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High strength and high creep resistant ZrB2/Al nanocomposites fabricated by ultrasonic-chemical in-situ reaction

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Journal of materials Science & Technology 2019年第9期35卷 2107-2114页

作者： Xizhou Kai Shuoming Huang Lin Wu Ran Tao Yanjie Peng Zemin Mao Fei Chen Guirong Li Gang Chen Yutao Zhao school of material Science and Engineering Jiangsu University

In this study, the ZrB2/Al nanocomposites were fabricated via in-situ reaction of the Al-K2ZrF6-KBF4 system, assisted with ultrasonic vibration and spiral electromagnetic stirring. Microstructure, tensile property and creep behavior of the fabricated nanocomposites were further investigated. Microstructure observation showed that the ultrasonic vibration could prevent the fast growth as well as break the clusters of in-situ synthesized nanoparticles in melt, resulted in smaller size (10-50 nm) and relatively more uniform distribution of the in-situ nanoparticles located on the boundary of and/or inside the aluminum matrix grains in the final composites. The fabricated nanocomposites exhibited an enhancement in both strength and ductility, due to the elevated work hardening ability, i.e., improved dislocation propagating ability and decreased dynamic recovery of the existing dislocations induced by the in-situ nanoparticles. Meanwhile, the nanocomposites exhibited excellent creep resistance ability, which was about 2-18 times higher than those of the corresponding aluminum matrix. The stress exponent of 5 was identified for the fabricated nanocomposites, which suggested that their creep behavior was related to dislocation climb mechanism. The enhanced creep resistance of the nanocomposites was attributed to the Orowan strengthening and grain boundary strengthening induced by the ZrB2 nanoparticles. Thus, the ultrasonicchemical in-situ reaction promises a low cost but effective way to fabricate aluminum nanocomposites with high strength and high creep resistance.

关键词： In-situ ZrB2/Al nanocomposites Microstructure High strength High creep behavior Mechanism

High Temperature Chemical Reaction of La_2O_3 in H_3BO_3-C System

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Journal of Rare Earths 2007年第3期25卷 282-285页

作者：吴文远徐璟玉彭可武涂赣峰 school of material and Metallurgy Northeastern University

The high temperature chemical reaction process of La2O3 in H3BO3-C system was studied by means of XRD and *** results showed that dehydration reaction of H3BO3 occurred in the temperature range of 82～390 ℃;La2O3 and B2O3 reacted to form LaB3O6,LaBO3,and B4C in the temperature range of 836～1400℃;at 1450 ℃,B4C and LaBO3 further reacted to form LaB4,and partial LaB4 and B reacted to form LaB6;at 1500 ℃,LaB4 and B reacting into LaB6 was the main reaction,and the content of LaB6 increased with prolonging time.

关键词： high temperature chemical reaction lanthanum boride boric acid-carbon lanthanum oxide rare earths

Boosting electrocatalytic hydrazine oxidation at single-crystalline Ni nanosheets with embedded NiZn

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Progress in Natural Science:materials International 2023年第5期33卷 710-717页

作者： Xia Wei Hongbin Dai Chuangwei Liu Song Li school of material Science and Engineering Northeastern University

Hydrazine oxidation reaction(Hz OR) plays a crucial role in direct hydrazine fuel cells and holds promise for replacing the kinetics-sluggish oxygen evolution reaction in splitting water. While Ni–Zn alloys exhibit exceptional activity for Hz OR, their synthesis under mild conditions remains a challenge. Herein, a Ni–Zn nanosheet catalyst with Ni Zn inclusion was prepared on Ni foam by controllable chemical etching together with ethylene glycol reduction. X-ray diffraction and transmission electron microscopy confirmed the single-crystalline nature and the presence of intermetallic Ni Zn. The strong interaction between Ni and Zn O, along with defects, facilitated the formation of this intermetallic compound. The Ni–Zn/Ni foam exhibits remarkable catalytic activity(214.3m A cm-2at 0.1 V) and durability(87.8 % retention after 24 h) towards hydrazine electrooxidation, thanks to the combined benefits of intermetallic Ni Zn, mesoporous nanosheets, microscopic defects, single-crystalline characteristics, and a coherent Ni–Ni Zn interface. This study provides a new method for designing highly active Ni–Zn electrocatalysts for Hz OR.

