检索结果-南通市图书馆

Acta metallurgica Sinica(English letters) 2022年第2期35卷 275-284页

作者： l.m.liu y.X.lai C.l.Wu z.zhang J.H.Chen Center for High-Resolution Electron microscopy College of Materials Science and EngineeringHunan UniversityChangsha 410082China

This study investigates the microstructure and local corrosion behavior of an Al-mg-Si-Cu alloy,which has been subjected to cold-rolling with different deformation strain ratios(DSRs)and followed by artificial *** corrosion tests show that peak-aged samples with a small DSR(5-10%)are sensitive to inter-granular corrosion(IGC)along both the normal and rolling *** the DSR increases to medium strength(20-40%),IGC sensitivity decreases along both directions and corrosion propagates *** the DSR is 60-80%,IGC sensitivity along the normal direction continues to decrease,but increases along the rolling direction,indicating pronounced corrosion *** characterization reveals the decreased IGC sensitivity is mainly attributed to a reduction in element segregation at high-angle grain boundaries and the kinked and discontinuous grain boundary corrosion *** increased IGC sensitivity along the rolling direction could be related to the significantly flattened grains.

关键词： Al alloys local corrosion Anisotropy Transmission electron microscopy(TEm) Electron backscattering diffraction(EBSD)

Uncovering the softening mechanism and exploring the strengthening strategies in extremely fine nanograined metals:A molecular dynamics study

在线全文

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 186-196页

作者： H.R.Peng z.y.Jian C.X.liu l.K.Huang y.m.Ren F.liu School of materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The strength of polycrystalline metals increases with decreasing grain size,following the classical HallPetch ***,this relationship fails when softening occurs at very small grain sizes(typically less than 10 to 20 nm),which limits the development of ultrahigh-strength *** this work,using columnar-grained nanocrystalline Cu-Ag‘samples’,molecular dynamics simulations were performed to investigate the softening mechanism and explore the strengthening strategies(e.g.,formation of solid solution or grain boundary(GB)segregation)in extremely fine nanograined ***,the softening of pure metals is induced by atomic sliding in the GB layer,rather than dislocation activities in the grain interior,although both occur during *** solid solution lowers the stacking fault energy and increases the GB energy,which leads to the softening of NC *** segregation stabilizes GB structures,which causes a notable improvement in strength,and this improvement can be further enhanced by optim.z.ng the solute concentration and GB *** work deepens the understanding of the softening mechanism due to atomic sliding in the GB layer and the strengthening mechanism arising from tailoring the GB stability of immiscible alloys and provides insights into the design of ultrahighstrength materials.

关键词： Softening Strengthening Cu-Ag alloy molecular dynamics Nanocrystalline

The role of melt cooling rate on the interface between 18R and mg matrix in mg_(97)zn_(1)y_(2) alloys

在线全文

学校读者我要写书评

暂无评论

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 *** 18R/mg interface is step-like both in the near-equilibrium alloy and non-equilibrium *** cooling rate makes the step size more regular and *** 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 *** 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

RESEARCH ON lASer DIRECT DEPOSITION PROCESS OF Ti-6Al-4V AllOy

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English letters) 2007年第3期20卷 171-180页

作者： S.y. Gao y.z. zhang l.K. Shi B.l. Du m.z. Xi H.z. Ji mechanical Engineering College Yanshan University O~mhuangdao 066004 China Beijing General Research Institute for Nonferrous metals Beijing 100088 China

laser direct deposition （lDD） of metallic components is an advanced technology of combining CAD/CAm （computer aided design/computer aided manufacturing）, high power laser, and rapid prototyping. This technology uses laser beam to melt the powders fed coaxiaUy into the molten pool by the laser beam to fabricate fuUy dense metallic components. The present article mainly studies the lDD of Ti-6Al-4V alloy, which can be used to fabricate aircraft components. The mechanical properties of the Ti-6Al-4V alloy, fabricated by lDD, are obtained using the tension test, and the oxygen content of used powders and deposited specimens are measured. In the present article, it can be seen that the mechanical properties obtained using this method are higher than the ones obtained by casting, and equal to those got by wrought anneal. One aircraft part has been made using the lDD process. Because of this aircraft part, with sophisticated shape, the effect of the laser scanning track on the internal soundness of the deposited part was discussed.

