检索结果-南通市图书馆

ductility Anisotropy Induced by Ferrite in Direct Laser Deposited 17-4 PH Steel: Combined Microstructure and Dislocation Density Simulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2021年第6期34卷 765-776页

作者： Chuanfeng Wu Junmei Chen Zhiyuan Yu Hao Lu Chun Yu Jijin Xu Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The anisotropic ductility of a direct laser deposited 17-4 PH cubic part was investigated.Anisotropic elongations in the specimens from varied surfaces of the part were obtained:~6.2%,~1.5%,and~4.5%in XY,YZ,and XZ samples,respectively.Furthermore,various orientations of ferrite were found in different specimens,taking the loading direction as reference.A finite element analysis depending on actual microstructures and dislocation density revealed that the orientation of ferrite caused the ductility anisotropy.The orientation of ferrite affected its plastic deformability and the deformation compatibility between phases during the uniaxial loading.The ferrite parallel to the tensile direction in the YZ sample had the worst deformability and induced severe strain localization and stress triaxiality,which resulted in inferior ductility.The ferrite perpendicular to the tensile direction showed the best deformability,whereas strain localization remained intense in the XZ sample owing to the unmatched deformability of martensite.The inclined ferrite in the XY sample exhibited moderate deformability and was found to enhance the plastic flow of martensite,leading to the best deformation compatibility and ductility.

关键词： Direct laser deposition Stainless steel ductility Anisotropy Microstructure Finite element analysis

Uncovering of the formation of rare earth texture and pseudo fiber bimodal microstructure in the high ductility Mg-2Gd-0.4Zr alloy during extrusion

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2024年第5期172卷 166-184页

作者： Tianxu Zheng Yaobo Hu Chao Zhang Tianshuo Zhao Bin Jiang Fusheng Pan Aitao Tang College of Materials Science and Engineering Chongqing UniversityChongqing400044China National Engineering Research Center for Magnesium Alloys Chongqing400044China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai200240China

The aim of this research was to elucidate the underlying mechanism involved in the formation of rare earth(RE)texture and pseudo fiber bimodal microstructure in the high ductility Mg-2Gd-0.4Zr alloy.The microstructure and texture evolution during the extrusion process were analyzed using various tech-niques,including optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),and electron probe microanalysis(EPMA).The findings revealed that the RE texture in the extruded Mg-2Gd-0.4Zr alloy emerged during the dynamic recrystallization(DRX)process and was further strengthened during the subsequent static recrystallization and grain growth processes.The nu-cleation and growth of grains in the streamline region of Zr particles were delayed in comparison to other regions due to the pinning effect of Zr particles,ultimately resulting in the formation of pseudofiber bi-modal microstructure in the extruded Mg-2Gd-0.4Zr alloy.

关键词： Magnesium alloys ductility Rare earth texture Bimodal microstructure

Enhancing Strength-ductility Synergy of CoCrNi-Based Medium-Entropy Alloy Through Coherent L1_(2)Nanoprecipitates and Grain Boundary Precipitates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 78-88页

作者： Leilei Li Kaikai Song Qingwei Gao Changshan Zhou Xiaoming Liu Yaocen Wang Xiaojun Bai Chongde Cao School of Physical Science and Technology Northwestern Polytechnical UniversityXi’an710016China Weihai Research Institute of Industrial Technology Shandong UniversityWeihai264209China Research and Development Institute of Northwestern Polytechnical University in ShenzhenShenzhen518057China

The L1_(2)-strengthened Co_(34)Cr_(32)Ni_(27)Al_(4)Ti_(3)medium-entropy alloy(MEA)with precipitations of grain boundaries has been developed through selective laser melting(SLM)followed by cold rolling and annealing,exhibiting excellent strength-ductility synergy.The as-printed alloy exhibits low yield strength(YS)of~384 MPa,ultimate tensile strength(UTS)of~453 MPa,and uniform elongation(UE)of 1.5%due to the existence of the SLM-induced defects.After cold rolling and annealing,the YS,UTS,and UE are significantly increased to~739 MPa,~1230 MPa,and~47%,respectively.This enhancement primarily originates from the refined grain structure induced by cold rolling and annealing.The presence of coherent sphericalγ'precipitates(L1_(2)phases)and Al/Ti-rich precipitates at the grain boundaries,coupled with increased lattice defects such as dislocations,stacking faults,and ultrafine deformation twins,further contribute to the property’s improvement.Our study highlights the potential of SLM in producing high-strength and ductile MEA with coherent L1_(2)nanoprecipitates,which can be further optimized through subsequent rolling and annealing processes.These findings offer valuable insights for the development of high-performance alloys for future engineering applications.

