冷却速度对Al-7Si-0.3Mg-0.15Fe合金凝固参数和微观组织的影响-论文.pdf

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1、Availableonlineat、^n^n^f．sciencedirect．comTransactionsof嘞ScienceDirectNonferrousMetalsSocietyofChinaELSJ三ⅥERPressTrans．NonferrousMet．Soc．China24(2014)1645—1652WwW．tnmsc．CrlEffectofcoolingrateoNsolidificationparametersandmicrostructureofA1—7Si一0．3Mg一0．15FealloyRuiCHEN，Yu—fengSHI，Qing—yah

2、XU，Bai—chengLIUKeyLaboratoryforAdvancedMaterialsProcessingTechnologyofMinistryofEducation，SchoolofMaterialsScienceandEngineering，TsinghuaUniversity，Beijing100084，ChinaReceived18June2013；accepted8September2013Abstract：Theeffectsofcoolingrateonthesolidificationparametersandmicrostructureo

3、fA1-7Si～0．3Mg一0．15Fealloyduringsolidificationprocesswerestudied．Toobtaindiferentcoolingrates．thestepcastingwithfivediferentthicknesseswasusedandthecoolingratesandsolidificationparametersweredeterminedbycomputer-aidedthermalanalysismethod．Theresultsshowthatathighercoolingrates．theprimary

4、a(A1)dendritenucleationtemperature．eutecticreactiontemperatureandsolidustemperatureshifttolowertemperatures．Besides．withincreasingcoolingratefrom0．19。C／supto6．25。C／sthesecondarydendriticarlnspacingdecreasesfrom68txmto20gm．andtheprimarydendriticvolumefractiondeclinesbyapproximately5％．Ina

5、ddition，itreducesthelengthofFe．bearingphasefrom28pmto18Binwithabetteruniformdistribution．Itisalsofoundthathighcoolingratesmakeformodi～ingeutecticsiliconintofibrousbranchedmorphology,anddecreasingblockorlamellashapeeutecticsilicon．Keywords：aluminiumalloys；coolingrate；thermalanab，sis；soli

6、dificationparameters：microstructurecoarseplate．1ikeeutecticsiliconintofineandfibrous1Introductionform．Coolingratecaninfluencethetemperaturegradientandsolidificationrate．andisoneofthemostWithgoodcombinationofcastability,corrosionimportantvariableswhichafectmicrostructureandresistance，hig

7、hspecificstrength，especiallyinheatmechanicalpropertiesofcastings[2,6，7】．Athighertreatedconditions。A1-Si—Mgcastingalloyshavecoolingrates．moredendriteswithsmallsizewillbeachievedwidespreadusageinautomotiveandaerospaceformed[8]，resultinginlowerandmoreuniformindustries．Thesealloyso