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Thermal and structural properties of Nd2O3-doped calcium boroaluminate glasses

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journal of Rare Earths 2016年第5期34卷 521-528页

作者： j.D.M.Dias G.H.A.Melo T.A.Lodi j.O.Carvalho P.f.facanha filho M.j.Barboza A.Steimacher f.Pedrochi Centro de Ciencias Sociais Saude e TecnologiaUniversidade Federal do Maranhao-Imperatriz MA Instituto federal de Educaceo Ciencia e Tecnologia do Maranhao Campus Imperatriz-Imperatriz-MA Instituto federal de Educacao Ciencia e Tecnologia do Tocantins Campus Araguaina-Araguaina-TO

Nd^3＋ doped CaO-Al2O-B2O3-Caf2 glasses were prepared by conventional melt-quenching technique,and their structural and thermal properties were *** amorphous nature of these samples was confirmed by X-ray diffraction（XRD）.The measured density showed an increase with Nd2O3 doping,at the expense of *** spectra presented changes with addition of Nd2O3,which indicated that the network structure of the glasses studied presented various borate groups,such as tetraborates,metaborates,ortho-borates and pyroborates *** N4 values calculated from fTIR spectra revealed that incorporation of Nd2O3 into glass network converted the structural units from BO4 to *** the analysis of DTA curves,we verified that Tg increased with the addition of Nd2O3;it was similar to the behavior caused by modifier oxides in the structure of borate *** that,the calculated glass stability Tx–Tg for doped samples presented a decrease if compared to the undoped *** heat and thermal conductivity did not present significant changes with Nd2O3 concentration,up to 2.30 mol.%.The results of density,DTA,Raman and fTIR reinforced the idea that Nd2O3 acted as network modifier.

关键词： Nd^3+ Nd^3+ doped glass borate glasses glass structure thermal properties rare earths

NUMERICAL SIMULATION Of COLUMNAR TO EQUIAXED TRANSITION fOR DIRECTIONALLY SOLIDIfIED Ti-44Al ALLOY

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Acta Metallurgica Sinica(English Letters) 2008年第2期21卷 146-156页

作者： K.f. Wang j.j. Guo G.f. Mi C. Y. Li H.Z. fu School of IVlaterials Science and Engineering Henan Polytechnic University Jiaozuo 454100 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

Solute diffusion controlled solidification model was applied to simulate the columnar to equiaxed transition （CET） during directional solidification of Ti-44Al alloy. The simulation results show that the solutal interactions from growing equiaxed grains play an important role on CET. The effects of the applied thermal gradient and pulling velocity, the equiaxed seed spacing and nucleation undercooling on the CET are investigated in the present simulation. The simulated results indicated that the columnar branch spacing depends not only on the thermal gradient and the pulling velocity, but also on number of the seeds. A spacing adjustment can occur through initiation of seeds that develop into new columnar grains. The dependence of the CET on the thermal gradient and pulling velocity, qualitatively agrees with the analytical CET model of Hunt,

关键词： Ti-44Al alloy Directional solidification columnar to equiaxedtransition (CET) Numerical simulation

Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy

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journal of Materials Science & Technology 2021年第1期60卷 206-215页

作者： K.j.Tan X.G.Wang j.j.Liang j.Meng Y.Z.Zhou X.f.Sun Superalloys Division Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Department of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Both surface and internal microstructures of a second-generation Ni-based single crystal(SX) superalloy were studied after creep and rejuvenation heat treatment(RHT).It is indicated that the microstructures,such as the dislocation network,the γ phase and the γ' phase,can be recovered to those after the standard heat treatment(SHT).It is found that RHT affected zone(RAZ) formed at the surface is composed of theγ'-free layer,the transition layer and the recrystallization(RX),which are less than 20 μm in depth *** depth of the RAZ doesn't affect the properties of the *** morphology of γ' phase at the RAZ is related to the composition of the *** average creep life after RHT is close to the average life after *** is concluded that RHT could effectively repair SX parts and increase the total life of the sample after a damage by creep.

