Mullite-Al合金復合材料界面微結構及微成分研究.pdf

1、四川大學碩士學位論文MulliteAl合金復合材料界面微結構及微成分的研究材料加工工程專業(yè)研究生:張先菊指導教師:李偉教授本文在詳細綜述國內外非連續(xù)增強鋁基復合材料界面研究進展的基礎上，用擠壓鑄造方法制備莫來石(Mullite)短纖維增強鋁基復合材料，采用掃描電子顯微鏡(SEM)、透射電子顯微鏡〔TEM，含高分辨透射電子顯微鏡HRTEM和分析透射電子顯微鏡ATEM，二者都附有EDS功能)、X射線衍射儀(XRD)等現(xiàn)代材料分析測試方法，研

2、究了Mullite纖維的微觀結構和MulliteAlCuMullliteAlCuMg以及MulliteAlCuSi復合材料的界面微觀結構及微區(qū)成分。研究結果表明:1.MulliteAl合金復合材料中的莫來石纖維由大小不等、位向不同的眾多3A1203.2SiO2單晶體組合而成，組織致密但分布不均，個別單晶結晶粗大，形狀呈球形或啞鈴形，纖維表面存在一斷續(xù)分布的Si02膜層。纖維晶體結構屬正交(orthorhombic)晶系:ao=0.749

3、0nmbo=0.9269nmco=0.5814nm。這一結果得到高分辨透射電鏡(HRTEM)實測結果的支持。2.MulliteAlCu復合材料的凝固過程為非平衡結晶，。(Al2Cu)相容易在纖維表面及。相晶間偏析。淬火態(tài)MulliteAlCu復合材料界面附近基體一側中存在高密度位錯。時效態(tài)MulliteAlCu復合材料界面處存在一“無析出物帶”(precipitatefreezonePFZ帶)。MulliteAlCu復合材料在擠壓鑄造時

4、容易發(fā)生纖維與基體合金間的界面反應，生成CUA12偽或和0CuA102，依附于纖維表面以一定角度向基體內生長。界面反應生成的CuA1204尖晶石尺寸粗大，平均直徑約為500nm，容易開裂。3.鑄態(tài)MulliteAICuMg復合材料的凝固組織中，纖維表面及“相晶IflJ存在非平衡結晶的S(A12CuMg)相和。(CuA12)相。淬火態(tài)復合四川大學碩士學位論文StudyontheInterfacialMicrostructureandMic

5、rochemistryofShortMulliteFiberReinforcedAluminiumbasedCompositesAbstractBasedonthedetailreviewsoftheinterfacialresearchprogressofdiscontinuouslyreinforcedaluminiumbasedmetalmatrixcompositesthisthesisinvestigatedboththemi

6、crostructureofshortmullitefibersandtheinterfacialmicrostructureandmicrochemistryofMulliteAlCuMulliteAlCuMgaswellasMulliteAICuSicompositesbymeansofscanningelectronmicroscopy(SEM)transmissionelectronmicroscopy(TEMincluding

7、highresolutionTEMandanalyticalTEMbothofthemhaveenergydispersespectrum(EDS)functions)Xraydifraction(XRD)respectively.Thecompositeswereproducedbysqueezecasting.Themainresultsareshowedasfollows:1.Themullitefibersimpededinth

8、eMulliteAlcompositesarecomposedofunevenscalecrystalparticleswithdiferentorientationarrangement.Itisfoundthatthegrainmicrostructureofmullitefiberiscompactbutitsdistributionisnotsohomogenous.Itisalsofoundthatpartialmullite

9、monocrystallineparticleswithsphericordumbbellshapearemuchlargerthansurroundings.Thechemicalcompositionofmullitefiberis3A12032Si0zanditscrystalstructureisrecognizedasorthorhombic(ao=0.7490nmbo=0.9269nmco=0.5814nm)whichisf

10、urtherverifiedbyHRTEM.ThereexistsathindiscontinuesSi02filmonthesurfaceofthefibersinthecomposites.2.ThesolidificationofMulliteAlCucompositeisnonequilibriumwithlargeamountofe(A12Cu)phasebeingdepositedeitheratthesurfaceofmu

11、llitefibersorattheboundaryof(XAl.Thereexistsmuchdenserdislocationinthenearvicinityoftheinterface(aluminiumside)inasquenchedMulliteAlCucompositeandaprecipitatefreezone(PFZ)attheinterfaceofagedMulliteAlCucomposite.IntheMul