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sTUDy ON sTRUCTUREs OF Al-CuAl_2 EUTECTIC sOLIDIFIED UNDER ELECTROMAGNETIC sTIRRING

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Acta Metallurgica sinica(English Letters) 1997年第6期10卷 461-464页

作者： W.q. zhang q.M. Liu y.F. zhu y.s. yang and z.q. hu(state Key Laboratory of RsA, Institute of Metal Research, Chinese Academy of sciences, shenyang 110015, China) Inst of Metal Research Chinese Acad of Sciences Shenyang China

An investigation on electromagnetically.s.irred solidification of Al-CuAl2 eutectic system is presented in this paper. With electromagnetic stirring in solidification, structural transition from lamellar to rod-like eutectic has been found in the as-cast structures, and provided strong stirring is applied, proeutectic growth of α-Al phase is enhanced. Moreover, the interphase spacing of eutectic is clearly increased with melt flow intensified. Numerical computation of flow field is also presented, and the effect of stirring on structural formation is discussed.

关键词： electromagnetic stirring eutectic,interphase spacing fluid flow

sOLIDIFICATION OF NICKEL-BAsED sINGLE CRysTAL sUPERALLOy By ELECTRIC FIELD

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Acta Metallurgica sinica(English Letters) 2005年第6期18卷 679-685页

作者： y.s. yang X.H. Feng G.F. Cheng y.J. Li z.q. hu Institute of Metal Research The Chinese Academy of Sciences Shenyang 110016China

The crystal growth of a nickel-based single crystal superalloy DD3 was researched via controlled directional solidification under the action of a DC electric field. The cellular or dendrite spacing of the single crystal superalloy is refined and microsegregation of alloying elements Al, Ti, Mo and W, is reduced by the electric field. The electric field decreases the interface stability and reduces the critical growth rate of the ceUular-dendritic translation because of Thomson effect and Joule heating. The precipitation of the γ＇ phase is more uniform and the size of the γ＇ phase is smaller with the electric field than that without the electric field.

关键词： single crystal superalloy DC electric field crystal growth segregation,γ' phase

FEM sIMULATION OF REsIDUAL sTREssEs INDUCED By LAsER sHOCK WITH OVERLAPPING LAsER sPOTs

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Acta Metallurgica sinica(English Letters) 2008年第2期21卷 125-132页

作者： y.X. hu z.q. yao state Key Laboratory of Mechanical system and Vibration Shanghai Jiaotong University Shanghai 200240China

The finite element method is presented to attain the numerical simulation of the residual stresses field in the material treated by laser shock processing. The distribution of residual stresses generated by a single laser shock with square and round laser spot is predicted and validated by experimental results. With the Finite Element Method （FEM） model, effects of different overlapping rates and impact sequences on the distribution of residual stresses are simulated. The results indicate that：（1） Overlapping laser shock can increase the compressive residual stresses. However, it is not effective on the growth of plastically affected depth; （2） Overlapping rate should be optimized and selected carefully for the large area treatment. Appropriate overlapping rate is beneficial to obtain a homogeneous residual stress field; （3） The impact sequence has a great effect on the residual stress field. It can greatly attenuate the phenomenon of the “residual stress hole” to obtain a homogeneous residual stress field.

关键词： Laser shock processing Overlapping Residual stress Finite element method

MICROsTRUCTURE AND MACROsEGREGATION OF Al-7%si ALLOy.s.LIDIFIED UNDER COMPLEX EFFECTs OF ELECTROMAGNETIC AND CENTRIFUGAL FORCEs

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Acta Metallurgica sinica(English Letters) 1997年第2期10卷 105-114页

作者： y.F. zhu W.q. zhang y.s. yang q.M. Liu and z.q. hu (state Key Lab. of RsA, Institute of Metal Research, Chinese Academy of sciences, shenyang 110015,Chilla) Inst of Metal Research Chinese Acad of Sciences Shenyang China

Macrosegregations and microstructures of Al-7%si alloy.s.lidified under complex of fects of magnetic field and centrifugal forces are studied by means of a set of selfdesigned electromagnetic centrifugal casting (EMCC) device. It is shown that electromagnetic field (EMF) has an important effect on the macrosegregation of centrifugal casting specimen of Al-7%si alloy in two respects: one is that there exists always a kind of convection in the liquid in front of the s/L interface caused by effect ofthe electromagnetic force; the other is that different atomic clusters of solidparticles with different physical characteristics are subjected to quite different electromagnetic (Lorentz) force. Therefore, their movements get changed. In addition, the formation process of a complex band structure consisting of primary α-Al dendrites and (α-Al+β-si) eutectics in hypoeutectic Al-si alloys during EMCC and the effect of EMF are discussed.

关键词： electromagnetic field (EMF) centrifugal force Al-7%si alloy macrosegregation solidification microstructure convection

sTUDy ON TEMPERATURE FIELD INDUCED IN HIGH FREqUENCy INDUCTION HEATING

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Acta Metallurgica sinica(English Letters) 2006年第3期19卷 190-196页

作者： H. shen z.q. yao y.J. shi J. hu school of Mechanical Engineering Shanghai Jiaotong University Shanghai 200030 China

A mathematical model was established for the temperature field developed during high frequency induction heating （HFIH） by Maxwell＇s equations. It required solving the coupled equations of the electromagnetic and temperature fields. The numerical simudation was performed using FEMLAB. The comparison of the calculations using the proposed model with experimental results showed a very good correlation. The effects of the heating parameters in high frequency induction such as the distance between the plate and the coil, the applied current, the frequency, and the turns of the coil on the temperature profiles developed in the plate were also discussed using the established model.

