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Nucleation and growth mechanisms of γ〞 phase with single-unit-cell height in Mg-RE-Zn(Ag) series alloys: a first-principles study

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Journal of Materials Science & Technology 2021年第20期79卷 133-140页

作者： Junyuan Bai Hongbo Xie Xueyong Pang Guo Yuan Lei Wang Yuping Ren Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Research Centre for Metallic Wires Northeastern UniversityShenyang 110819China

The highly thermal stability precipitates strengthen creep resistance for alloys,which require precipitates to resist coarsen at elevated temperature.In the Mg-RE-Zn(Ag)series alloys,the key strengthening phase-γ"phase,remains its single-unit-cell height throughout aging process.The origin of such extremely thermal stability ofγ"phase is still unclear.By using the first-principles calculations,it is found that the formation ofγ"phase introduces compressive strain to its surroundingα-Mg lattice and simultaneously alter charge distribution ofα-Mg lattice near theα-Mg/γ"hetero-interface.These two variations overα-Mg lattice lead to lower vacancy formation energies and migration energy barriers for solute atoms near theα-Mg/γ"hetero-interface in comparison with that of bulk condition.Consequently,the variations facilitate rapid diffusion of solute atoms near theγ"phase and promote nucleation rate of otherγ"plates around it.On the basis of ledge-thickening model,the origin of nucleation/growth ofγ"phase with single-unit-cell height was explained.Thermodynamically and kinetically,the solute atoms are not apt to migrate into the nearest basal plane adjacent to theγ"phase.Moreover,the lower aging temperature(~200℃)and almost completely coherentα-Mg/γ"hetero-interface lead to the ledges are extremely hard to nucleate on the hetero-interface.Therefore,γ"plates maintain single-unit-cell height throughout aging process.

关键词： Thermal stability Mg-RE-Zn(Ag)series alloys γ"phase First-principles Ledge-thickening

Phases equilibrated with long-period stacking ordered phases in the Mg-rich corner of the Mg-Y-Zn system

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Journal of Materials Science & Technology 2021年第9期68卷 147-159页

作者： Yongxin Ruan Changrong Li Yuping Ren Xiaopan Wu Schmid-Fetzer Cuiping Guo Zhenmin Du School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory for Anisotropy and Texture of Materials Ministry of EducationNortheastern UniversityShenyang 110819China Institute of Metallurgy Clausthal University of TechnologyRobert-Koch-Str.42D-38678 Clausthal-ZellerfeldGermany

Phase equilibria involving the long-period stacking ordered phases including 14 H,18 R and 10 H in the Mg-rich corner of the Mg-Y-Zn system at 400 and 500℃ have been experimentally investigated by using X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM).The coexistence of 14 H and 18 R as well as 18 R and 10 H was confirmed from atomic scales.The phases 14 H,18 R and 10 H were all stable phases from 400 to 500℃.The experimentally proved three-phase equilibrium of14 H,18 R and α-Mg instead of 14 H,18 R and Mg_(24)Y_(5) were presented in the modified isothermal sections.The latter three-phase equilibrium was reported in the available literature.The modified isothe rmal sections are conducive to guide the composition design to obtain the alloys with favorable microstructure constituents and mechanical properties.

关键词： Mg-Y-Zn system LPSO phases solubility thermodynamic stability isothermal sections

Two-dimensional interface superstructures assembled by well-ordered solute atoms

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Journal of Materials Science & Technology 2023年第11期142卷 253-259页

作者： Peijun Yang Shanshan Li Hongbo Xie Jianfeng Jin Chuangwei Liu Hucheng Pan Yuping Ren Weitao Jia Yaping Zong Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China School of Mechanical and Power Engineering Shenyang University of Chemical TechnologyShenyang 110142China College of Mechanical Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China

