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Journal of magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.lv H.l.Ge Q.Q.Jin x.H.Shao Y.T.Zhou B.Zhang x.l.ma Shenyang National laboratory for materials Science Institute of Metal Research Chinese Academy of Sciences School of materials Science and Engineering University of Science and Technology of China materials Science and Engineering Research Center Guangxi University of Science and Technology

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K, wt.%)alloy to improve the hardness. The results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250 ℃ is 1.64 GPa, which is approximately 64% higher than that of the samples before being treated. It is mainly attributed to γ' precipitates on the basal plane after irradiation and the high-density nanoscale β' precipitates on the prismatic plane after aging, which should be closely related to the irradiation-induced homogenous clusters. The latter plays a key role in precipitation hardening. This result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation Hardening Precipitates In-situ TEM

Structure evolution of the Fe_(3)C/Fe interface mediated by cementite decomposition in cold-deformed pearlitic steel wires

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Journal of materials Science & Technology 2022年第6期101卷 28-36页

作者： Y.T.Zhou x.H.Shao S.J.Zheng x.l.ma Shenyang National laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Tianjin Key laboratory of materials laminating Fabrication and Interface Control Technology School of Materials Science and EngineeringHebei University of TechnologyTianjin 300130China

Cold-drawn pearlitic steel wire is irreplaceably used in industry owing to its outstanding mechanical property which is dominated by the cementite/ferrite(Fe_(3)C/Fe) interfaces in the material. However, the fine structures of the Fe3C/Fe interfaces in the deformed wires are less known to date. In this work, transmission electron microscopic investigation was performed on the atomic structures of the interfaces with the Isaichev orientation relationship(OR) in the wires with progressive deformation strains. In addition to the effect of the dislocation/interface interactions, this work revealed that the deformation-induced partial decomposition of cementite plays an important role in the interface reconstruction during deformation. The interfacial carbon vacancies generated by cementite decomposition and particularly, the amorphization of cementite layers in the sample with ε > 1 could effectively annihilated the interfacial dislocations and consequently relaxed the interfacial stress. The correlations between the interface structure changes and the mechanical properties of the wires were discussed.

关键词： Pearlitic steel Cementite decomposition Interface structure Deformation Transmission electron microscopy

Synergetic deformation mechanisms in an Mg-Zn-Y-Zr alloy with intragranular lPSO structures

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Journal of magnesium and Alloys 2023年第5期11卷 1754-1768页

作者： Z.Z.Peng x.H.Shao Z.M.liang D.l.Wang l.W.Wang x.l.ma Hebei Key laboratory of material Near-Net Forming Technology School of Materials Science and EngineeringHebei University of Science and TechnologyShijiazhuang 050018China Shenyang National laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences72 Whenua RoadShenyang 110016China

Deformation kink is one of the important strengthening mechanisms of the long-period-stacking-ordered(lPSO)phase containing magnesium(Mg)alloys,while the deformation twin is generally suppressed.To optimize the mechanical properties of lPSO containing Mg alloy by simultaneously exciting kink and twin,we successfully prepared the Mg-Zn-Y-Zr alloy featuring intragranular lPSO phase and free grain boundary lPSO phase by homogenization.We unraveled the corresponding strengthening and toughening mechanisms through transmission electron microscopy characterization and theoretical analysis.The high strength and good plasticity of the homogenized alloy benefit from the synergistic deformation mechanism of multiple kinking and twining in the grains.And the activation of kinking and twinning depends on the thicknesses of lPSO lamellae and their relative spacing.These results may shed light on optimizing the design of Mg alloys regulating the microstructure of lPSO phases.

