资源描述：
《过共晶铝硅合金变质处理 毕业论文》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、摘要过共晶铝硅合金由于具有高强度、低密度、高耐磨性和良好的导热性等优异性能而得到人们的青睐，但是，随着硅含量的增加，合金组织中会生成板片状、针状的共晶硅以及大量粗大且不规则的块状初生硅，严重影响了其加工性能和力学性能。本文通过研究不同体系的变质剂和热处理工艺对过共晶铝硅合金中初生硅和共晶硅的作用，探讨复合变质以及T6热处理对过共晶Al-18Si-2Cu合金组织及性能的影响；并且研究了不同的变质温度下，过共晶铝硅合金组织及性能的变化规律，研究最适合Al-P和Ni基非晶复合变质剂的变质温度。实验分析发现，Al-P对初生硅有明显的细化变质作用，使过共晶Al-18Si-2Cu合金中的初生硅的
2、平均尺寸由未变质时的130um降低到20um；非晶能增加共晶硅的形核数量，使针状和板片状的共晶硅得到细化，其中，Ni非晶的变质效果比Fe非晶好；T6热处理能使初生硅圆钝化，并且使针状和板片状的共晶硅粒化，从而使Al-18Si-2Cu合金的抗拉强度和延伸率都有一定的提高；通过控制变量法，经对比分析，最适合Ni非晶的变质温度为820℃。关键词：铝硅合金初生硅非晶复合变质T6热处理iAbstractPeoplethinkhighlyofhypereutecticAl-Sialloy,becauseithasthepropertyofhighstrength,lowdensity,higha
3、brasionresistanceandgoodthermalconductivity,etc.However,withtheincreaseofthecontentofsilicon,itwillresultinplate-likeandneedle-likeeutecticsilicon,andalotofroughandirregularblockprimarysiliconinthealloystructure,whichwouldseriouslyaffecttheprocessingperformanceandmechanicalperformanceofthealloy
4、.ThroughresearchinghowdifferentkindofmodifierandheattreatmentaffecttheprimarysiliconandeutecticsiliconinthehypereutecticAl-Sialloy,toexploretheeffectofT6heattreatmentandcompositemodificationonmicrostructureandpropertiesofAl-18Si-2Cualloy.Besides,studiedtheeffectofdifferentmodifyingtemperatureon
5、microstructureandpropertiesofAl-18Si-2Cualloy,seekingthemostsuitablemodifyingtemperatureforAl-PandNibasedamorphousalloycompositemodifier.Experimentalshowsthat,Al-Phasobviouseffectongrainrefinementofprimarysilicon,aftermodificated,theaveragesizeofprimarysiliconineutecticAl-18Si-2Cualloyreducedfr
6、om130umto30um;theamorphousalloywillincreasethenumberofnucleationofeutecticsilicon,whichwillrefinetheplate-likeandneedle-likeeutecticsilicon,thereinto,themodificationeffectofNibasedamorphousalloyisbetteerthanFebasedamorphousalloy;T6heattreatmentcanmaketheprimarysiliconpassivation,andmaketheofnee
7、dleandplateshapeeutecticsilicongranular,sothatthetensilestrengthandelongationofAl-18Si-2Cualloyareimproved;bycontrollingvariables,contrastionshowsthat,themostsuitablemodifyingtemperatureofNibasedamorphousalloymodifieris820℃.iiiKey