Segregation of solutes/impurities in the interfaces plays a decisive role in material performances.However,the segregation of solutes/impurities remains elusive due to the diversity of interfacial structures.Here,in a Mg-Nd-Mn ternary model system,two ordered novel two-dimensional(2D)interfacial superstructures formed by periodic segregation of solute atoms in special symmetric and asymmetric tilt grain boundaries(GBs)have been systematically investigated.Z-Contrast high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)observations provided the atomic-level details on how solute atoms were arranged on these special partially coherent tilt GBs.The strained conditions of each atomic site at the tilt GBs were accurately reproduced by molecular dynamics(MD)simulations plus Voronoi analysis,and the rationality of solute segregation in each atomic-site was evaluated carefully based on the first-principles calculations.These findings expand our knowledge of solute/impurity segregation behaviors in the interfaces,especially the co-segregation behaviors in multi-component materials.

关键词： Magnesium alloy Interfacial segregation Molecular dynamics First-principles HAADF-STEM

Variable precipitation behaviors of Laves phases in an ultralight Mg-Li-Zn alloy

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镁合金学报(英文) 2023年第6期11卷 2018-2026页

作者： Weixin Lou Hongbo Xie Xiaobo Zhao Junyuan Bai Hehang Zhang Yi Wang Xinze Li Hucheng Pan Yuping Ren Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Research Center for Metal Wires Northeastern UniversityShenyang 110819China

Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a specific habit plane owing to the constraint of free-energy minimization of the system.Herein,in an aged ultralight Mg-Li-Zn alloy,we confirmed that the precipitates dominated by C15 Laves structure could form in a variety of habit planes,to generate three forms of strengthening-phases,i.e.,precipitate-rod,precipitate-lath,and precipitate-plate.Among which,the precipitate-plates are on basal plane as usually but precipitate-rods/laths are on non-basal plane,and such non-basal precipitates would transform into the basal(Mg,Li)Zn_(2)Laves structure with prolonged aging.These findings are interesting to understand the precipitation behaviors of multi-domain Laves structures in hexagonal close-packed crystals,and expected to provide a guidance for designing ultralight high-strength Mg-Li based alloys via precipitation hardening on the non-basal planes.

关键词： Laves phase Precipitation Habit plane Orientation Magnesium alloys

Anomalous crystal structure of γ" phase in the Mg-RE-Zn(Ag) series alloys:Causality clarified by ab initio study

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Journal of Materials Science & Technology 2020年第1期36卷 167-175页

作者： Junyuan Bai Xueyong Pang Xiangying Meng Hongbo Xie Hucheng Pan Yuping Ren Min Jiang Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Research Center for Metallic Wires Northeastern UniversityShenyang 110819China

The crystal structure of the single-unit-cell thickness γ " phase,as a key strengthening phase in Mg-REZn(Ag) series alloys,has been extensively studied,and several structural models have been proposed in the past two decades.However,these reported models,and even the lattice constants at the same proposed structure,are scattered severely,which has led to considerable confusion and not available for further mechanical property simulation and prediction of Mg alloys containing this phase.In this study,by using first-principles calculations,the crystal structure of y" phase is clarified,resolving the discrepancies among different experiments,and its intrinsic mechanical properties have also been studied for the first time.It is verified that the γ " phase contains quasi-five atomic layers,instead of the previously reported tri-layer,and surprisingly,its crystal structure has many variants,which would change with the alloy composition.Besides,with the help of the simulated selected area electron diffraction(SAED) patterns,it is found that the atoms in the central layer remain partially ordered distribution,and this ordered extent primarily depends on the atomic ratio of RE:Zn(Ag) and the solute content in an alloy.That is,the ordered extent increases with decreasing the atomic ratio of RE:Zn(Ag) and/or increasing solute content of alloy,and vice versa.Ag and Zn dissolved in the γ" phase would produce almost opposed mechanical anisotropy for the γ " phase under the identical crystal structure,and the addition of Ag shows more efficient on increasing the shear modulus of γ" phase.