关键词： Medium-entropy alloy Selective laser melting Precipitation Strength ductility

Achieving high strength and ductility in high-entropy alloys via spinodal decomposition-induced compositional heterogeneity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第10期141卷 149-154页

作者： Yujie Chen Yan Fang Ruixin Wang Yu Tang Shuxin Bai Qian Yu Department of Materials Science and Engineering Center of Electron Microscopy and State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhou 310027China College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

The compositional heterogeneity in high-entropy alloys(HEAs)has been reported to be an inherent en-tity,which significantly alters the mechanical properties of materials by tuning the variation of lattice resistance for dislocation motion.However,since the body-centered cubic(BCC)structure is not close-packed,the change of lattice resistance is less sensitive to the normal concentration wave compared to that in face-centered cubic(FCC)structured materials.In this work,we selected a refractory bcc HEAs TiZrNbTa for the matrix and added a small amount of Al to facilitate the special spinodal decomposition structure.In particular,(TiZrNbTa)98.5 Al 1.5 displayed a typical basket-weave fabric morphology of spinodal decomposition structure with a characteristic periodicity of∼8 nm and had an optimal combination of strength and ductility(the yield strength of 1123±9 MPa and ductility of∼20.7%±0.6%).It was de-termined that by doing in situ TEM mechanical testing,the plastic deformation was dominated by the formation and operation of dislocation loops which provided both edge and screw components of dislo-cations.The synergetic effect of the remarkable chemical heterogeneity created by the spinodal decompo-sition and the spreading lattice distortion in high entropy alloys is quite effective in tuning the mobility of different types of dislocations and facilitates dislocation interactions,enabling the combination of high strength and ductility.

关键词： Bcc high-entropy alloys Spinodal decomposition Compositional heterogeneity Dislocation loops High strength ductility

Orientation-dependent ductility and deformation mechanisms in body-centered cubic molybdenum nanocrystals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第23期154卷 107-113页

作者： Huayu Peng Yuxuan Hou He Zheng Ligong Zhao Ying Zhang Weiwei Meng Ting Liu Peili Zhao Shuangfeng Jia Jianbo Wang School of Physics and Technology Center for Electron Microscopy MOE Key Laboratory of Artificial Micro- and Nano-structures and Institute for Advanced Studies Wuhan University Wuhan 430072 China Suzhou Institute of Wuhan University Suzhou Jiangsu 215123 China Wuhan University Shenzhen Research Institute Shenzhen Guangdong 518057 China Core Facility of Wuhan University Wuhan 430072 China

The knowledge regarding anisotropic mechanical behaviors in nanoscale body-centered cubic (bcc) metals remains obscure. Herein, we report the orientation-dependent ductility in bcc Mo nanocrystals (NCs), which exhibit poor ductility along [110] direction but possess relatively better ductility along the [001] and [112] orientations. The origin of different deformability can be traced down to the distinct deformation mechanisms: the unexpected crack nucleation and propagation induce premature fractures in [110]-oriented NCs;in contrast, deformation twinning could contribute to the enhanced ductility in [001]-oriented NCs;interestingly, we find the activation of multiple dislocation slips in [112]-oriented NCs with the highest ductility. Further molecular dynamics simulations provide deeper insights into the defect dynamics that are closely interlinked with experimental observations. Our findings advance the basic understanding of orientation-dependent mechanical properties and help to guide endeavors to architecture the microstructures of bcc metals with enhanced ductility.

关键词： In-situ tension test ductility Crack Deformation twinning Dislocation slips Mo nanocrystals

Achieving High Strength and Tensile ductility in Pure Nickel by Cryorolling with Subsequent Low-Temperature Short-Time Annealing

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Engineering 2024年第2期33卷 190-203页

作者： Zhide Li Hao Gu Kaiguang Luo Charlie Kong Hailiang Yu Light Alloys Research Institute Central South UniversityChangsha 410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China College of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China Electron Microscope Unit University of New South WalesSydneyNSW 2052Australia

Ultra fine-grained pure metals and their alloys have high strength and low ductility.In this study,cryorolling under different strains followed by low-temperature short-time annealing was used to fabricate pure nickel sheets combining high strength with good ductility.The results show that,for different cryorolling strains,the uniform elongation was greatly increased without sacrificing the strength after annealing.A yield strength of 607 MPa and a uniform elongation of 11.7%were obtained after annealing at a small cryorolling strain(ε=0.22),while annealing at a large cryorolling strain(ε=1.6)resulted in a yield strength of 990 MPa and a uniform elongation of 6.4%.X-ray diffraction(XRD),transmission electron microscopy(TEM),scanning electron microscopy(SEM),and electron backscattered diffraction(EBSD)were used to characterize the microstructure of the specimens and showed that the high strength could be attributed to strain hardening during cryorolling,with an additional contribution from grain refinement and the formation of dislocation walls.The high ductility could be attributed to annealing twins and micro-shear bands during stretching,which improved the strain hardening capacity.The results show that the synergistic effect of strength and ductility can be regulated through low-temperature short-time annealing with different cryorolling strains,which provides a new reference for the design of future thermo-mechanical processes.

