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High-Speed Friction Stir Welding of T6-Treated B4Cp/6061Al Composite

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Acta Metallurgica Sinica(English letters) 2020年第1期33卷 67-74页

作者： Y.z.li Y.N.zan q.z.Wang B.l.Xiao z.Y.Ma Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China university of Science and Technology of China Shenyang 110016China

T6-treated 20 wt% B4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(FSW) with a threaded cermet pin. The macro-defect-free FSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. In the nugget zone(Nz) of the joints, the B4 C particles were broken up and uniformly redistributed. The Nz exhibited lower hardness than the base metal(BM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the BM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ~ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the Nz. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the Nz due to the kissing bond defects.

关键词： Metal-matrix composites Microstructures Mechanical properties Friction stir welding High-speed welding

Transfer or blockage:unraveling the interaction between deformation twinning and grain boundary in tantalum under shock loading with molecular dynamics

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Journal of Materials Science & Technology 2023年第25期156卷 118-128页

作者： z.C.Meng M.M.Yang A.H.Feng S.J.qu F.zhao l.Yang J.H.Yao Y.Yang q.B.Fan H.Wang Interdisciplinary Centre for Additive Manufacturing (ICAM) School of Materials and ChemistryUniversity of Shanghai for Science and TechnologyShanghai 200093China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Tongji UniversityShanghai 201804China Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China National Key laboratory of Science and Technology on Materials under Shock and Impact School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401135China

The interaction between{112}deformation twinning and grain boundary in coaxial polycrystalline tantalum under shock compression was studied with molecular dynamics simulation under different grain pair misorientation angles(MA)and geometric compatibility factor(m’).Generally,in the coaxial polycrystal,the value of MA determines the occurrence of twin transfer(TT)or twin blockage(TB),i.e.,twin transfer occurs at MA≤29°with twin blockage *** TT,the value of m’affects the selection of twin variants.,i.e.,the twin system with a larger m’is easier to *** morphology of twin pairs is ruler-shaped and lenticular under TT and TB,respectively,with different thickening mechanisms,including grain boundary dislocation emission.

关键词： Plasticity Grain boundary Twin Atomistic simulation Tantalum

Effect of post weld artificial aging and water cooling on microstructure and mechanical properties of friction stir welded 2198-T8 Al-li joints

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Journal of Materials Science & Technology 2022年第28期123卷 92-112页

作者： Y.Tao z.zhang P.Xue D.R.Ni B.l.Xiao z.Y.Ma Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

Friction stir welding(FSW)under both air cooling and water cooling conditions with welding parameters of 800-1200 rpm rotation rates and 50-200 mm/min welding speeds was carried out on 2198-T8 Al-li alloys,and post weld artificial aging was performed on the air cooled *** welding defects other than lazy S were observed in the nugget zone(Nz)for all *** air cooling condition,the lowest hardness zone(lHz)occurred in the heat affected zone(HAz).FSW resulted in gradual dissolution of original T_(1),θ′andδ′/β′from the base material(BM)to the thermo-mechanically affected zone(TMAz),and complete dissolution of all precipitates in the Nz withδ′/β′and Guinier-Preston zones precipitating during *** air cooled joints exhibited no noticeable changes in intrinsic tensile strength with a joint strength reaching 81.3%of the BM,but varied elongation with welding parameters,which was closely related to failure in the Nz and fracture along lazy *** weld artificial aging led to the largest hardness recovery in the TMAz but smaller hardness recovery in the initial lHz and the *** aging kinetics across the joint was determined by volume fraction of both original precipitate dissolu-tion during welding and coarse particles formed during aging,and by dislocation density inherited from *** weld artificial aging greatly enhanced the joint strength with the ultimate tensile strength reaching 87.3%of the *** compared to air cooling condition,water cooling hardly affected the Nz hardness and did not improve the joint strength,and the reason was discussed in light of precipitates,hardness changes and fracture behavior.

