coated and uncoated chemical reaction materials, water swelling materials and oil and gas swelling materials, and discusses the self-healing technology suitable for gas storage well conditions. This paper summarizes the repair effect and application potential of various materials in oil well cement paste and summarizes the improvement methods of coated and expanded materials in mechanical properties and repair efficiency. Studies have shown that expansive self-healing materials have rapid response and efficient repair characteristics and are widely used in oil wells, especially gas storage wells. In view of the problems of insufficient chemical stability and mechanical properties of self-healing materials in the application of oil and gas wells, this paper makes a comparative analysis of four types of self-healing materials suitable for oil and gas wells in terms of material composition, self-healing conditions, applicable crack width and repair effect. It is pointed out that the temperature resistance, alkali resistance and mechanical properties of the materials can be effectively optimized by introducing nanoreinforced phases and using capsule encapsulation. Through the comprehensive analysis of the mechanism evaluation, material application conditions and modification research of cement paste self-healing, this paper summarizes and prospects the improvement methods of self-healing materials and looks forward to the future that the strength of materials can be improved by organic–inorganic composite technology, and a multi-component collaborative repair system can be constructed to speed up the repair rate and enhance the repair effect. This paper summarizes the future challenges and development directions of self-healing materials for oil and gas wells, provides reference for cementing engineering researchers, and fills the gaps in the review of the performance improvement of self-healing materials for oil and gas wells and their potential applications in high-temperature and high-salt reservoir environments.

In industrial scenarios with frequent dynamic loading—such as heavy-duty factory buildings, military defense structures, and containment structures of nuclear power plants—cement-based materials are required to possess high toughness to resist impact loads. However, traditional cement-based materials suffer from high brittleness and low toughness. Therefore, developing high-toughness cement-based materials has become a key topic in the field of civil engineering materials. Inspired by the “brick–mortar” structure and exceptional toughness of nacre, nacre-inspired cement-based composites have been fabricated using methods such as ice templating, layer-by-layer stacking, and 3D printing. The findings demonstrate that nacre-inspired cement-based composites have ductile fracture properties without compromising strength, in contrast to the brittle fracture behavior of traditional cement. This review comprehensively examines the research advancements of nacre-inspired cement-based composites, focusing on the three toughening mechanisms of natural nacre, along with the fabrication process, performance benefits, toughening strategies, future outlook, and application potential of these composites. It underscores the necessity for comprehensive exploration of material properties, interface design, fabrication techniques, and gradient structures in the design and preparation of nacre-inspired cement-based composites to enhance the evolution of cement-based materials that combine high strength and exceptional toughness.

AlSiMg alloy has been found to enable the direct shaping of complex aluminum foam components via casting foaming methods, significantly broadening the processing and application potential of aluminum foams. This study comparatively analyzes the energy absorption capacity and deformation modes of such foams against traditional AlCa foams prepared by melt foaming, utilizing quasi-static compression tests coupled with digital image correlation (DIC). Compared to AlCa foams, the initial peak stress and plateau stress of AlSiMg foams at the relative density of 0.27 are 1.9 and 1.3 times higher, respectively. This enhancement was attributed to hard-phase reinforcement (Mg₂Si, Si, and MgAl₂O₄) in combination with a larger cell size, which also induced brittle fractures during compression. The collective influence of the hard phases and cell structure leads to fluctuations in the stress–strain curve. Stress–strain curves of AlCa foams exhibited smoother, and their energy absorption capacity was demonstrated better at lower densities (under 0.24) due to their better plasticity of the matrix. DIC results revealed distinct deformation modes of the two kinds of aluminum foams. The AlSiMg foam followed a "Hard-phase support—Brittle fracture" mechanism, with crack propagation along hard-phase interfaces, while the AlCa foam exhibited "Plastic coordination—Progressive buckling", enabled by uniform cell distribution and ductile matrix. Therefore, the alloy matrix critically governs the foam performance under the same relative density, with hard phases enhancing strength but weakening ductility in AlSiMg foams. This work provides fundamental insights for designing matrix alloys to tailor foam properties for energy-absorbing applications, highlighting the trade-offs between strength and toughness in aluminum foams.

