Journal of Materials Science & Technology最新文献

Precipitation at grain boundaries is typically not regarded as an efficient method for strengthening materials since it can induce grain boundary embrittlement, which detrimentally affects ductility. In this research, we developed a multi-principal element alloy (MPEA) with the composition Cr₃₀Co₃₀Ni₃₀Al₅Ti₅ (at.%), incorporating both intragranular and intergranular nanoprecipitates. Utilizing multiscale, three-dimensional, and in-situ electron microscopy techniques, coupled with computational simulations, we established that intergranular nanoprecipitation in this material plays a crucial role in enhancing strength and promoting dislocation plasticity. The structure of intergranular nanoprecipitation comprises multiple phases with varying composition and structure. Despite the diversity, the crystal planes conducive to the easy glide of dislocations are well-matched, allowing for the sustained continuity of dislocation slipping across different phase structures. Simultaneously, this structure generates an undulated stress field near grain boundaries, amplifying the strengthening effect and facilitating multiple slip and cross-slip during deformation. Consequently, it promotes the proliferation and storage of dislocations. As a result, our material exhibits a yield strength of approximately 1010 MPa and an ultimate tensile strength of around 1500 MPa, accompanied by a significant fracture elongation of 41%. Our findings illuminate the potential for harnessing intergranular nanoprecipitation to optimize the strength-ductility trade-off in MPEAs, emphasizing the strategy of leveraging complex compositions for the design of sophisticated functional microstructures.

Deep sea, with rich oil, gas, and mineral resources, plays an increasingly crucial role in scientific and industrial realms. However, the highly corrosive feature of deep sea hinders further exploration and development, which requires metal materials with robust corrosion resistance. This review covers an in-depth and all-around overview of the up-to-date advances in corrosion and protection of metals in deep-sea environment. Firstly, the unique characteristics of deep-sea environment are summarized in detail. Subsequently, the corrosion performances of metals in both in situ and simulated deep-sea environments are illustrated systematically. Furthermore, corrosion prevent strategies of metals, including sacrificial anode protection, organic coatings, as well as coatings achieved by physical vapor deposition (PVD coatings), are highlighted. Finally, we outline current challenges and development trends of corrosion and protection of metals in deep-sea environment in the future. The purpose of this review is not only to summarize the recent progress on metal corrosion and protection in deep sea, but also to aid us in understanding them more comprehensively and deeply in a short time, so as to boost their fast development.

The growing demand for material properties in challenging environments has led to a surge of interest in rapid composition design. Given the great potential composition space, the field of high/medium entropy alloys (H/MEAs) still lacks effective atomic-scale composition design and screening schemes, which hinders the accurate prediction of desired composition and properties. This study proposes a novel approach for rapidly designing the composition of materials with the aim of overcoming the trade-off between strength and ductility in metal matrix composites. The effect of chemical composition on stacking fault energy (SFE), shear modulus, and phase stability was investigated through the use of molecular dynamics (MD) and thermodynamic calculation software. The alloy's low SFE, highest shear modulus, and stable face-centered cubic (FCC) phase have been identified as three standard physical quantities for rapid screening to characterize the deformation mechanism, ultimate tensile strength, phase stability, and ductility of the alloy. The calculation results indicate that the optimal composition space is expected to fall within the ranges of 17%–34% Ni, 33%–50% Co, and 25%–33% Mn. The comparison of stress-strain curves for various predicted components using simulated and experimental results serves to reinforce the efficacy of the method. This indicates that the screening criteria offer a necessary design concept, deviating from traditional strategies and providing crucial guidance for the rapid development and application of MEAs.