关键词： Superalloys Rejuvenation heat treatment Microstructure Creep property

Transient vibration of thin viscoelastic orthotropic plates

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Acta Mechanica Sinica 2011年第1期27卷 98-107页

作者： j.Soukup f.Vale j.Volek j.Skoilas jan Evangelista Purkyně University in ústí nad Labem Faculty of Production Technology and Management Department of Machinery and Mechanics Centre of Material Diagnostics Institute of Thermomechanics AS CR v.v.i Academy of Sciences Czech Republic

This article deals with solutions of transient vibration of a rectangular viscoelastic orthotropic thin 2D plate for particular deformation models according to flu¨gge and *** linear model,a general standard viscoelastic body,of the rheologic properties of a viscoelastic material was *** time and coordinate curves of the basic quantities displacement,rotation,velocity,stress and deformation are *** results obtained by an approximate analytic method are compared with numerical results for 3D plate generated by fEM application and with experimental investigation.

关键词： Transient vibration thin plate Orthotropic General viscoelastic standard solid.

PRECIPITATION BEHAVIOR Of M_(2)N IN A HIGH-NITROGEN AUSTENITIC STAINLESS STEEL DURING ISOTHERMAL AGING

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 95-101页

作者： f. Shi L.j. Wang W.f. Cui C.M. Liu School of Materials ＆ Metallurgy Northeastern UniversityShenyang 110004 China

The precipitation behavior of M2N and the microstructural evolution in a Cr-Mn austenitic stainless steel with a high nitrogen content of 0.43mass% during isothermal aging has been investigated using optical microscopy （ OM）, scanning electron microscopy （SEM）, and transmission electron microscopy （TEM）. The aging treatments have led to the decomposition of nitrogen supersaturated austenitic matrix through discontinuous cellular precipitation. The precipitated cells comprise alternate lamellae of M2N precipitate and austenitic matrix. This kind of precipitate morphology is similar to that of pearlite. However, owing to the non-eutectoidic mechanism of the reaction, the growth characteristic of the cellular precipitates is different from that of pearlite in fe-C binary alloys. M2N precipitate in the cell possesses a hexagonal crystal structure with the parameters a = 0.4752nm and c = 0.4429nm, and the orientation relationship between the M2V precipitates and austenite determined from the SADP is [01^-10]M2N//[101]γ, [2^-1^-10]M2N//[010]γ.

关键词： austenitic stainless steel high nitrogen microstructureisothermal aging precipitation

Mechanism transition of cross slip with stress and temperature in face-centered cubic metals

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journal of Materials Science & Technology 2020年第22期54卷 159-171页

作者： K.Q.Li Z.j.Zhang j.X.Yan j.B.Yang Z.f.Zhang Laboratory of fatigue and fracture for Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

A/2 screw dislocation is commonly dissociated into two /6 Shockley partial dislocations on{111} planes in face-centered cubic *** the two partials are not purely screw,different mechanisms of cross-slip could take place,depending on the stacking fault energy,applied stress and tempe *** is crucial to classify the mechanisms of cross-slip because each mechanism possesses its own reaction path with a special activation *** this work,molecular dynamics simulations have been performed systematically to explore the cross-slip mechanism under different stresses and temperatures in three different metals Ag,Cu and Ni that have different stacking fault energies of 17.8,44.4 and 126.8 mj/m^2,re *** Ag and Cu with low stacking fault energy,it is observed that the cross-slip mechanism of screw dislocations changes from the fleischer obtuse angle(fLOA),to the friedel-Escaig(fE),and then to the fL acute angle(fLAA) at low temperatures,with increasing the applied ***,when the temperature increases,the fE mechanism gradually becomes dominant,while the fLAA only occurs at the high stress *** particular,the fLOA has not been observed in Ni because of its high stacking fault energy.

