欢迎来到天天文库
浏览记录
ID:5310747
大小:1.76 MB
页数:9页
时间:2017-12-07
《al含量对mg-7zn合金非枝晶组织的影响》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、第23卷第11期中国有色金属学报2013年11月、,01.23No.1lTheChineseJournalofNonferrousMetals文章编号:1004—0609(2013)11-3039.09Al含量对Mg.7Zn合金非枝晶组织的影响冯凯,黄晓锋,马颖,吕峥,李兴鹏,郝远(兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,兰州730050)摘要:采用等温热处理法研究Al含量对Mg.7Zn合金半固态组织的影响。结果表明:添加Al元素后,合金的固相率随温度变化曲线逐渐下移。在相同的等温处理工艺T(58o℃保温30min),随着Al含量的增加,合金的固相颗粒尺寸逐
2、渐减小,圆整度显著提高,同时固相率明显降低。非枝晶组织主要包括球状及类似球状的初生固相颗粒al-Mg,水淬二次凝固形成细小的等轴晶a2-Mg以及晶界处和包裹在初生颗粒间的共晶组织。随保温时间的延长,Mg一7Zn-xA1合金非枝晶组织中的初生固相颗粒的尺寸逐渐增加,形状因子逐渐降低,而在后期处于固液平衡阶段,固相率的变化不明显;同时,固相颗粒粗化符合Ostwald熟化机制,且Al元素的加入减小了初生固相颗粒的粗化速率,从而在较宽的保温时间范围内可获得细小圆整的固相颗粒。关键词:Al含量;Mg.Zn.A1合金;半固态;粗化中图法分类号:TG146.22文献标志码:AEflfec
3、t0fAlcontentonnon.dendriticmicrostructureofMg-7ZnmagnesiumalloyFENGKai,HUANGXiao-feng,MAYing,LOZheng,LIXing.peng,HAOYuan(StateKeyLaboratoryofGansuAdvancedNon-ferrousMetalMaterials,LanzhouUniversityofTechnology,Lanzhou730050,China)Abstract:TheefectofA1additiononsemi-solidmicrostructuresofMg
4、-7Znalloywasinvestigatedbyisothermalheat-treatment.TheresultsindicatethatthesolidfractionsofalloysaredeclinedbyelevatedtemperaturewhenaddingA1intoMg-7Znalloy.WithA1contentincreasing,theequivalentparticlesizegraduallydecreases,theroundnesssignificantlyincreasesandthesolidfractiondecreasesat
5、thesameisothermaltreatmentprocess(580℃,30min).Thenon.dendriticmicrostructuresarecomposedmainlyofglobularandsimilarglobularprimaryparticles6tI—Mg,thefinerequiaxiala2-Mgwhichformsfromquenchinwater,andtheeutecticdistributesonthegrain-boundaryandwithintheprimarysolidparticles.Withholdingtimein
6、creasing,thesizeofprimarysolidparticlesofnon_dendriticmicrostractureofMg.7Zn-xA1alloygraduallyincreasesandtheshapefactordecreases,whichhasnovisibleefectonthesolidfractionofalloysatthesolid-liquidequilibriumstage.Simultaneously,theparimaryparticlesizecoarseningwithholdingtimeobeystheOstwald
7、ripeningmechanism,andaddingA1elementintoMg-7Znalloyresultsinadecreaseofcoarseningrateofsolidparticlesinsemi-solidslurry,consequently,itcanobtaintheperfectsemi-solidmicrostructureonthewiderangeofholdingtime.Keywords:A1content;Mg-Zn—A1alloy;semi-solid;coarsening
此文档下载收益归作者所有