The corrosion behaviors of Fe-Cr alloy under three different pH values solutions with C1- and SO42- were investigated by localized electrochemical impedance spectroscopy （LEIS） measurements and the corrosion product...The corrosion behaviors of Fe-Cr alloy under three different pH values solutions with C1- and SO42- were investigated by localized electrochemical impedance spectroscopy （LEIS） measurements and the corrosion products were analyzed by laser Raman spectrometry. The results show that the high corrosion resistance of Fe-Cr Alloy is attributed to a passive film which is formed more easily when the alloy contains a large quantity of Cr element. However, its corrosion resistance varies in the solutions with different pH values, especially in the initial corrosion. The average impedance values in neutral and alkaline solution are much higher than that in acidic solution because the passive film is more likely to dissolve in the acidic condition. Moreover, the destructive effect of C1- and SO42 ions on the passive film is also demonstrated in corrosion process through the change of the impedance value with the steeping time.展开更多
Currently,the iron chromium redox flow battery(ICRFB)has become a research hotspot in the energy storage field owing to its low cost and easily-scaled-up.However,the activity of electrolyte is still ambiguous due to i...Currently,the iron chromium redox flow battery(ICRFB)has become a research hotspot in the energy storage field owing to its low cost and easily-scaled-up.However,the activity of electrolyte is still ambiguous due to its complicated solution environment.Herein,we performed a pioneering investigation on the coordination behavior and transformation mechanism of Cr^(3+)in electrolyte and prediction of impurity ions impact through quantum chemistry computations.Based on the structure and symmetry of electrostatic potential distribution,the activity of different Cr^(3+)complex ions is confirmed as[Cr(H2O)5Cl]^(2+)>[Cr(H2O)4Cl2]+>[Cr(H2O)6]^(3+).The transformation mechanism between[Cr(H2O)6]^(3+)and[Cr(H2O)5Cl]^(2+)is revealed.We find the metal impurity ions(especially Mg^(2+))can exacerbate the electrolyte deactivation by reducing the transformation energy barrier from[Cr(H2O)5Cl]^(2+)(24.38 kcal mol^(−1))to[Cr(H2O)6]^(3+)(16.23 kcal mol^(−1)).The solvent radial distribution and mean square displacement in different solvent environments are discussed and we conclude that the coordination configuration limits the diffusivity of Cr^(3+).This work provides new insights into the activity of electrolyte,laying a fundamental sense for the electrolyte in ICRFB.展开更多
It is promising for metal especially ferritic stainless steel（FSS）to be used as interconnector when the solid oxide fuel cell（SOFC）is operated at temperature lower than 800℃.However,there are many challenges for ...It is promising for metal especially ferritic stainless steel（FSS）to be used as interconnector when the solid oxide fuel cell（SOFC）is operated at temperature lower than 800℃.However,there are many challenges for FSS such as anti-oxidant,poisoning to cathode and high area specific resistance（ASR）when using as SOFC interconnector.The effect of Cr content（12-30 mass%）in Fe-Cr alloys on thermal expansion coefficient（TEC）,oxidation resistance,microstructure of oxidation scale and ASR was investigated by thermo-gravimetry,scanning electron microscopy,energy dispersive spectroscopy and four-probe DC technique.The TEC of Fe-Cr alloys is（11-13）×10^（-6） K^（-1）,which excellently matches with other SOFC components.Alloys have excellent oxidation resistance when Cr content exceeds 22mass% because of the formation of chromium on the surface of alloy.The oxidation rate constants kdand ksdecrease rapidly with increasing the Cr content and then increase slowly when the Cr content is higher than 22mass%.The kinetic results indicate that Cr evaporation must be considered at high temperature for Fe-Cr alloys.After the alloys were oxidized in air at 800℃ for500 h,log（ASR/T）（Tis the absolute temperature）presents linear relationship with 1/T and the conduct activation energy is 0.6-0.8eV（Cr16-30）.Optimal Cr content is 22-26mass%considering the oxidation resistance and ASR.展开更多
