材料科学与工程基础英文版试题

材料科学与工程基础”考试试题–英文原版教材班（注：第1、2、3题为必做题；第4、5、6、7题为选择题，必须二选一。共100分）1.Glossary(2pointsforeach)1)crystalstructure:Thearrangementoftheatomsinamaterialintoarepeatablelattice.2)basis(ormotif):Agroupofatomsassociatedwithalattice.3)packingfractor:Thefractionofspaceinaunitcelloccupiedbyatoms.4)slipsystem:Thecombinationoftheslipplaneandtheslipdirection.5)criticalsize:Theminimumsizethatmustbeformedbyatomsclusteringtogetherintheliquidbeforethesolidparticleisstableandbeginstogrow.6)homogeneousnucleation:Formationofacriticallysizedsolidfromtheliquidbytheclusteringtogetherofalargenumberofatomsatahighundercooling(withoutanexternalinterface).7)coherentprecipitate:Aprecipitatewhosecrystalstructureandatomicarrangementhaveacontinuousrelationshipwithmatrixfromwhichprecipitateisformed.8)precipitationhardening:Astrengtheningmechanismthatreliesonasequenceofsolidstatephasetransformationsinadispersionofultrafineprecipitatesofa2ndphase.Thisissameasagehardening.Itisaformofdispersionstrengthening.9)diffusioncoefficient:Atemperature-dependentcoefficientrelatedtotherateatwhichatom,ion,orotherspeciesdiffusion.TheDCdependsontemperature,thecompositionandmicrostructureofthehostmaterialandalsoconcentrationofthediffusionspecies.10)uphilldiffusion:Adiffusionprocessinwhichspeciesmovefromregionsoflowerconcentrationtothatofhigherconcentration.2.DeterminetheindicesfortheplanesinthecubicunitcellshowninFigure1.(5points)Fig.1Solution:A(-364),B(-340),C(346).3.Determinethecrystalstructureforthefollowing:(a)ametalwitha0=4.9489Å,r=1.75Åandoneatomperlatticepoint;(b)ametalwitha0=0.42906nm,r=0.1858nmandoneatomperlatticepoint.(10points)Solution:(a)fcc;(b)bcc.4-1.Whatisthecharacteristicofbrinellhardnesstest,rockwellhardnesstestandVickershardnesstest?Whataretheeffectsofstrainrateandtemperatureonthemechanicalpropertiesofmetallicmaterials?(15points)4-2.Whataretheeffectsofcold-workonmetallicmaterials?Howtoeliminatethoseeffects?Andwhatismicro-mechanismfortheeliminatingcold-workeffects?(15points)5-1.BasedonthePb-Sn-BiternarydiagramasshowninFig.2,tryto(1)Showtheverticalsectionof40wt.%Sn;(5points)(2)Describethesolidificationprocessofthealloy2#withverylowcoolingspeed(includingphaseandmicrostructurechanges);(5points)(3)Plottheisothermalsectionat150oC.(5points)5-2.A1mmsheetofFCCironisusedtocontainN2inaheatedexchangerat1200oC.TheconcentrationofNatonesurfaceis0.04atomicpercentandtheconcentrationatthesecondsurfaceis0.005atomicpercent.At1000oC,ifsameNconcentrationisdemandedatFig.2thesecondsurfaceandthefluxofNbecomestohalfofthatat1200oC,thenwhatisthethicknessofsheet?(15points)6-1.Supposedthatacertainliquidmetalisundercooleduntilhomogeneousnucleationoccurs.(15points)(1)Howtocalculatethecriticalradiusofthenucleusrequired?Pleasegivethedeductionprocess.(2)FortheMetalNi,theFreezingTemperatureis1453C,theLatentHeatofFusionis2756J/cm3,andtheSolid-liquidInterfacialEnergyis25510-7J/cm2.Pleasecalculatethecriticalradiusat1353C.(AssumethattheliquidNiisnotsolidified.)6-2.Fig.3isaportionoftheMg-Alphasediagram.(15points)(1)Ifthesolidificationistoorapid,pleasedescribethesolidificationprocessofMg-10wt%Alalloy.(2)PleasedescribetheequilibriumsolidificationprocessofMg-20wt%Alalloy,andcalculatetheamountofeachphaseat300C.Fig.37-1.Figure4showsustheAl-CubinarydiagramandsomemicrostructuresfoundinacoolingprocessforanAl-4%Cualloy.Pleaseanswerfollowingquestionsaccordingtothisfigure.(20points)Fig.4(1)Whatareprecipitate,matrixandmicroconstituent?Pleasepointthemoutintheinthefigureandexplain.(2)Whyisneed-likeprecipitatenotgoodfordispersionstrengthening?Thetypicalmicrostructureshowninthefigureisgoodornot?why?(3)Pleasetellushowtoobtaintheidealmicrostructureshowninthisfigure.(4)Candispersionstrengthenedmaterialsbeusedathightemperature?Pleasegivethereasons(comparingwithcoldworkingstrengthening)7-2.Pleaseanswerfollowingquestionsaccordingtothetime-temperature-transformation(TTT)diagramasshowninFig.5.(20points)(1)WhatsteelisthisTTTdiagramfor?AndwhatmeansP,B,andMinthefigure?(2)WhydosetheTTTdiagramexhibitsa‘C’shape?(3)PointoutwhatmicroconstituentwillbeobtainedafterausteniteiscooledaccordingtothecurvesI,II,IIIandIV.(4)WhatismicrostructuraldifferencebetweenthecurveIandthecurveII?(5)Howtoobtainthesteelwiththestructureof(a)P+B(b)P+M+A(residual)(c)P+B+M+A(residual)(d)FulltemperedmartensiteIfyoucan,pleasedrawtherelativecoolingcurveortheflowchartofheattreatment.Fig.5IIIIIIIV