关键词： Cryorolling Annealing Nickel Strain hardening ductility

Heterostructuring an equiatomic CoNiFe medium-entropy alloy for enhanced yield strength and ductility synergy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2022年第8期41卷 2894-2905页

作者： Xin-Xin Ding Jing Wang Dong Liu Chang Wang Ping Jiang Hua Qu Guang-Hua Liu Fu-Ping Yuan Xiao-Lei Wu School of Physical Science and Technology Tiangong UniversityTianjin300387China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of ScienceBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Special Steel Department Central Iron and Steel Research InstituteBeijing100081China

High-/medium-entropy alloys(H/MEAs)of face-centered-cubic-structured single phase usually suffer from a glaring drawback of low yield strength.Even worse,the trade-off emerges frustratingly between strength and ductility as strength increases.Here,the lamellar heterostructure(HS)is designed in an equiatomic ternary CoNiFe ME A by means of cold rolling followed by an incomplete recrystallization annealing.The lamellar HS consists of the soft recrystallized grains as well as severely deformed structures which are partly reserved.By comparison to the coarse-grained counterpart,the lamellar HS,shows a well enhanced yield strength-ductility synergy,together with an increased yield strength.This is ascribed to the hetero-deformation-induced(HDI)stress in HS during tensile deformation.Accordingly,the HDI strain hardening is induced,serving as an important addition to the conventional forest hardening.The HDI hardening is evidenced experimentally to account for a large proportion of global strain hardening.Furthermore,a fully recrystallized microstructure is obtained to show a simultaneous increase in both yield strength and ductility.The microstructures are evaluated in detail prior to and after tensile deformation by using the electron backscattered diffraction and transmission electron microscope observations.The mechanism for HDI strain hardening in various microstructures is analyzed to correlate to the evolution of microstructures in terms of the kernel average misorientation values,Schmid factor,and dislocation behaviors in response to plastic deformation.

关键词： Heterostructure(HS) Medium-entropy alloy(MEA) Hetero-deformation ductility Strength

Enhancing strength and ductility of AlSi10Mg fabricated by selective laser melting by TiB_(2)nanoparticles

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第14期109卷 254-266页

作者： Y.K.Xiao H.Chen Z.Y.Bian T.T.Sun H.Ding Q.Yang Y.Wu Q.Lian Z.Chen H.W.Wang State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghai 200240China

In the metallic components fabricated by the emerging selective laser melting(SLM)technology,most strategies used for strengthening the materials sacrifice the ductility,leading to the so-called strengthductility trade-off.In the present study,we report that the strength and ductility of materials can be enhanced simultaneously by introducing nanoparticles,which can break the trade-off of the metallic materials.In the case of in-situ nano-TiB_(2)decorated AlSi10Mg composites,the introduced nanoparticles lead to columnar-to-equiaxed transition,grain refinement and texture elimination.With increasing content of nanoparticles,the strength increases continually.Significantly,the ductility first increases and then decreases.Our results show that the ductility is controlled by the competition between the crack-induced catastrophic fracture and ductile fracture associated with dislocation activities.The first increase of ductility is mainly attributed to the suppression of crack-induced catastrophic fracture when TiB_(2)nanoparticles present.With the further increase of TiB_(2)nanoparticles,the subsequent decrease of ductility is mainly controlled by dislocation activities.Thus,the materials will exhibit the optimum strength and ductility combination in a certain range of TiB_(2)nanoparticles.This study clarifies the physical mechanism controlling ductility for nano-TiB_(2)decorated Al Si10Mg composites,which provides the insights for the design of structural materials.

关键词： Selective laser melting Aluminium matrix composites ductility Mechanical behavior Dislocations Cracks

Steel rings as seismic fuses for enhancing ductility of cross braced frames

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2022年第4期21卷 1103-1117页

作者： Farhad Behnamfar Saeid Arman Hassan Zibasokhan Department of Civil Engineering Isfahan University of TechnologyIsfahan ***Iran Department of Civil Engineering Kermanshah University of TechnologyKermanshah ***Iran

A new remedy is proposed in this study to increase the ductility of cross-braced frames to a level comparable with ductile moment frames.The suggested system consists of one or two concentric steel rings installed in the cross-braced bay vertically.The steel rings are designed such that they fail in bending sooner than failure of the braces in compression.Then the rings act as seismic fuses with multiple bending plastic hinges.Using nonlinear static analysis,it is shown that the proposed system can be designed to behave like cross-braced frames with regard to stiffness and strength,and like special moment frames with regard to ductility.Seismic design factors for the proposed system are recommended based on nonlinear pushover and cyclic analysis studies.

关键词： cross brace special moment frame steel ring seismic fuse ductility