The effect of chromium content on the fundamental mechanical properties of Fe-Cr alloys has been studied by first-principles calculations. Within a random solid solution model, the lattice constants and the elastic co...The effect of chromium content on the fundamental mechanical properties of Fe-Cr alloys has been studied by first-principles calculations. Within a random solid solution model, the lattice constants and the elastic constants of ferromagnetic bcc Fel-xCrx （04 x 40.156） alloys were calculated for different compositions. With addition of Cr content, the lattice parameters of Fe-Cr alloys are larger than that of pure Fe solid, and the corresponding Young＇s modulus and shear modulus rise non- monotonically with the increasing Cr content. All alloys （except 9.4 at% Cr） exhibit less ductile behavior compared with pure bcc Fe. For the Fel-xCrx （04 x 40.156） alloys, the average magnetic moment per atom decreases linearly with the increasing Cr concentration.展开更多
The properties of all materials depend largely on their chemical compositions.Compositional analysis by using the atom probe suggests that it is necessary to invent new parameters to describe some aspects of microstru...The properties of all materials depend largely on their chemical compositions.Compositional analysis by using the atom probe suggests that it is necessary to invent new parameters to describe some aspects of microstructures.Experimental and calculation work indicates that fractal dimension can be used to describe structural aspects not readily expressible with normal parameters.The application of fractal concept in mate- rials studies will enable us to understand from a brand-new angle the ultra-fine microstructures of materials.展开更多
Magnetic properties of nanocrystalline Fe_~60 Cr_~40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ~ ~57 Fe Mssbauer...Magnetic properties of nanocrystalline Fe_~60 Cr_~40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ~ ~57 Fe Mssbauer spectrum. The results show that the Fe_~60 Cr_~40 powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe_~60 Cr_~40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe_~60 Cr_~40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.展开更多
A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics an...A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics and interracial strength were investigated by the high temperature sessile drop method and element area scanning. The linear expansion coefficients of the materials were measured using TAH100 thermal analyzer. The results show that the wettability of Fe-Cr alloy on TiO are small, with a wetting angle about 90°. After adding some Si in Fe-Cr alloy, its wetting angle can be decreased to about 25°, the interracial reactions can be prevented effectively and high interface binding can be formed. Fe-25% Cr-1.5% Si matches the thermal expansion coefficient of TiO, so it is a kind of relatively perfect binder for TiO based cermets imitated gold.展开更多
Dense arrays of Fe-Cr alloy clusters with different Cr ratios were fabricated by gas-phase cluster beam deposition. The complex multiphase structure and various coupling effects in the cluster arrays were studied. A l...Dense arrays of Fe-Cr alloy clusters with different Cr ratios were fabricated by gas-phase cluster beam deposition. The complex multiphase structure and various coupling effects in the cluster arrays were studied. A lattice mismatched tetragonal-like morphology of the Fe-Cr alloy cluster was observed at large Cr ratio. An exchange bias effect was observed and was shown to be dependent on the proportion of the Cr components in the alloy. With the increase of the Cr composition, the exchange bias field became smaller and stronger dipolar interactions between the clusters developed. Residual coercivity and magnetization, which were more remarkable in the tetragonal-like clusters, were observed above the ferromagnetic-superparamagnetic transition temperature. The experimental results of the coercive field and the bias field at different temperatures demonstrated that the tetragonal-like clusters had better thermal stability and greater anisotropy.展开更多
A piecewise potential was constructed with combination of the concentration-dependent EAM(CD-EAM)potential and Ziegler-Biersack-Littmark(ZBL)potential,and the displacement cascades in random Fe-Cr binary alloys with a...A piecewise potential was constructed with combination of the concentration-dependent EAM(CD-EAM)potential and Ziegler-Biersack-Littmark(ZBL)potential,and the displacement cascades in random Fe-Cr binary alloys with a wide range of Cr concentration from 0 to 20%were simulated to evaluate the effect of Cr concentration on defect formation and evolution during the cascades.The Cr concentration has little or no effect on the fraction of vacancy clusters,the number of surviving Frenkel pairs,or the self-interstitial and vacancy cluster sizes and a slight effect on the peak time and peak defect number,but a considerable effect on the Cr enrichment in the peak and surviving defects in the cascaded Fe-Cr alloys.With the increase in Cr concentration,the Cr enrichment in the peak and surviving defects exhibits a downtrend.The higher enrichment degree in the surviving defects than in the peak defects shows more difficult recombination of Cr SIAs with vacancies.展开更多
