鋁合金定向凝固過程中氣泡與固相協(xié)同生長的研究.pdf

1、東南大學碩士學位論文鋁合金定向凝固過程中氣泡與固相協(xié)同生長的研究姓名：范冉申請學位級別：碩士專業(yè)：材料科學與工程；材料加工工程指導教師：廖恒成20120530AbstractAbstractMechanismsofcoupled—growthbetweenporeandsolidifyingsolidinA1alloyanditsinfluencefactorswerereviewedinthispaperfocusingontheef

2、fectofhydrogencontentandsolidificationvelocityInordertoachieveultralowandconstantsolidificationvelocityandsteadytemperaturefield，significantlymodifyingworksontheX—rayimagingdirectionalsolidificationsetup(XIDS)havebeenmad

3、eEffectofsolidificationvelocityonthecoupled—growthinA1—127％SialloyhasbeenstudiedusingthenewXIDSset—upConclusionsobtainedareasfollowingInthemodificationoftheset—up，newandbetterdesignedslideblockstructureandhigheraccuracyl

4、eadscrewandguideswereadoptedtoeliminatecrawlingandvibratingoftheslideblock，thusthemotionofitbecomesfairlysmoothAbigreductionratiotransmissionandaDCservomotorsystemareselectedtocontroltherotation，SOamuchwiderspeedcontrolr

5、angeandsteadyrotatespeedsofultra—lowmicronscaleareobtainedTheheightofthenewset—uphasbeenshortenedfrom2000mmto1400mm，andthecomplexityofithasbeenreducedandtheoperabilityhasbeenimprovedThemicrostructureevolutionduringsolidi

6、ficationofA1一Sieutecticalloyandtheinteractionbetweenporeandsolidphasecanbeobservedinreal—timebyaddingacertainamountofheavymetalelementSnintothemeltDuringdirectionalsolidificationatlowvelocityitisfoundthatporescoupled—gro

7、wlocallywiththesolidifyingsolid，dependingonradiusofcurvatureofpore，solidificationvelocityandhydrogencontentinthemeltIfasteadycouplegrowthisobtained，theradiusofcurvatureofporewillremainconstantduringtheliquid／solidinterfa

8、ceadvancingforward，thustheporeformedwillbecylindrical；ifthecoupledgrowthisunsteadytheporewillbecomecone—shapedorturbinationIncaseofsteadycoupledgrowth，boththeaverageradiusofporesandratioofcouple—grownporestothetotalporen