查看更多>>摘要：? 2022 Elsevier B.V.Ni3Al and Nickel (Ni) rich Ni3Al thin films were deposited on Si (100) substrate by magnetron sputtering and co-sputtering process respectively. Variations in elemental composition, microstructure, surface topography, and mechanical properties were investigated as a function of Ni enrichment via EDS, SEM, AFM, and nanoindentation respectively. Results revealed that the hardness and young's modulus decrease with increase in Ni content in the film. A maximum hardness of 12.75 GPa was achieved with the elemental composition of Al (20.8 at%) and Ni (79.2 at%). The increase in surface roughness as a result of Ni enrichment led to the increase in hydrophobic properties up to the elemental composition of Al (14.9 at%) and Ni (85.1 at%) beyond which it declined. This study shows that the surface roughness, microstructure, and elemental composition influence the mechanical and hydrophobic properties of the Nickel rich Ni3Al coatings.
查看更多>>摘要：? 2022 Elsevier B.V.We realized a good combination of shape memory effect and mechanical properties in a hot-rolled Fe47.7Mn15.5Co9.8Cr10.8Ni5.1Si11.1 high entropy alloy (HEA) by Si alloying and proper heat treatment to guarantee a low density of annealing twin boundaries. Its maximal recovery strain of 5.7% reached the level that conventional FeMnSi-based and Co-based shape memory alloys (SMAs) showing the same FCC to HCP martensitic transformation can realize. It showed a better combination of ultimate tensile strength and fracture strain than the reported CoCrFeNiMn-based HEAs with FCC matrix did. This result showed that to marry the shape memory effect with the excellent mechanical properties will be a promising direction for developing novel HEAs.
查看更多>>摘要：? 2022 Elsevier B.V.The demand for increased aircraft engine efficiency requires continual development of high performance heavily-alloyed nickel-based superalloys. However, nickel-based superalloy castings with heavy alloying usually suffer from severe macro-segregation that results in poor hot workability or cracking during hot forging. To address this issue, hot extrusion is introduced as a transitional process between casting and forging to process a newly developed and highly alloyed nickel-based superalloy, GH4151. The results demonstrate that with hot extrusion, the GH4151 ingots can be successfully processed in the subsequent forging without cracking, thanks to the unique three-dimensional compressive stresses imposed on the billets and the development of chemical and microstructural homogeneity during hot extrusion. The refined microstructure endowed by further forging and heat treatment gives rise to superior stress rupture properties as compared with a number of the state-of-the-art disc superalloys. Moreover, it is shown that the stress rupture lifetime of the material decreases continuously with increased temperature and stress level while the elongation increases with increased temperature. The deformation at 650 °C mainly occurred by dislocation slipping in γ channels and formation of stacking faults in γ′. At 750 °C and 800 °C, microtwins were formed and cut through large regions. Paired dislocations associated with anti-phase boundaries were even found in the samples that were tested at 800 °C. In general, with increased temperature, the deformation becomes increasingly planar and easier, which accounts for the improved elongation. Large grain boundary MC carbides and primary γ′ were found to act as crack initiation sites and thus are harmful for stress rupture properties.
查看更多>>摘要：? 2022 Elsevier B.V.The individual addition of Nb, Fe, or Mn to Ti has been greatly studied, but their combined addition has been much less understood, especially for the Ti-Nb-Mn system. Moreover, the full potential of using powder metallurgy to reduce their manufacturing cost has not been properly exploited and, even though proposed for structural applications, rarely tensile properties were reported. In this study new powder metallurgy Ti‐6Nb‐x(Fe or Mn) alloys were produced and the correlation between their microstructure and tensile properties established. It was found that, for a similar addition of Nb, Mn is a stronger eutectoid β stabiliser compared to Fe leading to more refined lamellar structures and a greater amount of stabilised β phase. Accordingly, higher tensile properties (832–1050 MPa yield stress and 910–1080 MPa ultimate tensile strength) and lower ductility (6.3–1.7 %) were, thus, obtained in ternary Ti-Nb-Mn alloys compared to Ti-Nb-Fe alloys, but the actual stress/strain pairs and hardness are the compromise between the volumetric fraction of residual porosity (3.6–4.9 %), which increases with the amount of alloying elements, and the microstructural changes induced by actual chemical composition.
查看更多>>摘要：? 2022 Elsevier B.V.The pursuit of more efficient and safer treatments is a major challenge in preclinical nanoparticle-mediated magnetic hyperthermia research. Herein, Mn0.5Zn0.5Fe2O4/MWCNTs (MZFC) nanocomposites were synthesized via the chemical co-precipitation method for cancer treatment. The experiments interestingly demonstrated that the saturation magnetization (Ms) increases first and then decreases by doping a small amount MWCNTs (Multi-walled carbon nanotubes), which reaches the maximum value of 90.6 emu/g when the doping amount is 1.0 wt%. Furthermore, the induction heating ability of MZFC with good magnetic induction heating properties when the calcination temperature (TCA) of the samples is 700 ℃. Surprisingly, although the magnetic saturation of MZFC-2–700 (MZFC-m-n, where m, n present the content of MWCNTs and calcination temperature, respectively) and MZFC-4–700 is lower than that of MZFC-1–700, the ?T and SAR values of MZFC-2–700 and MZFC-4–700 are both larger than that of MZFC-1–700 in the low-frequency range (238 ~ 260 kHz). However, further increasing the frequency to the high-frequency range (300–380 kHz) presents the opposite conclusion. The same conclusion was also confirmed in tissue-mimicking phantoms, which suggests Mn0.5Zn0.5Fe2O4/MWCNTs could obtain the temperature suitable for tumor treatment at a lower magnetic field frequency, thus avoiding the harm of high-frequency magnetic field to human body from eddy current. In vitro experiments verified, MZFC provides the potential to serve as biological materials for magnetic hyperthermia and good biocompatibility. Therefore, these magnetically responsive nanocomposites could be a promising platform for hyperthermia treatment.