关键词： Mg alloy lPSO distribution Kink Twin Transmission electron microscopy

Formation of β' phase in lPSO structures in an Mg88Co5Y7 alloy

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Journal of magnesium and Alloys 2022年第1期10卷 175-182页

作者： Q.Q.Jin x.H.Shao Y.T.Zhou B.Zhang S.J.Zheng x.l.ma Shenyang National laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua Road110016 ShenyangChina materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China School of materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China

Formation of β’ phase in long-period stacking ordered(lPSO) structures in an Mg;Co;Y;(at.%) alloy after aging at 200 °C for 24 h or electron beam(EB) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM). β’ phase was precipitated only in the Mg matrix but not in lPSO structures after aging at 200 °C for 24 h. lPSO structure containing stacking defects transforms into the β’-long phase during EB irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β’(lPSO) structures formed in the alloy after EB irradiation, such as β’(12 H) structure with an orthorhombic lattice(Mg;Y, Cmcm,a = 2 _(a0)= 0.642 nm, b=4√3_(a0), c = 6 _(c0)= 3.12 nm).

关键词： magnesium alloys long-period stacking ordered(lPSO)structure HAADF-STEM β’phase

The role of melt cooling rate on the interface between 18R and Mg matrix in Mg_(97)Zn_(1)Y_(2) alloys

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Journal of magnesium and Alloys 2023年第8期11卷 2883-2890页

作者： Q.Q.Jin x.H.Shao J.M.li Z.Z.Peng M.lv B.Zhang Y.M.li x.l.ma materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China Shenyang National laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering Hebei University of Science and TechnologyShijiazhuangHebei 050018China

The role of melt cooling rate on the interface morphology and dislocation configuration between 18R long-period stacking ordered(lPSO)structure and Mg matrix in Mg_(97)Zn_(1)Y_(2)(at.%)alloys was investigated by atomic-scale HAADF-STEM imaging.The 18R/Mg interface is step-like both in the near-equilibrium alloy and non-equilibrium alloy.lower cooling rate makes the step size more regular and larger.Only 54R structure can be observed at the interface in the near-equilibrium alloy,and the dislocations are highly ordered.54R and 54R′structure sandwiched by b1 and b2+b3 dislocation arrays,and new dislocation configuration can be detected at the interface in the non-equilibrium alloy,but the dislocations are less ordered.18R/Mg interface containing 54R or 54R′in equilibrium width,parallel to the(010)plane,should be most stable based on elastic calculation.The segregation of solute atoms and its strong interaction with dislocations dominate the lPSO/Mg interface via diffusion-displacive transformation.

关键词： magnesium alloys long-period stacking ordered phases Dislocations Interface structure

A review——Pitting corrosion initiation investigated by TEM

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Journal of materials Science & Technology 2019年第7期35卷 1455-1465页

作者： B.Zhang x.l.ma Shenyang National laboratory for materials Science Institute of Metal Research Chinese Academy of Sciences

Passive metals have superior resistance to general corrosion but are susceptible to pitting attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, the mechanism of pitting corrosion has attracted corrosion community striving to study. However, the mechanism at the pitting initiation stage is still controversy, due to the difficulty encountered in obtaining precise experimental information with enough spatial resolution.Tracking the accurate sites where initial dissolution occurs as well as the propagation of the dissolution by means of multi-scale characterization is key to deciphering the link between microstructure and corrosion at the atomic scale and clarifying the pitting initiation mechanism. Here, we review our recent progresses in this issue by summarizing the results in three representative materials of 316F, and Super 304H stainless steel as well as 2024-Al alloy, using in situ ex-environmental TEM technique.

关键词： Pitting initiation Dissolution TEM Inclusion Second phase

Microstructure of Si Cones Prepared by Ar^+-Sputtering Si/Mo Target

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Journal of materials Science & Technology 2002年第2期18卷 173-175页

作者： x.l.ma N.G.Shang 等 ShenyangNationallaboratoryformaterialsScience InstituteofMetalResearchChineseAcademyofSciencesShenyang110016China CenterofSuper-DiamondandAdvancedFilms&DepartmentofPhysicsand

By Ar+ sputtering onto Si wafers which were surrounded by Mo plates, uniform cones over a large area on the Si surface were formed. Scanning electron microscopic study showed that the cones were formed on the entire surface of the Si wafer. The dimensions of the uniform cones were one micrometer in diameter and 5similar to6 micrometer's high. They were further characterized by means of cross-sectional transmission electron microscopy, with the technique of micro-diffractions. It was found that the cone contained a pure Si regime and a Mo-rich regime. In the binary Mo-Si zone, we identified three distinct areas vertically: (1) domains of Mo-induced Si ordered structures, (2) a small volume of a new Mo3Si2 structural variant, intergrown with the Si ordered structure, and (3) a small amount of pure Mo nanoparticles covering the surface of the cones. The formation of the large and uniform cones may provide a new surface configuration for potential applications in surface science and technology.

