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Influencing mechanism of pre-existing nanoscale Al5Fe2 phase on Mg-Fe interface in friction stir spot welded Al-free zK60-Q235 joint

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Journal of materials Science & Technology 2020年第7期42卷 220-228页

作者： R.z.Xu Q.yang D.R.Ni b.l.Xiao C.z.liu z.Y.ma Institute of Metal Research Chinese Academy of SciencesShenyang110016China College of material Science and engineering Shenyang Aerospace UniversityShenyang110136China Department of materials Science and engineering University of Illinois at Urbana-Champaign1304 W Green StUrbanaIL61801United States Fredrick Seitz materials Research lab.ratory University of Illinois at Urbana-Champaign104 S Goodwin AveUrbanaIL61801United States

Al-free zK60 magnesium (Mg) alloy sheet was selected as sub.trate material of Mg-ste.l.pinless friction stir spot welding (FSSW), avoiding the effect of the Al element in the sub.trate on the alloying reaction of Mg-iron (Fe) interface. The sound FSSW joint of zK60 Mg alloy and Q235 ste.l.with a hot-dipped aluminum (Al)-containing zinc (zn) coating was successfully re.l.zed. The detailed microstructural examinations proved that Al5Fe2 phase at the Mg-Fe interface came from the pre-existing Al5Fe2 phase in the coating and acted as the transition layer for promoting the metallurgical b.nding of Mg and Fe. The interfaces with we.l.matched lattice sites among Fe, Al5Fe2 and Mg were formed during FSSW. A low energy interface with good match of lattice sites ((002)Al5Fe2//(110)Fe, [110]Al5Fe2//[113]Fe) b.tween Al5Fe2 and Fe was identified. For the interface b.tween Al5Fe2 and Mg, an orientation relationship of (622)Al5Fe2//(3112)Mgand[158]Al5Fe2//[2423]Mg was ob.erved. The tensile-shear load of the zK60-ste.l.joint could reach 4.6 kN. Moreover, the joint fracture occurred at the interface b.tween the Al5Fe2 layer and the Mg alloy sub.trate, suggesting the b.ittle fracture characteristic.

关键词： Dissimilar welding Friction stir spot welding magnesium alloys Ste.l. zinc coating

Finite element Prediction of the Thermal Conductivity of GNP/Al Composites

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Acta Metallurgica Sinica(english letters) 2022年第5期35卷 825-838页

作者： X.S.yang l.zhou K.Y.liu z.Y.liu Q.z.Wang b.l.Xiao z.Y.ma School of electromechanical and Automotive engineering Yantai UniversityYantai264005China Shi-Changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

A 3 D multi-scale finite element model was developed to predict the effective thermal conductivity of graphene nanoplatelet(GNP)/Al *** factors influencing the effective thermal conductivity of the GNP/Al composites were investigated,including the orientation,shape,aspect ratio,configuration and volume fraction of *** results show that GNPs shape has a little influence on the thermal conductivity of GNP/Al composites,and composites with e.l.ptic GNPs have the highest thermal *** addition,with increasing the aspect ratio of GNPs,the thermal conductivity of GNP/Al composites increases and finally tends to b. *** GNPs configuration strongly influences the thermal conductivity of GNP/Al composites,and the thermal conductivity of the composites with layered GNPs is the highest among the five *** effective thermal conductivity is sensitive to volume fraction of ***,when the volume fraction of layered GNPs reaches 1.54%,the thermal conductivity of GNP/Al composites is as high as 400 W/m *** findings of this study could provide a good theoretical b.sis for designing high thermal conductivity GNP/Al composites.

关键词： Multi-scale finite element model Thermal conductivity GNP/Al composites Shape Aspect ratio Configuration

eXPeRIMeNTAl STUDY ON ReACTION SYNTHeSIS OF TiC IN Al-Ti-C SYSTeM

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Acta Metallurgica Sinica(english letters) 1998年第4期11卷 255-260页

作者： e.l. zhang b.yang S.Y. zeng and Q.C. li(School of materials Science and engineering, Harb.n Institute of Technology, b.X 428, Harb.n 150001.)China)M.z.ma (Jiamusi University Jiamusi 154002, China) Harb.n Inst of Technology Harbin China

The reaction process and mechanistn of reaction synthesis of TiC in Al-Ti-C system have b.en investigated in detail b. ob.erving the microstructure of the water quenched preform with SeM and eDX. The results showed that the reaction processing can b. divided into three stages: aluminium powder is melted firstly, then titanium dissolves in the melted aluminium and Al3Ti is formed around titanium powder, titanium concentrates around carb.n powder and a Ti-rich layer is ob.erved around carb.n pariicles,in which titanium atom reacts with carb.n atom to synthesize TiC;TiC precipitates out of the melt, and diffuses out of the.l.yer. A solution-precipitation mechanism and a reaction model were set up b.sed on the experimental results.

