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1.
Effect of Bimodal Grain Size Distribution on the Strain Hardening Behavior of a Medium-Entropy Alloy
The evolution of strain hardening behavior of the Fe_(50)(CoCrMnNi)_(50) medium-entropy alloy as a function of the fraction of recrystallized microstructure and the grain size was studied using the Hollomon and Ludwigson equations.The specimens under study were partially recrystallized,fully recrystallized with ultrafine-grained microstructure,and fully recrystallized with coarse grains.The yield strength decreases steadily as the fraction of recry stallized micro structure and grain size increases due to the recovery process and the Hall-Petch effect.Interestingly,the bimodal grain distribution was found to have a significant impact on strain hardening during plastic deformation.For instance,the highest ultimate tensile strength was exhibited by a 0.97 μm specimen,which was observed to contain a bimodal grain distribution.Furthermore,using the Ludwigson equation,the effect of the bimodal grain distribution was established from the behavior of K_2 and n1 curves.These curves tend to show very high values in the specimens with a bimodal grain distribution compared to those that show a homogenous grain distribution.Additionally,the bimodal grain distribution contributes to the extensive L(u|")ders strain observed in the 0.97 μm specimen,which induces a significant deviation of the Hollomon equation at lower strains. 相似文献
2.
Siyao Li Shoulei Xu Xiangyu Wang Daini Wang Bernard A. Goodman Xing Hong Wen Deng 《Ceramics International》2021,47(3):3346-3353
Cubic zirconia single crystals stabilized with yttria and doped with Gd2O3 (0.10–5.00 mol%) were prepared by the optical floating zone method, and characterized by a combination of X-ray diffraction (XRD), and Raman, electron paramagnetic resonance (EPR), ultraviolet–visible (UV–Vis), photoluminescence excitation (PLE) and photoluminescence (PL) spectroscopic techniques. XRD and Raman spectroscopy showed that the crystal samples were all in the cubic phase, whereas the ceramic sample consisted of a mixture of monoclinic and cubic phases. The absorption spectrum showed four peaks at 245, 273, 308, and 314 nm in the ultraviolet region, and the optical band gap differed between samples with ≤3.00 mol% and those with >3.00 mol% Gd2O3. The emission spectrum showed a weak peak at 308 nm and a strong peak at 314 nm, which are attributed to the 6P5/2 → 8S7/2 and 6P7/2 → 8S7/2 transitions of Gd3+, respectively. The intensities of the peaks in the excitation and emission spectra increased with Gd3+ concentration, reached a maximum at 2.00 mol%, then decreased with higher concentrations. This quenching is considered to be the result of the electric dipole-dipole interactions, and this interpretation is supported by the Gd3+ EPR spectra, which showed progressive broadening with increasing Gd3+ concentration throughout the concentration range investigated. 相似文献
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Patchimaporn Udomkun Rony Swennen Cargele Masso Bhundit Innawong Apollin Fotso Kuate Amos Alakonya Bernard Vanlauwe 《International Journal of Food Science & Technology》2021,56(10):5417-5431
The present study investigated the effect of ripening stages and chemical precursors on acrylamide formation in deep-fried chips of five plantains and one cooking banana. The highest level of acrylamide was found in the cooking banana, followed by False Horn plantain and French plantain, respectively. French plantain hybrids exhibited a significantly lower (P < 0.05) level of acrylamide when compared to French plantain. The ripening stage demonstrated a positive Pearson correlation (P < 0.05, r = 0.57) with acrylamide formation. As ripening progressed, the levels of glucose and fructose significantly increased (P < 0.05) and showed a positive correlation with acrylamide formation (r = 0.85 and 0.96, respectively). The level of the amino acid asparagine during ripening was not correlated with acrylamide formation. In contrast, the level of histidine, arginine, iso-leucine and cystine during ripening was positively correlated (P < 0.05, r > 0.60) with acrylamide formation in fried chips. The higher level of TP was significantly related (P < 0.05) to the lower level of acrylamide (r = −0.62). The reduced levels of carotenoid isomers, except lutein, during fruit ripening were positively correlated (P < 0.05) with acrylamide formation, especially trans-BC (r = 0.72) and 9-cis-BC(r = 0.64). 相似文献
6.
