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1、SynthesisofTiB2nanocrystallinepowderbymechanicalalloyingSciencePressAvailableonlineatwww.sciencedirect.corn●C_lENCETram.NonferrousMet.Soc.China16(2006)613—617TransactionsofNonferrou$MetalsSocietyofChinaWWW.CSU.edu.cn/ysxb/SynthesisofTiB2nanocrystallinepowderbymechanicalalloyingTANGWen—ming(汤文明),Z
2、HENGZhi-xiang(郑治祥),WUYu—cheng(吴玉程),WANGJian—min(T建民),LOJun(吕瑁),LIUJun一,vu(刘君武)SchoolofMaterialsScienceandEngineering,HefeiUniversityofTechnology,Hefei230009,ChinaReceived19January2005;accepted29July2005Abstract:TiB,nanocrystallinepowderwassynthesizedbymechanicalalloyingofTi一67Belementalpowder.X—r
3、aydiffraction(XRD)andtransmissionelectronmicroscopy(TEM)wereusedtostudythes仃uctlⅡlalevolutionofthepowderduringballmilling.Theeffectsofheattreatmentonthestruc~alevolutionandthermalstabilityofthemechanicallyalloyed(MAed)Ti一67Bpowderwerealsodiscussed.DuringballmillingtheTi.67Bpowder,asolidsolutionof
4、BinTi.Ti(B)isfirstlyformed.,Ⅳhenthepowderismilledfor10h,theamorphoustransitionofTi(B)fromthecrystallinetotheamorphousphaseoccurs.,Ⅳhellthepowderismilledfor20h,nanocrystallineTiB2isformedfromtheamorphousTi(B).,Ⅳhenthepowderismilledfor60h,onlyTiB2isdetectedwithgrainsizeof10nlrl1.TheformationofTiB,n
5、anocrystallineiscontrolledbythegradualdiflusionreactionmechanism.Duringheat.treatmentoftheMAedTi.67Bpowder,thestructuralchangesofTiB2,includinggraingrowthandlatticeorderingdegreeincreasingmayoccur.Keywords:TiB2;mechanicalalloying;structuralevolution;nanocrystalline1IntroductionTiB,hasbeenwidelyus
6、edinsomeindustrialfieldsowingtoitshighmeltingtemperature,hardness,elasticmodulus.electro—conductibilityandthermaldiffusivity,andexcellentrefractorypropertiesandchemicalinertness.Usually,TiB2hasbeenproducedbythereductionofTiO2andB2O3withcarbonandactivemetal,andtheself-propagatinghigh—temperaturesy
7、nthesis[1-4]Becausethereactiontemperatureisveryhighintheseprocesses,thegraingrowthrateofTiB2israpid.So,itisverydifficulttoobtainpureandultrafine—grainTiB,powderbytheseprocesses.Thishasaninevitableeffectonthepropertieso
