The influences of rare earth elements（cerium and lanthanum） on the microstructure and phases of Al-3.0 wt%Mg alloys used for electromagnetic shielding wire were characterized by scanning electron microscopy（SEM）, ...The influences of rare earth elements（cerium and lanthanum） on the microstructure and phases of Al-3.0 wt%Mg alloys used for electromagnetic shielding wire were characterized by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）, X-ray diffraction（XRD） and differential scanning calorimetry（DSC）. The mechanical properties and electrical resistivity were also investigated. The results indicated that a certain content of rare earth could improve the purification of the aluminum molten, enhance the strength, and reduce the electrical resistivity of Al-3.0 wt%Mg alloys. The strength reached the top value when RE content was 0.3 wt% while the alloy with 0.2 wt% RE addition had the smallest electrical resistivity. The elongation varied little when RE addition was no more than 0.2 wt%. But the excessive addition of rare earth would be harmful to the microstructure and properties of Al-3.0 wt%Mg alloys.展开更多
The high-temperature oxidation behavior of Fe-5 wt% Cr alloys was investigated in both N+5 vol% HO and N2+21 vol% O+5 vol% HO atmospheres at 900-1000 ℃ for 120 min by the thermogravimetric analysis(TGA). The oxidatio...The high-temperature oxidation behavior of Fe-5 wt% Cr alloys was investigated in both N+5 vol% HO and N2+21 vol% O+5 vol% HO atmospheres at 900-1000 ℃ for 120 min by the thermogravimetric analysis(TGA). The oxidation kinetics, phase composition and cross-sectional microstructure of the oxide scale were contrastively analyzed in both environments. Also, the phase composition of oxide scale was measured by X-ray diffraction(XRD). The cross-sectional microstructure and the interface elements distribution were studied by electron probe microanalysis(EPMA). The experimental results demonstrated that the growth rate and the mass gain of the oxide scale in the N+5 vol% HO atmosphere were both significantly lower than the growth rate and the mass gain in the N+21 vol% O+5 vol% HO atmosphere. The apparent layer structure of the oxide scale could be observed in an oxygen-enriched environment and did not appear in a pure water vapor without oxygen. In addition, the inner oxide layer growth mechanisms and the outward diffusion of the metal cations were introduced in the atmosphere of N+5 vol% HO. Consequently, the effects of temperature and humid atmosphere on the Fe-Cr spinal scale evolution were also discussed.展开更多
The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different tech...The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different techniques. Among them, the microstructure was analyzed by optical microscope, SEM, low-angle X-ray diffraction (LAXRD) and the corrosion test was made in aerated solution of 0.1 M H2SO4 at a temperature of 25°C ± 0.5°C. As result was shown, the micrograph of LSR-treated material displaying can be a fine cellular structure and the existence of certain nano-porosities and a similar to a nano-dendritic growth was observed too. The characteristic of melted zone was constituted of metastable phases according to the result of x-rays and the behavior corrosion as a result of the LSR-treated sample, which it was shown to be more resistant to corrosion than the untreated sample. A comparative study was carried out of the cyclic polarization of the laser-treated and untreated samples, demonstrating that the reduction and oxidation reverse peaks were not observed and being the cyclic polarization behavior was of irreversible character in both samples, however, the LSR-treated sample propitious the passivity on the surface also reduced the corrosion phenomena. Wherefore, this type of laser-treated alloy can be applied in the aerospace, aeronautic and automobilist industries.展开更多
将1 mm 6.5wt%高硅电工钢复合板在450~650℃范围内进行中温轧制。通过光学显微镜观察了温轧后和不同热处理工艺处理后复合板的显微组织;测试了温轧0.5 mm复合板不同状态的磁感应强度和铁损,通过显微硬度测试确定了硅元素均匀化的情况。...将1 mm 6.5wt%高硅电工钢复合板在450~650℃范围内进行中温轧制。通过光学显微镜观察了温轧后和不同热处理工艺处理后复合板的显微组织;测试了温轧0.5 mm复合板不同状态的磁感应强度和铁损,通过显微硬度测试确定了硅元素均匀化的情况。研究表明,中温变形后的复合板塑性差、裂纹多、硬度高、磁性能差;退火工艺不能消除复合板高硅层的裂纹,对其磁性能没有本质提高;合适的扩散退火工艺可以消除中温变形中芯层出现的裂纹、降低复合板芯层的硬度、大幅度提高磁性能。展开更多
Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Result...Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Results reveal that Mg-4 wt% Zn alloy with dendritic microstructure exhibits typical { 0002} basal texture along growth direction. Based on this, the effect of grain orientation on corrosion behavior of directionally solidified Mg-4 wt% Zn alloy in 0.9 wt% NaCl solution was investigated. Result shows that {0002} oriented planes have better corrosion resistance than {1120} and {1010 } ones, which is attributed to a synergistic effect of surface energy, atomic packing density and the stability of oxidation film,2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology,展开更多
