Journal of Materials Science & Technology最新文献

Molybdenum (Mo) alloys are essential for applications requiring outstanding mechanical properties at high temperatures across various industrial sectors. Understanding and predicting the creep properties of Mo alloys is crucial for service safety and the design of new materials. This study introduces a physics-based crystallographic creep model dedicated to the characteristic hierarchical microstructure of Mo–La₂O₃ alloys. By sourcing most parameters from existing literature and calibrating others within recommended ranges, the model efficiently predicts creep behavior beyond its initial calibration scope. Through the integration of microstructure descriptors, we systematically explored the impact of different microstructural features on creep behavior and identified underlying mechanisms. This analysis yielded two pivotal concepts: the minimum acceptable grain size and the necessary nanoparticle number density. These metrics, readily obtainable from the model, quantify the requisite grain size and nanoparticle content to achieve the target steady-state creep rates for operational demands, thus providing essential insights for the creep condition-oriented design of Mo–La₂O₃ alloys. The model is also expected to be adaptable for developing other Mo alloys reinforced by second phase particles, aimed at achieving desired creep properties under specified conditions, assuming that relevant parameters are accessible through literature or lower-scale simulations.

A principle was proposed for designing a method to seal anodized aluminum used in semiconductor processing apparatuses. Thermodynamic calculations and Fick's second law were used to reveal trends in the metal ion deposition, deposition product stability, vapor pressures of halides for selected metal ions, the holding temperature, and time. Interactions between ion concentrations and the sealing temperature were also revealed. According to the design principles, anodized aluminum dipped in 1 mM Cr³⁺ ion solution and steam-sealed for 18 h exhibited the highest corrosion resistance when exposed to 5 wt.% HCl solution and HCl gas, verifying the designed results.

The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials. In this study, the effect of stoichiometric and non-stoichiometric Mn modification, namely Pb(Mn_1/3Nb_2/3)O₃ (PMnN) and MnO₂, on the microstructure and properties of Pb(Yb_1/2Nb_1/2)O₃-PbZrO₃-PbTiO₃ (PYN-PZT) piezoelectric ceramics are systematically investigated. It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO₂ modification promotes it, and thus the former yields stronger high-power characteristics (higher internal bias field E_i and larger mechanical quality factor Q_m) than the latter. Specifically, with an equivalent amount of Mn modification (2 mol%), PMnN and MnO₂ modification PYN-PZT ceramics exhibit significantly different values for average grain size (1.21 μm vs. 14.12 μm), E_i (8.5 kV/cm vs. 5 kV/cm), and Q_m (2376 vs.1134). To further evaluate high-power performance, the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured. Under an AC electric field of 3.5 V/mm, the PYN-PZT+6PMnN ceramics exhibit a v of up to 0.95 m/s, larger than both MnO₂-doped PYN-PZT (0.72 m/s) and unmodified PYN-PZT ceramics (0.1 m/s), and far outperformance than both PZT-4 and PZT-8 ceramics. Furthermore, to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT, we performed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion. Consequently, the small grain size (high grain boundary density) in PMnN-modified PYN-PZT exhibits a strong pinning effect, resulting in a large Q_m and outstanding high-power performance.

In this study, Ge⁴⁺-substituted cordierite, Mg₂Al₄(Si_1–xGe_x)₅O₁₈ ceramics, were successfully prepared by the traditional solid-state method to broaden its application potential. Notably, the excellent dielectric properties with ε_r = 4.90, Q·f = 128,200 GHz, and τ_f = −21.01 ppm °C^–1 were achieved. The increase in ε_r value is mainly due to the heightened content of Ge⁴⁺ with high polarizability. The Q·f value improved by 2.21 times compared to the cordierite matrix, which can be primarily attributed to enhanced lattice energy, bond covalency, and hexagonal ring symmetry. The alteration in τ_f value arises from the variation of bond energy, bond strength, and distortion in the [MgO₆] octahedra. These conclusions provide valuable insights for the design of silicate ceramics with higher Q·f values. In addition, the dielectric properties in the microwave and terahertz bands were compared. The higher Q·f and lower ε_r values in the terahertz band mainly result from the withdrawal of partial polarization mechanisms and differences in measurement methods. Mg₂Al₄(Si_0.92Ge_0.08)₅O₁₈ ceramics, demonstrating an ultra-low ε_r value of 4.54 and an ultra-high Q·f value of 286,533 GHz in the terahertz band, emerge as formidable contenders for future terahertz communications materials. Finally, a microstrip patch antenna was fabricated, achieving a bandwidth of 150 MHz at 4.78 GHz, which confirms the application in the n79 band for wireless communication.

With the rapid development of 5G technology and the interconnection of industrial production, electromagnetic pollution has become a serious problem. Achieving lightweight and controllable loads of absorbers while obtaining corrosion-resistant absorbers with high electromagnetic response properties is still considered a huge challenge. In this work, carbon fiber with a multichannel hollow structure is obtained by PAN/PS hybrid electrospinning and subsequent high-temperature roasting process. The spatial structure inside the carbon fiber plays an active role in optimizing the impedance matching characteristics of the absorber. In addition, bimetallic metal-organic frameworks (MOFs) derivatives are obtained by a precisely controlled ion exchange as well as a high-temperature gas-phase selenization process. The resulting introduction of a non-homogeneous interface induces interfacial polarization and improves the absorption behavior of the absorber. The analysis of the experimental results shows that the electromagnetic wave (EMW) absorption performance can be effectively enhanced due to the mechanisms of interface polarization and dipole polarization. The prepared NiSe/ZnSe/MHCFs composite can obtain excellent EMW absorption properties in C, X, and Ku bands by adjusting the thickness. Structural design and component modulation play a crucial role in realizing the strong absorption and wide bandwidth of the absorber. Radar cross-section calculations indicate that NiSe/ZnSe/MHCFs have tremendous potential in practical military stealth technology. And the prepared composite coating can provide periodic corrosion resistance to Q235 steel sheet when dealing with complex and extreme environments.