查看更多>>摘要：? 2022 Elsevier B.V.High-entropy nitride coatings have become a promising alternative to traditional protective coatings due to their excellent mechanical properties, thermal stability, oxidation, and wear resistance. However, the design and fabrication of hard high-entropy nitride coatings remain a great challenge. In this study, (MoSiTiVZr)Nx high-entropy nitride coatings were deposited by reactive DC magnetron sputtering at different nitrogen flow. The chemical compositions, structures, hardness, damage-tolerance, friction and corrosion resistances of the coatings were investigated. With the increase of nitrogen content in the coatings, the phase structure transforms from an amorphous structure to a single face centered cubic structure, and all alloying elements form metal-nitrogen bonds. The coating with nitrogen content of 53.7 at% exhibits an ultrahigh hardness of 45.6 GPa and the best damage-tolerance and wear resistance. The coatings with low nitrogen contents show better corrosion resistance than 304 stainless steels, however, an increase in nitrogen content results in a slight decrease in corrosion resistance. The mechanism of the structures, mechanical properties and corrosion resistance of (MoSiTiVZr)Nx coatings are discussed in details.
查看更多>>摘要：? 2022 Elsevier B.V.Alloying-type anodes exhibit unique advantages in terms of capacity and working potentials for practical application in sodium-ion batteries (SIBs). Sb-based nanocrystallites are prepared through a low-cost and large-scalable route by reducing the industrial antimony white (Sb2O3) in aqueous solutions under mild conditions and studied as the anode materials of SIBs. Compared with the pristine Sb2O3 and partially reduced Sb/Sb2O3 hybrid, the totally reduced product (pure Sb nanocrystallite) manifests the most steady desodiation potential, highest capacity at around 0.75 V vs. Na+/Na, highest initial Coulombic efficiency, longest cycling life, and fastest charge/discharge rate. The different electrochemical performance of as-prepared materials is discussed from the perspective of Na-storage mechanisms. The results demonstrate that the as-prepared pure Sb nanocrystallite is more promising than its oxides for practical application in SIBs.
查看更多>>摘要：? 2022 Elsevier B.V.CoTiO3 microrods (CTO MRs) and CoTiO3 nanoparticles (CTO NPs) were successfully prepared by a solvothermal method followed by thermal annealing in air. The correlation between structure and electrochemical properties of both CTO NPs and CTO MRs was studied by a series of material analysis and characterizations, as well as electrochemical tests. When used as anode materials for lithium-ion batteries (LIBs), CTO MRs exhibit a higher discharge capacity (410 mAh g?1 at 100 mA g?1 after 200 cycles) and better rate capability, compared with those of CTO NPs. The enhanced electrochemical properties of CTO MRs can be attributed to good Li+ diffusion ability, large specific surface area and porous rod-like structure composed of a large number of NPs. This work provides a feasible strategy to develop a promising material with improved performance as anode for LIBs.
查看更多>>摘要：? 2022 Elsevier B.V.A great deal of attention has been paid to flexible energy storage devices in recent years, but it remains a challenge to obtain integratable 1D energy storage devices with high specific capacitance and mechanical flexibility that can operate normally under common extrusion, bending, and tensile deformations. Herein, a flexible 1D yarn-shaped supercapacitor (YSC) was constructed based on Polypyrrole (PPy) @NiCo-layered double hydroxide (LDH) @stainless steel yarn (SSY) electrode prepared by facile hydrothermal and electrochemical deposition method. The as-obtained PPy@NiCo-LDH@SSY electrode exhibited an enhanced specific capacitance of 1196 F g?1 at 1 A g?1, owing to the synergistic impact of electroactive materials as well as the stratified core-shell structure. The electrospun separator automatically ensured the regular operation of the YSC device throughout use. Moreover, the YSC exhibited an energy density of 6.6 mWh cm?3 at the power density of 159.2 mW cm?3 and outstanding cycle performance (about 85.7% after 10 000 cycles). In addition, the YSC still maintained high electrochemical performance under different bending angles. The low cost, excellent overall performance and scalability make YSC a promising flexible wearable energy storage device.
查看更多>>摘要：? 2022 Elsevier B.V.Crystalline (Ba1-xLax)SnO3 micron sheets and amorphous CdSnO3 nanospheres were prepared by dehydrating their precursors. The doping of La3+ results in the formation of localized excitons, which are composed of positively charged La?Ba (La+) and negatively charged oxygen vacancies (V′). These excitons cause the blue shift of UV absorption and the improvement of ethanol sensitivity for pure BaSnO3. CdSnO3 sample exhibits a broad UV absorption and its decoration can make (Ba1-xLax)SnO3 sample red shift. The (Ba0.93La0.07)SnO3 sample is more sensitive to ethanol at 500 ppm than other samples, with a maximum gas response (Rmax) of 205.0 at 240 °C. CdSnO3 decoration can reduce the operating temperature of (Ba0.93La0.07)SnO3 sensor under 385 nm UV light, achieving a Rmax of 132.1 at 160 °C for the same gas concentration. The improvement of ethanol sensitivity is owing to the thermal and UV dissociation of localized excitons, which are discussed detailedly in this paper.
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