关键词： high frequency induction temperature field numerical simudation

First-principles Investigation of Bi segregation at the solder Interface of Cu/Cu_3sn(010)

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Journal of Materials science & Technology 2010年第12期26卷 1057-1062页

作者： X.y. Pang z.q. Liu s.q. Wang J.K. shang shenyang National Laboratory for Materials science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials science and Engineering University of Illinois at Urbana-Champaign IL 61801 USA

Density functional theory was employed to investigate the bismuth segregation at Cu/Cu3sn（010） interface. Five initial constructions were introduced by adopting the adhesion energy criterion. Among them, the so-called ＂between-Cu＂ construction in which the interface Cu atoms of Cu slab locate along Cu-Cu bond direction in Cu3sn slab was found to be the most energy-favored at an adhesion energy of 1.96 J/m^2. Based on this construction, five possible segregation sites were examined, and the most likely.s.gregation site was determined with adhesion energy as low as 1.06 J/m^2, which was almost half of the initial one. Comparing with other sitest adhesion energies, it was concluded that size effect took a large part in embrittlement. The analyses of atomic structure and electronic density revealed that the slabs shifted away from interfaces due to bismuth segregation, and the atoms around Bi atom were Dressed away. This calculated work agreed aualitativelv with reported experimental results.

关键词： First-principles calculation segregation Bismuth Interface snBi solder

NUMERICAL INVEsTIGATION OF sTRAIGHT-LINE LAsER FORMING UNDER THE TEMPERATURE GRADIENT MECHANIsM

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Acta Metallurgica sinica(English Letters) 2006年第2期19卷 144-150页

作者： y.J. shi H. shen z.q. yao J. hu school of Mechanical and Power Engineering Shanghai Jiaotong University Shanghai 200030 China

Laser forraing is a new flexible and dieless forming technique. To achieve the high accuracy forming, the temperature gradient mechanism （TGM） is studied. In the analysis of TGM, the plate bends about x-axis and about y-axis as well. To understand the deformation trend, the numerical simulation of deformation of plate is conducted by choosing different laser powers, laser spot diameters, scanning speeds, lengths, widths and thicknesses. From the results of simulation, it can be seen that the laser spot diameter, the scanning speed, laser power and thickness of plate play dominant roles in the laser forming process. However, the bending angles αx and αy.s.ow different trends with the variation of parameters. In addition, in comparison with above four parameters, the effect of length and width of plate on the beading angle may be neglected, but their effects are significant for the bending radius R.

关键词： laser forming temperature gradient mechanism metal plate

synthesis and Characterization of Fe_(50)Cr_(14)Mo_(14)C_(14)B_6Gd_2 Bulk Amorphous steel

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Journal of Materials science & Technology 2010年第9期26卷 783-786页

作者： M. Iqbal J.I. Akhter H.F. zhang z.q. hu Physics Division Pakistan Institute of Nuclear Science &: Technology P.O. Nilore Islamabad Pakistan shenyang National Laboratory for Materials science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

Bulk amorphous steel having 7 mm thickness was synthesized to evaluate its thermal stability and mechanical *** steel was synthesized by Cu mold casting technique using 1-2N pure *** of the material was done by X-ray diffraction,differential scanning calorimetry and scanning electron *** activation energies were calculated by Kissinger equation and it was found that the steel had better stability against *** properties like Vicker s hardness,nanohardness,elastic modulus and elastic recovery of as-cast and annealed samples were *** was concluded that the present steel had good glass-forming ability（GFA） and mechanical properties.

关键词： Bulk amorphous steels Activation energy Glass-forming ability Mechanical properties

Template-free Fabrication and Luminescent Characterization of Highly Uniform and Monodisperse y_2O_2s:sm^(3+) Hollow submicrospheres

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Journal of Materials science & Technology 2012年第7期28卷 666-672页

作者： s.q. Deng z.P. Xue y.H. yang q. yang y.L. Liu Department of Chemistry Jinan University Guangzhou 510632 China

Well dispersed and homogeneous y2O2s：sm3＋ hollow submicrospheres were successfully achieved by a template- free solvothermal method combining with a postcalcining process. The crystalstructure and particle morphology were investigated by the X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectra, scanning and transmission electron microscopy （sEM and TEM）, respectively. A possible growth mechanism was proposed to reveal the formation process. Luminescence properties of the y202s：sm3＋ long-lasting phosphor were an- alyzed by measuring the excitation spectra, emission spectra, afterglow decay curve and thermoluminescence curve. The excitation spectra indicated that the phosphor could be excited effectively by the ultraviolet-light emitting diode （UV-LED） or blue LED, and the emission spectra showed that the phosphor could emit red light from 600 to 650 nm.

关键词： yttrium oxysulfide Hollow submicrosphere Luminescence Long-lasting phosphor