In present paper, by using of the relaxation times approximation method, we have calculated the oscillation of magnetoresistance (MR) in Fe/Cr superlattice with the thickness of Cr film .A quite good result has been o...In present paper, by using of the relaxation times approximation method, we have calculated the oscillation of magnetoresistance (MR) in Fe/Cr superlattice with the thickness of Cr film .A quite good result has been obtained which is agree with the experiments.展开更多
基金National Natural Science Foundation of China (No. 50871021)
文摘The corrosion behaviors of Fe-Cr alloy under three different pH values solutions with C1- and SO42- were investigated by localized electrochemical impedance spectroscopy （LEIS） measurements and the corrosion products were analyzed by laser Raman spectrometry. The results show that the high corrosion resistance of Fe-Cr Alloy is attributed to a passive film which is formed more easily when the alloy contains a large quantity of Cr element. However, its corrosion resistance varies in the solutions with different pH values, especially in the initial corrosion. The average impedance values in neutral and alkaline solution are much higher than that in acidic solution because the passive film is more likely to dissolve in the acidic condition. Moreover, the destructive effect of C1- and SO42 ions on the passive film is also demonstrated in corrosion process through the change of the impedance value with the steeping time.
基金Fundamental Research Funds for the Central Universities(2023MS125)。
文摘Currently,the iron chromium redox flow battery(ICRFB)has become a research hotspot in the energy storage field owing to its low cost and easily-scaled-up.However,the activity of electrolyte is still ambiguous due to its complicated solution environment.Herein,we performed a pioneering investigation on the coordination behavior and transformation mechanism of Cr^(3+)in electrolyte and prediction of impurity ions impact through quantum chemistry computations.Based on the structure and symmetry of electrostatic potential distribution,the activity of different Cr^(3+)complex ions is confirmed as[Cr(H2O)5Cl]^(2+)>[Cr(H2O)4Cl2]+>[Cr(H2O)6]^(3+).The transformation mechanism between[Cr(H2O)6]^(3+)and[Cr(H2O)5Cl]^(2+)is revealed.We find the metal impurity ions(especially Mg^(2+))can exacerbate the electrolyte deactivation by reducing the transformation energy barrier from[Cr(H2O)5Cl]^(2+)(24.38 kcal mol^(−1))to[Cr(H2O)6]^(3+)(16.23 kcal mol^(−1)).The solvent radial distribution and mean square displacement in different solvent environments are discussed and we conclude that the coordination configuration limits the diffusivity of Cr^(3+).This work provides new insights into the activity of electrolyte,laying a fundamental sense for the electrolyte in ICRFB.
基金funded by Ministry of Science and Technology of China(2012CB215405)Fundamental Research Funds for Central Universities of China(FRF-TP-15-052A3)Chinese Postdoctoral Science Foundation(2014M560046)
文摘It is promising for metal especially ferritic stainless steel（FSS）to be used as interconnector when the solid oxide fuel cell（SOFC）is operated at temperature lower than 800℃.However,there are many challenges for FSS such as anti-oxidant,poisoning to cathode and high area specific resistance（ASR）when using as SOFC interconnector.The effect of Cr content（12-30 mass%）in Fe-Cr alloys on thermal expansion coefficient（TEC）,oxidation resistance,microstructure of oxidation scale and ASR was investigated by thermo-gravimetry,scanning electron microscopy,energy dispersive spectroscopy and four-probe DC technique.The TEC of Fe-Cr alloys is（11-13）×10^（-6） K^（-1）,which excellently matches with other SOFC components.Alloys have excellent oxidation resistance when Cr content exceeds 22mass% because of the formation of chromium on the surface of alloy.The oxidation rate constants kdand ksdecrease rapidly with increasing the Cr content and then increase slowly when the Cr content is higher than 22mass%.The kinetic results indicate that Cr evaporation must be considered at high temperature for Fe-Cr alloys.After the alloys were oxidized in air at 800℃ for500 h,log（ASR/T）（Tis the absolute temperature）presents linear relationship with 1/T and the conduct activation energy is 0.6-0.8eV（Cr16-30）.Optimal Cr content is 22-26mass%considering the oxidation resistance and ASR.