Polylactide is widely used in cardiovascular surgery and regenerative medicine. Despite its numerous advantages as a biomaterial, its lack of radiopacity limits the applications of polylactide in medical fields that require intra- and postoperative monitoring of the implant (e.g., for positioning, displacement, migration) and in vivo tracking of its biodegradation This study investigates the development of radiopaque composite materials based on polylactide and barium sulfate. A holistic assessment was conducted to examine the influence of filler concentration on the mechanical, physicochemical, and radiopaque properties of these materials. The feasibility of utilizing them for 3D printing objects with complex geometries was demonstrated. Optimal processing parameters yielded a uniform distribution of predominantly submicron-sized particles (100–300 nm) within the polymer matrix while preserving a high weight-average molecular weight (130.8 kDa). The predominantly hydrophobic surface radiopaque composite materials (RCMs) exhibited significant anisotropy in their mechanical properties. The adding of the BaSO₄ was found to have no effect on tensile strength. However, it substantially influenced the compressive yield strength and flexural yield strength. Specifically, the incorporation of 7.5% barium sulfate increased the compressive yield strength to 88.4 MPa and the flexural yield strength to 106.0 MPa. It was established that introducing 7.5% barium sulfate represents the minimum concentration required to ensure an optimal balance between radiopacity and mechanical characteristics. Consequently, it has been substantiated that composite biomaterials based on polylactide and barium sulfate demonstrate significant potential for application as a radiopaque material for biomedical 3D printing.

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To overcome the limited resolution—typically exceeding 100 μm—of Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) conductive hydrogel microstructures fabricated via conventional approaches, this study introduces a femtosecond laser direct-writing technique. This method enables the efficient and high-resolution fabrication of complex PEDOT: PSS conductive hydrogel microstructures at sub-100 μm scales. The influence of hydrogel constituents, specifically gelatin (Gel) and sodium alginate (SA), on the rheological, mechanical, swelling, and electrical conductive properties was systematically examined, leading to the optimization of the formulation at 15% Gel and 0.75% SA. By precisely modulating laser parameters—energy at 1.372 μJ, frequency at 1000 kHz, and scanning speed at 900 mm/s—microgrid structures with finely tunable feature sizes, including spacings below 10 μm, were successfully fabricated. The material ablation threshold was determined to be 0.132 J/cm². The resulting microstructured hydrogels demonstrated excellent electrical conductivity (1.16 mS/cm at 84% ablative density), robust structural stability, and favorable biocompatibility. In vitro cellular assays revealed that these microstructures, particularly the grids with 84% ablative density, effectively directed the orientation, adhesion, and spreading of mouse fibroblasts (L929). Notably, when combined with electrical stimulation at a scan rate of 20 mV/s, the system exhibited a significant synergistic effect, enhancing cell proliferation, increasing spreading area, and promoting orderly cellular growth. This work pioneers the integration of femtosecond laser high-precision processing with conductive hydrogel properties, offering an innovative platform for engineering dynamic cellular microenvironments that provide both structural guidance and precise electrical stimulation.

The thermal stability of PVC/PEO blends critically determines their utility in flexible electronics and sustainable packaging, yet their degradation pathways remain challenging to control. To address this, CoFe₂O₄ nanoparticles were synthesized via an auto-combustion method and incorporated (1 wt%) into a PVC/PEO (75:25) matrix using the casting method. Structural characterization by XRD confirmed the formation of pure spinel-phase CoFe₂O₄ nanoparticles with an average crystallite size of ~ 24.6 nm. Optical analysis revealed that nanoparticle incorporation reduced the band gap from 4.22 to 3.75 eV, suggesting localized state formation at the polymer–nanoparticle interface. FTIR spectroscopy confirmed strong molecular interactions between PVC and PEO, further modified by nanofiller incorporation. Contrary to most conventional nanofillers, CoFe₂O₄ decreased thermal stability in the 200–350 °C range. Kinetic analysis using the KAS, FWO, and Friedman methods showed slightly lower activation energies for the nanocomposite. Master plot analysis revealed a mechanistic shift from diffusion-controlled (D2) degradation in the pure blend to (D2/L2) of diffusion and random scission in the nanocomposite, highlighting the role of CoFe₂O₄ in altering degradation pathways.