关键词： Hydrazine electrooxidation Intermetallic NiZn Single-crystalline Coherent interface Microscopic defects

Upconversion luminescence of KGd(MoO_4)_2:Er^(3+),Yb^(3+) powder prepared by Pechini method

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Journal of Rare Earths 2011年第9期29卷 843-848页

作者：陈起静秦连杰冯志强葛如赵相金徐惠忠 school of Environmental and material Engineering Yantai University

Er3＋ doped potassium gadolinium molybdate （KGM） phosphor with sensitizer Yb3＋ ion was synthesized by the Pechini method using citric acid and ethylene glycol. The crystallization processes of the phosphor precursors were characterized by X-ray diffraction （XRD） and thermogravimetry-differential scanning calorimetry （TG-DSC）, which indicated that ultrafine uniform crystallites of KGM：Er,Yb were obtained by sintering the precursors at above 650 ℃ for 5 h. Upconversion luminescence （UL） spectra of the samples were studied by a 976 nm semiconductor laser diode （LD） excitation. The UL spectra exhibited the green and red emission bands that were attributed to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3＋, respectively. The possible UL mechanisms of Er3＋ were explained by means of an energy level diagram. The maximum luminescent intensity was achieved when the concentration of Er3＋, Yb3＋ arrived at 1 mol.% and 20 mol.%, respectively.

关键词： KGd(MoO4)2:Er3+ Yb3+ upconversion luminescence Pechini method rare earths

Effect of temperature on corrosion behavior of 3003 aluminum alloy in ethylene glycol–water solution

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Chinese Journal of Aeronautics 2016年第4期29卷 1142-1150页

作者： Chen Xin Tian Wenming Li Songmei Yu Mei Liu Jianhua school of material Science and Technology Beihang University

The effect of temperature on the corrosion behavior of 3003 aluminum alloy in ethylene glycol–water solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The surface characterization was observed and determined by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive spectrometer (EDS). The results demonstrate that the anodic aluminum dissolution and the cathodic oxygen reduction were accelerated by the increased temperature. However, as temperature was over 60 °C, the solubility and concentration of oxygen decreased, resulting in the inhibition of cathodic reaction. The cathodic reaction rate of 3003 aluminum alloy rose to the maximum at 60 °C. The Warburg impedance in Nyquist diagram diminished and then was replaced by a negative capacitance caused by the absorption of intermediate corrosion product on electrode. On the other hand, after potentiodynamic measurements, 3003 aluminum alloy suffered pitting corrosion. The dissolution of aluminum alloy around secondary phase particles expanded both horizontally and vertically. © 2016 The Authors

关键词： Aluminum Atomic force microscopy Corrosion Corrosive effects Dissolution Electrochemical corrosion Electrochemical impedance spectroscopy Electrolytic reduction Ethylene Ethylene glycol Pitting Polyols Scanning electron microscopy Spectrometers Temperature

Preparation and tensile properties of DD5 single crystal castings

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International Journal of Minerals,Metallurgy and materials 2016年第6期23卷 683-690页

作者： Xiang-feng Liang Yu-tao Zhao Zhi-hong Jia Chi Zhang school of material Science and Engineering Jiangsu University

The preparation procedure of DD5 single crystal castings was optimized. The microstructure characteristics of DD5 single crystal superalloy were investigated by microstructure observation and segregation behavior examination. The results show that the grain orientation is optimized by constraining the spiral crystallizer in [001] orientation and spatial scale. Also, the γ＇ phase of inter-dendrites is larger and more irregular than that in dendrite arms. High temperature tensile tests of DD5 single crystal castings exhibit that the peak stress increases with increasing temperature, while the area reduction shows an opposite trend, when the temperature is below 800℃; meanwhile, when the temperature is between 800℃ and 1000℃, the fracture stress of the alloy is the same as the peak stress. The fracture mode changes from shear to ductile with increasing temperature from 600℃ and 1000℃.