关键词： First-principles γ"phase Mg-RE-based series alloys Crystal structure Mechanical-properties

Network pharmacology and molecular docking identify mechanisms of medicinal plant-derived 1,2,3,4,6-penta-O-galloyl-beta-D-glucose treating gastric cancer

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BIOCELL 2023年第5期47卷 977-989页

作者： MAN ren YUAN YANG DAN LI NANNAN ZHAO yuping WANG YONGNING ZHOU The First Clinical Medical College Lanzhou UniversityLanzhou730000China Gansu Key Laboratory of Gastroenterology Lanzhou UniversityLanzhou730000China Department of Geriatrics Gerontology The First Hospital of Lanzhou UniversityLanzhou730000China Office of National Drug Clinical Trial Institutions The First Hospital of Lanzhou UniversityLanzhou730000China School of Pharmacy Lanzhou UniversityLanzhou730000China Department of Gastroenterology The First Hospital of Lanzhou UniversityLanzhou730000China

Background:1,2,3,4,6-penta-O-galloyl-beta-D-glucose(PGG)is a natural polyphenolic compound derived from multiple medicinal plants with favorable anticancer activity.Methods:In this study,the mechanisms of PGG against gastric cancer were explored through network pharmacology and molecular docking.First,the targets of PGG were searched in the Herbal Ingredients’Targets(HIT),Similarity Ensemble Approach(SEA),and Super-PRED databases.The potential targets related to gastric cancer were predicted from the Human Gene Database(GeneCards)and DisGeNET databases.The intersecting targets of PGG and gastric cancer were obtained by Venn diagram and then subjected to protein-protein interaction analysis to screen hub targets.Functional and pathway enrichment of hub targets were analyzed through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway databases.The differential expression and survival analysis of hub targets in gastric cancer were performed based on The Cancer Genome Atlas database.Finally,the affinity of PGG with hub targets was visualized by molecular docking.Results:Three hub targets were screened,including mitogen-activated protein kinase 14(MAPK14),BCL2 like 1(BCL2L1),and vascular endothelial growth factor A(VEGFA).MAPK14 had a higher expression,while BCL2L1 and VEGFA had lower expression in gastric cancer than in normal conditions.Enrichment analysis indicated enrichment of these hub targets in MAPK,neurotrophin,programmed death-ligand 1(PD-L1)checkpoint,phosphatidylinositol 3-kinases/protein kinase B(PI3K-Akt),Ras,and hypoxia-inducible factor-1(HIF-1)signaling pathways.Conclusion:Therefore,network pharmacology and molecular docking analyses revealed that PGG exerts a therapeutic efficacy on gastric cancer by multiple targets(MAPK14,BCL2L1,and VEGFA)and pathways(MAPK,PD-L1 checkpoint,PI3K-Akt,Ras,and HIF-1 pathways).

关键词： 1,2,3,4,6-penta-O-galloyl-beta-D-glucose Gastric cancer Network pharmacology Molecular docking MAPK14 BCL2L1 VEGFA

In-situ constructing Cu_(1)Bi_(1)bimetallic catalyst to promote the electroreduction of CO_(2)to formate by synergistic electronic and geometric effects

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Journal of Energy Chemistry 2023年第4期79卷 263-271页

作者： Houan ren Xiaoyu Wang Xiaomei Zhou Teng Wang yuping Liu Cai Wang Qingxin Guan Wei Li College of Chemistry State Key Laboratory of Elemento-Organic ChemistryKey Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)Nankai UniversityTianjin 300071China

Electrochemical CO_(2)reduction to formate is a potential approach to achieving global carbon neutrality.Here,Cu1Bi1bimetallic catalyst was prepared by a co-precipitation method.It has a ginger like composite structure(CuO/CuBi_(2)O_(4))and exhibited a high formate faradaic efficiency of 98.07%at–0.98 V and a large current density of–56.12 mA.cm^(-2)at–1.28 V,which is twice as high as Bi2O3catalyst.Especially,high selectivity(FE^(–)_(HCOO)>85%)is maintained over a wide potential window of 500 mV.In-situ Raman measurements and structure characterization revealed that the reduced Cu1Bi1bimetallic catalyst possesses abundant Cu-Bi interfaces and residual Bi-O structures.The abundant Cu-Bi interface structures on the catalyst surface can provide abundant active sites for CO_(2)RR,while the Bi-O structures may stabilize the CO_(2)^(*–)intermediate.The synergistic effect of abundant Cu-Bi interfaces and Bi-O species promotes the efficient synthesis of formate by following the OCHO^(*)pathway.