关键词： laser direct deposition Ti-6Al-4V alloy mechanical property depositing process aircraft component

Solid-state alloying of Al-mg alloys by accumulative roll-bonding:microstructure and properties

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2022年第30期125卷 238-251页

作者： X.m.mei Q.S.mei J.y.li C.l.li l.Wan F.Chen z.H.Chen T.Xu y.C.Wang y.y.Tan School of Power and mechanical Engineering Wuhan UniversityWuhan 430072China Key laboratory of Hydraulic machinery Transients(Wuhan University) Ministry of EducationWuhan 430072China School of mechanical Engineering Wuhan Polytechnic UniversityWuhan 430023China

In this study,a novel solid-state alloying approach was adopted to fabricate Al-mg alloys with high mg contents(C_(mg)) by accumulative roll-bonding(ARB)of Al and mg elemental materials to ultrahigh *** results showed that the degree of alloying increased with the increase of ARB cycles and a supersaturatedα-Al solid solution accompanied with nanoprecipitates was formed in the Al-mg alloys by ARB to 70 *** as-prepared Al-mg alloys exhibited enhanced mechanical properties,with a maximum tensile strength of∼615 mPa and a tensile elongation of∼10%at C_(mg)=13 wt.%.The high strength can be attributed to different mechanisms,namely solid solution strengthening,grain boundary strengthening,dislocation strengthening,and precipitation *** Al-mg alloys showed increased work hardening with increasing C_(mg),due to the enhanced formation of ***,no obvious drop in the intergranular corrosion(IGC)resistance was found in the Al-mg alloys with C_(mg) up to 13 wt.%.moreover,sensitization treatment was found to induce little decrease in the IGC resistance of the Al-mg alloys with C_(mg)≤13 wt.%.We found that the excellent IGC resistance was due to the suppression of grain boundary precipitation by the preferred formation of precipitates within the grains that were induced by *** study indicated the novelty of the present solid-state alloying approach to achieving a superior combination of high mechanical properties and IGC resistance in Al-mg alloys.

关键词： Solid-state alloying Al-mg alloys mechanical properties IGC resistance ARB

Tailoring precipitation/properties and related mechanisms for a high-strength aluminum alloy plate via low-temperature retrogression and re-aging processes

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2022年第25期120卷 15-35页

作者： l.G.Hou H.yu y.W.Wang l.you z.B.He C.m.Wu D.G.Eskin l.Katgerman l.z.zhuang J.S.zhang State Key laboratory for Advanced metals&materials University of Science&Technology BeijingBeijing 100083China BCAST Brunel University LondonKingston LaneUxbidge Middlesex UB83PHUnited Kingdom Institute of mineral resources Chinese Academy of Geological SciencesBeijing 100037China Nanjing Advanced Transportation Equipment New Technology Research Institute Nanjing 211800China Tomsk State University Tomsk634050Russian Federation Katgerman Aluminium Technology van Beuningenlaan 102334CC LeidenNetherlands Department of materials Science and Engineering Delft University of TechnologyMekelweg 22628CD Delftthe Netherlands

The retrogression and re-aging(RRA)processes,aimed mainly at tailoring intergranular precipitates,could significantly improve the corrosion resistance(i.e.,stress corrosion cracking resistance)without considerably decreasing the strength,which signifies that an efficient control of the size,distribution and evolution of intergranular and intragranular precipitates becomes critical for the integrated properties of the(mid-)thick high-strength Al alloy *** to RRA process with retrogression at200℃ (T77),this study investigated the impact of a modified RRA process(mT77)with lower retrogression temperatures(155-175℃ )and first-stage under-aging on the properties of a high-strength AA7050 Al alloy,in combination with detailed precipitate *** study showed that the strength/microhardness of the RRA-treated alloys decreased with raising retrogression temperature and/or prolonging retrogression time,along with the increased electrical *** rapid responsiveness of microstructure/property typical of retrogression at 200℃ was obviously postponed or decreased by using mT77 process with longer retrogression time that was more suitable for treating the(mid-)thick *** the other hand,higher retrogression temperature facilitated more intragranularηprecipitates,coarse intergranular precipitates and wide precipitate free zones,which prominently increased the electrical conductivity alongside a considerable strength loss as compared to the mT77-treated *** the preferred mT77 process,the high strength approaching T6 level as well as good corrosion resistance was ***,though a relatively homogeneous through-thickness strength was obtained,some small discrepancies of properties between the central and surface areas of an 86-mm thick 7050 Al alloy plate were observed,possibly related to the quenching *** precipitate evolution and mechanistic connection to the properties were discussed and reviewed for high-strengt

关键词： Aluminum alloy Heat treatment Precipitation Strength Grain boundary

Synergetic deformation mechanisms in an mg-zn-y-zr alloy with intragranular lPSO structures

在线全文

学校读者我要写书评

暂无评论

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 *** optim.z. 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 *** unraveled the corresponding strengthening and toughening mechanisms through transmission electron microscopy characterization and theoretical *** high strength and good plasticity of the homogenized alloy benefit from the synergistic deformation mechanism of multiple kinking and twining in the *** the activation of kinking and twinning depends on the thicknesses of lPSO lamellae and their relative *** results may shed light on optim.z.ng the design of mg alloys regulating the microstructure of lPSO phases.

