In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular...In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.展开更多
Phase equilibria in the Al-rich corner of the Al-Er-Y ternary system from 65 at.% to 100 at.% Al at 673 and873 K were investigated,and the two isothermal sections were established by X-ray diffraction(XRD),scanning el...Phase equilibria in the Al-rich corner of the Al-Er-Y ternary system from 65 at.% to 100 at.% Al at 673 and873 K were investigated,and the two isothermal sections were established by X-ray diffraction(XRD),scanning electron microscope(SEM) and electron probe micro analysis(EPMA).Three ternary-phase regions are observed and the phase relations are similar at both isothermal sections.There are two ternary compounds,and a complete crystal structures and composition ranges of the two ternary compounds are determined as τ_(1)(Al_(75-76)Er_(15-22)Y_(2-10),R-3 m) and τ_(2)(Al_(75-76)Er_(11-17)Y_(7-14),P6_(3)/mmc) via XRD,focused ion beam coupled with transmission electron microscope(FIB-TEM) and EPMA.Meanwhile,the solubilities of the third element in the binary compounds at both temperatures are measured.The solubility of Er inβ-Al_(3) Y phase reaches to 6.6 at.% and that of Y in Al_(3) Er phase reaches to 1.5 at.% after annealing at 873 K.The temperature effect is not obvious for the phase equilibria at 673 and 873 K,but it increases the solubility of Er in β-Al_(3) Y,while it is not obvious for both the solubility of Y in Al_(3) Er and that of Er and Y in(Al).The phase equilibria of the Al-Er-Y ternary system determined by the present work have provided new phase diagram data for a future thermodynamic assessment of this system.展开更多
Study on the diffusion growth of ternary intermetallic compounds in Mg-Al-Zn based light-weight alloys is important due to its close interrelation with alloy property.However,there is a very lack of existing data due ...Study on the diffusion growth of ternary intermetallic compounds in Mg-Al-Zn based light-weight alloys is important due to its close interrelation with alloy property.However,there is a very lack of existing data due to difficulties in both experimental and computational aspects.The current work aims at presenting the experimental observation on the diffusion growth behavior of Φ phase at 360℃ as well as calculating its composition-dependent interdiffu sion coefficients.We designed and succes s fully fabricated four Mg-τ ternary diffusion couples annealed at 360℃ for different times,where the diffusion path goes across the Φ phase region and the diffusion growth of ternary intermetallic compound can be solely detected.In-situ observation of the time-dependent growth of Φ phase was performed to accurately determine the parabolic growth constant.The experimental data were then subjected to a numerical inverse method to generate a set of self-consistent interdiffusivities of the ternary intermetallic compounds,which can reproduce the presently observed diffusion growth behavior of Φ ternary intermetallic compound in Mg-τ diffusion couples.展开更多
The Ce_(0.8)Gd_(0.2)O_(2)−δ(CGO)interlayer is commonly applied in solid oxide fuel cells(SOFCs)to prevent chemical reactions between the(La_(1−x)Sr_(x))(Co_(1−y)Fe_(y))O_(3−δ)(LSCF)oxygen electrode and the Y_(2)O_(3...The Ce_(0.8)Gd_(0.2)O_(2)−δ(CGO)interlayer is commonly applied in solid oxide fuel cells(SOFCs)to prevent chemical reactions between the(La_(1−x)Sr_(x))(Co_(1−y)Fe_(y))O_(3−δ)(LSCF)oxygen electrode and the Y_(2)O_(3)-stabilized ZrO_(2)(YSZ)electrolyte.However,formation of the YSZ–CGO solid solution with low ionic conductivity and the SrZrO_(3)(SZO)insulating phase still happens during cell production and long-term operation,causing poor performance and degradation.Unlike many experimental investigations exploring these phenomena,consistent and quantitative computational modeling of the microstructure evolution at the oxygen electrode–electrolyte interface is scarce.We combine thermodynamic,1D kinetic,and 3D phase-field modeling to computationally reproduce the element redistribution,microstructure evolution,and corresponding ohmic loss of this interface.The influences of different ceramic processing techniques for the CGO interlayer,i.e.,screen printing and physical laser deposition(PLD),and of different processing and long-term operating parameters are explored,representing a successful case of quantitative computational engineering of the oxygen electrode–electrolyte interface in SOFCs.展开更多
基金supported by National Natural Science Foundation of China,China(No.51901117,51801116)Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities,China(No.2020KJA002)+2 种基金Youth Fund of Shandong Academy of Sciences,China(2020QN0021)Innovation Pilot Project for Fusion of Science,Education and Industry(International Cooperation)from Qilu University of Technology(Shandong Academy of Sciences),China(No.2020KJC-GH03)Several Policies on Promoting Collaborative Innovation and Industrialization of Achievements in Universities and Research Institutes,China(No.2019GXRC030)。
文摘In an effort to clarify the formation mechanism of LPSO structure in Mg-Y-Zn alloy,the chemical environment and structural ordering in liquid Mg-rich Mg-Y-Zn system are investigated with the aid of ab-initio molecular dynamics simulation.In liquid Mg-rich Mg-Y alloys,the strong Mg-Y interaction is determined,which promotes the formation of fivefold symmetric local structure.For Mg-Zn alloys,the weak Mg-Zn interaction results in the fivefold symmetry weakening in the liquid structure.Due to the coexistence of Y and Zn,the strong attractive interaction is introduced in liquid Mg-Y-Zn ternary alloy,and contributes to the clustering of Mg,Y,Zn launched from Zn.What is more,the distribution of local structures becomes closer to that in pure Mg compared with that in binary Mg-Y and Mg-Zn alloys.These results should relate to the origins of the Y/Zn segregation zone and close-packed stacking mode in LPSO structure,which provides a new insight into the formation mechanism of LPSO structure at atomic level.
