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Orientation dependence of mechanically induced grain boundary migration in nano-grained copper

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Journal of Materials Science & Technology 2021年第9期68卷 30-34页

作者： J.x.Hou x.y.li K.Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of China.Hefei 230026China

Tensile tests were carried out on gradient nanograined copper samples to investigate the grain orientation dependence of mechanically induced grain boundary migration(GBM) process. The relationship between GBM and the orientations of nanograins relative to loading direction was established by using electron backscatter diffraction. GBM is found to be more pronounced in the grains with higher Schmid factors where dislocations are easier to slip. As a result, the fraction of high angle grain boundaries decreases and that of low angle grain boundaries increases after GBM.

关键词： Grain boundary migration Orientation dependence Texture Nano-grain Copper

EFFECT OF CHEMICAL COMPOSITION AND PROCESSES ON THE TExTURE OF HOT-ROLLED DEEP DRAWING STEEL SHEET

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Acta Metallurgica Sinica(English Letters) 2002年第3期15卷 324-330页

作者： y.Chen x.Chen C.y.li x.y.li y.L.Kang Technical Center of Wuhan Iron and Steel Group Co. Wuhan 430080China Wuhan University of Science and Technology Wuhan 430080China Central General Iron and Steel Research Institute Beijing 100081China University of Science and Technology Beijing Beijing 100083China

A hot-rolled deep drawing(HDD)steel with high r-value and uniformdistribution of{111}texture in thickness was developed by hot rolling in ferrite region withlubricating between the roller and the *** experimental results show that the carbon contentand finish rolling temperature have significant effects on beneficial texture{111},and lubricatingduring hot rolling at low temperature in alpha-region makes the distribution of the *** basic requirements needed to meet for HDD steel were concluded by comparing differentcarbon contents and hot rolling processes.

关键词： ultra low carbon hot rolling in alpha-region lubricating r-value {111}texture

Transition of deformation mechanisms from twinning to dislocation slip in nanograined pure cobalt

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Journal of Materials Science & Technology 2022年第26期121卷 124-129页

作者： y.W.Qi Z.P.Luo x.y.li K.Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Deformation mechanisms of nanograined and submicron-grained pure cobalt processed by means of high strain rate shear deformation at cryogenic temperatures were *** analysis revealed a transition of governing deformation mechanism from deformation twinning and dislocation slip in submicron-grains to and dislocations slip in *** tests illustrated that the Hall-Petch relation slope changes consequently with the transition of deformation mechanism.

关键词： Nanograin Cobalt Deformation mechanism Hall-Petch relation

Thermal stability of nanograins with grain boundary relaxation in microalloyed Cu-Sb and Cu-Fe

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Journal of Materials Science & Technology 2023年第24期155卷 66-71页

作者： R.J. Zhu x.Zhou x.y. li Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Materials Science and Engineering University of Science and Technology of China Shenyang 110016 China

Grain refinement into nanoscale significantly enhances the strength and hardness of metallic materials but generally reduces the thermal stability by the introduced strong tendency for grain boundary(GB)*** nanograins through GB relaxation had been proven as an effective way in several metals recently when the grain size is below a critical ***,we discovered that the abnormally enhanced thermal stability induced by GB relaxation can be realized in 0.5%Sb or Fe doped Cu,similar to that in pure *** observed critical grain sizes for GB relaxation in the two Cu alloys are almost the same as pure ***,the GB relaxation effect on thermal stability is kind of suppressed compared to pure Cu with similar grain sizes because of the segregation/precipitation of Sb/Fe during the annealing process,which accelerates the detwinning and the failure of relaxed GBs.

关键词： Thermal stability Grain boundary relaxation Nanograined Cu alloy Segregation Precipitate

Multiple time step molecular dynamics simulation for interaction between dislocations and grain boundaries

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Acta Mechanica Sinica 2005年第4期21卷 371-379页

作者： x.y.li W.yang Department of Engineering Mechanics,Tsinghua University,Beijing 100084.China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

A multiple time step algorithm, called reversible reference system propagator algorithm, is introduced for the long time molecular dynamics simulation. In contrast to the conventional algorithms, the multiple time method has better convergence, stability and efficiency. The method is validated by simulating free relaxation and the hypervelocity impact of nano-clusters. The time efficiency of the multiple time step method enables us to investigate the long time interaction between lattice dislocations and low-angle grain boundaries.

