冷坩埚定向凝固Ti44A16Nb合金的组织演变规律.pdf

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1、第49卷第11期金扁学破VO1．49NO．112013年11月第1356—1362页ACTAMETALLURGICASINICANov．2013PP．1356—1362冷坩埚定向凝固Ti44A16Nb合金的组织演变规律陈瑞润)王纪超，z)马腾飞)郭景杰)丁宏升苏彦庆)傅恒志)1)哈尔滨工业大学材料科学与工程学院，哈尔滨1500012)中船重工天津修船技术研究所，天津300456摘要利用无污染的电磁冷坩埚进行定向凝固，对大尺寸Ti44A16Nb(原子分数，％)定向合金锭进行研究，研究了抽拉速率和加热功率对合金表面质量、固／液界面形态、枝晶形态以及相选

2、择的影响．结果表明，随抽拉速率降低和功率增大，铸锭表面质量提高，它们通过改变熔体过热度和糊状区体积而影响铸锭的表面质量；随抽拉速率增加，凝固界面变凹，且晶粒宽度变大，抽拉速率超过临界值后，柱状晶不能连续生长；随功率增加，晶粒宽度减小；在抽拉速率较低或功率较高时，易发生CET转变；抽拉速率为0．5mm／min时的初始凝固相为OL相，其它抽拉速率下初始凝固相为相·关键词Ti44A16Nb合金，冷坩埚，定向凝固，微观组织中图法分类号TG132．32文献标识码A文章编号0412—1961(2013)11—1356—07MICRoSTRUCTUREEVoLU

3、TION0FTi44A16NbALL0YDIRECTIoNALLYSoLIDIFIEDWITHC0LDCRUCIBLE删Ruirun¨，WⅣGJichao，，』Tengfei¨，GUOJingjie¨，DGHongsheng¨，Synnqing¨．FUHengzhi)1)SchoolofMaterialsScienceandEngineering，HarbinInstituteofTechnology,Harbin1500012)TianjinRepairTechnologyResearchInstitute，CSIC，Tianjin300456C

4、orrespondent：CHENRuirunassociateprofessor,Tel：(o451)86413931E—mail：ruirunchen@hit．edu．cnSupportedbyNationafBasicResearchProgramofChinaNo．2011CB6055o4)andProgramforNeWCenturyExcellentTalentsinUniversity(No．NCET-12—0153)andNationafNatura2ScienceFoundationofChina(No．512076)Manusc

5、riptreceived2013-09一O4一，inrevisedform2o39—24ABSTRACTTi44A16Nbfatomicfraction，％1ingotswithindustrysizeweredirectionallysolidifiedwithoutcontaminationwithelectromagneticcoldcrucible．Efiectsofpullingratesandpowersonthesurfaeequality，theS／Linterface，grainmorphologyandphaseselectio

6、nwerestudied．Theresultsshowthatthesurfacequalityareimprovedbydecreasingpullingrateorincreasingpower，theyinfluencethesurfacequalitybychangingthesuperheatdegreeofthemeltorthevolumeofthemushyzone．TheS／Linterfacebecomesconcaveandthegrainwidthbecomesbigwithincreasingofpullingrate，t

7、hecolumnargrainsgrowdiscontinuouslywhenthepullingrateisincreased．Thegrainwidthdecreaseswiththeincreaseofthepower．ColumnargraintoequiaxedgraintransitionfCET1iSeasytooccurredwhenthepullingrateiSlowerorthepoweriShigher．Atthebeginningofsolidification．theinitialphaseisphasewhenthep

8、ullingrateis0．5mm／min，whereas，itisphasewhenthepullingratesare