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cREEP BEHAVIOR OF γ-TiAl POLYSYNTHETIcALLY TWINNED cRYSTALS

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 577-583页

作者： Y.g. Zhang J.g. Lin Y.J. Zhou and c.q. chen(Department of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics,Beijing 100083, china Beijing Univ of Aeronautics and Astronautics Beijing China

creep behavior of γ-TiAl polysynthetically twinned (PST) crystals has been investigated at temperature between 700 and 800℃. The results show that the creep behavior of the crystals is strongly dependent on the angle between the lamellar boundaries and loading axis. The samples with the angle φ=45 deg. have the lowest creep resistance, while the samples with φ=0 deg., rather than φ=90 deg.,show the strongest creep resistance. The stress exponent and creep activation energy for the power law creep vary with the orientations of samples, which indicates that the creep mechanisms of the samples with different angle φ are quite *** deformation substructure has been examined by transmission electron microscopy (TEM),which shows that both gliding, perhaps also climbing, of dislocations and twinning contribute to the creep deformation with some particular observation in the samples with φ=90 deg. in which rotation of the γ plates across a true twin boundary was observed, which indicates the deformation mechanism of the samples is different from the samples in other orientations.

关键词： TiAl alloy PST crystal creep behavior lamellar microstructure

Mathematical modeling and numerical computation of the effective interfacial conditions for Stokes flow on an arbitrarily rough solid surface

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Applied Mathematics and Mechanics(English Edition) 2021年第5期42卷 721-746页

作者： A.T.TRAN H.LE qUANg q.c.HE D.H.NgUYEN Research and Application center for Technology in civil Engineering University of Transport and CommunicationsHanoi 10000Vietnam Laboratoire Modelisation et Simulation Multi-Echelle Unite Mixte de Recherche 8208Centre National de la Recherche ScientifiqueUniversite Gustave EiffelMarne-la-Vallee F-77454France School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

The present work is concerned with a two-dimensional(2D)Stokes flow through a channel bounded by two parallel solid *** distance between the walls may be arbitrary,and the surface of one of the walls can be arbitrarily *** main objective of this work consists in homogenizing the heterogeneous interface between the rough wall and fluid so as to obtain an equivalent smooth slippery fluid/solid interface characterized by an effective slip *** solve the corresponding problem,two efficient numerical approaches are elaborated on the basis of the method of fundamental solution(MFS)and the boundary element methods(BEMs).They are applied to different cases where the fluid/solid interface is periodically or randomly *** results obtained by the proposed two methods are compared with those given by the finite element method and some relevant ones reported in the *** comparison shows that the two proposed methods are particularly efficient and accurate.

关键词： effective slip length method of fundamental solution(MFS) boundary element method(BEM) Stokeslet micro-channel fluid/solid interface

cLE peptide-mediated signaling in shoot and vascular meristem development

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Frontiers in Biology 2017年第6期12卷 406-420页

作者： Thai q. Dao Jennifer c. Fletcher Plant gene Expression center United States Department of Agriculture-Agricultural Research Service Albany CA 9471 O USA Department of Plant and Microbial Biology University of California Berkeley Berkeley CA 94720 USA

Background Multicellular organisms rely on the transmission of information between cells to coordinate various biological processes during growth and development. Plants, like animals, utilize small peptide ligands as signaling molecules to transmit information between cells. These polypeptides typically act as extracellular messengers that are perceived by membrane-bound receptors, which then transduce the signal into the recipient cell to modify downstream gene transcription. The cLAVATA3/EMBRYO SURROUNDINg REgION-RELATED (cLE) proteins represent one of the largest and best understood families of small polypeptides in plants. Members of the cLE family play critical roles in mediating cell fate decisions during plant development, particularly within the unique meristem structures that contain stem cell reservoirs acting as sources of cells for continuous organ *** Here we review the roles of cLE family members in regulating the activity of the shoot apical meristems that generate the aerial parts of the plants, and of the vascular meristems that produce the sugar- and water-conducting *** A systematic literature search was performed using the google Scholar and PubMed search engines. The keywords “cLE”, “cLV3”, “TDIF”, “meristem”, and “plant stem cells” were used as search terms. The 95 retrieved articles, dating from 1992, were organized by topic and their key findings incorporated into the *** We summarize our current understanding of how the cLE peptide cLV3 orchestrates the activity of shoot apical meristems, describing its expression, processing and movement, as well as its intracellular signal transduction pathways, key target genes and downstream gene regulatory networks. We also discuss the roles of cLE peptide signaling in the vascular meristems to promote procambial cell proliferation and suppress xylem *** Signaling pathways mediated by cLE peptides are critical for stem cell maintenance and di

