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ID:33999904
大小:5.63 MB
页数:59页
时间:2019-03-02
《合金元素cd和nd对zk60镁合金力学性能及腐蚀性能的影响》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、中南大学硕士学位论文摘要本论文以添加合金元素Cd和Nd的ZK60镁合金为研究对象,通过X.射线衍射分析、光学显微镜观察、扫描电镜观察、透射电镜观察等手段,研究了合金元素Cd和Nd对ZK60镁合金热变形行为、显微组织、力学性能及腐蚀性能的影响,实验结果表明:1、ZK60.1.7Nd.0.7Cd镁合金在同一应变速率下,随变形温度提高,动态再结晶晶粒尺寸增大,体积分数增加;在同一温度下,随应变速率增加,动态再结晶晶粒尺寸减小,体积分数减少。2、合金元素Cd和Nd均能细化ZK60镁合金晶粒,Nd细化效果优于Cd,两者共同作用细化效果最
2、佳。同时加入后,铸态平均晶粒尺寸由1009m细化到359m,挤压态平均晶粒尺寸由209m左右细化到7“m左右。因Cd与Mg完全互溶,起固溶强化作用;Nd与Mg、Zn发生共晶反应生成Nd3M96Znll相,Nd3M96Znll相阻碍位错运动,提高合金强度。故同时加入Cd和Nd后,挤压态合金极限抗拉强度由296MPa提高到334MPa,屈服强度由240MPa提高到300MPa。3、ZK60.1.7Nd.0.7Cd合金经T6处理后强度下降,宜采用T5处理。在本实验条件下,最佳T5处理工艺为:120℃/15h。经最佳时效工艺处理后,极
3、限抗拉强度提高到349MPa,屈服强度达到315MPa。4、同时加入Cd和Nd后降低了合金的腐蚀性能,各个状态下ZK60.1.7Nd.0.7Cd合金的腐蚀性能均比ZK60合金差。ZK60.1.7Nd.0.7Cd合金的腐蚀性能T5态(120。C/15h)优于挤压态,挤压态好于铸态。关键词:ZK60镁合金,挤压,热处理,力学性能,腐蚀性能中南大学硕士学位论文AbS仃actAbstractTheinfluenceofCdandNdonthemicrostructure.mechanicalpropertiesandcorrosion
4、resistanceofZK60alloywasinvestigatedbyopticalmicroscopy(OM),X—raydiffraction(XRD),scanningelectronicmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM).Someexperimentresultsaleobtainedasfollows.1.Thedynamicallyrecrystallizedgrainsizeandtherecrystallizationvolumefr
5、actionofZK60.1.7Nd.0.7Cdalloyincreasewithincreasingdeformationtemperatureunderthesamestrainrateandreducewithincreasingstrainrateunderthesamedeformationtemperature.2.TheadditionofCdorNdcailrefinethemicrostructuresandimprovetheyieldstrengthofZK60alloy.TheeffectofCdadd
6、itionongrainrefinementisbetterthanthatofNdadditionwhiletheeffectiSthebestfortheCO.additionofCdandNd.CdcompletelydissolvedinMgmatrix,whichresultsinincreasingoftheyieldstrengthofZK60alloy.OwingtotheadditionofNd,aNd3M96Znnphaseappeals,whichblocksthemovementofdislocatio
7、nlinesandimprovethestrength.OwingtotheCO—additionofCdandNd,thegrainsizeofas.castZK60alloyCanberefinedto35I.tmandas.extrudedZK60alloycanberefinedto7¨m.Foras-extrudedZK60alloy,theyieldstrengthCallbeimprovedto300MPaandtheultimatetensilestrengthCallbeimprovedto334MPa.3.
8、AfterT6treatment,thestrengthofZK60.1.7Nd.0.7Cdalloydecreased.Theheattreatmentofas.extrudedZK60.1.7Nd.0.7CdalloyshouldadoptT5treatment.Theo
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