Journal of Materials Science最新文献

Bearing steel wear performance critically affects bearing service life and reliability. Microstructural characteristics—including carbide morphology, size, distribution, and matrix phase constitution—fundamentally govern wear resistance. This review systematically examines the strategies for tailoring bearing steel microstructure and their intrinsic relationships with wear behavior. The roles of microalloying, nonmetallic, and rare-earth elements in phase transformations are addressed, focusing on liquid-phase behavior (inclusion and solidification control) and solid-phase modulation (precipitate evolution, bainite/martensite kinetics, and matrix refinement). Heat treatment processes—spheroidizing annealing, quenching, and tempering—are reviewed for their regulation of carbide and matrix microstructures. The correlation between microstructural features and wear mechanisms (abrasive, adhesive, and contact fatigue) is analyzed in depth. Key conclusions reveal that: (1) wear resistance is governed by the synergistic interplay of matrix type, carbide characteristics, and RA stability; (2) the mechanical stability of RA is more critical than its content; and (3) microstructural control can actively shift dominant wear mechanisms. Current limitations and future directions are also discussed.

This study reports the synthesis of Mn_0.25Fe_2.75O₄/AC nanocomposites via coprecipitation and the fabrication of PVA–PVP-based ferrogels to address the limited integration of Mn-composition control, activated-carbon-assisted dispersion, and magnetothermal evaluation in ferrite-based systems for tunable magnetic heating and hyperthermia-related applications. Characterization was conducted using XRD, FTIR, SEM, TEM, SAXS, VSM, and magnetothermal testing at 965 Hz. XRD confirmed the spinel magnetite phase with characteristic reflections (220), (311), (400), (422), (511), and (440), alongside amorphous AC peaks at 2θ 25°–30°. Rietica refinement revealed a reduction in crystallite size from 15.95 to 3.66 nm and crystallinity from 76.45 to 56.45% after AC incorporation. FTIR spectra identified Fe–O vibrations at 430 cm⁻¹ and 651 cm⁻¹. The composite exhibited 67.34% porosity, while SAXS analysis indicated particle sizes of μ₁ = 2.51 nm and μ₂ = 6.23 nm. VSM results showed decreased saturation magnetization (Ms) from 6.72 to 2.72 emu/g and coercivity (Hc) from 92.45 to 4.12, indicating enhanced magnetic softness. Magnetothermal evaluation showed Tmax of 71.93 °C and SAR of 34.38 W/g for Mn_0.25Fe_2.75O₄, and 65.5 °C and 31.51 W/g for Mn_0.25Fe_2.75O₄/AC. The ferrogel exhibited improved performance with increasing filler (5–15%), achieving SAR of 22.93–28.42 W/g and T_max of 72.54–77.13 °C. ILP increased from 0.26 to 0.32 nH m² kg⁻¹ in gels and reached 0.39–0.36 nH m² kg⁻¹ in powders, indicating enhanced energy dissipation with filler addition despite reduced gel heating due to thermal loading and dispersion effects.

