Nb、Ta添加對 Zr-Cu-Al-Ni大塊非晶合金結構、熱穩(wěn)定性、晶化行為和性能影響的研究.pdf

1、華中科技大學碩士學位論文Nb、Ta添加對ZrCuAlNi大塊非晶合金結構、熱穩(wěn)定性、晶化行為和性能影響的研究姓名：孫民申請學位級別：碩士專業(yè)：材料學指導教師：柳林20040428AbstractInthisdissertationtheeffectofsubstitutionofZrwithNbTaonstructurethermalstabilitycrystallizationbehavicompressivemechanicalc

2、rosionpropertiesoftheascastZr65Cu17.5Ni10Al7.5bulkmetallicglasswereinvestigatedusingXraydiffraction(XRD)opticalmicroscopy(OM)scanningelectronmicroscopy(SEM)coupledwithenergydispersiveXraydetect(EDX)differentialscanningca

3、limetry(DSC)differentialthermalanalysis(DTA)mechanicaltestingsystemhighresolutiontransmissionelectronmicroscopy(HRTEM)electrochemicalpolarization..BulkZr65xCu17.5Al7.5Ni10Mx(M=NbTa)(x=0~10at%)alloyswithadiameterof3mmwere

4、preparedbycoppermoldcasting.XRDpatternsSEMobservationshowthatthesubstitutionofZrwithasmallamountofNbTadoesnotchangetheamphousnatureofobtainedalloys.HoweverifNbTacontentreachesacertainleverbulkmetallicglassmatrixcomposite

5、scontainingcrystallinephaseswillbefmed.ThemphologiesamountoftheprecipitatesintheamphousmatrixvarieswiththecontentofNbTa.DSCDTAanalysesrevealthatthethermalstabilityofZr65Cu17.5Al7.5Ni10Mx(M=NbTa)decreaseswiththeincreaseof

6、NbTacontent.FthesamecontentofTaNbtheTabearingalloyexhibitsahigherthermalstabilityascomparedtotheNbbearingalloy.MeovertheadditionofNbTachangestheexothermicmodeofthebaseBMGfromsinglestagetomultiplestages.Inadditiontheentha

7、lpy?HfcrystallizationdecreaseswiththeincreasingNbTaconcentration.Itisverifiedinthefirsttimethatthefirststageexothermicreactionfalloyscontaining2at%5at%NbTacrespondstothefmationoficosahedralquasicrystalsthefollowingonesto

8、thephasetransfmationofthequasicrystalsintothestablephaseZr2Cucompound.BesidescompositionanalysisonpartiallyquasicrystallizedsamplesdemonstratesthatNbmainlylocatedinquasicrystalsindicatingNbpromotethefmationofquasicrystal

9、s.FurthermethequasilatticedistanceofthequasicrystalvariedwithdifferentNbTacontents.Studyonthecompressivemechanicalbehavifracturefeaturerevealthattheplasticitystrengthofthebasealloyareenhancedbytheadditionofappropriateamo