文摘The effect of chromium content on the fundamental mechanical properties of Fe-Cr alloys has been studied by first-principles calculations. Within a random solid solution model, the lattice constants and the elastic constants of ferromagnetic bcc Fel-xCrx （04 x 40.156） alloys were calculated for different compositions. With addition of Cr content, the lattice parameters of Fe-Cr alloys are larger than that of pure Fe solid, and the corresponding Young＇s modulus and shear modulus rise non- monotonically with the increasing Cr content. All alloys （except 9.4 at% Cr） exhibit less ductile behavior compared with pure bcc Fe. For the Fel-xCrx （04 x 40.156） alloys, the average magnetic moment per atom decreases linearly with the increasing Cr concentration.
文摘The properties of all materials depend largely on their chemical compositions.Compositional analysis by using the atom probe suggests that it is necessary to invent new parameters to describe some aspects of microstructures.Experimental and calculation work indicates that fractal dimension can be used to describe structural aspects not readily expressible with normal parameters.The application of fractal concept in mate- rials studies will enable us to understand from a brand-new angle the ultra-fine microstructures of materials.
文摘Magnetic properties of nanocrystalline Fe_~60 Cr_~40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ~ ~57 Fe Mssbauer spectrum. The results show that the Fe_~60 Cr_~40 powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe_~60 Cr_~40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe_~60 Cr_~40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.
文摘A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics and interracial strength were investigated by the high temperature sessile drop method and element area scanning. The linear expansion coefficients of the materials were measured using TAH100 thermal analyzer. The results show that the wettability of Fe-Cr alloy on TiO are small, with a wetting angle about 90°. After adding some Si in Fe-Cr alloy, its wetting angle can be decreased to about 25°, the interracial reactions can be prevented effectively and high interface binding can be formed. Fe-25% Cr-1.5% Si matches the thermal expansion coefficient of TiO, so it is a kind of relatively perfect binder for TiO based cermets imitated gold.
基金supported by the National Natural Science Foundation of China(No.11627806 and No.61301015)the Priority Academic Programme Development of Jiangsu Higher Education Institutions
文摘Dense arrays of Fe-Cr alloy clusters with different Cr ratios were fabricated by gas-phase cluster beam deposition. The complex multiphase structure and various coupling effects in the cluster arrays were studied. A lattice mismatched tetragonal-like morphology of the Fe-Cr alloy cluster was observed at large Cr ratio. An exchange bias effect was observed and was shown to be dependent on the proportion of the Cr components in the alloy. With the increase of the Cr composition, the exchange bias field became smaller and stronger dipolar interactions between the clusters developed. Residual coercivity and magnetization, which were more remarkable in the tetragonal-like clusters, were observed above the ferromagnetic-superparamagnetic transition temperature. The experimental results of the coercive field and the bias field at different temperatures demonstrated that the tetragonal-like clusters had better thermal stability and greater anisotropy.
基金This work was supported by the National Natural Science Foundation of China(Grant numbers:11572135,11772137).
文摘A piecewise potential was constructed with combination of the concentration-dependent EAM(CD-EAM)potential and Ziegler-Biersack-Littmark(ZBL)potential,and the displacement cascades in random Fe-Cr binary alloys with a wide range of Cr concentration from 0 to 20%were simulated to evaluate the effect of Cr concentration on defect formation and evolution during the cascades.The Cr concentration has little or no effect on the fraction of vacancy clusters,the number of surviving Frenkel pairs,or the self-interstitial and vacancy cluster sizes and a slight effect on the peak time and peak defect number,but a considerable effect on the Cr enrichment in the peak and surviving defects in the cascaded Fe-Cr alloys.With the increase in Cr concentration,the Cr enrichment in the peak and surviving defects exhibits a downtrend.The higher enrichment degree in the surviving defects than in the peak defects shows more difficult recombination of Cr SIAs with vacancies.
文摘In present paper, by using of the relaxation times approximation method, we have calculated the oscillation of magnetoresistance (MR) in Fe/Cr superlattice with the thickness of Cr film .A quite good result has been obtained which is agree with the experiments.