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

Evolution mechanisms of microstructure and mechanical properties in a friction stir welded ultrahigh-strength quenching and partitioning steel

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2022年第7期102卷 213-223页

作者： z.W.Wang J.F.zhang G.m.Xie l.H.Wu H.zhang P.Xue D.R.Ni B.l.Xiao z.y.ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China State Key laboratory of Rolling and Automation Northeastern UniversityShenyang110819China

Ultrahigh-strength quenching and partitioning(Q&P) steels have attracted strong interests in the auto manufactory,while the comprehensive understanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their *** the present work,it is designed to make an insight into these imperative *** strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding(FSW) technique under different parameters. Apparent hardening and softening were observed in stir zone(Sz) and heat-affected zone(HAz) respectively,whose microstructures strongly depended on the peak temperature and cooling rate during *** formation of fresh martensite was the main mechanism for the Sz hardening,while the decomposition of metastable phases played key roles in the microhardness drop of the HAz.A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength under parameter *** dual-phase structure,nano-carbide particles,tempered initial martensite,and ultrafine-grained ferrite synergistically improved the strain hardening ability of the HAz,which eventually resulted in the equal strength FSW joints.

关键词： Ultrahigh-strength Q&P steel Friction stir welding microstructure mechanical property Strain hardening

Temperature Effect on Early Oxidation Behavior of NiCoCrAly Coatings: microstructure and Phase Transformation

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English letters) 2022年第6期35卷 975-984页

作者： A.Ullah A.Khan z.B.bao y.F.yang m.m.Xu S.l.zhu F.H.Wang University of Chinese Academy of Sciences Beijing 100049China Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key laboratory of Green Fabrication and Surface Technology of Advanced metal materials Ministry of EducationSchool of Materials Science and EngineeringAnhui University of TechnologyMaanshan 243000China Institute of Advanced Wear and Corrosion Resistant and Functional material Jinan UniversityGuangzhou 510632China Shenyang National laboratory for materials Science Northeastern UniversityShenyang 110819China

Initial oxidation behavior of NiCoCrAly coating prepared by arc-ion plating has been studied in air at 900, 1000 and 1100 ℃. The results showed that phase transformation from transient θ-Al_(2)O_(3) to α-Al_(2)O_(3) was highly related to the temperature and oxidation time. The oxide scale in the initial stage was mainly composed of θ-Al_(2)O_(3) at 900 ℃. Instead, more amount of α-Al_(2)O_(3) emerged out with increasing oxidation temperature. The elemental distribution after oxidation confirmed that faster chromium diffusion to the oxide scale played an important role in the speedy transformation from θ-Al_(2)O_(3) to α-Al_(2)O_(3). y segregation at scale/coating interface resulted in less cavity formation and hence improved the oxide scale adherence.

关键词： mCrAly coating Phase transformation Isothermal oxidation Temperature effect

Simultaneous enhancement of mechanical and shape memory properties by heat-treatment homogenization of Ti_(2)Ni precipitates in TiNi shape memory alloy fabricated by selective laser melting

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2022年第6期101卷 205-216页

作者： H.z.lu l.H.liu C.yang X.luo C.H.Song z.Wang J.Wang y.D.Su y.F.Ding l.C.zhang y.y.li National Engineering Research Center of Near-net-shape Forming for metallic materials South China University of TechnologyGuangzhou 510640China musculoskeletal Oncology Department Sun Yat-Sen University Cancer CenterGuangzhouGuangdong ProvinceChina Shenyang Aircraft Design and Research Institute Shenyang 110035China Guangdong Huayi Plumbing Fittings Industry Co. Ltd.Kaiping 529321China School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia

The excellent shape memory and mechanical properties of Ti Ni shape memory alloys(SmAs) fabricated using selective laser melting(Slm) are highly desirable for a wide range of critical applications. In this study, we examined the simultaneous enhancement of mechanical and shape memory properties using heat-treatment homogenization of Ti_(2)Ni precipitates in a Ti_(50.6)Ni_(49.4)SmA fabricated using Slm. Specifically, because of the complete solution treatment, nanoscale spherical Ti_(2)Ni precipitates were homogeneously dispersed throughout the grain interior. Interestingly, the resultant SmA exhibited an ultrahigh tensile strength of 880 ± 13 mPa, a large elongation of 22.4 ± 0.4%, and an excellent shape memory effect, with a recovery rate of > 98% and ultrahigh recoverable strain of 5.32% after ten loading–unloading cycles. These simultaneously enhanced properties are considerably superior than those of most previously reported Ti Ni SmAs fabricated using additive manufacturing. Fundamentally, the enhancement in tensile strength is ascribed to precipitation strengthening and work hardening, and the large plasticity is mainly attributed to the homogeneous nanoscale globular Ti_(2)Ni precipitates, which effectively impeded the rapid propagation of microcracks. Furthermore, the enhanced shape memory properties are derived from the suppression of dislocation movement and formation of retained stabilized martensite by the presence of high-density dislocations, nanoscale Ti_(2)Ni precipitates, and abundant interfaces. The obtained results provide insight into the enhancement of the two types of properties in Ti Ni SmAs and will accelerate the wider application of SmAs.

关键词： Shape memory alloy Selective laser melting Heat treatment mechanical properties Shape memory properties