Lithium-rich manganese cathode materials are regarded as next-generation lithium-ion battery cathodes due to their high theoretical specific capacity and low cost. However, some disadvantages such as low initial coulombic efficiency, voltage decay and poor rate performance hinder their commercial application. In this study, a series of lithium-rich manganese materials with the general formula 0.5Li₂MnO₃·0.5LiNi_xCo_(2/3-x)Mn_1/3O₂ is designed and synthesized for x = 1/3, 4/9, 5/9 and 2/3. The effect of the nickel–cobalt ratio on the structure and performance is studied and the results show that the increasing of Ni content favors the suppression of the Mn⁴⁺/Mn³⁺ reaction occurring in the low-voltage region, enabling the material to exhibit a higher discharge voltage and a smaller voltage decay rate, but the synergistic effect of Co is also important. 0.5Li₂MnO₃·0.5LiNi_5/9Co_1/9Mn_1/3O₂ (LNCMO-513) is identified as the optimal composition with high discharge voltage and long cycle life. Although the initial 0.1C discharge capacity of LNCMO-513 is slightly lower than 0.5Li₂MnO₃·0.5LiNi_1/3Co_1/3Mn_1/3O₂ (LNCMO-333), the mid-discharge voltage increases from 3.58 to 3.73 V. After 200 cycles at 1 C, the capacity of LNCMO-513 remains at 163.6 mAh/g with a capacity retention rate of 90.44%, whereas LNCMO-333 exhibits only 146.2 mAh/g and 73.62%. Notably, the initial mid-discharge voltages at 1C for LNCMO-513 exhibits 3.62 V and an average voltage decay rate of 1.10 mV/cycle over 200 cycles, while these two values for LNCMO-333 are only 3.40 V and 2.01 mV/cycle, significantly mitigating the severe voltage decay drawback common in lithium-rich materials. Furthermore, LNCMO-513 exhibits outstanding rate performance with an average discharge capacity of 121.4 mAh/g and an average mid-discharge voltage of 3.31 V at 5C, which is more greatly excessive than 55.28 mAh/g and 2.75 V of LNCMO-333.

The urea oxidation reaction (UOR) has garnered significant attention as a promising alternative to the oxygen evolution reaction (OER) for water electrolysis, owing to its superior kinetic properties that enable enhanced hydrogen production efficiency. However, the practical deployment of UOR technology remains hindered by the persistent challenge of developing electrocatalysts that simultaneously achieve high activity, long-term operational stability, and cost-effectiveness. Herein, we report a facile, eco-friendly, one-step synthesis process to fabricate nickel–tin electrocatalyst (Ni–Sn) on Ni foam for catalyzing UOR via electrodeposition, using SnCl₂·2H₂O and NiSO₄·6H₂O as the Sn and Ni sources, respectively. Notably, the Ni–Sn electrocatalyst with a Ni/Sn ratio (90.39:8.61 at%) exhibits remarkable UOR activity, delivering a low potential of 1.493 V versus RHE to reach 10 mA·cm⁻², a small Tafel slope of 83.5 mV·dec⁻¹, and excellent stability with minimal decay after 100 h of continuous operation in alkaline urea electrolyte (1.0 M KOH + 0.33 M urea). The excellent activity of the Ni–Sn electrocatalyst for UOR benefits from the synergistic interaction between Ni and Sn, which modulates the electronic structure and accelerates charge transfer kinetics, thereby significantly enhancing reaction dynamics. Furthermore, the intrinsic superhydrophilicity of the Ni–Sn catalyst promotes efficient mass transport of reactants and products, contributing to its superior bifunctional catalytic performance for UOR.

Al–Mg–Si (6xxx) aluminum alloys are extensively utilized in automotive, construction, and aerospace sectors due to their superior mechanical properties and lightweight nature. There is a growing demand for materials that combine enhanced performance with production efficiency. Microalloying has emerged as a promising approach to optimize the mechanical properties of 6xxx alloys. However, few studies have comprehensively investigated the influences of microalloying on microstructural evolution and mechanical properties across the entire production chain. This study systematically examines the role of vanadium (V) in modifying microstructural development from the as-cast state to the deformed microstructure and its subsequent impact on the mechanical behavior of Al–Mg–Si–Mn–Cr alloys. The addition of V was found to significantly accelerate the dissolution of Fe-rich intermetallic phases during homogenization at 550 °C. Trace amounts of V were detected in α-Al (Mn, Cr, Fe, V)Si dispersoid phases, where it contributed to a reduction in dispersoid size. The deformed microstructure was governed by synergistic interactions between strain energy, dispersoid phases, and V atoms in solid solution. For samples homogenized for 5 h, the recrystallization fraction decreased with increasing V content. In contrast, after 10 h of homogenization, the recrystallization fraction increased with higher V levels. The alloy containing 0.15 wt% V, homogenized at 550 °C for 5 h, achieved an optimal combination of enhanced strength and toughness while maintaining high production efficiency. The synergistic enhancement of strength and elongation in V-modified alloys was attributed to V-induced solid solution strengthening, deformed microstructures, and accelerated dissolution of Fe-rich phases.