关键词： Cross-slip Molecular dynamics simulation face-centered cubic metals Stacking fault energy

Dual effect of Cu on the Al3Sc nanoprecipitate coarsening

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journal of Materials Science & Technology 2020年第2期37卷 38-45页

作者： Y.H.Gao L.f.Cao j.Kuang j.Y.Zhang G.Liu j.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China International joint Laboratory for Light Alloys(Ministry of Education) Chongqing UniversityChongqing 400044China

It is generally considered that the Al3Sc nanoprecipitates are highly thermal stable,mainly due to quite slow Sc diffusion in theα-Al *** this paper,we demonstrate in an Al-Cu-Sc alloy that the Cu atoms have dual effect on the coarsening of Al3Sc *** the one hand,the Cu atoms with high diffusivity tend to accelerate the Al3Sc coarsening,which results from the Cu-promoted Sc *** the other hand,some Cu atoms will segregate at the Al3Sc/matrix interface,which further stabilizes the Al3Sc nanoprecipitates by reducing the interfacial *** between these two effects is tailored by temperature,which rationalizes the experimental findings that the coarsening kinetics of Al3Sc nanoprecipitate is greatly boosted at 300℃-overaging while significantly suppressed at 400℃-overaging.

关键词： Al alloys Precipitate coarsening Interfacial segregation Microstructural evolution

Lightning ablation suppression of aircraft carbon/epoxy composite laminates by metal mesh

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journal of Materials Science & Technology 2019年第11期35卷 2693-2704页

作者： f.S.Wang Y.Zhang X.T.Ma Z.Wei j.f.Gao School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710129China The Research Institute for Special Structures of Aeronautical Composite Ji’nan250023China

Three-dimensional finite element(fE)models of carbon/epoxy composite laminates with copper mesh and aluminum mesh protection were established subjected to lightning strike,in which different mesh spacing was *** of numerical method was verified and impulse current waveforms with different current peaks were applied according to aircraft lightning ***-electrical material parameters varying with temperature were added into numerical *** deletion method was used to deal with lightning ablation elements of composite *** results show that ablation area and depth of composite laminates with metal mesh protection are significantly smaller,which proves good protection effectiveness of metal meshes on anti-lightning *** denser the mesh spacing,the better the anti-lightning strike will *** of composite laminates with copper mesh has better effects than that of aluminum *** the effect of mesh spacing variation on composite structural weight and anti-lightning strike,the ideal mesh spacing was obtained.

关键词： Lightning strike Carbon/epoxy composites Ablation Mesh protection

SELf-CONSISTENT ELECTRONIC STRUCTURES STUDIES Of MAGNETISM AND SUPERCONDUCTIVITY IN CI5 COMPOUNDS: ZrZn2 AND ZrV2

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Science China Mathematics 1987年第6期30卷 661-672页

作者：黄美纯,H.j.f.jANSEN,A.j.fREEMAN Department of Physics Xiamen University Department of Physics Northwestern University Evanston Illinois U. S. A. Department of Physics Northwestern University Evanstton Illinois and Center for Materials Science Los Alamos National Laboratory U. S. A.

The applications of the newly developed all-eleatron full potential linearized augmented plane wave （fLAPW） method for bulk in the electronic structure of the cubic Laves phase （C15） compound ZrZn2and ZrV2are presented and the results have been applied to the calculation and discussion of the magnetic and superconducting properties in these materials. The computations are performed in two states: （ⅰ） self-consistent warped muffin-tin and （ⅱ） self-consistent full potential with spinorbit coupling included after either stage. The effects of the inclusion of the non-spherlcal terms inside the muffin-tins on the eigenvalues is small, of order 1 mRy. However, as some of the bands near the Efare flat, this effect could become noticeable in the value of DOS at Ef. The most important difference between the materials ZrZn2and ZrV is the position of the d-bands derived from the Zn and V *** results for superconducting transition temperature for these materials are much improved compared to the ea

关键词： LMT LAPW SELf-CONSISTENT ELECTRONIC STRUCTURES STUDIES Of MAGNETISM AND SUPERCONDUCTIVITY IN CI5 COMPOUNDS