关键词： Friction stir welding Aluminum-lithium alloys Microstructure Mechanical properties

EXPERIMENTAl RESEARCH AND NuMERICAl SIMulATION OF lASER SHOCK FORMING OF TA2 TITANIuM SHEET

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Acta Metallurgica Sinica(English letters) 2006年第5期19卷 347-354页

作者： F. Wang z. q. Yao J. Hu q.l. Deng School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200030 China

laser shock forming （ISF） was a new technique realized by applying an impulsive pressure generated by laser-induced shock wave on the surface of metal sheet. lSF of metal sheet was investigated with experiments and numerical simulation. The basic theories were introduced; the surface quality and deformation of the processed titanium sample （TA2） were examined; ABAquS was used to simulate ISF and the central displacement of the shocked region was measured and compared with the simulation. Overlapped ISF treatment was experimentally carried out to produce groove and simulation. The results showed that the surface quality and the microstructure with single laser pulse had no remarkable change, and ablation was observed on the surface of the sample with overlapped pulses. The deformation observed in the numerical simulation agreeed with that observed in the experimental measurement quite well.

关键词： laser shock forming numerical simulation surface quality deformation

Spectral and Timing Analysis of the Black Hole Transient MAXI J1631–479 During its 2019 Outburst Observed with Insight-HXMT

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Research in Astronomy and Astrophysics 2022年第11期22卷 21-33页

作者： Yu-Cong Fu l.M.Song G.q.Ding S.N.zhang J.l.qu S.zhang l.zhang q.C.Bu Y.Huang X.Ma z.X.Yang Y.l.Tuo X.F.lu D.K.zhou B.Y.Wu T.M.li Y.C.Xu Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqiXinjiang 830011China university of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Institut fur Astronomie und Astrophysik Kepler Center for Astro and Particle PhysicsEberhard Karls UniversitatSand 1D-72076 TübingenGermany

We report spectral and timing analysis of the black hole transient MAXI J1631–479 during the hard intermediate state of its 2019 outburst from the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)*** find that the energy dependence of the type-C quasi-periodic oscillation(qPO)frequency evolves with time:during the initial rise of a small flare(~MJD 58526.0-58527.1),the qPO frequency increases with increasing energy from~1 to~100 ke V,and then the frequency remains constant after MJD *** discover a possible new phenomenon of Fe line’s qPO frequency jump that has never been observed for other black hole transients:during the small flare,the qPO frequency around the Fe line energy is higher than any other energy band,with the frequency difference Δf=0.25±0.08 Hz between 5.5–7.5 ke V and other energy *** spectral analysis shows that the evolution of qPOs is related to the equivalent width of the narrow Fe line,and its equivalent width increases during this small *** propose that the qPO frequency difference results from the differential precession of a vertically extended jet,and the higher qPO frequency of Fe line could be caused by the layered jet when the jet scale *** the same time,the evolution of qPOs is related to the accretion rate,while the energy dependence of qPOs supports the existence of deceleration in the vertically distributed jet.

关键词： accretion accretion disks stars:black holes X-rays:binaries

Inhibiting effect of I-phase formation on the plastic instability of the duplex structured Mg-8li-6zn-1.2Y(in wt.%)alloy

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镁合金学报(英文) 2023年第6期11卷 2196-2204页

作者： B.J.Wang D.K.Xu X.q.zhuang l.Y.Sheng School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang110159China Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Peking university Shenzhen InstituteShenzhen Key Lab Human Tissue Regenerate&RepairShenzhen 518057China

In this work,the tensile behaviors of Mg-8%li and Mg-8%li-6%zn-1.2%Y alloys at ambient temperature were investigated and *** revealed that the plastic instability of Mg-8%li alloy was quite remarkable and the variation range of serrated flowing stress can reach5 *** the Mg-8%li-6%zn-1.2%Y alloy,the formation of I-phase(Mg_(3)zn_(6)Y)can simultaneously enhance the tensile strength and eliminate the plastic instability phenomenon,whilst its ductility was *** in-situ tensile tests revealed that for the Mg-8%li alloy,the severity and number of slip traces present in bothα-Mg andβ-li matrix phases increased remarkably with the applied tensile ***,slip traces were quite fine inβ-li matrix phase and could be clearly observed when the applied tensile strain exceeded 18%.Due to the incompatibility of plastic deformation occurred in two matrix phases,the induced strain concentration atα-Mg/β-li interfaces caused their subsequent *** the Mg-8%-6%zn-1.2%Y alloy,the I-phase distributed atα-Mg/β-li interfaces suppressed the plastic deformation ofα-Mg matrix phase and the tensile strain was dominated by theβ-li matrix phase,resulting in the disappearance of plastic ***,the plastic strain would preferentially concentrate at I-phase/β-li interfaces and subsequently induced the cracking of I-phase.