Highly developed electronic information technology has undoubtedly resulted in numerous benefits to the military and public life. However, the resulting electromagnetic wave (EW) pollution cannot be ignored. Therefore, the application of highly efficient EW materials is becoming an important requirement. In this study, magnetic-dielectric heterointerface strategy was applied to construct absorbers with desirable electromagnetic wave properties. A novel CoO/Co nanoparticle anchored to N-doped mesoporous carbon (CoO/Co/N-CMK-3) composites was fabricated by facile precipitation reaction and the electromagnetic characteristics have been well optimized by adjusting pyrolysis temperature. The CoO/Co/N-CMK-3 yielded its highest performance at an annealing temperature of 800 °C, with an extended effective absorption bandwidth of 5.83 GHz and unusually low minimum reflection loss of−63.82 dB, even at a thickness of just 1.8 mm and low filler loading (10%). For the excellent microwave absorption property, the advantages of the CoO/Co/N-CMK-3 can be summed up as follows. Firstly, the incorporation of heterointerfaces among N-CMK-3, CoO, and Co introduces abundant polarization centers, triggering various polarization effects and increasing dielectric losses. Secondly, the CoO/Co magnetic component introduced the strong magnetic loss and improved the impedance matching capability of CoO/Co/N-CMK-3. Thirdly, the extraordinary magnetic-dielectric behavior is supported by multiple magnetic coupling networks and enriched air-material heterointerfaces, boosted the magnetoelectric cooperative loss for further optimizing the electromagnetic dissipation and broadening the effective absorption frequency band. Moreover, the CST simulation results validate the impressive operational bandwidth and reflection loss characteristics of the obtained absorbers. This study demonstrates a novel heterointerface engineering strategy for designing lightweight, wide-band, and high-performance EW absorbers.

Laser additive manufacturing (LAM) has been widely used in high-end manufacturing fields such as aerospace, nuclear power, and shipbuilding. However, it is a grand challenge for direct and continuous observation of complex laser-matter interaction, melt flow, and defect formation during LAM due to extremely large temperature gradient, fast cooling rate, and small time (millisecond) and space (micron) scales. The emergence of synchrotron radiation provides a feasible approach for in situ observation of the LAM process. This paper outlines the current development in real-time characterization of LAM by synchrotron radiation, including laser-matter interaction, molten pool evolution, solidification structure evolution, and defects formation and elimination. Furthermore, the future development direction and application-oriented research are also discussed.

Myocardial infarction (MI) continues to be the primary cause of death globally. Oxidative stress in the initial phase of MI, followed by uncontrolled and excessive myocardial fibrosis, significantly impedes cardiac repair efficiency post-MI, culminating in adverse ventricular remodeling and potential heart failure. To address the diverse pathological stages of MI, an injectable composite hydrogel containing versatile nanoparticles was developed. In this study, mesoporous silicon nanoparticles (MSNs) served as carriers for encapsulating microRNA-29b (miR-29b) mimics with antifibrotic activity, subsequently coated with a complex of natural antioxidant tannic acid and zinc ions (TA/Zn). These nanoparticles were then embedded into a biocompatible alginate hydrogel to enhance retention within the infarcted myocardium. Upon injection into the infarcted region of MI mice, the composite hydrogel gradually released the nanoparticles as it degraded. Initially, the TA/Zn complex on the outer layer scavenged reactive oxygen species, thereby inhibiting cell apoptosis. The subsequent dissociation of the TA/Zn complex led to the release of the encapsulated miR-29b mimics that could inhibit the activation of cardiac fibroblasts and collagen production, thereby alleviating fibrosis progression. Overall, this composite hydrogel demonstrated the potential to reduce infarct size and improve cardiac function, suggesting its promise as a synergistic therapeutic approach for repairing infarcted myocardium.

The good combination of mechanical and wear properties for cemented carbides is crucial. In this work, the wear behavior of functionally graded cemented carbide (FGCC) and non-graded cemented carbide (CC), with CoNiFeCr multi-principal-element alloy (MPEA) binder, has been investigated by performing sliding wear tests and composition characterization. The results showed that compared with CC, FGCC had higher hardness, stronger fracture toughness, better wear performance, and similar TRS. FGCCs exhibited lower wear rates (3.44 × 10^-7-6.95 × 10^-6 mm³/(N·m)) and coefficients of friction (COFs) (0.27-0.39) than CCs from RT to 600 °C due to mitigation of multiple risks caused by binder removal, fragmentation and pull-out of WC grains, high-temperature oxidation and softening. In the low-temperature wear stage, the MPEA binder underwent dynamic recrystallization (DRX) and twinning deformation before removing from the surface. The binder removal caused dislocation pile-ups and stacking faults (SFs) to form under high stress, resulting in fragmentation and pull-out of WC grains. The low-temperature wear was dominated by abrasive wear and adhesive wear, with a low wear rate and a high and unstable COF. In the high-temperature wear stage, initial pitting oxidation of WC grains generated many subgrain boundaries, reducing heat transfer and exacerbating oxidation, resulting in an oxide layer enriched with WO₃, M_xO_y, and MWO₄. High-temperature wear was dominated by oxidation wear and high-temperature softening, with a high wear rate and a low and smooth COF. The results from the present study do not only provide theoretical guidance for an understanding of the antiwear mechanism of WC-CoNiFeCr, but also a new approach for the preparation of cemented carbides with high wear resistance.