一種含稀土高溫合金偏聚行為的動態(tài)原位分析和晶界強度理論研究.pdf

1、鋼鐵研究總院碩士學位論文一種含稀土高溫合金偏聚行為的動態(tài)原位分析和晶界強度理論研究姓名：楊春申請學位級別：碩士專業(yè)：材料物理與化學指導教師：朱衍勇20070501塑墾型塞些墮堡圭蘭壘堡奎SegregationDynamicInsituAnalysisofaSuperalloyandStudyofGrain—boundaryStrengthTheoryAbstract：ThePairBondingtheorywasimprovedinth

2、ispaperVacancieswereintroducedintothegrainboundarymodelAndthefractureenergyoftheimprovedmodelWasdeducedAndwealsogottheconclusionthattheresultbasedontheimprovedmodelincludestheresultbasedontheoriginalmodelTheresultshowsth

3、atforsomeelementwhichwasconsideredtobeembrittlingelementintheprimarytheorysometimeswouldexhibitremedialeffect，iftheatomspreferentiallysegregatedonthesiteswhicharevacanciesButtheremedialeffectwouldbeobservedwhenthesegrega

4、tionconcentrationWassmallerthanacertainvalueonlyIfthesegregationconcentrationishigherthanthatvalue，theembrittlingcharacterwouldbeobservedallthesameThechangingofthegrainboundarystructurecausedbythesegregationwasconsidered

5、toresultintheforegoingphenomenonThekineticsofsegregationanddepthprofileonthefreesurfaceofasuperalloyGH742usinginsituAugerElectronSpectroscopy(AES)WasalsopresentedTheresultshowsthatS，La，Chasdiffusedfromthematrixandenriche

6、donthesurface，butCrMohasdiffusedintothematrixanddepletedonthesurfaceThekineticsshowsmesegregationofSandLawereequilibriumsegregation，butCwasnonequilibriumsegregationThedepthprofilesshowthatthereisalaminawhichC，N，Ti，Nbisen

7、richedin，andtheinterfacebetweenthelaminaandmatrixissharpwhentheagingtimeisshortInthelanlinatheconcentrationofCrMoislowerthanmatrix，anddecreasedintheagingperiod，buttheconcentrationofTi，Nbishigherthanmatrix，andincreasedint