共晶系和勻晶系二元合金熔體結(jié)構(gòu)轉(zhuǎn)變及其對凝固的影響.pdf

1、合肥工業(yè)大學博士學位論文共晶系和勻晶系二元合金熔體結(jié)構(gòu)轉(zhuǎn)變及其對凝固的影響姓名：李先芬申請學位級別：博士專業(yè)：材料學指導教師：丁厚福祖方遒20060801Liquid—liquidstructuretransitionsineutecticandsolidsolutionbinaryalloysandtheireffectsonsolidificationABSTRACTTheknowledgeonnatureofliquidstruc

2、turesandpmpertiesiscloselyrelatedtothedevelopmentofscienceandtechnologyinmanyfields；thereforeithasbeenbecomingacommonconcemforcondensedphysics，materialsscienc島lifesciencechemistrymetallur目andsoonAlthoughtheknowledgeOilli

3、quidstructuresandpropertiesismoresuperficialthanthatofsolidandgas，manyrespectablestaggeredachievementshavebeenobtainedinrecentyears，whichprovideabundantphenomendlogybasisforftlrtherexplorationof舭characterofliquidstmeture

4、婦1thetheorypo誠ofviewThetopologicalandchemicalshortrangeordersrevealedbyvariousdiffractionmethodandcomputerSimulations，enrichtheinUinsicphysicalmeaningOilshortrangeorderinliquidstructureThedirectevidenceofpressuredrivendi

5、scontinuousliquidliquidStroeturelavatsition(LLST)inliquidphosphorusbreaksthetraditionalconceptthat1iquidslructarechangescontinuouslyandgraduallywithtemperatureandpressurechangingThediscoveryoftempemaneinducedLLSTinbinary

6、liquidalloyssuppliesagapbetwtntheliquidusandliquidgascriticalpoin‘whichwillplayaprofoundeffectonunderstandingofsofidificalionmechanismdevelopmentofmaterialsanditsprocessingtechnologyHowevertheuniversalityandessenceofLLST

7、includingthetemperaturerange，conditionandrole，arestillunknownMoreove5althoughthetechnologyofmelttemperaturetreatment，meltoverheatingandthermal—ratetreatmentarenotinfrequentlyadoptedtoinvestigatetherelationbetweenthemelta

8、ndsolid，clearandsystematicinvestigationisnotfoundyetontheeffectofLLSTonthesolidificationbehaviorandmicrostructureInthepresentpapertheeutecticandsolidsolutionbinaryalloysarechosenastheinvestigationobjectTheelectricaltrans

9、portpropertiesandDSCanalysisofliquidPb—Sn，SnBi，PbBiandInSbeutecticlikealloysaresystematicallyexploredwithtemperaturechangingandtheresultiscomparedwiththatofsolidsolutionalloyBiSbBasedontheexperimentalresults，thecharacter

10、istics，rulesandmechanismofLLSTarealsoanalyzedtheoreticallyinthispaperForthefirsttime，thereversibilityanditscharacterofLLSTinbinaryalloysarealsodiscussedfromtheLLSTpointofviewFurthermore，basedonthepriorstudyandfromthenewp

11、ointviewofLLST’theeffectofLLSTonsolidificationbehaviorandmicrostructureisinvestigatedTheresultsaresummarizedasfollows：ILLISTexistsinalmostallinvestigatedliquidbinaryalloysexceptInSbduringheatingprocessinthefirstcyclewith

12、inmeasuredtemperaturerange，andtheLLSTtemperaturesareallfarabovetheirliquidus；ⅡItisobservedthatLLSTexistsinSn，Bi，SbonecomponentsystemduringheatingprocessinthefirstcycleForthefirsttime，thecharacteristicofpartialreversibili