Retained austenite plays a significant role in third-generation advanced high-strength steels (AHSS 3. Gen.), renowned for their excellent combination of strength and ductility. Silicon (Si) is a key element in stabil...Retained austenite plays a significant role in third-generation advanced high-strength steels (AHSS 3. Gen.), renowned for their excellent combination of strength and ductility. Silicon (Si) is a key element in stabilizing retained austenite. However, it introduces challenges in galvannealing and welding processes in Zn-coated steels, such as inhibited Fe-Zn alloying and increased susceptibility to liquid metal embrittlement (LME). This study investigated the mechanism of Si enrichment at the Zn/steel interface and its role in suppressing Fe-Zn interdiffusion during annealing. Using advanced techniques such as high-resolution transmission electron microscopy and atomic probe tomography, and Thermo-Calc DICTRA simulations, we analyzed the diffusion behavior and microstructural evolution in Zn-coated steels with varying Si contents. Si, driven by its low solubility in liquid Zn and Fe-Zn intermetallic phases, accumulates at the interface, forming a Si-enriched region that significantly suppresses Zn diffusion while permitting limited Fe diffusion. Numerical simulations revealed that the Si-enriched layer forms via the drag effect of the Fe-Zn reaction line, progressively concentrating Si at the interface as Zn diffuses. As annealing progresses, the morphology of the Si-enriched region evolves from layered, cloud-like structures to droplets and elongated dendritic forms, driven by Zn penetration and Fe consumption. These findings provide novel insights into the role of Si enrichment in mitigating LME and optimizing the Zn-coated AHSS 3. Gen., paving the way for advancements in automotive material design.展开更多
采用高温固相法制备了系列Zn改性的层状K-Fe-Zn-Ti催化剂,用于CO2加氢经费托合成直接制烯烃反应。采用SEM、TEM、XRD、H2-TPR、CO2-TPD、XPS、N2吸附-脱附和TG等手段对反应前后的催化剂进行了表征,对K-Fe-Zn-Ti催化剂的组成-结构-性能...采用高温固相法制备了系列Zn改性的层状K-Fe-Zn-Ti催化剂,用于CO2加氢经费托合成直接制烯烃反应。采用SEM、TEM、XRD、H2-TPR、CO2-TPD、XPS、N2吸附-脱附和TG等手段对反应前后的催化剂进行了表征,对K-Fe-Zn-Ti催化剂的组成-结构-性能关系进行了关联研究。结果表明,所制备的催化剂均出现K2.3Fe2.3Ti5.7O16物相,为典型的层状金属氧化物(Layered Metal Oxides,LMO)结构;Zn改性后生成了ZnFe2O4物相,降低了催化剂样品结晶度,增强了表面碱性,促进了CO2表面吸附。在CO2加氢反应中,K-Fe-Zn-Ti系列催化剂均具有较高的烯烃选择性(O/P>6.5),Zn改性促进了C5+的生成,显著提高了C4+线性α-烯烃(linearα-olefins,LAOs)的选择性,C4+烃中LAOs含量由Zn改性前的54.6%提高至75.2%。在所考察的范围内,随Zn/Fe比的增加,烯/烷比(C2-4=/C2-40,O/P)先增加后降低,但对重烃含量以及LAOs选择性影响不明显。K-FeZn-Ti催化剂具有较好的稳定性,经100 h在线反应后,仍保持LM O结构。展开更多
The slow degration of iron limits its bone implant application.The solid solution of Zn in Fe is expected to accelerate the degradation.In this work,mechanical alloying(MA)was used to prepare Fe-Zn powder with supersa...The slow degration of iron limits its bone implant application.The solid solution of Zn in Fe is expected to accelerate the degradation.In this work,mechanical alloying(MA)was used to prepare Fe-Zn powder with supersaturated solid solution.MA significantly decreased the lamellar spacing between particles,thus reducing the diffusion distance of solution atoms.Moreover,it caused a number of crystalline defects,which further promoted the solution diffusion.Subsequently,the MA-processed powder was consolidated into Fe-Zn part by laser sintering,which involved a partial melting/rapid solidification mechanism and retained the original supersaturated solid solution.Results proved that the Fe-Zn alloy became more susceptible with a lowered corrosion potential,and thereby an accelerated corrosion rate of(0.112±0.013)mm/year.Furthermore,it also exhibited favorable cell behavior.This work highlighted the advantage of MA combined with laser sintering for the preparation of Fe-Zn implant with improved degradation performance.展开更多
The methanol conversion over Fe-Zn-Zr catalyst was studied at 0.1 MPa and 280-360 ℃ The experimental results indicate that the main products of methanol conversion are methane and butane, and that other hydrocarbons ...The methanol conversion over Fe-Zn-Zr catalyst was studied at 0.1 MPa and 280-360 ℃ The experimental results indicate that the main products of methanol conversion are methane and butane, and that other hydrocarbons are scarcely produced. All results show that propylene is most probably the olefin formed first in methanol conversion rather than ethene over Fe-Zn-Zr catalyst. Methane is formed from methoxy group, and C4 is possibly yielded on the surface from propylene through binding with a methoxy group.展开更多
