各向異性條件下過冷熔體中晶體生長的相場模型研究.pdf

1、上海交通大學(xué)博士后學(xué)位論文各向異性條件下過冷熔體中晶體生長的相場模型研究姓名：趙達(dá)文申請學(xué)位級別：博士后專業(yè)：材料加工工程指導(dǎo)教師：李金富20091001上海交通大學(xué)博士后出站報(bào)告AbstractAhi曲lyefficientalgorithm—adaptivefiniteelementanalysissystemisconstructedforsolvingthephase—fieldequationsWiththephase—fie

2、ldmodel，theeffectsofcapillaryanisotropy，kineticanisotropyandtheinteractionofthetwoanisotropyonthecrystalfreegrowthbehaviorintheundercooledmeltsisextensivelyinvestigatedThemainconclusionsareasfollows：(1)Efficientdynamicad

3、aptivefiniteelementanalysissystemisachievedTheZienkiewicz—Zhumethodisusedtoestimatetheerrorofelements，meanwhile，themethodofmasslumpingareadoptedtoreducethecomputationconsumptionThegenerationalgorithmofadaptivemeshwhichis

4、basedonthequadtreedatastllJctllreispresentedWiththisalgorithm，thecomputationtimeisreducedfromⅣu—∥inuniformgridstoNf0andthecapacityofmemoryrequirementisreducedfromMretoMrL(2)Thephase—fieldmethodsimulationindicatesthatthef

5、reedendritegrowthissensitivetothemagnitudeofcapillaryanisotropyIncreasetheanisotropyCanpromotedendritegrowth，thedendritetipgrowthvelocityincreases、Ⅳiththeanisotropicstrength，whilethedendritetipradiusdecreasesFurtherstuay

6、indicatesthatthestabilityparameterincreaseswiththeanisotropicstrengthinapowerlawrelationship(3)Thesimulationillustratedthattheselectionofthegrowthbehaviorisdeterminedbythekineticanisotropicparameterifthecapillaryanisotro

7、pyismissedWhentheanisotropylessthan002，themeltsolidifiesinafractalpattem，duringwhichthereisnoobviouspreferredgrowthdirection，andanysteadystategrowthcannotbedetectedAstheanisotropybecomesgreaterthan002，thegrowthmorphology

8、changestoadendriticpatterngrowthalongtheorientationAnalysisindicatesthatthestabilityparameterincreaseslinearly、Ⅳimtheincreaseofkineticanisotropicparameterandisindependentofthekineticcoefficient(4)Thecomprehensiveeffectof