Zr基非晶合金激光熔覆与诱导自蔓延合成

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1、大连理工大学博士学位论文Zr基非晶合金激光熔覆与诱导自蔓延合成姓名：李刚申请学位级别：博士专业：材料物理化学指导教师：董闯20030101大连理工大学博士学位论文—摘要激光束作用下的晶化行为，并对非晶晶化过程瞬态温度场进行了数值模拟。由于激光作用区内存在很大的温度梯度，导致激光晶化样品出现了非晶一树枝晶一非晶夹层结构。关键词：激光熔覆：大块非晶合金；自蔓延：晶化II大连理工大学媾士学证论文—摘要AbstractInrecentyears，therehaveconstantlybeenbreakthroughsintheresearchof

2、bulkamorphousalloys+Thearriorphousalloyswithlargeglass-formingabilityhavebeenfoundinanumberofalloysystemssuchasZr-based，Ln_based，Ti-based，Mg_basedandFe--basedalloysystems．Thediscover3,anddevelopmentinbulkamorphousnotontyhelp埝makebreakthroughinthepreparationoflasersurfacea

3、morphouscoating，thatis，thickamorphouscoatingswithmicrondimentionCallbeproducedbythenewlyalloyingdesigningandlasercladprocessing，butalsoofferanopportunitytoexplorenewpreparationmethodofbulkfllllol泽housalloys。Againstsuchabackground，threeaspectsofresearchworkhavebeensequenfl

4、ycarriedoutinthispaperTobeginwith，Zr-basedalnorphousalloycoatingsweresuccessfullyproducedbylasercladdingonaTisubstrate．MicrostmctureofthecoatingsweresystematicallystudiedbyusingXRD、SEM、EDSandTEM。Theresultsshowthatthecoatingswerecomposedofamorphous，nanocrystallines，A12Zr3，

5、Cul0Zr7，Nil0Zr7phases．However,thecontentoftheeachconstituentvariesobviouslywi也coatingdepthowingtochangesofcompositionandcrystalparameters，Theresultobtainedbysemiquantitativeanalysisoflayer-by-layerXRDshowsthatthecontentofamorphousobviouslyincreasesinsubsurfacelayeroftheco

6、ating．Inthebondingzonebetweencoatingandsubstrate，thephasesspeciesWascompletelychangedduetodilutionfromsubstrate。Ticoltmmarcrystaland旺一(Ti／Zr)solidsolutionwereformed．Microstructureandpropertiesofthecoatingsarecloselyrelatedtocompositionofdopedcomponents，thicknessofpresetla

7、yer,processingparametersandtechnicalprocessoflasercladding．WhenCand(B、si)withdefinitiveproportionwereaddedintocladmaterials，respectively,notonlydoesthecontentofamorphousincrease，butalsodohardnessandwearresistanceincrease；Presetlayerthicknessandlaserscanningspeedhavedefini

8、tivematchingrelationtothecontentofamorphousinthecoatings，respectively；Increasinglaserpowerandrem