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Shear banding-inducedslip enables unprecedented strength-ductility combination of laminated metallic composites

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Journal of Materials Science & Technology 2022年第15期110卷 260-268页

作者： Shuang Jiang Ru Lin Peng Kristián Máthis Hai-Le Yan Gergely Farkas Zoltán Hegedues Ulrich Lienert Johan Moverare Xiang Zhao Liang Zuo Nan Jia Yan-Dong Wang Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China Division of Engineering Materials Department of Management and EngineeringLinköping UniversityLinköping 58183Sweden Department of Physics of Materials Faculty of Mathematics and PhysicsCharles UniversityKe Karlovu 5Prague 12116Czech Republic Nuclear Physics Institute of the Czech Academy of Sciences Rež130Husinec-ˇRež25068Czech Republic Deutsches Elektronen-Synchrotron(DESY) Notkestr.85Hamburg 22607Germany Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijing 100083China

Shear bands in metallic materials have been reported to be catastrophic because they normally lead to non-uniform plastic deformation. Ductility of laminated metallic composites deteriorates with increasing processing strain, particularly for those having hexagonal-close-packed(hcp) constituents due to inadequate slip systems and consequently prominent shear banding. Here, we propose a design strategy that counterintuitively tolerates the bands with localized strains, i.e. the shear banded laminar(SBL) structure, which promotes dislocation activation in hcp metals and renders unprecedented strengthductility combination in hcp-metal-based composites fabricated by accumulative roll bonding(ARB). The SBL structure is characterized with one soft hcp metal constrained by adjacent hard metal in which dislocations have been accumulated near the bimetal interfaces. High-energy X-ray diffraction astonishingly reveals that more than 90% of dislocations are non-basal in Ti layers of the SBL Ti/Nb composite processed by eight ARB cycles. Moreover, dislocations occupy a high fraction of ~30%, promoting further cross slip. The unique stress field tailored by both shear banding and heterophase interface-mediated deformation accommodation triggers important slip. This SBL design is of significance for developing hcp-based laminates and other heterostructured materials with high performances.

关键词： Shear band Laminated metallic composites Ductility High-energy X-ray diffraction dislocation slip

Unveiling the twinning and dynamic recrystallization behavior and the resultant texture evolution in the extruded Mg-Bi binary alloys during hot compression

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Journal of Materials Science & Technology 2022年第10期105卷 274-285页

作者： Yu-qin Zhang Wei-li Cheng Hui Yu Hong-xia Wang Xiao-feng Niu Li-fei Wang Hang Li School of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of Education Taiyuan University of TechnologyTaiyuan 030024China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300132China

The twinning behavior, dynamic recrystallization(DRX) mechanism and the resultant texture evolution of the extruded Mg-xBi(x=0.5 wt.%, 2.0 wt.%) alloys were systematically investigated during hot compression at the strain rate of 10 s^(-1) and temperature of 200℃. The results indicate that the types and intensities of the texture are greatly dependent on the twining behavior and DRX mechanism. At the initial stage, the evolution of texture is mainly domination by the formation and variation of {1012} extension twins, which is benefcial to the compression direction(CD)-tilted basal texture. With an increase in the strain, the texture evolution is more greatly regulated by the DRX mechanism. Besides, the pyramidal slip and basal slip are activated during the compression process, resulting in the Schmid factors(SF) of pyramidal slip remain at ~0.4 and the average SFs for basal slip increase from 0.2 to0.34 as the strain increase. These fndings provide a new insight into controlling the texture of wrought Mg-Bi-based alloys during hot deformation processing.

关键词： Wrought Mg-Bi alloys Hot deformation Twinning Dynamic recrystallization dislocation slip Texture

Anisotropic cyclic deformation behavior of an extruded Mg-3Y alloy sheet with rare earth texture

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Journal of Magnesium and Alloys 2022年第6期10卷 1581-1597页

作者： Tianjiao Li Jinsong Rao Jiang Zheng Dongdi Yin Haoge Shou Yongfa Zhang Rong Shi Weichao Jing Lihong Xia International Joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing University174 Shazhengjie StreetShapingba DistrictChongqing 400044China Shenyang National Laboratory for Materials Science Chongqing UniversityChongqing 400044China Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengduSichuan 610031China College of Mechanical Engineering Chongqing Technology and Business UniversityChongqing 400067China

Mg-RE(magnesium-rare earth)alloys exhibit pronounced in-plane anisotropy of mechanical response under quasi-static monotonic loading resulting from the RE texture,as extensively reported.In this work,an obvious in-plane anisotropy of cyclic deformation behavior was observed in an extruded Mg-3Y alloy sheet during strain-controlled tension-compression low-cycle fatigue(LCF)at room temperature.The extrusion direction(ED)samples displayed better fatigue resistance with almost symmetrical hysteresis loops and longer fatigue life compared with the transverse direction(TD)samples.The influences of texture on the deformation modes,cracking modes,and mechanical behavior of Mg-Y alloy sheets under cyclic loading were studied quantitatively and statistically.The activation of various slip/twinning-detwinning systems was measured at desired fatigue stages via EBSD observations together with in-grain misorientation axes(IGMA)analysis.The results indicate that the activation of deformation modes in the TD sample was featured by the cyclic transition,i.e.,prismatic slip(at the tensile interval)→{10–12}tension twinning(at the compressive reversal)→detwinning+prismatic slip(at the re-tensile reversal).In the case of the ED sample,the cyclic deformation was dominated by the basal slip throughout the fatigue life.For cracking modes,intergranular cracking and persistent slip bands(PSB)cracking were the primary cracking modes in the ED sample while the TD sample showed a high tendency of{10–12}tension twinning cracking(TTW cracking).The underlying mechanisms influencing the activation of various slip/twinning-detwinning systems,as well as cracking modes and cyclic mechanical behavior,were discussed.