关键词： superalloys single crystals segregation tensile properties alloy preparation castings

Monogamy of quantum correlations in the one-dimensional anisotropic XXXYYY model

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Chinese Physics B 2014年第1期23卷 60-65页

作者：徐帅宋学科叶柳 school of Physics & material Science Anhui University

In this paper, the monogamy properties of some quantum correlations, including the geometric quantum discord, concurrence, entanglement of formation and entropy quantum discord, in the anisotropic spin-1/2 XY model with stag- gered Dzyaloshinskii-Moriya （DM） interaction have been investigated using the quantum renormalization group （QRG） method. We summarize the monogamy relation for different quantum correlation measures and make an explicit compar- ison. Through mathematical calculations and analysis, we obtain that no matter whether the QRG steps are carried out, the monogamy of the given states are always unaltered. Moreover, we conclude that the geometric quantum discord and concurrence obey the monogamy property while other quantum correlation measures, such as entanglement of formation and quantum discord, violate it for this given model.

关键词： monogamy relation geometric quantum discord entanglement of formation entropy quantum discord

Scheme to implement optimal asymmetric economical 1→3 phase-covariant telecloning via cavity QED

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Chinese Physics B 2010年第8期19卷 127-132页

作者：宋庆敏叶柳 school of Physics and material Science Anhui University

We propose an experimentally feasible scheme to implement the optimal asymmetric economical 1→3 phasecovariant telecloning protocol, which works without ancilla, based on cavity quantum electrodynamics （QED）. The scheme is insensitive to the cavity field states and the cavity decay. In the telecloning process, the cavity is only virtually excited, it greatly prolongs the efficient decoherent time. Therefore, the scheme may be experimentally realized in the field of current cavity QED techniques.

关键词： telecloning cavity QED

Effects of friction stir processing on the microstructure and superplasticity of in situ nano-ZrB2/2024Al composite

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Progress in Natural Science:materials International 2016年第1期26卷 69-77页

作者： Yutao Zhao Xizhou Kai Gang Chen Weili Lin Chunmei Wang school of material Science and Engineering Jiangsu University

In this study, in situ nano-ZrB2/2024 Al composites fabricated from 2024Al–K2ZrF6–KBF4system were processed by friction stir processing（FSP） to achieve superplasticity of the composites. And the effects of particle contents（1 wt%, 3 wt%, 5 wt%）, matrix grain size（micron or submicron）, strain rates(5×10-3s-1, 1×10-2s-1, 2×10-2s-1and deformation temperatures（400 K, 480 K, 600 K, 700 K, 750 K） on the superplasticity of the composites were investigated. After the friction stir processing, the coarse grains of the cast composites with matrix grain size of about 80–100 μm and nano-Zr B2 reinforcement size of 30–100 nm were crushed into small grains about 1 μm in size, and the uniformity of the nano-Zr B2reinforcements was also improved. And under the same superplastic tensile testing condition at the temperature of 750 K and strain rate of 5×10-3s-1, the FSP nano 3 wt%Zr B2/2024 Al composite exhibited an superplastic elongation of 292.5%, while the elongation of the corresponding cast composite was only less than 100%. Meanwhile, the m values of the FSP composites were always higher than the cast composites, especially the FSP composites with 3 wt% particles has the m value of 0.5321 i.e., the FSP composites should had better superplastic properties than cast ones. Furthermore, the FSP composites had higher apparent deformation activation energy（Q） than that of the lattice diffusion of pure aluminium, indicating that the deformation mechanisms of the FSP composites should be grain boundary sliding mechanisms.

关键词： In situ nano-ZrB2/2024Al composite Friction stir processing Superplasticity Deformation mechanism