关键词： Si cones Ordered structure Mo silicide

Achieving high hetero-deformation induced(HDI)strengthening and hardening in brass by dual heterostructures

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Journal of materials Science & Technology 2022年第3期98卷 244-247页

作者： x.T.Fang Z.K.li Y.F.Wang M.Ruiz x.l.ma H.Y.Wang Y.Zhu R.Schoell C.Zheng D.Kaoumi Y.T.Zhu Department of materials Science and Engineering North Carolina State UniversityRaleighNC 27695USA Key laboratory for Anisotropy and Texture of materials of Ministry of Education Northeastern UniversityShenyang 110819China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China Department of materials Science and Engineering Texas A and M UniversityCollege StationTX 77840USA Department of Mechanical and Aerospace Engineering North Carolina State UniversityRaleighNC 27695USA Department of Nuclear Engineering North Carolina State UniversityRaleighNC 27695USA Science and Technology on Thermostructural Composite materials laboratory Northwestern Polytechnical UniversityXi’an 710072China

Heterostructured materials,defined as materials that contain multiple zones with dramatically different flow stresses,have the potential to push the envelope of the strength-ductility of metals and alloys beyond what can be obtained conventionally[1–3].A prominent example is the heterogeneous lamella Ti that is as strong as its ultrafine-grained Ti,while as ductile as the coarsegrained Ti[4].

关键词： grain strengthening deformation

Microstructural evolution and mechanical properties of Mg-9.8Gd-2.7Y-0.4Zr alloy produced by repetitive upsetting

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Journal of materials Science & Technology 2018年第7期34卷 1067-1075页

作者： H.Zhou H.Y.Ning x.l.ma D.D.Yin l.R.xiao x.C.Sha Y.D.Yu Q.D.Wang Y.S.li Nano and Heterogeneous materials Center School of Materials and EngineeringNanjing University of Science and TechnologyNanjing210094China Institute of Microstructure and Property of Advanced materials Beijing University of TechnologyBeijing 100124China School of Mechanical and Electrical Engineering Heilongjiang Institute of TechnologyHeilongjiang 150050China School of materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040China Department of materials Science&Engineering North Carolina State UniversityRaleighNC 27695USA Key laboratory of Advanced Technologies of materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengduSichuan 610031China National Engineering Research Center of light Alloys Net Forming and State Key Laboratory of Metal Matrix CompositeShanghai Jiao Tong University200240 ShanghaiChina

A newly developed severe plastic deformation （SPD） technique, i.e. repetitive upsetting （RU）, is employed to improve the strength and ductility of a Mg-Gd-Y-Zr alloy. During the RU processing, dynamic recrystallization occurs in the Mg alloy, which leads to a significant grain refinement from 11.2 p.m to 2.8 μm. The yield strength （YS）, ultimate tensile strength （UTS） and elongation increase simultaneously with increasing RU passes. The microstructural evolution is affected by processing temperatures. Dynamic recrystallization prevails at low temperatures, while dynamic recovery is the main effect factor at high temperatures. Texture characteristics gradually become random during multiple passes of RU processing, which reduces the tension-compression asymmetry of the Mg-Gd-Y-Zr alloy. 2018 Published by Elsevier ltd on behalf of The editorial office of Journal of materials Science ＆ Technology.

关键词： Severe plastic deformation （SPD） Repetitive upsetting （RU） Mg-RE alloy Mechanical properties

INDExING OF x-RAY POWDER DIFFRACTOGRAMS OF PHASES WITH GIANT UNIT-CEllS WITH THE AID OF ElECTRON DIFFRACTION PATTERNS

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INDEXING OF X-RAY POWDER DIFFRACTOGRAMS OF PHASES WITH GIANT...