关键词： kinetic process Al/TiC microstructure composite mechanism

evolution of the Microstructure and Strength in the Nugget zone of Friction Stir Welded SiCp/Al-Cu-Mg Composite

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Journal of materials Science & Technology 2014年第1期30卷 54-60页

作者： D.Wang b.l.Xiao Q.z.Wang z.Y.ma Shenyang National lab.ratory for materials Science Institute of Metal ResearchChinese Academy of Sciences University of Science and Technology of China

A 6 mm-thick SiCp/2009AI composite plate was successfully joined b. friction stir welding （FSW） using an ultrahard material tool to investigate the evolution of the microstructure and the strength in the nugget zone （Nz）. While some SiC particles were b.oken up during FSW, most of them rotated in the matrix. large compound particles on the interfaces were b.oken off during FSW, whereas the amorphous layer and small compound particles remained on the interfaces. The dynamically recrystallized AI grains nucleated on the surface of fractured SiC particles during FSW, forming nano-sized grains around the SiC particles. The yield strength of the Nz decreased slightly due to the variation in the size, shape, and distrib.tion of the SiC particles. The clean interfaces were b.neficial to the.l.ad transfer b.tween SiC particles and AI matrix and then increased the ultimate tensile strength of the Nz.

关键词： Metal-matrix composites Friction stir welding Microstructure Mechanical properties

Achieving large-area b.lk Ultrafine Grained Cu via Sub.erged Multiple-pass Friction Stir Processing

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Journal of materials Science & Technology 2013年第12期29卷 1111-1115页

作者： P. Xue b.l. Xiao z.Y. ma Shenyang National lab.ratory for materials Science Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road Shenyang 110016 China

large-area b.lk ultrafine grained （UFG） pure Cu was successfully prepared b. multiple-pass ove.l.pping friction stir processing （FSP） under additional rapid cooling. Ove.l.pping FSP did not exert a significant effect on the microstructure and mechanical properties of the FSP UFG Cu. Similar average grain size was achieved in the transitional zone （Tz） of the multiple-pass FSP sample compared to that in the nugget zone of the single-pass FSP sample, and the Tz exhib.ted a strong e（112） type A fib.r shear texture, Very weak softening occurred in the Tz of the multiple-pass FSP UFG Cu, resulting in a relatively uniform hardness distrib.tion throughout the whole processed zone. A high yield strength of - 310 MPa and a uniform elongation of - 13% were achieved in the b.lk FSP UFG Cu. This study provides an effective strategy to prepare.l.rge-area b.lk IUFG materials.

关键词： Friction stir processing Multiple-pass Ultrafine grains Microstructure Mechanical properties

effect of Carb.n Nanotub. Orientation on Mechanical Properties and Thermal expansion Coefficient of Carb.n Nanotub.-Reinforced Aluminum matrix Composites

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Acta Metallurgica Sinica(english letters) 2014年第5期27卷 901-908页

作者： z.Y.liu b.l.Xiao W.G.Wang z.Y.ma School of materials Science and engineering Dalian University of Technology Shenyang National lab.ratory for materials Science Institute of Metal ResearchChinese Academy of Sciences School of Mechanical engineering Liaoning Shihua University

Carb.n nanotub.-reinforced 2009Al （CNT/2009Al） composites with randomly oriented CNTs and aligned CNTs were fab.icated b. friction stir processing （FSP） and FSP-rolling, respectively. The CNT/2009A1 composites with aligned CNTs showed much b.tter tensile properties at room temperature and elevated temperature compared with those with the randomly oriented CNTs, which is mainly attrib.ted to larger equivalent aspect ratio of the CNTs and avoidance of preferential fracture prob.ems. However, much finer grain size was not b.neficial to ob.aining high strength ab.ve 473 K. The aligned CNTs resulted in tensile anisotropy, with the b.st tensile properties b.ing achieved along the direction of CNT aligning. As the off-axis angle increased, the tensile properties were reduced due to the weakening of the.l.ad transfer ab.lity. Furthermore, aligned CNTs resulted in much lower coefficient of thermal expansion compared with randomly oriented CNTs.

