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Characterization of high-press.r. die-cast hy.ereutectic Al-si alloy. based on micros.r.ctural dis.r.bution and fracture morphology

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Journal of Materials science & Technology 2019年第6期35卷 1099-1107页

作者： x.y. Jiao J. Wang C.F. Liu Z.P. guo g.D. Tong s.L. Ma y. bi y.F. Zhang s.M. xiong school of Materials science and Engineering Tsinghua University Beijing 100084 China state Key.Laboratory.of Automobile safety.and Energy Tsinghua University Beijing China China FAW Foundry.Co. Ltd. Changchun 130011. China

The fracture behavior of high-press.r. die-cast hy.ereutectic(HPDC) Al-si alloy. was investigated using a high-resolution laboratory.CT and sy.chrotron x-ray.tomography.with a particular focus on the influence of HPDC micros.r.cture. results showed that micros.r.cture of the alloy.was mainly.comprised of primary.silicon particles(PsPs), Al dendrites, Cu-rich phases and pores. Most of the coarse PsPs, Cu-rich phases and pores were located in the center of the specimen. The rapid solidification of HPDC led to a heterogeneous micros.r.ctural feature. Elemental Cu was enriched in the frontiers of solid-liquid interface, causing the formation of large size dendritic arms. The pores were formed in the interdendrites which endured high s.r.ss intensity.under high applied s.r.ss. Microcracks were originated from pores and further connected Cu-rich phases causing intergranular fracture. PsPs worked as obstacles causing piling-up dislocations in the phase interface. In the regions where large size of PsPs enriched in, PsPs.r.ptured rather than debonded from matrix, indicating trans.r.nular fractures of PsPs. Microcracks originated around pores and PsPs tended to converge on the main cracks to decrease the energy.required for crack propagation.

关键词： Hy.ereutectic Al-si alloy Primary silicon particles Porosity Fracture morphology High press.r. die casting

Mechanosy.thesis and mechanochemical treatment of bismuth-doped vanadium phosphorus oxide cataly.ts for the partial oxidation of n-butane to maleic anhy.ride

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Journal of Natural gas Chemis.r. 2008年第3期17卷 232-237页

作者： y. H. Taufiq-y.p y.C. Wong y. Kamiy. W.J. Tang Putra Center for Cataly.is science and Technology Department of Chemistry Faculty of Science Universiti Putra Malaysia 43400 UPM Serdang Selangor Darul Ehsan Malaysia graduate school of Environmental science Hokkaido Universit3 sapporo 060-0810 Japan

Three bi-doped vanady. py.ophosphate cataly.ts were prepared via dihy.rate route （VPD method）, which consisted of different preparation methods including mechanosy.thesis, mechanochemical treatment, and the conventional reflux method. The cataly.ts produced by.the above three methods were characterized by.x-ray.diffraction （xrD）, scanning electron microscopy.（sEM）, and temperature programmed reduction （TPr）. Cataly.ic evaluation for the partial oxidation of n-butane to maleic anhy.ride （MA） was also carried out. The xrD patterns of all the bi-doped cataly.ts showed the main peaks of py.ophosphate phase. Lower intensity.peaks were obs.r.ed for the mechanochemically.treated bi-doped cataly.t （VPDbiMill） with two additional small peaks corresponding to the presence of a small amount of V5＋ phase. The TPr profiles showed that the highest amount of active ox.g.n species, i.e, V4＋–O- pair, responsible for n-butane activation, was.r.moved from VPDbiMill. Furthermore, from the cataly.ic test results, the graph of selectivity.to MA as a function of the conversion of n-butane demons.r.ted that VPDbiMill was the most selective cataly.t. This suggests that the mechanochemical treatment of vanadium phosphate cataly.t （VPDbiMill） is a potential method to improve the cataly.ic properties for the partial oxidation of n-butane to maleic anhy.ride.

