英文原版教材班材料科学基础考试试题Word文档格式.docx
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英文原版教材班材料科学基础考试试题Word文档格式.docx
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2)basis(ormotif):
3)packingfractor:
4)slipsystem:
5)criticalsize:
6)homogeneousnucleation:
7)coherentprecipitate:
8)precipitationhardening:
9)diffusioncoefficient:
10)uphilldiffusion:
2.DeterminetheindicesfortheplanesinthecubicunitcellshowninFigure1.(5points)
Fig.1
3.Determinethecrystalstructureforthefollowing:
(a)ametalwitha0=4.9489Å
r=1.75Å
andoneatomperlatticepoint;
(b)ametalwitha0=0.42906nm,r=0.1858nmandoneatomperlatticepoint.(10points)
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;
(4points)
(2)Describethesolidificationprocessofthealloy2#withverylowcoolingspeed(includingphaseandmicrostructurechanges);
(3)Plottheisothermalsectionat150oC.(7points)
5-2.A1mmsheetofFCCironisusedtocontainN2inaheatedexchangerat1200oC.TheconcentrationofNatonesurfaceis0.04atomicpercentandtheconcentrationatthesecondsurfaceis0.005atomicpercent.At1000oC,ifsameNconcentrationisdemandedatthesecondsurfaceandthefluxofNbecomestohalfofthatat1200oC,thenwhatisthethicknessofsheet?
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.3
7-1.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)Fulltemperedmartensite
Ifyoucan,pleasedrawtherelativecoolingcurveortheflowchartofheattreatment.
II
III
I
IV
Fig.5
英文原版教材班“材料科学基础”考试试题答案
Solutionsofthecourseof“fundamentofmaterialsscience”
1)Thearrangementoftheatomsinamaterialintoarepeatablelattice.
2)Agroupofatomsassociatedwithalattice.
3)Thefractionofspaceinaunitcelloccupiedbyatoms.
4)Thecombinationoftheslipplaneandtheslipdirection.
5)Theminimumsizethatmustbeformedbyatomsclusteringtogetherintheliquidbeforethesolidparticleisstableandbeginstogrow.
6)Formationofacriticallysizedsolidfromtheliquidbytheclusteringtogetherofalargenumberofatomsatahighundercooling(withoutanexternalinterface).
7)Aprecipitatewhosecrystalstructureandatomicarrangementhaveacontinuousrelationshipwithmatrixfromwhichprecipitateisformed.
8)Astrengtheningmechanismthatreliesonasequenceofsolidstatephasetransformationsinadispersionofultrafineprecipitatesofa2ndphase.Thisissameasagehardening.Itisaformofdispersionstrengthening.
9)Atemperature-dependentcoefficientrelatedtotherateatwhichatom,ion,orotherspeciesdiffusion.TheDCdependsontemperature,thecompositionandmicrostructureofthehostmaterialandalsoconcentrationofthediffusionspecies.
10)Adiffusionprocessinwhichspeciesmovefromregionsoflowerconcentrationtothatofhigherconcentration.
2.Solution:
A(-364),B(-340),C(346).
3.Solution:
(a)fcc;
(b)bcc.
(5points)
(3)Plottheisothermalsectionat150oC.(5points)
(3)Howtocalculatethecriticalradiusofthenucleusrequired?
(4)FortheMetalNi,theFreezingTemperatureis1453︒C,theLatentHeatofFusionis2756J/cm3,andtheSolid-liquidInterfacialEnergyis255⨯10-7J/cm2.Pleasecalculatethecriticalradiusat1353︒C.(AssumethattheliquidNiisnotsolidified.)
(3)Ifthesolidificationistoorapid,pleasedescribethesolidificationprocessofMg-10wt%Alalloy.
(4)PleasedescribetheequilibriumsolidificationprocessofMg-20wt%Alalloy,andcalculatetheamountofeachphaseat300︒C.
Fig.5
试卷二
1.Youwouldliketobeabletophysicallyseparatedifferentmaterialsinascraprecyclingplant.Describesomepossiblemethodsthatmightbeusedtoseparatematerialssuchaspolymers,aluminumalloys,andsteelsfromoneanother.(5points)
2.Plotthemeltingtemperatureoftheelementsinthe1Acolumnoftheperiodictableversusatomicnumber(i.e.,plotmeltingtemperaturesofLithroughCs).Discussthisrelationship,basedonatomicbondingandbindingenergy.(10points)
3.Above882℃,titaniumhasaBCCcrystalstructure,witha=0.332nm.Belowthistemperature,titaniumhasaHCPstructure,witha=0.2978nmandc=0.4735nm.DeterminethepercentvolumechangewhenBCCtitaniumtransformstoHCPtitanium.Isthisacontractionorexpansion?
(10points)
4.ThedensityofBCCironis7.882g/cm3andthelatticeparameteris0.2866nmwhenhydrogenatomsareintroducedatinterstitialpositions.Calculate(a)theatomicfractionofhydrogenatomsand(b)thenumberofunitcellsrequiredonaveragetocontainonehydrogenat
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