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1、Chap.1HEATFLOWINSOLIDFICATION1-3Alargeslabofaluminum,25cmthick,ispouredinasandmoldwithnosuperheat.(a)Howlongwillittakefortheslabtosolidify?(Assumenegligibleresistancetoheatflowatthemold-metalinterfaceandwithinthesoliditymetal)(b)Showschematicallycoolingcurves
2、forathermocouple6.25cmformthesurfaceandoneatthecenterofthecasting.(Remember,thesolidifiedportionofthecastingremainsveryclosetountilthecastingiscompletelysolid)1-10(a)Aslabofiron,25cmthick,ispouredwithnosuperheatintoanironmold.Calculatethesolidificationtimeass
3、umingnomold-metalinterface.(b)Howmuchlongerisrequiredforsolidificationoftheslabinasandmold?Neglectresistancetoflowwithinthesolidifiedmetalandatthemold-metalinterface.(c)Whatpercentageerrordidyouintroducein(b)byneglectingresistancetoheatflowwithinthesolidified
4、metal?1-14Youaretohelpdesignaverticalcontinuous-castingmachinetomake8-in-thicklow-carbonsteelslabs.Castingspeedtobeaimedforis100in/min.Whatistheminimum-heightcastingtoweryoumustplantobuild?Chap.2PLANEFRONTSOLIDIFICATIONOFSINGLE-PHASEALLOYS2-1AGe-Gaingotcontai
5、ning10ppmGaissolidifiedatR=8*cm/swithnegligibleconvection.Showschematically,thecompositionalongthelengthofthefullysolidifiedingot,givingtheinitialcompositionandlengthsoftheinitialandfinaltransient.Assume=5*/s,k=0.1.2-5AnAl-1%Cualloyisnormallysolidifiedwith=k.
6、ThephasediagramforthisalloyisschematicallyasinFig.2-3with=33%Cu,=5.65%Cu,=660℃，and=548℃.(a)Howmucheutecticwillbepresentinthefinallysolidifiedbarassumingnosoliddiffusion?(a)Atasolidificationvelocityofcm/s,doyouexpectsignificantdiffusioninthesolid?[Note:=0.29*/
7、s;R=1.99cal/(mol)(°K).]Chap.3CELLULARSOLIDIFICATION3-2AnAl-1%Cualloyisgrownbynormalfreezingat3*cm/swithconvectioncompletelysuppressed.(ThephasediagramforthisalloyisasshownschematicallyinFig.2-3,=33%Cu,=5.65%Cu,=660℃,=548℃,andconstantkand;=3*/s.)3-3Whatthermal
8、gradientwouldberequiredtomaintaintheplanefrontinProb.3-2,accordingtotheMullinsandSekerkainterfacestabilitycriterion?(Assumethethermalconductivityofthesolidishalfthatoftheliquid;σ=1.2*cal/