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The Mg-2Dy-0.5Zr alloy was fabricated via semi-continuous casting followed by hot extrusion. Employing the Mg-0.5Zr alloy as a reference, we investigated the role of Dy in the deformation mechanisms of magnesium alloys and the origins of its excellent strength–ductility balance. Dynamic recrystallization occurred during extrusion, forming fine equiaxed grains, while the Zr-rich phase exhibited a streamlined distribution along the extrusion direction. The Mg-0.5Zr alloy exhibited a distinct fibrous texture, with a yield strength, tensile strength, and elongation of 231 MPa, 244 MPa, and 27.7%, respectively. In contrast, the Mg-2Dy-0.5Zr alloy exhibited a typical rare-earth texture, with its elongation significantly increased to 50.1%. Although the yield strength decreased slightly, evaluation via the strength–ductility product revealed an approximately 48% improvement over the Mg-0.5Zr alloy, indicating an excellent strength–ductility balance. Quasi-in situ quantitative tensile analysis indicated that the rare-earth texture promoted the early activation of basal slip and induced a synergistic effect between tensile twinning and extensive non-basal slip during deformation. As strain increased, the total number of activated slip systems rose rapidly, effectively alleviating local stress concentrations and preventing early grain boundary cracking. First-principles calculations further elucidated that the Mg₂₄Dy₅ intermetallic phase and Zr particles possess higher Young’s moduli than that of the Mg matrix, thereby providing second-phase strengthening. In contrast, the Mg-Dy solid solution not only exhibits a higher elastic modulus than pure Mg but also displays a substantially improved B/G ratio (2.54) and Poisson’s ratio (0.33), with a tensile-shear anisotropy ratio closest to unity. This reveals the physical mechanism by which Dy solid solution simultaneously enhances the matrix stiffness and intrinsic ductility while effectively reducing elastic mismatch at the atomic scale. These results elucidate the atomic-scale origins of the excellent strength–ductility balance in the Mg-2Dy-0.5Zr alloy.

The fundamental conflict between achieving high energy storage density and maintaining high optical transmittance remains a critical challenge in multifunctional ceramic design. This study introduces lead-free relaxor ferroelectric ceramics (1-x)((K_0.5Na_0.5)NbO₃)_0.87((K_0.296Bi_0.9)(Zn_0.667Nb_0.334)O₃)_0.13-x(Bi(Mg_0.67Ta_0.333)O₃ (x = 0.02, 0.04, 0.06, 0.08), synthesized by a solid-state method. The 0.96(KNN-KBZN)-0.04BMT ceramic achieves a recoverable energy storage density of 2.21 J/cm³ with 87% efficiency under a dielectric breakdown strength of 220 kV/cm, while exhibiting a maximum optical transmittance of 53% at 1800 nm. This integration of transparency with superior energy storage performance demonstrates significant potential for transparent pulse power capacitors.

Magnesium alloys are widely regarded as promising materials for the fabrication of bioresorbable implants. However, their application is limited by relatively low mechanical strength and poor corrosion resistance. These properties are strongly governed by the material’s microstructural state. In the present study, a novel processing route for an Mg–8.6Zn–1.2Zr alloy is proposed, namely equal-channel angular pressing (ECAP) combined with ultrasound. It is demonstrated that the simultaneous application of ultrasound during ECAP increases the fraction of recrystallised grains, elevates the dislocation density, and promotes the formation of a more homogeneous grain structure, as compared with samples processed by conventional ECAP. The principal effect of incorporating ultrasound into the ECAP process is a substantial increase in the time required for complete dissolution of the material in Ringer’s solution. Samples processed using ECAP with ultrasound exhibit markedly improved corrosion resistance relative to those processed without ultrasound, withstanding 55–60 days of exposure prior to complete dissolution. The corrosion rate of the ultrasonically processed samples was determined to be 3.4 mm year⁻¹ on the final day of testing.

In line with Wagner’s oxidation theory, the Cr content of ferritic–martensitic (F–M) T91 steel is only marginally higher than the critical value ((N_{{{text{Al}}}}^{{(1)}})) required for external chromia scale formation at 750 °C. This study presented that the oxidation of T91 steel in air at 750 °C resulted in the formation of a discontinuous chromia scale frequently interrupted by thick Fe-rich oxide nodules. However, surface spraying α-Al₂O₃ nanoparticles promoted the selective oxidation of Cr in T91, facilitating the formation of an external continuous chromia scale and reducing the oxidation rate by an order of magnitude. The widespread α-Al₂O₃ nanoparticles assisted the nucleation and growth of Cr₂O₃ at the onset of oxidation by utilizing the structural template effect. This novel strategy offers a promising route for expanding the application of 9Cr1Mo F–M steels to harsher environments through simple surface modification.