关键词： cLE cLV3 TDIF WUS stem cells procambium

FATIgUE cRAcK gROWTH FEATURE OF Fe-cr-Ni MATRIX cOMPOSITE REINFORcED BY TITANIUM cARBIDE PARTIcULATE AT 1023K

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Acta Metallurgica Sinica(English Letters) 1999年第6期12卷 0-0,0-0+0-0页

作者： Z. F. Wan X.D. Hui g.q. Yuan Y. S. Yang X.c chen Shandong University of Technology Jinan 250061 China Institute of Metal Research The Chinese Academy of Sciences Shenyang 110015 China Institute of Physics The Chinese Academy of Sciences Beijing 100080 China

The initiation and propagation of the short fatigue crack in a 10vol% titanium carbide particulate reichreed cast Fe-26cr-14Ni mathe coopsite at 1023K were *** is shown that the titanium carbide particulate may hinder the crack propagation and fatigue fracture of the composite. The relationships between fatigue crack propagation rate and stress intensity factor are da/dN=4.2×10-c(△K)4 for the matrix alloy and da/dN=1.4×10-19(△K)c for the composite. The fatigue thresholds of the composite and mathe alloy are 78 and 3.2MPa.m1/2, respectively. Microcracks initiate at the intedece between titanium carbide particulate and austenite and then propagate in carkide particles. The fracture sudece of the composite shows a distinct transition from wavy and serated cleavage near the threshold regime to striation-type splitting in the stable fatigue crack propagation stage and to a veined morphology characteristic in unstable rapid region.

关键词： fatigue crack initiation and propagation Fe-cr-Ni matrix composite titanium carbide particulate

SYNTHESIS AND IDENTIFIcATION OF cONDUcTINg POLYANILINE DOPED WITH RARE EARTH cHLORIDE

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Acta Metallurgica Sinica(English Letters) 2000年第3期13卷 872-876页

作者： Yang, c.M. Zhang, q.R. Fang, Z. central South Univ of Technology Changsha China

Polyaniline doped with rare earth chloride was synthesized in organic solvent and identified by elemental analysis and infrared spectroscopy. The experimental results show that there exists both doping and complexation at the same time in the resulting product. When pH4. Moreover, polyaniline doped with rare earth chloride exhibits better thermal stability than that doped with hydrochloric acid.

关键词： chlorine compounds composition conductive materials Electric conductivity Organic polymers Rare earth compounds Synthesis (chemical)

EVOLUTION OF MIcROSTRUcTURE OF Sn-Ag-cu LEAD-FREE FLIP cHIP SOLDER JOINTS DURINg AgINg PROcESS

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 301-306页

作者： Y.H. Tian c.q. Wang W.F. Zhou State Key Lab of Advanced Welding Production and Technology Harbin Institute of Technology Harbin 150001 China

Flip chip bonding has become a primary technology that has found application in the chip interconnection process in the electronic manufacturing industry in recent years. The solder joints of the flip chip bonding are small and consist of complicated microstructures such as Sn solution, eutectic mixture, and intermetallic compounds （IMcs）, whose mechanical performance is quite different from the original solder bulk. The evolution of microstructure of the flip chip solder joints under thermal aging was analyzed. The results show that with an increase in aging time, coarsening of solder bulk matrix and AuSn4 IMcs occurred within the solder. The IMcs that are formed at the bottom side of the flip chip bond were different from those on the top side during the aging process. （cu, Ni, Au）0Sn5 were formed at the interfaces of both sides, and large complicated （Au,Ni, cu）Sn4 IMcs appeared for some time near the bottom interface after aging, but they disappeared again and thus （cu,Ni, Au ）0Sn5 IMc thickness increased considerably. The influence of reflow times during the flip chip bonding （as-bonded condition） on the characteristics of interfacial IMcs was weakened when subjected to the aging process.