关键词： Multiple time step Molecular dynamics ,Dislocation Grain boundary

Compression Stability of Reversed Austenite in 9Ni Steel

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Journal of Materials Science & Technology 2012年第6期28卷 558-561页

作者： S.H.Chen M.J.Zhao x.y.li L.J.Rong Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The effect of compressive stress on the stability of reversed austenite in gNi steel was investigated by uni- axial and hydrostatic compression. It was found that the uniaxial compressive pressure promoted the Υ-α transformation, while the hydrostatic pressure suppressed the -Υ-α transformation. The pressure dependent transformation behavior can be explained according to thermodynamic analysis.

关键词： 9Ni steel Martensite Reversed austenite Hydrostatic pressure Uniaxial compressive pressure

STUDy ON DyNAMIC J-INTEGRAL OF MECHANICAL HETEROGENEOUS WELDED JOINT

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 934-939页

作者： F.Q.Tian D.y.He x.y.li y.W.Shi D.Zhang InstituteofCompositeMaterials ShanghaiJiaotongUniversityShanghai200030China SchoolofMaterialsScienceandEngineering BeijingPolytechnicUniversityBeijing100022China

Welded joint is a mechanical heterogeneous body, and mechanical heterogeneity has great effect on dynamic fracture behaviour of welded joints. In the present investigation, dynamic response curve and dynamic J-integral of practical undermatched welded joint and whole base and whole weld three-point-bend (TPB) models containing longitudinal crack are com- puted. Dynamic J-integral is evaluated using virtual crack extension (VCE) method and the computation is performed using MARC finite element code. Because of the effect of inertia, dynamic load response curve of computed model waves periodically. Dynamic J-integral evaluated by VCE method is path independent. The effect of inertia has little influence on dynamic J-integral curve. The value of dynamic J-integral of undermatched welded joint is lower than that of whole base metal and higher than that of whole weld metal. The results establish the foundation of safety evaluation for dynamic loaded welded structures.

关键词： virtual crack extension welded joint dynamic response curve dynamic J-integral

Experimental and numerical study of the effect of pulsatile flow on wall displacement oscillation in a flexible lateral aneurysm model

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Acta Mechanica Sinica 2019年第5期35卷 1120-1129页

作者： L.Z.Mu x.y.li Q.Z.Chi S.Q.yang P.D.Zhang C.J.Ji y.He G.Gao School of Energy and Power Engineering Dalian University of TechnologyDalian 116024China School of Biomedical Engineering Capital Medical UniversityBeijing 100069China The First Affiliated Hospital of University of Science and Technology of China Hefei 230036China

This study experimentally and numerically investigated the effect of pulsatile flow of different frequencies and outflow resistance on wall deformation in a lateral aneurysm.A method for constructing a flexible aneurysm model was developed,and a self-designed piston pump was used to provide the pulsatile flow conditions.A fluid-structure interaction simulation was applied for comparison with and analysis of experimental *** maximum wall displacement oscillation increased as the pulsation frequency and outflow resistance increased,especially at the aneurysm *** is an obvious circular motion of the vortex center accompanying the periodic inflow fluctuation,and the pressure at the aneurysm dome at peak flow increased as the pulsatile flow frequency and terminal flow resistance *** results could explain why abnormal blood flow with high frequency and high outflow resistance is one of the risk factors for aneurysm rupture.

关键词： Lateral aneurysm In vitro experiment Pulsatile flow Wall displacement oscillation Fluid-structure interaction simulation

A novel species of Diaporthe causing twig blight of Phellodendron chinense in Sichuan,China

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A novel species of Diaporthe causing twig blight of Phellode...