Journal of Materials Science最新文献

Cold multi-DoF forming (CMDFF) has a broad applicative perspective in manufacturing the complex thin-walled structural components of hard-deforming materials. During CMDFF process, the nonlinear die–workpiece interactions cause complex macro and micro deformation behaviors, which has great impact on cracking failure and thus affected the forming quality and forming limit. In this study, the cracking failure behavior of Al7075 sheet during CMDFF process was systematically investigated. The evolutions of plastic deformation uniformity and microstructure uniformity were analyzed, and the final fracture surface morphology was characterized. Moreover, the slip behaviors were analyzed to discuss the fracture failure mechanism by CMDFF deformation. The results show that the strong lattice rotation caused severe dislocation clustering along randomly activated slip systems during CMDFF process, leading to UFG formation and stress localization throughout original cell blocks. Due to the more sufficient τ-fiber transformation and obvious Y texture preferential formation in center layer of CMDFF deformed sheet, it is difficult for dislocation gliding along slip systems in these high-M “hard grains”, resulting in severer stress localization in center layer. Once the stress localization reached critical value, micro-cracks got initiated and coalesced in center layer, and rapidly propagated to other region, resulting in the overall fracture.

Methane(CH₄), as a widely used clean energy source and industrial feedstock, poses both flammable and explosive safety risks while exhibiting a strong greenhouse effect. Its precise detection is crucial for industrial safety and environmental monitoring. Semiconductor metal oxides, favored for their low cost, fast response, and strong process compatibility, serve as the core sensing material for CH₄ sensors. However, traditional devices rely on high-temperature operation, leading to high energy consumption and poor low-temperature adaptability. Current research employs strategies such as noble metal doping, morphology control, heterostructure construction, and visible light activation to effectively reduce operating temperatures, with some achieving near-room-temperature operation. Through multi-method synergistic optimization, these approaches enhance response performance using light energy and doping while improving selectivity to reduce interference, thereby establishing high-performance composite sensing systems. Future efforts should focus on further “temperature reduction and efficiency enhancement” while overcoming high-humidity challenges. Additionally, integrating artificial intelligence with sensing systems—utilizing AI algorithms to model sensor data—addresses issues such as poor selectivity and signal drift. Combining machine learning models has improved sensor performance, expanded application scenarios in complex environments, and driven innovation in sensing technology.

This study investigates the mechanical properties, biocompatibility, and cytotoxicity of additively manufactured β-TCP bone scaffolds with triply periodic minimal surface (TPMS) based designs. Compression strength testing revealed that the diamond TPMS structure exhibited superior mechanical stability compared to other geometries, despite minor variability. Pore formers introduced controlled porosity, resulting in uniform spherical pores without compromising structural integrity. Biocompatibility assessments demonstrated robust cell proliferation across all scaffolds, comparable to 2D controls, with minimal cytotoxic effects observed over the testing period. The manufacturing process had no adverse impact on scaffold performance, reinforcing the potential of high-resolution diamond TPMS-based β-TCP scaffolds for bone tissue engineering applications.

Fretting wear caused by flow induced vibration (FIV) is one of the main reasons for the failure of pressurized water reactor (PWR) fuel cladding. To enhance the fretting wear resistance of zirconium (Zr) alloys, surface modification treatment was applied using QPQ nitriding technology at varying temperatures. The fretting wear behaviour of Zr alloys and QPQ samples was investigated under atmospheric and boron-lithium aqueous environments using a self-built fretting wear testing equipment. The results indicate that a gradient structure comprising an oxide layer and a co-diffusion layer of N and O formed on the Zr alloy surface following QPQ treatment. This is primarily due to the oxygen element in the QPQ nitride salt inhibiting the formation of the ZrN phase. The thickness of the oxide layer increases with rising QPQ treatment temperatures. The thickness of the N and O co-diffusion layer reached 100 μm. The high hardness of the oxide layer and its excellent resistance to plastic deformation significantly enhance the fretting wear resistance of Zr alloys. Among these, the QPQ550 sample demonstrated the most favorable resistance to fretting wear under both atmospheric and boron-lithium aqueous conditions. Compared to Zr alloy substrates, wear volume decreased by 78.55% and 88.30% respectively. These findings can offer new insights into the development and application of Zr alloy surface modification.