关键词： mechanosy.thesis mechanochemical treatment bismuth vanady. py.ophosphate

Micros.r.cture evolution and hot deformation behavior of carbon nanotube reinforced 2009Al composite with bimodal grain s.r.cture

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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.bi 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 behaviors of the bimodal carbon nanotube reinforced 2009Al(CNT/2009Al)composite were studied by.establishing processing map and characterizing the micros.r.cture *** results indicate that the grain size in the ultra-fine grained zones was stable during hot deformation,while the coarse grained zones were elongated with their long axis directions tending to be perpendicular to the compression *** temperature with high s.r.in rate(LTHr),as well as high temperature with low s.r.in rate(HTLr)could increase the length/width ratio of the coarse grained ***,LTHr and HTLr could cause the instable *** instable deformation at LTHr was induced by.severe intragranular plastic deformation and the localized shear crack,while the instable 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 boundaries between the coarse and the ultra-fine grained zones.

关键词： Carbon nanotube bimodal Aluminum matrix composite Hot deformation Processing map

Effect of Temperature on Material Transfer Behavior at Different stages of Friction stir Welded 7075-T6 Aluminum Alloy

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Journal of Materials science & Technology 2013年第10期29卷 955-960页

作者： s.D.Ji y.y.jin y.M.y.e s.s.gao y.x.Huang L.Wang Faculty.of Aerospace Engineering Shenyang Aerospace University state Key.Laboratory.of Advanced Welding and Joining Harbin Institute of Technology

In this work, the morphologies of weld of 7075-T6 aluminum alloy.via friction stir welding （FsW） were analy.ed by.optical microscopy. the temperature field was attained by.numerical simulation, and the effect of temperature on material transfer behavior in the thermal-mechanical affected zone （TMAZ） at different stages was mainly.investigated. The FsW process consists of three stages. It is very.interesting to find that the maximum transfer displacement of material appears at the final stage of welding process, then at the stable stage and at the initial stage, which results from the difference of peak temperatures at different stages. At any.stage, the material in TMAZ near the s.r.ace of weld transfers downwards, the material in the middle of weld moves upwards and the material near the bottom of weld hardly.moves. In any.cross section of weld, the largest transfer displacement of material appears in the middle of weld. The increase of rotational velocity.and the decrease of welding speed are both beneficial to the transfer displacement of material in the middle of weld.

关键词： Friction stir welding 7075-T6 aluminum alloy Thermal-mechanical affected zone Material transfer Numerical simulation

ANALy.Is OF TEMPErATUrE DEPENDENCE OF PHAsEs AND s.r.ACE MOrPHOLOgy.OF bi_2sr_2Ca_(x-1)Cu_xO_y.THIN FILMs UsINg rEACTIVE CO-DEPOsITION METHOD

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Acta Metallurgica sinica(English Letters) 2007年第3期20卷 199-204页

作者： Z.H. Zou x.M. y. B.s. Zhang y. Qi school of science Northeastern University Shenyang 110004 China

A reactive co-deposition processing for obtaining high-quality.single-phase bi2sr2Cax-1CuxOy.（bi2212） thin films has been investigated using molecular beam epitaxy.（MBE） with 2.7 ×10^-3pa ozone gas introduction for oxidation. The thin films with a constant composition of almost 2 ： 2 ： 1 ： 2 were designed to be fabricated at the subs.r.te temperature between 675 and 780℃, the subs.r.te temperature dependence of the s.r.ace morphology.and the emergence phases were investigated in detail. A noticeable result is that the dis.r.bution of Cu element in the thin films is sensitively.changed with the subs.r.te temperature. At 750℃ it is inclined to locate in the periphery.of each grain through the diffusion process. At 780℃ the Cu-compositional fluctuation brought around the dendritic cry.tal growth in the thin films. Below 705℃, the bi2212 single-phase cannot be achieved in the thin films.