The influences of applied magnetic field on the corrosion behavior of Al-3.0 wt%Mg alloy in 3.5 wt% NaCl solution were investigated by electrochemical measurements,scanning electron microscopy（SEM）and energy-dispers...The influences of applied magnetic field on the corrosion behavior of Al-3.0 wt%Mg alloy in 3.5 wt% NaCl solution were investigated by electrochemical measurements,scanning electron microscopy（SEM）and energy-dispersive spectroscopy（EDS）.Stochastic analysis was applied to investigate the influences of applied magnetic field.The results indicate that the application of horizontal magnetic field of 0.4 T would increase the pitting corrosion potential（E_（pit））,decrease the corrosion current density（i_（corr））,prolong the pit initiation time,slow down the pit generation rate and inhibit the growth of pitting of the tested alloys in 3.5 wt% NaCl solution.The applied magnetic field would also change the mechanism of pit initiation of Al-3.0 wt%Mg alloy from A_3 model（without magnetic field）to A_3＋A_4 model（with magnetic field）.The intermediate product Al_（（ad））~＋ is the paramagnetic ion that would be influenced by magnetic field sensitively.展开更多
By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 kHz...By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 kHz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6-35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more { 110} （116） grains in the subsurface and the central layer of the sheets have a lot of 20°-45° high-energy boundaries in addition to Goss grains, {110} （116） can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110} （116） grains and therefore enhance the sharpness of Goss texture.展开更多
当控排企业的配额交易以履约为驱动力时,碳市场会出现集中交易现象,并导致碳价格非线性、非平稳。针对这一问题,结合交易频率信息的相关特性,首先,采用迭代累积平方和算法分析碳市场的成交量,进而依碳配额交易频率对交易期进行划分;然后...当控排企业的配额交易以履约为驱动力时,碳市场会出现集中交易现象,并导致碳价格非线性、非平稳。针对这一问题,结合交易频率信息的相关特性,首先,采用迭代累积平方和算法分析碳市场的成交量,进而依碳配额交易频率对交易期进行划分;然后,借助小波变换(Wavelettransform,WT)提取碳价的市场发展趋势;最后,使用双向长短期记忆神经网络(Bi-directional long short-term memory,BiLSTM)对交易趋势进行预测。实验验证结果表明,若进行预测时能够考虑交易频率信息的影响,则能够提高模型预测精度;利用WT提取到的交易趋势信息进行预测,可使预测的效果优于直接对原序列进行预测;与长短期记忆模型相比,BiLSTM模型有更好的预测表现。展开更多
基金Funded by the National Natural Science Foundation of China(No.51379070)the Fundamental Research Funds for the Central Universities(No.2017B40314)
文摘The influences of rare earth elements（cerium and lanthanum） on the microstructure and phases of Al-3.0 wt%Mg alloys used for electromagnetic shielding wire were characterized by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）, X-ray diffraction（XRD） and differential scanning calorimetry（DSC）. The mechanical properties and electrical resistivity were also investigated. The results indicated that a certain content of rare earth could improve the purification of the aluminum molten, enhance the strength, and reduce the electrical resistivity of Al-3.0 wt%Mg alloys. The strength reached the top value when RE content was 0.3 wt% while the alloy with 0.2 wt% RE addition had the smallest electrical resistivity. The elongation varied little when RE addition was no more than 0.2 wt%. But the excessive addition of rare earth would be harmful to the microstructure and properties of Al-3.0 wt%Mg alloys.
基金Funded by the National Nature Science Foundation of China(No.U1660117)the National Science and Technology Pillar Program of China(No.2011BAE13B04)
文摘The high-temperature oxidation behavior of Fe-5 wt% Cr alloys was investigated in both N+5 vol% HO and N2+21 vol% O+5 vol% HO atmospheres at 900-1000 ℃ for 120 min by the thermogravimetric analysis(TGA). The oxidation kinetics, phase composition and cross-sectional microstructure of the oxide scale were contrastively analyzed in both environments. Also, the phase composition of oxide scale was measured by X-ray diffraction(XRD). The cross-sectional microstructure and the interface elements distribution were studied by electron probe microanalysis(EPMA). The experimental results demonstrated that the growth rate and the mass gain of the oxide scale in the N+5 vol% HO atmosphere were both significantly lower than the growth rate and the mass gain in the N+21 vol% O+5 vol% HO atmosphere. The apparent layer structure of the oxide scale could be observed in an oxygen-enriched environment and did not appear in a pure water vapor without oxygen. In addition, the inner oxide layer growth mechanisms and the outward diffusion of the metal cations were introduced in the atmosphere of N+5 vol% HO. Consequently, the effects of temperature and humid atmosphere on the Fe-Cr spinal scale evolution were also discussed.
