mgyznzr耐热镁合金组织和性能研究

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1、摘要镁合金是实际应用中最轻的金属结构材料，在汽车轻量化方面的作用日益受到人们的重视。但是，目前已有的镁合金往往室温力学性能较差或者高温抗蠕变性能较差，这限制了它在汽车工业中的应用。目前已有的MEZ（Mg-2RE-0.35Zn-0.3Zr）合金具有优良的高温抗蠕变性能，但室温拉伸性能较差，本文通过用Y元素替代MEZ合金中的混合稀土，并在合金中增添少量的Zn元素，希望在保持合金优良的抗蠕变性能的基础上提高合金的强度。本研究首先研究了重力铸造条件下Mg-Y-Zn-Zr合金的组织与性能，并在此基础上采用Mg-Y-Zn-Zr合金成功的实现了汽车吸尘器底板的压铸试验，并对压铸合金的组织与性能进行

2、了系统地研究。对重力铸造Mg-Y-Zn-Zr合金的组织与性能进行研究发现，Mg-0.8%Zn-0.35%Zr合金组织为单相α-Mg，在合金中添加Y元素，随着添加的Y元素含量的增加，合金晶粒得到细化，晶界离异共晶相的数目增多，且出现了大量的层片状关键词：镁合金；压铸；蠕变性能；钇；强度IAbstractAsthelightestmetalstructurematerial,magnesiumalloysofferhighspecificstrength,specificstiffness,superiordampingcapacity,excellentmachinabiltyandc

3、astability.Demandsfromautomotiveindustryforincreasinglylightweightcomponentshaveresultedinanincreasedinterestinmagnesiumalloy.However，mostdie-castmagnesiumalloyshavepoorstrengthorbadcreepresistantproperty,whichlimittheirapplicationinautomobilepowertraincomponents.ConsideringthatMEZalloy(Mg-2RE-

4、0.35Zn-0.3Zr)isanalloywithexcellentcreeppropertybutlowstrength,cerium-richmischmetalwassubstitutedbyyttriumandzirconiumwasaddedintothealloyinordertoimprovethetensilestrength.Theeffectsofyttriumonthemicrostructureandpropertiesofgravity-castingMg-Y-Zn-Zralloywerestudied,whichwasthebasisoftheresea

5、rchonthemicrostructureandpropertiesofdie-castingMg-Y-Zn-Zralloy.Itindicatedthatwithmoreyttriumaddedtogravity-castingMg-Zn-Zralloy,thegrainwasrefinedandtheamountofthesecondaryphaseonthegrainboundaryincreased,thereforthethensilestrengthatambientandelevatedtemperaturesaswellascreeppropertywereimpr

6、oved.Asresult,when3.5%Ywasadded,thetensilestrengthatroomtemperatureandelevatedtemperatureaswellasthecreepresistantpropertyreachedthepeak.ThenMg-2.64%Y-0.96%Zn-0.35%ZrandMg-4.51%Y-0.99%Zn-0.41%Zralloyswereusedinthedie-castingofautomobilesoleplate,whichwasprovedtobeagreatsuccess.Themicrostructure

7、andpropertyofthetwodie-castingMg-Y-Zn-Zralloywerestudied.Itwasshownthatthegrainwasrefinedandthesecondaryphaseonthegrainboundarymanifoldedinthedie-castingMg-Y-Zn-Zralloy,whichresultedtheimprovementofthethensilestrengthatambientande