Up-and-coming high-temperature materials, refractory high entropy alloys, are suffering from lower oxidation resistance, restricting their applications in the aerospace field. In this study, two novel treatments of Al-deposited and remelted were developed to refine the microstructure and enhance the oxidation resistance of refractory high entropy alloy using electron beam freeform fabrication (EBF³). Finer and short-range ordering structures were observed in the remelted sample, whereas the Al-deposited sample showcased the formation of silicide and intermetallic phases. High-temperature cyclic and isothermal oxidation tests at 1000 °C were carried out. The total weight gain after 60 h of cyclic oxidation decreased by 17.49 % and 30.46 % for the remelted and deposited samples, respectively, compared to the as-cast state. Oxidation kinetics reveal an evident lower mass gain and oxidation rate in the treated samples. A multilayer oxide consisting of TiO₂+Al₂O₃+SiO₂+AlNbO₄ was studied for its excellent oxidation resistance. The oxidation behavior of rutile, corundum and other oxides was analyzed using first principles calculations and chemical defect analysis. Overall, this research, which introduces novel treatments, offers promising insights for enhancing the inherent oxidation resistance of refractory high entropy alloys.

The rapid development of industrialization requires the advancement of multifunctional coatings. In this study, successful self-assembly of iron porphyrin on BP nanosheets resulted in the synthesis of IBP nanosheets with a sandwich structure. Characterization tests including SEM, XPS, SPM, and XRD confirmed the successful preparation of IBP nanosheets with robust structural stability and antioxidation. Subsequently, a water-based epoxy resin (WEP) coating containing IBP nanosheets was prepared. Test results revealed that the composite coating containing 0.4 wt.% IBP nanosheets exhibited outstanding anti-corrosion, wear-resistant, and flame-retardant properties. After 42 days of immersion in a 3.5 wt.% NaCl solution, the R_ct value of the 4-IBP/WEP coating was 1.79 × 10⁹ Ω cm², surpassing the Pure WEP coating by more than 3 orders of magnitude. Additionally, the peak heat release rate (PHRR) and wear rate of the 4-IBP/WEP coating decreased by 19.29% and 90.97% compared to the Pure WEP coating. This research presents a novel idea for the utilization of BP nanosheets in multifunctional coatings.

Metastable β-Ti alloys exhibiting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP) generally have excellent ductility, but typically at the expense of relatively low yield strengths which has restricted their widespread use. Our work shows that interstitial oxygen can be employed to regulate β phase stability to significantly enhance both strength and ductility of TWIP/TRIP alloys. For a Ti-32Nb wt.% base alloy, inclusion of 0.3 wt.% O enhanced ductility by more than 140%, reaching up to 54% strain, and improved the tensile yield strength by over 95% to 632 MPa. Compared to other common engineering alloys such as Ti-45Nb, elongation was increased by 29%, and the yield strength increased by 182 MPa, respectively. Here, we elucidate on impacts of oxygen doping on TWIP/TRIP behaviors in the Ti-32Nb alloy. We reveal that oxygen regulates the critical stress for martensitic transformation, twinning, and dislocation slip. At lower oxygen doping concentrations (≤ 0.3 wt.% O), multi-stage martensitic transformation and martensitic twinning resulted in high ductility. In higher oxygen content alloys (≥ 0.5 wt.% O), deformation occurred initially via twinning, while strain induced martensite was subsequently induced in retained β phase regions. Oxygen concentrations control the deformation mechanisms, providing a flexible means to synergistically balance an alloy's strength and ductility. The use of oxygen to enhance stability of the β phase and regulate deformation behaviors is a promising new approach for creating high-performance TWIP/TRIP metastable β-Ti alloys with outstanding mechanical properties.

The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting, but its low cost-effectiveness severely restricts its large-scale application. The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost. However, the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface between the matrix and pores, ultimately leading to decreased figure of merit, ZT. Here, we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_0.5Sb_1.5Te₃ for preparing high-performance porous thermoelectric materials. Experimental results indicate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering, thereby optimizing carrier/phonon transport behaviors, and effectively increasing the ZT by 23.2% (from 0.99 to 1.22 at 350 K). Besides, our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi₂Te_2.7Se_0.3, therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.