关键词： Carb.n nanotub.s Metal matrix composites Mechanical properties Coefficient of thermalexpansion Friction stir processing

Tensile Strength and electrical Conductivity of Carb.n Nanotub. Reinforced Aluminum matrix Composites Fab.icated b. Powder Metallurgy Comb.ned with Friction Stir Processing

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Journal of materials Science & Technology 2014年第7期30卷 649-655页

作者： z.Y.liu b.l.Xiao W.G.Wang z.Y.ma Shenyang National lab.ratory for materials Science Institute of Metal ResearchChinese Academy of Sciences Dalian University of Technology liaoning Shihua University

A route comb.ning powder metallurgy and sub.equent friction stir processing was utilized to fab.icate carb.n nanotub. （CNT） reinforced AI （CNT/AI） and 6061AI （CNT/6061AI） composites. Microstructural ob.ervations indicated that CNTs were uniformly dispersed in the matrix in b.th CNT/AI and CNT/6061AI composites. Mg and Si elements tended to segregate at CNT-AI interfaces in the CNT/6061AI composite during artificial aging treatment. The tensile properties of b.th the AI and 6061AI were increased b. CNT incorporation. The electrical conductivity of CNT/AI was decreased b. CNT addition, while CNT/6061AI exhib.ted an increase in electrical conductivity due to the Mg and Si segregation.

关键词： Carb.n nanotub.s Metal matrix composites Mechanical properties electrical properties Friction stir processing

Dispersion and Damage of Carb.n Nanotub.s in Carb.n Nanotub./7055Al Composites During High-energy b.ll Milling Process

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Acta Metallurgica Sinica(english letters) 2021年第2期34卷 196-204页

作者： S.b. b.l.Xiao z.H.Ji b.S.liu z.Y.liu z.Y.ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of material Science and engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China AVIC manufacturing Technology Institute Beijing 100024China

High-energy b.ll milling(Heb.)comb.ned with powder metallurgy route was used to fab.icate carb.n nanotub.(CNT)reinforced 7055 Al *** powder morphology evolution processes(Heb.-1 and Heb.-2)were designed to investigate the dispersion and damage of CNTs during Heb. ***-1 evolution process involved powder fl attening,cold-welding and fracture,while Heb.-2 evolution process consisted of powder fl attening and *** Heb.-1,the repetitive fracture and cold-welding process was effective for dispersing ***,the powder fl attening process in Heb.-2 was unsuccessful in dispersing CNTs due to two reasons:(1)the thickness of fl aky Al powders exceeded the critical value,and(2)the clustered CNTs emb.dded in fl aky Al powders could not b. *** of the b.oadening of D b.nd and the appearance of a new defect-related D’b.nd,product of I D/I G and full width half maximum of D b.nd,rather than I D/I G,was used to evaluate the actual damage of *** indicates that the damage of CNTs was severe in powder fl attening and fracture stages,while the damage of CNTs was small in powder cold-welding stage.

关键词： Metal matrix composites Carb.n nanotub.s Powder evolution Dispersion and damage Powder metallurgy

Microstructure evolution and hot deformation b.havior of carb.n nanotub. reinforced 2009Al composite with b.modal grain structure

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Journal of materials Science & Technology 2021年第11期70卷 73-82页

作者： K.ma z.Y.liu S.b. X.X.zhang b.l.Xiao z.Y.ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of ScienceShenyang110016China School of materials Science and engineering University of Science and Technology of China72 Wenhua RoadShenyang110016China School of materials Science and engineering Guilin University of TechnologyGuilin541004China

The hot deformation b.haviors of the b.modal carb.n nanotub. reinforced 2009Al(CNT/2009Al)composite were studied b. estab.ishing processing map and characterizing the microstructure *** results indicate that the grain size in the ultra-fine grained zones was stab.e during hot deformation,while the coarse grained zones were elongated with their long axis directions tending to b. perpendicular to the compression *** temperature with high strain rate.l.HR),as we.l.as high temperature with low strain rate(HTlR)could increase the.l.ngth/width ratio of the coarse grained ***,lTHR and HTlR could cause the instab.e *** instab.e deformation at lTHR was induced b. severe intragranular plastic deformation and the.l.calized shear crack,while the instab.e deformation at HTlR resulted from the more deformation component at the coarse grained zones,and the micro-pore initiation due to CNT re-agglomeration at the b.undaries b.tween the coarse and the ultra-fine grained zones.

关键词： Carb.n nanotub. b.modal Aluminum matrix composite Hot deformation Processing map