In this study, multiple gradient microstructures such as austenite volume fraction, grain size and dislocation density were introduced into medium manganese steel by friction stir processing combined with inter-critical annealing. Uniaxial tensile tests showed that the steel exhibited excellent strength-ductility synergy after friction stir processing and inter-critical annealing at 800 °C for 10 min, that is, the yield strength increased from 570 to 605.5 MPa, the tensile strength increased significantly from 914.9 to 1041 MPa, and the total elongation increased from 48.7 to 50.1%. Microstructure analysis showed that during the tensile deformation process, the hardness difference induced by the gradient microstructure of the gradient medium manganese steel enhances the mechanical incompatibility between different regions, thereby activating significant heterogeneous deformation-induced strengthening and hardening. At the early stage of deformation, the strain distribution associated with the gradient microstructure effectively inhibits the austenite transformation in the stir zone, favoring its stability under large strains. Simultaneously, it promoted austenite transformation in the heat-affected zone and, in synergy with heterogeneous deformation-induced hardening, led to simultaneous improvements in both strength and ductility. Among these mechanisms, heterogeneous deformation-induced strengthening is considered the primary contributor to the observed increase in yield strength. This study offers new insights into the design of gradient microstructures and the fundamental mechanisms behind strength–ductility synergy in medium manganese steel.

This study investigates the effects of a duplex surface treatment, consisting of sub-β-transus heat treatment followed by W-DLC coating via closed-field unbalanced magnetron sputtering (CFUBMS), on the fatigue behavior of Ti6Al4V ELI alloy fabricated using laser powder bed fusion (L-PBF). Post-processing techniques were analyzed for their influence on fatigue performance under diverse ambient conditions (steady and cyclic). Fatigue tests were conducted using the stress-life methodology at 25 ℃ (room temperature), 50 ℃, 250 ℃, −50 ℃, and cyclic conditions ( −50/ + 50 ℃). Structural, morphological, and mechanical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Vickers hardness testing. The microstructural analysis highlighted significant strain accumulation near fracture sites and the presence of micropores, which contributed to microcrack initiation. Results demonstrated that test temperature notably influenced fatigue life, significantly reducing under cyclic conditions ( −50/ + 50 ℃) compared to room temperature. Heat treatment and W-DLC coating notably enhanced fatigue performance across all test conditions by forming a protective barrier and reducing residual stresses.

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GCr15 bearing steel, the primary material for high-end bearings, is widely employed in automotive manufacturing, precision machine tools, and aerospace applications. However, surface degradation due to wear and fatigue in service environments often leads to premature failure. Therefore, enhancing the wear resistance of bearing surfaces is of critical importance. This study aims to optimize the microstructure and properties of RE-GCr15 bearing steel through a combined process of carbonitriding and ultrasonic rolling, investigating the resultant microstructural evolution and tribological behavior. Results indicate that while carbonitriding forms a deep carbonitride layer on RE-GCr15, excessive carbon infiltration elevates retained austenite (RA) content to 40.04%, resulting in a lower surface hardness (697.78 HV) compared to conventionally quenched-tempered specimens (780.42 HV). Ultrasonic rolling, however, induces stress-driven martensitic transformation, reducing RA content to 28.39% and significantly increasing surface hardness to 881.11 HV. The composite strengthening layer depth exceeds 150 μm. Carbonitrided specimens exhibit severe adhesive wear due to high RA content, with a wear rate (22.975 × 10^–4 mm³/m·N) significantly higher than that of quenched-tempered specimens (6.956 × 10^–4 mm³/m·N). Conversely, ultrasonic rolling introduces compressive residual stresses and grain refinement, reducing the wear rate to 2.098 × 10^–4 mm³/m·N and shifting the dominant mechanism to abrasive wear. In summary, the synergistic combination of carbonitriding and ultrasonic rolling provides an effective technical approach to enhancing the wear resistance and extending the service life of bearing steels.