An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction(ORR)is crucial for energy conversion and storage devices.However,most of the high-efficiency ORR catalysis was reported in...An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction(ORR)is crucial for energy conversion and storage devices.However,most of the high-efficiency ORR catalysis was reported in alkaline conditions.Herein,we demonstrated the preparation of atomically dispersed Fe-Zn pairs anchored on porous N-doped carbon frameworks(Fe-Zn-SA/NC),which works efficiently as ORR catalyst in the whole pH range.It achieves high half-wave potentials of 0.78,0.85 and 0.72 V in 0.1 M HClO4,0.1 M KOH and 0.1 M phosphate buffer saline(PBS)solutions,respectively,as well as respectable stability.The performances are even comparable to Pt/C.Furthermore,when assembled into a Zn-air battery,the high power density of 167.2 mWcm−2 and 120 h durability reveal the feasibility of Fe-Zn-SA/NC in real energy-related devices.Theoretical calculations demonstrate that the superior catalytic activity of Fe-Zn-SA/NC can be contributed to the lower energy barriers of ORR at the Fe-Zn-N6 centers.This work demonstrates the potential of Fe-Zn pairs as alternatives to the Pt catalysts for efficient catalytic ORR and provides new insights of dual-atom catalysts for other energy conversion related catalytic reactions.展开更多
57Fe Mossbauer spectroscopy was used to investigate the evolution of Fe-Zn binary metal oxide sorbent in the process of high-temperature fuel gas desulfurization. The results of phase analyses show that Fe-Zn binary m...57Fe Mossbauer spectroscopy was used to investigate the evolution of Fe-Zn binary metal oxide sorbent in the process of high-temperature fuel gas desulfurization. The results of phase analyses show that Fe-Zn binary metal oxide sorbent is rapidly reduced in hot fuel gas and decomposed to new phases of highly dispersed microcrystalline elemental iron and zinc oxide, both of which become the active desulfurization constituents. A complementary and synergistic effect between active iron acting as a high sulfur capacity constituent and active zinc oxide acting as a deep refining desulfurization constituent exists in this type of sorbent for hot fuel gas desulfurization.展开更多
基金supported by the Fundamental Research Program of the Korea Institute of Materials Science(No.PNK9820).
文摘Retained austenite plays a significant role in third-generation advanced high-strength steels (AHSS 3. Gen.), renowned for their excellent combination of strength and ductility. Silicon (Si) is a key element in stabilizing retained austenite. However, it introduces challenges in galvannealing and welding processes in Zn-coated steels, such as inhibited Fe-Zn alloying and increased susceptibility to liquid metal embrittlement (LME). This study investigated the mechanism of Si enrichment at the Zn/steel interface and its role in suppressing Fe-Zn interdiffusion during annealing. Using advanced techniques such as high-resolution transmission electron microscopy and atomic probe tomography, and Thermo-Calc DICTRA simulations, we analyzed the diffusion behavior and microstructural evolution in Zn-coated steels with varying Si contents. Si, driven by its low solubility in liquid Zn and Fe-Zn intermetallic phases, accumulates at the interface, forming a Si-enriched region that significantly suppresses Zn diffusion while permitting limited Fe diffusion. Numerical simulations revealed that the Si-enriched layer forms via the drag effect of the Fe-Zn reaction line, progressively concentrating Si at the interface as Zn diffuses. As annealing progresses, the morphology of the Si-enriched region evolves from layered, cloud-like structures to droplets and elongated dendritic forms, driven by Zn penetration and Fe consumption. These findings provide novel insights into the role of Si enrichment in mitigating LME and optimizing the Zn-coated AHSS 3. Gen., paving the way for advancements in automotive material design.