文摘The laser surface remelting (LSR) treatment was performed to Al-2.0 wt% Fe alloy with a 2 kW Yb-fiber laser (IPG YLR-2000S). The substrate and laser-treated material characterization were executed using different techniques. Among them, the microstructure was analyzed by optical microscope, SEM, low-angle X-ray diffraction (LAXRD) and the corrosion test was made in aerated solution of 0.1 M H2SO4 at a temperature of 25°C ± 0.5°C. As result was shown, the micrograph of LSR-treated material displaying can be a fine cellular structure and the existence of certain nano-porosities and a similar to a nano-dendritic growth was observed too. The characteristic of melted zone was constituted of metastable phases according to the result of x-rays and the behavior corrosion as a result of the LSR-treated sample, which it was shown to be more resistant to corrosion than the untreated sample. A comparative study was carried out of the cyclic polarization of the laser-treated and untreated samples, demonstrating that the reduction and oxidation reverse peaks were not observed and being the cyclic polarization behavior was of irreversible character in both samples, however, the LSR-treated sample propitious the passivity on the surface also reduced the corrosion phenomena. Wherefore, this type of laser-treated alloy can be applied in the aerospace, aeronautic and automobilist industries.
文摘将1 mm 6.5wt%高硅电工钢复合板在450~650℃范围内进行中温轧制。通过光学显微镜观察了温轧后和不同热处理工艺处理后复合板的显微组织;测试了温轧0.5 mm复合板不同状态的磁感应强度和铁损,通过显微硬度测试确定了硅元素均匀化的情况。研究表明,中温变形后的复合板塑性差、裂纹多、硬度高、磁性能差;退火工艺不能消除复合板高硅层的裂纹,对其磁性能没有本质提高;合适的扩散退火工艺可以消除中温变形中芯层出现的裂纹、降低复合板芯层的硬度、大幅度提高磁性能。
文摘Microstructure and crystallographic orientation of directionally solidified Mg-4 wt% Zn alloy were characterized by X-ray computed tomography （XCT） and electron backscatter diffraction （EBSD） in this study. Results reveal that Mg-4 wt% Zn alloy with dendritic microstructure exhibits typical { 0002} basal texture along growth direction. Based on this, the effect of grain orientation on corrosion behavior of directionally solidified Mg-4 wt% Zn alloy in 0.9 wt% NaCl solution was investigated. Result shows that {0002} oriented planes have better corrosion resistance than {1120} and {1010 } ones, which is attributed to a synergistic effect of surface energy, atomic packing density and the stability of oxidation film,2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology,
基金financially supported by the National Natural Science Foundation of China(No.51379070)the Fundamental Research Funds for the Central Universities(No.2014B31714)
文摘The influences of applied magnetic field on the corrosion behavior of Al-3.0 wt%Mg alloy in 3.5 wt% NaCl solution were investigated by electrochemical measurements,scanning electron microscopy（SEM）and energy-dispersive spectroscopy（EDS）.Stochastic analysis was applied to investigate the influences of applied magnetic field.The results indicate that the application of horizontal magnetic field of 0.4 T would increase the pitting corrosion potential（E_（pit））,decrease the corrosion current density（i_（corr））,prolong the pit initiation time,slow down the pit generation rate and inhibit the growth of pitting of the tested alloys in 3.5 wt% NaCl solution.The applied magnetic field would also change the mechanism of pit initiation of Al-3.0 wt%Mg alloy from A_3 model（without magnetic field）to A_3＋A_4 model（with magnetic field）.The intermediate product Al_（（ad））~＋ is the paramagnetic ion that would be influenced by magnetic field sensitively.
基金Financial support from the National HighTechnology Research and Development Program of China(No.2012AA03A505)
文摘By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 kHz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6-35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more { 110} （116） grains in the subsurface and the central layer of the sheets have a lot of 20°-45° high-energy boundaries in addition to Goss grains, {110} （116） can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110} （116） grains and therefore enhance the sharpness of Goss texture.
文摘当控排企业的配额交易以履约为驱动力时,碳市场会出现集中交易现象,并导致碳价格非线性、非平稳。针对这一问题,结合交易频率信息的相关特性,首先,采用迭代累积平方和算法分析碳市场的成交量,进而依碳配额交易频率对交易期进行划分;然后,借助小波变换(Wavelettransform,WT)提取碳价的市场发展趋势;最后,使用双向长短期记忆神经网络(Bi-directional long short-term memory,BiLSTM)对交易趋势进行预测。实验验证结果表明,若进行预测时能够考虑交易频率信息的影响,则能够提高模型预测精度;利用WT提取到的交易趋势信息进行预测,可使预测的效果优于直接对原序列进行预测;与长短期记忆模型相比,BiLSTM模型有更好的预测表现。