Evolution of the microstructure, optical, and magnetic properties have been investigated systematically in multiferroic CuFe1-xSnxO2 (x?=?0–0.05) ceramics. Substitution of Sn4+ for Fe3+ results in expansion of CuFeO2 lattice, and reduces the density of the material, but the metal oxidation states are unchanged. Observation of the optical properties shows that the value of the direct optical band gap (Eg) decreases with increasing Sn doping level, and that the CuFe1-xSnxO2 (x?=?0–0.04) series with values >?3.1?eV. Magnetic susceptibility measurements show that Sn4+ doping decreases the Curie-Weiss temperature, i.e. weakens the strength of the antiferromagnetic interaction between high-spin Fe3+ ions, but does not affect the stability of the antiferromagnetic phase, and all samples undergo successive magnetic transitions at about TN1 =?15?K and TN2 =?11?K. However, magnetization curves show that changes occur in the magnetic interactions and both ferromagnetism and antiferromagnetism co-exist in the Sn4+-doped samples. The maximum value of the saturation magnetization of 1.8?emu·g?1 was observed for the x?=?0.03 sample in a 2.5?kOe field. The changes in the magnetic behavior are closely related to the lattice distortion and charge compensation, which are discussed in detail in this work. 相似文献
7.
Souvik Ghosh Xiaoshuang Chen Chenxi Li Bernard A. Olson Christopher J. Hogan Jr 《American Institute of Chemical Engineers》2020,66(4):e16874
Aerosol deposition with gas phase-synthesized chain-like nanoaggregates can yield dense coatings from the impaction of particles on a substrate; however, dense coating formation is not well understood. Here, we study coating consolidation at the single nanoaggregate level. Flame spray pyrolysis-made tin oxide nanoaggregates are mobility (size) filtered, accelerated through a de Laval nozzle, and impacted on alumina substrates. TEM images obtained from low velocity collection and supersonic deposition are compared via quantitative image analysis, which reveals that upon supersonic impact nanoaggregates fragment into smaller aggregates. This suggests that fragmentation is a key step in producing coatings denser than the depositing nanoaggregates themselves. We supplement experiments with detailed particle trajectory calculations, which show that the impact energies per atom during nanoaggregate deposition are below 0.2 eV/molecule. These results suggest that fragmentation can only occur at locations where nanoaggregates bonded by van der Waals and capillary interactions. 相似文献
8.
Streptococcus mutans (S. mutans) is widely regarded as the main cause of human dental caries via three main virulence factors: adhesion, acidogenicity, and aciduricity. Citric acid is one of the antibiotic agents that can inhibit the virulence capabilities of S. mutans. A full understanding of the acidic resistance mechanisms (ARMs) causing bacteria to thrive in citrate transport is still elusive. We propose atomic force microscopy (AFM) equipped with a fluid cell to study the S. mutans ARMs via surface nanomechanical properties at citric acid pH 3.3, 2.3, and 1.8. Among these treatments, at pH 1.8, the effect of the citric acid shock in cells is demonstrated through a significantly low number of high adhesion zones, and a noticeable reduction in adhesion forces. Consequently, this study paves the way to understand that S. mutans ARMs are associated with the variation of the number of adhesion zones on the cell surface, which is influenced by citrate and proton transport. The results are expected to be useful in developing antibiotics or drugs involving citric acid for dental plaque treatment. 相似文献
9.
Valentin Segouin Mathieu Domenjoud Yves Bernard Laurent Daniel 《Journal of the European Ceramic Society》2019,39(6):2091-2102
The strain response of a polarised PZT was characterised using Digital Image Correlation (DIC). The DIC algorithm is based on a global approach and regularises the displacement field using the balance equations of solid mechanics. The measurement error is reduced by correcting the displacements that are mechanically not admissible. A ferroelectric test showed that the standard deviations of strain fields remain mostly under 1.2 × 10?4 for an element size of 64 px. The standard deviation on the average value is 3 × 10?6. The strain field is homogeneous and its average value is consistent with the strain obtained from a CCD laser measurement device. The longitudinal strain, transverse strain and polarisation response of the PZT were measured for bipolar and unipolar loadings ranging from 50 to 5000 V/mm. Material properties were extracted from these measurements. This work shows the advantages of a novel 2D-DIC algorithm for piezoelectric strain characterisation. 相似文献
10.
Rakhi Sood Mona Marie Obadia Bhanu Prakash Mudraboyina Biao Zhang Anatoli Serghei Julien Bernard Eric Drockenmuller 《Polymer》2014
Nitroxide-mediated radical polymerization of a tailor-made acrylate carrying a 1,2,3-triazole group with an undecanoyl spacer affords a well-defined (Mn = 7860 g mol−1 and D = 1.39) neutral polyacrylate precursor. A series of 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) is then obtained by straightforward quaternization of the 1,2,3-triazole groups with methyl iodide and subsequent anion metathesis reactions. Among the prepared materials, TPIL with bis(trifluoromethane)sulfonimide anion exhibits low glass transition temperature (Tg = −40 °C), high thermal stability (Td10 = 325 °C) and anhydrous ionic conductivity of 4 × 10−6 S cm−1 at 30 °C, as measured by differential scanning calorimetry, thermogravimetric analysis and broadband dielectric spectroscopy, respectively. 相似文献