文摘采用高温固相法制备了系列Zn改性的层状K-Fe-Zn-Ti催化剂,用于CO2加氢经费托合成直接制烯烃反应。采用SEM、TEM、XRD、H2-TPR、CO2-TPD、XPS、N2吸附-脱附和TG等手段对反应前后的催化剂进行了表征,对K-Fe-Zn-Ti催化剂的组成-结构-性能关系进行了关联研究。结果表明,所制备的催化剂均出现K2.3Fe2.3Ti5.7O16物相,为典型的层状金属氧化物(Layered Metal Oxides,LMO)结构;Zn改性后生成了ZnFe2O4物相,降低了催化剂样品结晶度,增强了表面碱性,促进了CO2表面吸附。在CO2加氢反应中,K-Fe-Zn-Ti系列催化剂均具有较高的烯烃选择性(O/P>6.5),Zn改性促进了C5+的生成,显著提高了C4+线性α-烯烃(linearα-olefins,LAOs)的选择性,C4+烃中LAOs含量由Zn改性前的54.6%提高至75.2%。在所考察的范围内,随Zn/Fe比的增加,烯/烷比(C2-4=/C2-40,O/P)先增加后降低,但对重烃含量以及LAOs选择性影响不明显。K-FeZn-Ti催化剂具有较好的稳定性,经100 h在线反应后,仍保持LM O结构。
基金Projects(51935014,82072084,81871498)supported by the Natural Science Foundation of ChinaProjects(20192ACB20005,2020ACB214004)supported by the Jiangxi Provincial Natural Science Foundation of China+4 种基金Project(20201BBE51012)supported by the Provincial Key R&D Projects of Jiangxi Province,ChinaProject(2018)supported by the Guangdong Province Higher Vocational Colleges&Schools Pearl River Scholar Funded Scheme,ChinaProject(2017RS3008)supported by Hunan Provincial Science and Technology Plan,ChinaProject supported by the Open Research Fund of Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology,ChinaProject(2020M682114)China Postdoctoral Science Foundation。
文摘The slow degration of iron limits its bone implant application.The solid solution of Zn in Fe is expected to accelerate the degradation.In this work,mechanical alloying(MA)was used to prepare Fe-Zn powder with supersaturated solid solution.MA significantly decreased the lamellar spacing between particles,thus reducing the diffusion distance of solution atoms.Moreover,it caused a number of crystalline defects,which further promoted the solution diffusion.Subsequently,the MA-processed powder was consolidated into Fe-Zn part by laser sintering,which involved a partial melting/rapid solidification mechanism and retained the original supersaturated solid solution.Results proved that the Fe-Zn alloy became more susceptible with a lowered corrosion potential,and thereby an accelerated corrosion rate of(0.112±0.013)mm/year.Furthermore,it also exhibited favorable cell behavior.This work highlighted the advantage of MA combined with laser sintering for the preparation of Fe-Zn implant with improved degradation performance.
基金Foundation item:this work was Financially supported by the National Natural Science Foundation of China(Project No.29973056).
文摘The methanol conversion over Fe-Zn-Zr catalyst was studied at 0.1 MPa and 280-360 ℃ The experimental results indicate that the main products of methanol conversion are methane and butane, and that other hydrocarbons are scarcely produced. All results show that propylene is most probably the olefin formed first in methanol conversion rather than ethene over Fe-Zn-Zr catalyst. Methane is formed from methoxy group, and C4 is possibly yielded on the surface from propylene through binding with a methoxy group.
基金This work was financially supported by National Key R&D Program of China(No.2017YFA0700104)the National Natural Science Foundation of China(Nos.22075211,21601136,51971157,51761165012,and 62005173)+2 种基金Project funded by China Postdoctoral Science Foundation(No.2020TQ0201)Tianjin Science Fund for Distinguished Young Scholars(No.19JCJQJC61800)The authors also acknowledge National Supercomputing Center in Shenzhen for providing the computational resources and materials studio(version 7.0,DMol3).
文摘An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction(ORR)is crucial for energy conversion and storage devices.However,most of the high-efficiency ORR catalysis was reported in alkaline conditions.Herein,we demonstrated the preparation of atomically dispersed Fe-Zn pairs anchored on porous N-doped carbon frameworks(Fe-Zn-SA/NC),which works efficiently as ORR catalyst in the whole pH range.It achieves high half-wave potentials of 0.78,0.85 and 0.72 V in 0.1 M HClO4,0.1 M KOH and 0.1 M phosphate buffer saline(PBS)solutions,respectively,as well as respectable stability.The performances are even comparable to Pt/C.Furthermore,when assembled into a Zn-air battery,the high power density of 167.2 mWcm−2 and 120 h durability reveal the feasibility of Fe-Zn-SA/NC in real energy-related devices.Theoretical calculations demonstrate that the superior catalytic activity of Fe-Zn-SA/NC can be contributed to the lower energy barriers of ORR at the Fe-Zn-N6 centers.This work demonstrates the potential of Fe-Zn pairs as alternatives to the Pt catalysts for efficient catalytic ORR and provides new insights of dual-atom catalysts for other energy conversion related catalytic reactions.
文摘57Fe Mossbauer spectroscopy was used to investigate the evolution of Fe-Zn binary metal oxide sorbent in the process of high-temperature fuel gas desulfurization. The results of phase analyses show that Fe-Zn binary metal oxide sorbent is rapidly reduced in hot fuel gas and decomposed to new phases of highly dispersed microcrystalline elemental iron and zinc oxide, both of which become the active desulfurization constituents. A complementary and synergistic effect between active iron acting as a high sulfur capacity constituent and active zinc oxide acting as a deep refining desulfurization constituent exists in this type of sorbent for hot fuel gas desulfurization.
