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1、摘要本論文采用傳統(tǒng)的電沉積法制各Ni8lPl9非晶合余,利用銅模吸鑄、落管無容器凝固、助熔劑反復(fù)熔煉等實(shí)驗(yàn)手段對Ni-P合金進(jìn)行處理,并通過視差掃描量熱(DSC)、X射線衍射、金相顯電鏡、掃描電鏡等材料分析手段對非晶的晶化以及無容器處理后試樣的組織進(jìn)行了研究。DSC分析獲得Ni—P非晶合金的玻璃轉(zhuǎn)變溫度疋,結(jié)晶開始溫度L,結(jié)晶放熱峰濕度昂,和昂:,利用Kissinger方程得到其玻璃轉(zhuǎn)變激活能乓=374.8KJ/tool,晶化激活能易尸148.9KJ/mol和昂?=274.9KJ/tool,分析表明Ni-P非晶合金非晶容
2、易晶化。利用銅模吸鑄方法制各出了NislPl9共晶合金,晶化產(chǎn)物為Ni—P固溶體和Ni3P金屬間化合物。助熔劑反復(fù)熔煉后,凝固組織中出現(xiàn)異常共晶團(tuán),利用單相枝晶狀共晶的熔斷模型,解釋了過冷熔體異常共晶團(tuán)的形成原因。通過落管實(shí)驗(yàn)得到了直徑0.1-2.0rnm的凝固樣品小球,其凝固組織由不規(guī)則的粒狀共晶團(tuán)和規(guī)則的棒狀共晶組成。樣品下落過程中的冷卻速率嚴(yán)重影響其共晶組織。隨小球直徑減小,共晶組織細(xì)化;小球邊緣處組織較一11,部細(xì)化。這都是由于冷速不同所引起的。計算分析表明:在Ni8IPl9合金落管無容器凝固過程中,5000Pa
3、氦氣和適當(dāng)氬氣的混合氣體利于得到高冷速、大尺寸的合金小球。關(guān)鍵詞Ni.P非晶合金;電沉積;落管;助熔劑;無容器凝固燕山大學(xué)工學(xué)碩士學(xué)位論文AbstractNiglPl9amorphousalloywaspreparedbyelectro—deposition,andthenwasmeltinarcfurnaceandcastincoppermold,DroptubeandfluxingprocesswasusedtostudythecontainerlesssolidificationbehaviorofNi—Pallo
4、y,andtheassolidifiedsamplewasanalyzedandinvestigatedbydifferentialscanningcalorimeter(DSC),X—raydiffractometer(XRD),opticalmicroscope,andscanningelectronmicroscope(SEM).Glasstransformationtemperature瓦,crystallinetemperature疋,peaktemperature昂1and碭weregotbyDSCanaly
5、sis,andtheseparameterswerefittedwithKissingerfunction,glasstransformationactivationenergyEg=374.8KJ/molandcrystallineactivation易?=148.9KJ/molandE一=274.9Kl/molcouldbecomputed.TheseparametersshowedthatNi-Pamorphousalloywasliabletobecrystallizedeasily,Bycastingincop
6、permold,NislPi9eutecticalloywasprepared;andtheoutcomeofphaseswasNiandNi3Pcompound,whichwereidentifiedbyXRDpattern,Afterfluxingprocess,anomalouseutecticmicrostructurecouldbeobservedintheassolidifiedsample,andmodelofdendriteremeltingwasusedtoexplainthisphenomenon.T
7、heassolidifieddropletswithdiameterfrom0.1mmto2.0mmwereachievedbydroptube.Duringthefallingprocess,coolingratedeterminedthemicrostructureofthedroplets.Themicrostructureswereconsistedofrodandanomalouseutecticphases.Withthedeceasingofdiameterofdroplet,botheutecticpha
8、seswererefinedwhichwascausedbylargeundercoolingrate.Duringthecontainerlesssolidification,Ni—Pdropletswithbigsizeandlargeundercoolingratecouldeasilybecollectedw