基金financially supported from the Open Research Project of State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive UtilizationNational Natural Science Foundation of China(Nos.51671219 and 51801116)。
文摘Phase equilibria in the Al-rich corner of the Al-Er-Y ternary system from 65 at.% to 100 at.% Al at 673 and873 K were investigated,and the two isothermal sections were established by X-ray diffraction(XRD),scanning electron microscope(SEM) and electron probe micro analysis(EPMA).Three ternary-phase regions are observed and the phase relations are similar at both isothermal sections.There are two ternary compounds,and a complete crystal structures and composition ranges of the two ternary compounds are determined as τ_(1)(Al_(75-76)Er_(15-22)Y_(2-10),R-3 m) and τ_(2)(Al_(75-76)Er_(11-17)Y_(7-14),P6_(3)/mmc) via XRD,focused ion beam coupled with transmission electron microscope(FIB-TEM) and EPMA.Meanwhile,the solubilities of the third element in the binary compounds at both temperatures are measured.The solubility of Er inβ-Al_(3) Y phase reaches to 6.6 at.% and that of Y in Al_(3) Er phase reaches to 1.5 at.% after annealing at 873 K.The temperature effect is not obvious for the phase equilibria at 673 and 873 K,but it increases the solubility of Er in β-Al_(3) Y,while it is not obvious for both the solubility of Y in Al_(3) Er and that of Er and Y in(Al).The phase equilibria of the Al-Er-Y ternary system determined by the present work have provided new phase diagram data for a future thermodynamic assessment of this system.
基金supported financially by the National Key Research and Development Program of China(No.2016YFB0701202)the National Natural Science Foundation of China(Nos.51801116 and 51901117)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR2017BEM022)the Youth Fund of Shandong Academy of Sciences(Nos.2018QN0032 and 2019QN0023)。
文摘Study on the diffusion growth of ternary intermetallic compounds in Mg-Al-Zn based light-weight alloys is important due to its close interrelation with alloy property.However,there is a very lack of existing data due to difficulties in both experimental and computational aspects.The current work aims at presenting the experimental observation on the diffusion growth behavior of Φ phase at 360℃ as well as calculating its composition-dependent interdiffu sion coefficients.We designed and succes s fully fabricated four Mg-τ ternary diffusion couples annealed at 360℃ for different times,where the diffusion path goes across the Φ phase region and the diffusion growth of ternary intermetallic compound can be solely detected.In-situ observation of the time-dependent growth of Φ phase was performed to accurately determine the parabolic growth constant.The experimental data were then subjected to a numerical inverse method to generate a set of self-consistent interdiffusivities of the ternary intermetallic compounds,which can reproduce the presently observed diffusion growth behavior of Φ ternary intermetallic compound in Mg-τ diffusion couples.
基金This work is supported by European Horizon 2020-Research and Innovation Framework Programme(H2020-JTI-FCH-2015-1)under grant agreement No.735918(INSIGHT project)by EUDP through project no.64017-0011(EP2Gas)+3 种基金In addition,the National Natural Science Foundation of China(Nos.51801116 and 52001176)Shandong Province Key Research and Development Plan(Nos.2019GHZ019,2019JZZY010364,and 2019JZZY020329)the Youth Innovation and Technology Support Program of Shandong Provincial Colleges and Universities(No.2020KJA002)are acknowledged.The authors would like to acknowledge Dr.Arata Nakajo and Dr.Giorgio Rinaldi from EPFL for providing the original FIB-SEM data and fruitful discussion.
文摘The Ce_(0.8)Gd_(0.2)O_(2)−δ(CGO)interlayer is commonly applied in solid oxide fuel cells(SOFCs)to prevent chemical reactions between the(La_(1−x)Sr_(x))(Co_(1−y)Fe_(y))O_(3−δ)(LSCF)oxygen electrode and the Y_(2)O_(3)-stabilized ZrO_(2)(YSZ)electrolyte.However,formation of the YSZ–CGO solid solution with low ionic conductivity and the SrZrO_(3)(SZO)insulating phase still happens during cell production and long-term operation,causing poor performance and degradation.Unlike many experimental investigations exploring these phenomena,consistent and quantitative computational modeling of the microstructure evolution at the oxygen electrode–electrolyte interface is scarce.We combine thermodynamic,1D kinetic,and 3D phase-field modeling to computationally reproduce the element redistribution,microstructure evolution,and corresponding ohmic loss of this interface.The influences of different ceramic processing techniques for the CGO interlayer,i.e.,screen printing and physical laser deposition(PLD),and of different processing and long-term operating parameters are explored,representing a successful case of quantitative computational engineering of the oxygen electrode–electrolyte interface in SOFCs.