Precipitation–strengthened high entropy alloys (HEAs) exhibit excellent strength–ductility combinations due to precipitation hindering dislocation gliding and work hardening ability of the matrix. However, the effect of compositions on the microstructure and related deformation mechanism of HEAs is still unclear. In this study, we developed two types of L1₂–strengthened Al₅Ti₈Fe_x(CoNi)_86.9–xB_0.1 (x=17, 28) HEAs to study the effect of Fe content on the deformation mechanism. Our results reveal that an increased Fe concentration substantially increases the strength and ductility of Al₅Ti₈Fe_x(CoNi)_86.9–xB_0.1 HEAs at room temperature. For the Al₅Ti₈Fe₁₇(CoNi)_69.9B_0.1 HEA, the presence of a large amount of ordered L1₂ phase leads to strain strengthening governed by dynamically refined slip bands. For the Al₅Ti₈Fe₂₈(CoNi)_58.9B_0.1 HEA, the increasing Fe content raises the stacking fault energy of the matrix and reduces the stability of the FCC matrix, making it less stable than the BCC structure. Additionally, the reduced volume fraction of the ordered L1₂ precipitated phase and the increased stack fault energy of the FCC matrix lead to an increase in the cross-slip frequency during deformation, which in turn promotes avalanche glide of dislocations on highly stressed crystallographic slip planes and the generation of microbands. The microbands and phase transformation inside the microbands promote the strain strengthening, resulting in enhanced strength and ductility. These findings clarify the effect of the Fe content on the deformation behaviours and provide new insight into the formation mechanism of microbands in precipitation-strengthened HEAs, which will open new avenues for the design of ultra-strong yet ductile alloys in the future.

Achieving a delicate synergy between mechanical robustness and antifouling attributes in coatings remains a formidable challenge for marine applications. Inspired by the assembly of nacre, we present a novel approach to fabricate a nacre-like metallic coating. This coating comprises an amorphous matrix with excellent anti-corrosion and anti-wear properties, as well as Cu-rich 3D interconnected channels for antifouling function. The coating is produced by high velocity oxygen fuel (HVOF) thermal spraying of surface-modified Fe-based amorphous powders with a Cu-layer. The resulting coating exhibits exceptional mechanical robustness, including high resistance to erosion, abrasion, and impact, surpassing conventional polymer antifouling coatings. Furthermore, the controlled Cu⁺ leaching capability of the in-situ constructed 3D interconnected diffusion channels, facilitated by the Cu-rich intersplats, contributes to the remarkable antifouling performance. This includes nearly 100% resistance to bacterial adhesion after 1 day of immersion and over 98% resistance to algal attachment after 7 d of immersion, resulting in a prolonged service lifetime. Notably, even after 200 cycles of wear damage, the Cu-modified amorphous coating still maintains its excellent antifouling properties. The Cu-rich intersplats play a critical role in transporting and sustainably leaching Cu ions, thereby accounting for the outstanding antifouling performance. Ultimately, we aim to advance the design of high-performance coatings suited for diverse marine applications, where both the mechanical robustness and antifouling properties are essential.

Al₂O₃-based eutectic ceramics are considered as promising candidates for ultra-high-temperature structural materials due to their exceptional thermal stability and mechanical properties. Nonetheless, several challenges must be overcome before they can be widely used. This paper reviews in detail the tailoring of microstructure from the aspect of process parameters, the updated knowledge gained in microstructure (crystallographic orientation, high-resolution interfacial structures) and the latest means of optimizing eutectic microstructure (seed-induced method, introducing low-energy grain boundaries and high-entropy phase). Additionally, the paper explores future techniques for the fabrication of bulk ceramic materials and effective toughening approaches. This review highlights the achievements made especially in the last 15 years, current limitations in Al₂O₃-based eutectic ceramics, and offers comprehensive insights and strategic guidance for further mechanical breakthroughs.