稀土元素添加AZ91镁合金非平衡凝固组织研究  

Non-equilibrium Solidification Microstructure of AZ91 Magnesium Alloy Containing Rare Earth Elements

作　　者：杨伟[1] 张燕龙[1] 余欢[1] 严青松[1] 胡啸 杨根仓[3] 

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,江西南昌330063 [2]中航工业南方航空工业集团有限公司,湖南株洲412002 [3]西北工业大学凝固技术国家重点实验室,陕西西安710072

出　　处：《稀有金属材料与工程》2014年第10期2402-2406,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51164028;51261025);江西省教育厅青年基金(GJJ12446);轻合金加工科学与技术国防重点学科实验室开放课题(GF201201003)

摘　　要：采用铜模喷铸方式进行了稀土元素添加AZ91镁合金非平衡凝固实验,对比研究了稀土元素种类(Re=Ce,Er)及含量(0.25%,0.5%,0.75%,1%,质量分数)对镁合金晶粒尺寸、基体成分及相结构的影响规律。结果表明,同等含量条件下,Ce元素在α-Mg中的固溶度更低,溶质富集程度更明显,易形成Al11Ce3高熔点化合物相,合金细化效果比Er更好。随Ce含量增加,晶粒尺寸不断减小,β-Mg17Al12共晶相数量减少,分布趋于弥散。当Ce含量大于0.75%时,出现明显的晶粒粗化现象。在此基础上,从形核和生长的角度对上述细化机理进行了合理解释,并利用差热分析实验进行了有效验证。Non-equilibrium solidification of AZ91 magnesium alloy containing RE elements was performed by a copper mould casting method,and the effects of category of RE（RE=Ce,Er） and its content（0.25,0.5,0.75,1 wt%） on the primary grain size,solute concentration and phase structures were researched.Results show that less solute content exists in α-Mg grain for Ce addition,accompanied by the serious solute enrichment ahead of solid/liquid interface and the formation of Al11Ce3 phase with high melting point.Consequently,the refinement effect of Ce is more significant than that of Er.With increasing the amount of Ce,both the primary grain size and the ratio of β-Mg17Al12 phase decrease continuously,with the dispersive distribution of eutectic phase in the matrix.In contrast,grain coarsening appears when the Ce content is larger than 0.75 wt%.On this basis,the refinement mechanism was explained according to nucleation and growth processes,which was further verified by the differential thermal analysis experiment.

关 键 词：镁合金 非平衡凝固 组织细化 形核 生长 

分 类 号：TG146.22[一般工业技术—材料科学与工程]