Bi对过共晶Al-15Mg_2Si合金Mg_2Si相的变质作用  

Effect of Bi Modification on Mg_2Si Phase in Hypereutectic Al-15Mg_2Si Alloy

作　　者：司颐[1] 王喆[2] 武晓峰[2] 

机构地区：[1]辽宁石化职业技术学院应用化学系,辽宁锦州121001 [2]辽宁工业大学材料科学与工程学院,辽宁锦州121001

出　　处：《铸造技术》2013年第3期259-262,共4页Foundry Technology

基　　金：辽宁省教育厅重点实验室资助项目(20060394)

摘　　要：通过XRD、SEM和EDS等分析手段,研究了过共晶Al-15Mg2Si合金的Bi变质效果,并对Bi的变质机理进行了分析。结果表明:在过共晶Al-15Mg2Si合金中添加适量的金属Bi对初生Mg2Si和共晶Mg2Si能够同时起到良好的变质作用。当Bi含量达到1.0%时,初生Mg2Si的形貌由粗大的树枝状或多角形块状转变为细小的块状,平均尺寸由70μm左右减小到6μm左右;同时,共晶Mg2Si也由粗大的片状转变为细小的片状、纤维状或点状。其变质机理可能与Bi元素富集于Mg2Si相固-液界面降低Mg2Si相与Al液间界面张力及由富集所引起的成分过冷有关。The influence of Bi additions on the microstructure of hypereutectic AI-15Mg2Si alloy was investigated by XRD, SEM and EDS, and the modification mechanism was analyzed. The results show that the proper amount of Bi has a significant modification effect on both primary and eutectic Mg2Si in the alloy. When 1.0%Bi is added, the morphology of primary Mg2Si changes from dendritic to polyhedral shape, its average grain size significantly decreases from 70 p.m to 6 μm; at the same time, the eutectic Mg2Si from flake-like to very short fibrous or dot-like. The modification mechanism may be related to the decrease of the interracial tension between the Mg2Si phase and A1 liquid and the composition supercooling caused by the segregation of Bi at the front of the solid/liquid interface of Mg2Si during solidification.

关 键 词：过共晶Al-Mg2Si合金 BI 变质 初生Mg2Si 共晶Mg2Si 

分 类 号：TG146.21[一般工业技术—材料科学与工程]