关键词： Anisotropic cyclic deformation dislocation slip Twinning-detwinning Cracking modes Mechanical behavior

Microstructural Evolution of Rapidly Solidified ZK60 Powders during Extrusion

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Journal of Materials Science & Technology 2011年第2期27卷 159-164页

作者： Zhenya Zhang Huashun Yu Shaoqing Wang Hui Yu Guanghui Min Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials Ministry of EducationShandong UniversityJinan 250061China School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China

The microstructural evolution of rapidly solidified（RS） ZK60 powders extruded at 250 C was investigated.It was shown that formation of new ultrafine grains took place through continuous dynamic recrystallization（CDRX）,accompanied by the perfect bonding of powders via severe plastic deformation.At a low strain level,a well-defined structure made up of equiaxed and elongated subgrains was developed.Simultaneously,the operation of basal and non-basal dislocation slip led to the formation of low-angle dislocation cells（LADC） within the elongated subgrains.With increasing strain,the number and average misorientation of LADC increased,resulting in fragmentation of original elongation subgrains into a finally homogeneous fine-grained structure.Almost full-recrystallized structure with an average grain size of 0.4 μm was finally evolved after large cumulative strain.The results suggested that structural change was connected with thermal strain,where dislocation activities dominated this process.

关键词： Microstructure Extrusion ZK60 powders dislocation slip

Tensile and fracture properties of an Mg-RE-Zn alloy at elevated temperatures

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Journal of Rare Earths 2014年第6期32卷 564-572页

作者： TROJANOVZuzanka DONI Tibor LUK Pavel PALEK Peter CHALUPOV Mária TILLOV Eva BASTOVANSKY Ronald Faculty of Mathematics and Physics Charles University Faculty of Mechanical Engineering University of Zilina

Magnesium alloy EZ10 （Mg-RE-Zn） was deformed in tension at temperatures from 20 up to 520℃. A rapid decrease of the yield and tensile strength with temperature was observed at temperatures higher than 300 ℃. On the other hand, ductility of sam-ples rapidly increased in the same temperature range. Light microscopy and scanning electron microscopy was used to reveal the rea-son for these behaviours. Intermetallic particles in grain boundaries are responsible for excellent mechanical properties at lower tem-peratures. Diffusional processes occurring at temperatures higher than 300 ℃ significantly influenced the deformation mechanism as well as the fracture character.

关键词： magnesium alloy tension dislocation slip twinning dynamic recrystallization grain boundary sliding, fracture, cavitation rare

On the Taylor principles for plastic deformation of polycrystalline metals

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Frontiers of Materials Science 2016年第4期10卷 335-345页

作者： Weimin MAO School of Materials and Metallurgy Inner Mongolia University of Science and Technology Arding Street 7 Baotou 014010 China Department of Materials University of Science and Technology Beijing Xue-Yuan Road 30 Beijing 100083 China

Grain orientation evolutions and texture formation based on the Taylor principles offer important references to reveal crystallographic mechanisms of deforma- tion behaviors. Strain equilibrium between grains is achieved in Taylor theory, however, stress equilibrium has not yet been reached perfectly even in many modifications of the theory though the textures predicted become very close to those of experimental observations. A reaction stress model is proposed, in which mechanical interactions between grains are considered in details and grain deformation is conducted by penetrating and non-penetrating slips. The new model offers both of the stress and strain equilibria and predicts the same textures indicated by Taylor theory. The rolling texture simulated comes very close to the experimental observations if the relaxation effect of the non-penetrating slips on the up-limits of reaction stresses is included. The reaction stress principles open theoretically a new field of vision to consider deformation behaviors of poiycrystaliine materials, whereas the Taylor principles become unnecessary both theoretically and practically. Detailed engineering conditions have to be included in simulations if the deformation textures of industrial products should be predicted.

关键词： Taylor principles micormechanical equilibrium plastic deformation dislocation slip texture simulation

Micro-mechanisms of plastic deformation of two-phase TiAl-base alloy at room temperature

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Progress in Natural Science:Materials International 1998年第4期 95-104页

作者：梁伟杨德庄黄孝瑛陆路 Beijing 100081 Center of Testing and Measuring Central Iron and Steel Research Institute China Department of Materials Science and Engineering Harbin 150001 Harbin Institute of Technology Taiyuan 030024 Taiyuan University of Technology

The room-temperature deformation modes and the activities of various deformation systems in two-phase TiAl-base alloys have been studied by means of TEM diffraction-contrast examination on compressively deformed structures and in-situ tensile observations. The resolts show that ordinary dislocation slipping and deformation twinning are very active in y- matrix, while the critical resolved shear stress for superdislocation slip systems is at least 3.8-4.2 times as large as that of ordinary dislocation ones. The dislocation slipping. Besides, a detailed analysis on deformation compatibility shows that the necessary condition for compatible deformation among polycrystalline grains cannot be satisfied only by ordinary dislocation slipping and deformation twinning. Based on the above consideration, the relationship between room-temperature ductility and grain size has been established:εf =a/(d+b)

关键词： TiAl-base alloy dislocation slip twinning deformation mechanism deformation compatibility.

Evolution of microstructure and textures in drawn-torsion ferrite wire

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Evolution of microstructure and textures in drawn-torsion fe...