关键词： Mg-li alloys Microstructure Plastic deformation Basal slip Cracking

Oxygen and Nitrogen Effects on MC Carbide in K465 Nickel-Base Superalloy

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稀有金属材料与工程 2009年第A3期38卷 13-16页

作者： Wang l N zheng q Sun X F Guan H R Hu z q Institute of Metals Research Chinese Academy of Sciences Shenyang 110015 China

Effects of oxygen and nitrogen on MC carbide in nickel-base superalloy K465 were investigated, because neither of the two gas elements was found to decide MC carbide morphology monotonically. The morphology of MC carbide under alloy solidified in conventional investment casting condition was observed to transform from script-type to block-type with the total oxygen and nitrogen content (gas content) in samples rising up from 1.2×10-6 mol/g to 2.6×10-6 mol/g. The area fraction and composition of the MC carbide also varied with increase of gas content. However, the morphology of MC carbide kept to be script-type even when gas content was up to 3.4×10-6 mol/g in samples solidified with a much higher cooling rate. These results indicate that effects of gas content on formation of MC carbide can be observed in specimens solidified with low cooling rate, but such changes in MC carbide cannot be found when the cooling rate is high.

关键词：氧碳化物氮含量物理性能碳化物

Competition among the two-plasmon decay of backscattered light,filamentation of the electron-plasma wave and side stimulated Raman scattering

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High Power laser Science and Engineering 2023年第6期11卷 87-94页

作者： K.q.Pan z.C.li l.Guo T.Gong S.W.li D.Yang C.Y.zheng B.H.zhang X.T.He laser Fusion Research Center China Academy of Engineering PhysicsMianyangChina Center for Applied Physics and Technology Peking UniversityBeijingChina Institute of Applied Physics and Computational Mathematics BeijingChina

Competition among the two-plasmon decay(TPD)of backscattered light of stimulated Raman scattering(SRS),filamentation of the electron-plasma wave(EPW)and forward side SRS is investigated by two-dimensional particlein-cell *** previous work[*** et al.,*** 58,096035(2018)]showed that in a plasma with the density near 1/10 of the critical density,the backscattered light would excite the TPD,which results in suppression of the backward ***,this work further shows that when the laser intensity is so high(>10^(16)W/cm^(2))that the backward SRS cannot be totally suppressed,filamentation of the EPW and forward side SRS will be *** the TPD of the backscattered light only occurs in the early stage and is suppressed in the latter *** distribution functions further show that trapped-particle-modulation instability should be responsible for filamentation of the *** research can promote the understanding of hot-electron generation and SRS saturation in inertial confinement fusion experiments.

关键词： laser plasma instability inertial confinement fusion high energy density physics particle-in-cell simulation super-hot electrons

Constitutive equation and model validation for a 31 vol.% B_4Cp/6061Al composite during hot compression

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Journal of Materials Science & Technology 2018年第10期34卷 1730-1738页

作者： l. zhou C. Cui q.z. Wang C. li B.l. Xiao z.Y. Ma Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China School of Electromechanical and Vehicle Engineering Yantai University Yantai 264005 China School of Mechanical Engineering Shenyang Ligong University Shenyang 110159 China Nuclear and Radiation Safety Center Ministry of Environmental Protection Beijing 100082 China

An accurate constitutive equation is essential to understanding the flow behavior of B4C/A1 compos-ites during the hot deformation. However, the constitutive equations developed previously in literature are generally for low strain rate deformation. In the present work, we modified the general consti-tutive equation and take the high strain rate correction into account. The constitutive equation for a 31 vol.% B4Cp/6061AI composite was constructed based on the flow stresses measured during isothermal hot compression at temperatures ranging from 375 to 525 ℃ and strain rates from 0.01 to 10 s^-1. The experimental flow stresses were corrected by considering temperature-dependent Arrhenius factor. The modified equation was then verified by using DEFORM-3D finite element analysis to simulate the exper-imental hot compression process. The results show that the modified equation successfully predicts flow stress, load-displacement, and the temperature rise. This helps to optimize the hot deformation process, and to obtain desirable properties, such as reduced porosity and homogenous particle distribution in B4C/AI composites.

关键词： Composites B4C/AI Constitutive equation Hot compression Finite element simulation