关键词： CO_(2)electroreduction Bimetallic catalyst Formate Cu-Bi interfaces Bi-O structure

Effect of extrusion speed on microstructure and mechanical properties of the Mg-Ca binary alloy

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Journal of Magnesium and Alloys 2021年第4期9卷 1304-1310页

作者： Jingren Li Aiyue Zhang Hucheng Pan Yuping Ren Zhuoran Zeng Qiuyan Huang Changlin Yang Lifeng Ma Gaowu Qin Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819China Department of Materials Science and Engineering Monash UniversityVic.3800Australia Institute of Metal Research Chinese Academy of SciencesShenyang 110016China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072China Shanxi Provincial Key Laboratory of Metallurgical Equipment Design and Technology Taiyuan University of Science and TechnologyTaiyuan 030024China

This work reported the effect of extrusion speeds on the microstructures and mechanical properties of Mg-Ca binary alloy.The results showed that yield strength of the as-extruded Mg-1.2wt.%Ca alloys decrease from∼360MPa to∼258MPa as the ram speed increases from 0.4mm/s to 2.4 mm/s,and the elongation increases from∼3.9%to∼12.2%.The microstructure changes from bimodal grain feature to the complete dynamical recrystallization(DRX)with increase of the extrusion speed.The ultrafine DRXed grains in size of∼0.85μm,the numerous nano-Mg_(2)Ca particles dispersing along the grain boundaries and interiors,as well as the high density of residual dislocations,should account for the high strength.It is believed that the high degree of dynamic recrystallization and the resulting texture randomization play the critical roles in the ductility enhancement of the high-speed extruded Mg alloys.

关键词： Extrusion speed Microstructure Mechanical properties Mg-Ca alloy

Achieving high strength above 400 MPa in conventionally extruded Mg-Ca-Zn ternary alloys

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Science China(Technological Sciences) 2022年第3期65卷 519-528页

作者： DU Sen YANG Kun LI Man LI Jingren ren yuping HUANG QiuYan PAN HuCheng QIN GaoWu Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang 110819China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

In this work,the role of Zn content in modifying the microstructure and mechanical properties of the Mg-1.2Ca-xZn(x=0.6,2.0 wt.%,named as XZ10-0 and ZX21-0,respectively)based alloys was studied,and it is found that the yield strength(YS)of the present Mg-(Zn)-Ca based alloys increases monotonically with increasing the Zn concentration,from~339 MPa in low-Zn content XZ10-0 sample to~406 MPa in high-Zn content ZX21-0 sample.Microstructure characterization shows that the enhanced YS can be attributed to the grain refinement,fine and dispersed nano-phases,a large number of lamellae structures,and the decrease of recrystallization fraction.TEM results show that the formation mechanism for the ultra-fine grains in present Mg-(Zn)-Ca based alloys can be attributed to the co-segregation of Ca and Zn elements at the grain boundary,as well as the dynamic nanoprecipitations.When the Zn content is high,the nano-phases in ZX21-0 sample belong to the Ca;Mg;Zn;ternary phases,which exert much higher thermal stability than the nano-sized Mg2 Ca binary phases formed in the low-Zn content XZ10-0 sample.The finer size and higher number density of the nano-Mg Zn Ca phases lead to the much finer grain size and sub-grain lamellae thickness in ZX21-0 sample,which thus results in the higher YS of~406 MPa.

关键词： wrought Mg alloy dynamic recrystallization mechanical property co-segregation