关键词： bi2212 (bi2sr2Cax-1CuxOy. single-phase dendritic growth subs.r.te temperature

The characterization of Fe-rich phases in a high-press.r. die cast hy.oeutectic aluminum-silicon alloy

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Journal of Materials science & Technology 2020年第16期47卷 54-62页

作者： x.y.Jiao C.F.Liu Z.P.guo g.D.Tong s.L.Ma y.bi y.F.Zhang s.M.xiong school of Materials science and Engineering Tsinghua UniversityBeijing 100084China Key.Laboratory.for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084China China FAW Foundary.Co. LTDChangchun 130011China

Both micros.r.ctural characteristics and fracture behavior of Fe-rich phases in a high-press.r. die-cast hy.oeutectic Al-si alloy.were *** was focused on the morphology.and formation mechanism of Fe-rich phases,together with their influence on *** show that primary.Ferich phases exhibited in blocky.shape precipitated from liquid while secondary.Fe-rich phase in a large net shape was dis.r.buted along eutectic boundary.participating in a ternary.eutectic *** sy.chrotron x-ray.tomography.characterization,three Fe-rich phases with different morphologies,i.e.,poly.edral shape,fine compact shape and Chinese s.r.pt-ty.e shape were extracted along the radial *** slow-shot speed promoted the poly.edral Fe-rich phase to precipitate in slow-shot sleeve while decreased the formation of fine compact and Chinese s.r.pt-ty.e Fe-rich phases in die *** of a worse deformation compatibility.poly.edral Fe-rich phases fractured and became s.r.ss concentration sources before the failure of the casting.

关键词： Hy.oeutectic Al-10si Fe-rich phases Fracture morphology High press.r. die casting

PrEDICTION OF THErMODy.AMICs DATA OF TErNArV AND QUAfErNAry.MOLTEN ALLOy. WITH NrTL EQUATION

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Acta Metallurgica sinica(English Letters) 1999年第3期12卷 245-250页

作者： H. y. Hou g. xie g.H. Liu and s.r. Chen (Department of Metallurgy. Kunming University.of science and Technology. Kunming 650093, China)(Department of Metallurgy. Kunming University.of science and Technology. Kunming 650093, China)(Department of Metallur Kunming Univ of science and Technology Kunming China

NrTL equation is one of the equations that widely.used in chemical engineering thermody.amics. The marked advantage of the NrTL equation is that it can be used for predicting the thermody.amics.r.perties of multicomponent sy.tems only.with the data of binary.sy.tems. However the application of it to molten alloy. and the other melts in metallungy.has been mrsly.reported. In this article, it was used to correlate thermody.amics data of binary.molten alloy. which are included in the sy.tems-Cd-bi-sn, Cd-bi-Pb, Cd-sn-Pb. The data of those ternary.sy.tems were predicted by.NrTL equation. The activities of Cd in quaternary.sy.tem Cd-bi-Pb-sn were also calculated.

关键词： NrTL equation molten alloy activity.coefficient

Inconel 617 and stellite 6 alloy. for tooling in thixoforming of steels

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Transactions of Nonferrous Metals society.of China 2010年第9期20卷 1656-1662页

作者： y.bi rOL Materials Institute Marmara Research Centre

Thermal fatigue and high temperature wear are the two principle failure mechanisms for thixoforming dies. samples of Inconel 617 and stellite 6 alloy. were submitted to thermal cy.ling under conditions which approximate thixoforming of steels and to sliding wear tests at 750 ℃. The experimental results thus obtained were compared with those of the x32CrMoV33 hot work tool steel. The Inconel 617 and stellite 6 samples are much more resistant to oxidation and to softening than the hot work tool steel, providing a superior resistance to thermal fatigue cracking. The wear resistance of the Inconel 617 and stellite 6 alloy. at 750 ℃ is also markedly.superior. The adhesive oxides growing slowly.on Inconel 617 and stellite 6 alloy. sustain the wear action without spalling and are claimed to be responsible for the superior wear resistance of these alloy. at 750 ℃.

关键词： steel thixoforming tooling thermal fatigue wear

rEsEArCH ON THE FOrMATION MECHANIsM OF INTErNAL CrACK IN THE CONTINUOUs CAsTINg sLAB

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Acta Metallurgica sinica(English Letters) 2007年第1期20卷 35-39页

作者： g.W. Chang g.C. jin s.y. Chen x.D. y.e Department of Materials ＆ Chemical Engineering Liaoning Institute of Technology Jinzhou 121000 China

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary.dendrites. The initial crack formed during the middle and final stage of solidification may.extend to the s.r.ace of the casting slab and become an internal crack. The results of the theoretical analy.is are basically.in agreement with that of the experiment.

关键词： continuous casting dendritic spacing internal crack