关键词： lead free solder flip chip aging

STUDY THE INFLUENcE OF H_(3)BO_(3)ON THE ZINc ELEcTROPLATINg USINg ELEcTROcHEMIcAL NOISE TEcHNIqUE

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Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 661-666页

作者： Z.Zhang c.S.Wu q.Y.cai Y.L.cheng F.H.cao J.q.Zhang c.N.cao Departmentofchemistry ZhejiangUniversityHangzhou310027China StateKeyLaboratoryforcorrosionandProtection InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of H3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.

关键词： zinc electroplating electrochemical noise electrocrystallization

DEcREASINg PITTINg SUScEPTIBILITY OF PASSIVE FILMS ON X70 PIPELINE STEEL IN Nacl SOLUTIONS BY ILLUMINATION

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 91-97页

作者： W.c. Zhu W.H. Leng J.q. Zhang c.N. cao Department of chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for corrosion and Protection of Metals Institute of Metal Research The Chinese Academy of Sciences Shenyang 110016 China

The influence of UV illumination on passivity and pitting susceptibility on X70 pipoeline steel in a borate buffer （pH=8.4 ） solution containing Nacl is described. It is observed that illumination of the sample leads to a decrease in its pitting susceptibility as indicated by pitting potential and incubation time measurements in chloride containing electrolytes. This effect is strongly dependent on the applied potential during passivation. The electronic properties of the passive films on X70 steel were studied by Mott-Schottky analysis and photocurrent transient measurements. The results indicated that illumination during passivation led to modifications in the electronic properties of the passive films, mainly to a decrease of the bulk doping and an increase in the surface state density. The cause for the decrease in the pitting susceptibility is preliminary explained in terms of such modifications of the passive flm.

关键词： X70 pipeline steel pitting susceptibility illumination passivation

Delayed plasticity during spherical nanoindentation of an iron-chromium-aluminum alloy:Effect of ferric ion irradiation

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Journal of Materials Science & Technology 2023年第36期167卷 228-236页

作者： Y.Zhang c.W.Li J.L.Jiang J.F.gu H.Wang Y.D.Jia g.Wang X.g.An q.Wang J.Lu Institute of Materials Shanghai UniversityShanghai 200072China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Mechanical Engineering City University of Hong KongKowloonSARChina Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu 610041China Interdisciplinary Materials Research center Institute for Advanced StudyChengdu UniversityChengdu610106China

Spherical nanoindentation of an iron-chromium-aluminum alloy was conducted to study the effect of ferric-ion(Fe 3+)irradiation on the time-dependent plasticity behavior in the surface layers of this *** was observed that the initiation of plasticity by the appearance of displacement burst or“pop-in”event occurred after a period of waiting time in the apparent elastic regime and that Fe^(3+)irradiation at 360°c and up to∼0.5 displacements per atom could make it happen under the lower applied loads but with a reduced *** the experimental data,an activation volume and activation energy were extracted for the delayed *** results show that Fe^(3+)-irradiation significantly reduced its acti-vation volume from∼3.05 b 3 to∼1.75 b 3(where b=Burgers vector),but slightly increased its activation energy from∼0.65 to∼0.71 *** the other hand,high-resolution scanning transmission electron mi-croscopy observations reveal that the irradiation at the elevated temperature created interstitial atom pair onto the(100)habit plane that can serve as the nucleation site of a100dislocation loop while elim-inating the pre-existing ***,it is indicated that heterogeneous nucleation of the dislocation loop was predominant in the delayed plasticity initiation of this alloy and that the nucleation of the interstitial-type dislocation loop was involved due to Fe^(3+)-irradiation.

关键词： Spherical nanoindentation Delayed plasticity FecrAl alloy Fe^(3+)-irradiation