The environmental risks of conventional fluorine-based superhydrophobic coatings have gained prominence due to the growth of the idea of green and sustainable development as well as the textile industry’s growing environmental demands. As a result, the creation of environmentally benign, multifunctional, superhydrophobic coated fabrics that are free of fluorine has become a research focus. Nitrogen-doped titanium dioxide (N–TiO₂) particles were created using urea as a nitrogen source. These particles were subsequently mixed with environmentally friendly biomass-derived coconut shell activated carbon powder (CSAC). By adding the low-surface-energy material hydroxyl-terminated polydimethylsiloxane (HTPDMS) using a straightforward impregnation procedure, a strong functional superhydrophobic material was further produced, leading to N–TiO₂@CSAC/HTPDMS (NTCH)-coated cotton fabric. While the ecologically friendly and fluorine-free HTPDMS offers low surface energy and improves the adhesion between the particles and the cotton fabric, guaranteeing environmental stability, N–TiO₂ and CSAC contribute to the micro-/nanohierarchical roughness in this composite. With a water contact angle (WCA) of 159.8°, this coated fabric has exceptional superhydrophobicity. The fabric’s high superhydrophobic qualities allow it to prevent liquid contamination in a variety of hostile situations, even after repeated mechanical abrasion, continuous washing, acid and alkali soaking, and UV irradiation. The fabric demonstrated an 85.92% photocatalytic effectiveness against Rhodamine B (RhB) solution after 4 h of UV exposure. Additionally, the modified fabric showed good self-cleaning qualities and photocatalytic self-healing capabilities following oleic acid contamination. Furthermore, the modified fabric performs exceptionally well in oil–water separation, with a separation effectiveness of over 95.00% for a variety of oil-based compounds. In particular, dichloromethane has a separation efficiency of 99.50%. The material is recyclable, and the oil–water separation efficiency is above 97% even after ten cycles. There are many potential applications for this discovery, including enhanced treatment of industrial oily wastewater, environmental self-cleaning, and sustainable water treatment.

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This paper studied the effects of Nb element addition on the microstructure, mechanical properties, thermal stability, and two-way shape memory effect of Cu–12.0Al–4.0Ni–1.5Mn high-temperature shape memory alloy. The results demonstrate that adding Nb significantly refines the grain size of Cu–12.0Al–4.0Ni–1.5Mn alloys. After adding Nb, the alloy transforms from 18R and 2H martensites to single 18R martensite and Nb(Al, Cu)₂ phase precipitates. The grain refinement and second-phase strengthening significantly improved the mechanical properties of the alloy. Among all Cu–12.0Al–4.0Ni–1.5Mn-xNb alloys, the Nb5 alloy exhibits the best compressive fracture stress of 1320 MPa and a desirable strain of 17.6%. Differential thermal analyzer (DTA) tests show that adding Nb maintains the alloy’s good thermal stability. The compression tests indicate that the addition of Nb slightly reduces the one-way shape memory effect of Cu–12.0Al–4.0Ni–1.5Mn-xNb alloy. Notably, the Nb5 alloy achieves a stable two-way shape memory effect of ~ 1.9% strain after only a few training cycles, which remains durable over 100 thermal cycles.

Fe–Mn–Si-based alloys are attractive shape memory materials that offer notable economic and processing advantages compared with conventional NiTi systems, making them promising candidates for large-scale and structural applications. In this study, Fe–30Mn–6Si alloy was fabricated via laser powder bed fusion (PBF-LB/M) using different combinations of laser power and hatch distance, followed by post-process annealing heat treatment. The microstructural characteristics, transformation behaviour, and shape recovery response were systematically evaluated. The results indicated that variations in hatch distance did not lead to a clear systematic change in the shape recovery response under constant laser power, although differences in transformation characteristics were observed. On the other hand, within the present limited dataset, the specimens produced at higher laser powers exhibited higher average early-cycle shape recovery ratios during the investigated five-cycle window. The annealed specimens exhibited high shape recovery performance, with first-cycle shape recovery ratios approaching 80%. Within the investigated five-cycle window, the largest increase generally occurred between the first and second cycles, while only limited additional changes were observed from the second to the fifth cycle under 4% compression loading.

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