Er在Al-Mg-Si合金中的存在形式及其热力学分析  

Form and thermodynamic analysis of element Er in Al-Mg-Si alloy

作　　者：孙顺平[1] 易丹青[1] 陈振湘[1] 周明哲[1] 王斌[1] 

机构地区：[1]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《材料热处理学报》2011年第1期138-143,共6页Transactions of Materials and Heat Treatment

基　　金：国家"973高性能铝材和铝资源高效利用基础研究"子课题(2005CB623705)

摘　　要：制备了3种不同铒元素含量的Al-Mg-Si合金,利用显微组织观察(OM)、扫描电镜(SEM)、能谱分析(EDS)、X射线衍射物相分析(XRD)、硬度测试与差热分析(DSC)等分析测试手段,研究元素Er在Al-Mg-Si合金中的存在形式,并运用Miedema模型对Er在Al-Mg-Si合金中的热力学行为进行了分析。结果表明:在Al-Mg-Si合金中,Er元素的添加可以有效细化铸态晶粒,减小枝晶间距。Al-Mg-Si-Er合金凝固过程时可形成α(Al)+Er5Si3初生共晶组织,显微组织呈鱼骨状,合金中大量Er5Si3相的形成,使可时效析出的Mg2Si相减少,合金硬度值减小。原子亲和力和金属间化合物生成焓的计算结果显示Er-Si原子之间的亲和力大于Mg-Er和Al-Er原子之间的亲和力,且铒硅二元金属间化合物生成焓负值更大,熔点更高,因此,在Al-Mg-Si-Er合金中,Er原子与Si原子优先形成铒硅相。Al-Mg-Si alloys containing different content of Er were prepared by casting.The form of Er in Al-Mg-Si alloys were studied by using of OM,SEM,EDS,XRD and DSC,and thermodynamic behavior of Er in Al-Mg-Si alloy was analyzed based on Miedema model.The results show that the addition of Er reduces the dendrite arm spacing of as-cast alloys and refines grains obviously.The＂fishbone＂α（Al） ＋ Er5 Si3 eutectic structure appeares during the solidification process in Al-Mg-Si-Er alloys.Owing to the addition of Er,Er5 Si3 formed as intermetallic compound,making the amount of Mg2 Si phase decrease consequently.Thus,it causes lower strength of alloys than that without Er.The calculating results of chemical affinity and formation enthalpies indicate that chemical affinity of Er-Si atoms is stronger than that of Mg-Er and Al-Er atoms,and the formation enthalpies of binary intermetallic compounds of Er and Si atoms have bigger negative values.Moreover,the melting points of the intermetallics are higher,thus the intermetallics of Er-Si atoms form preferentially in Al-Mg-Si-Er alloys.

关 键 词：AL-MG-SI合金 铒 铸态组织 热力学分析 MIEDEMA模型 

分 类 号：TG146.2[一般工业技术—材料科学与工程]