To address the hydrogen-induced cracking failures of age-hardened nickel-based corrosion-resistant alloys, this study systematically investigated the effects of cold deformation before aging on the hydrogen embrittlement susceptibility. Nickel–based alloy 718 (UNS N07718), a representative oilfield corrosion-resistant alloy, was subjected to cold deformation via room-temperature rolling with ε = 0–30% strain before aging. Microstructural characterization was performed on aged alloys with different levels of cold deformation, and hydrogen embrittlement behavior was evaluated through thermal desorption spectroscopy, hydrogen-induced discoloration experiments, and slow strain rate tensile (SSRT) tests. Results showed that the residual microstructures introduced by cold deformation were preserved after aging, which increase dislocation density and the fraction of low-angle grain boundaries, which regulated the distribution of shallow hydrogen traps and mitigated local hydrogen accumulation. Furthermore, increased grain boundary density not only influenced hydrogen diffusion paths but also enhanced the tortuosity of crack propagation, while the formation of triple junctions further reduced crack growth rates. Optimal 20% pre-strain deformation reduces hydrogen embrittlement susceptibility by 37.3%, as evidenced by the reduction in elongation loss in SSRT from 16.9 to 10.6%. The moderate cold deformation-induced before aging increase in hydrogen trapping sites and grain boundary density synergistically limits hydrogen diffusion and promotes crack path tortuosity, thereby effectively mitigating hydrogen embrittlement susceptibility.

The characteristics of MXenes, a novel family of two-dimensional transition metal carbides and nitrides, have drawn a lot of interest recently in many engineering fields. MXene's distinctive two-dimensional layered structure, high mechanical strength, good stability, large specific surface area, and excellent electrical conductivity make it extremely promising for electrochemical performance and hydrogen storage. Thus, contributing to the development of safe and effective hydrogen storage systems. The promising future of MXene materials in the field of energy storage (ES) is highlighted in this review. MXenes are attractive candidates for the creation of high-performance electrical devices because of their exceptional qualities, compatibility, and tunability. An extensive review of MXene materials is provided in this study, with particular attention focused on their synthesis, characterization, functionalization techniques, inherent qualities, and their promising prospects in ES applications. Furthermore, the existing challenges in the development of MXene for ES are discussed, and certain characteristics for enhanced electrochemical performance and MXene-based hydrogen storage are highlighted. The review's conclusions demonstrate MXene's potential to solve important ES problems, including limited capacity and poor cycling stability. They also offer direction for future studies aimed at streamlining synthesis procedures and improving the functionality of MXene-based materials for real-world uses.

Fe–Mn–Al–C low-density high-strength (LDHS) steels possess significant application potential in the automotive industry. However, the failure to achieve a higher synergy of strength and ductility remains one of the key bottlenecks hindering the further development of such steels. This study designed an Fe–30Mn–10Al–2Ni–1.5C–0.5Ti–xCr (wt.%, x = 1/3/5) LDHS steel to investigate the influence mechanism of Cr addition on its microstructure and properties. The results indicate that after solution treatment, the alloy's microstructure consists of single-phase austenite and two types of precipitates: TiC and κ-carbides ((Fe, Mn)₃AlC_x). Increasing the Cr content from 1 wt.% to 5 wt.% raised the critical nucleation energy of κ-carbides, resulting in a reduction of their average size and volume fraction. The alloy with 5 wt.% Cr exhibited optimal comprehensive performance: a 15–20% reduction in density (ρ = 6.57 g/cm³), a tensile strength of 936.8 MPa, an elongation of 64.1%, and an outstanding strength–ductility product (60.1 GPa·%). This study provides a potential alloy design and processing route for automotive applications requiring ultra-high strength and lightweight characteristics.

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