Nd对原位自生Mg_2Si/Al复合材料的变质作用  

Effect of Nd Modification on Microstructure of In-situ Mg_2Si/Al Composite

作　　者：王孝良[1] 周崎[1] 王喆[1] 

机构地区：[1]辽宁工业大学材料科学与工程学院,辽宁锦州121001

出　　处：《热加工工艺》2013年第8期115-117,120,共4页Hot Working Technology

摘　　要：采用稀土元素Nd对原位自生Mg2Si/Al复合材料进行变质处理;利用X射线衍射仪和金相显微镜等方法分析了变质前后合金的微观组织;并对Nd的变质机理进行了分析。结果表明:在原位自生Mg2Si/Al复合材料中添加适量的Nd对初生和共晶Mg2Si能够同时起到良好的变质作用。当Nd含量达到0.5%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47.5μm减小到13.0μm;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Nd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。Nd was adopted to modify AI-Mg2Si in-situ metal matrix composite. The microstructure before and after modification was investigated by OM （metallurgical microscope） and XRD （X-ray diffraction）, and the modification mechanism was analyzed. The results show that the addition of proper amount of Nd has significant modification effect on both primary and eutectic Mg2Si in Al-18%Mg2Si in-situ metal matrix composite. When 0.5%Nd is added, the morphology of primary Mg^Si changes from dendritic into polyhedral shape, the average grain size significantly decreases from 47.5 μm into 13.0 μm; the morphology of eutectic Mg2Si changes from flake-like to very short fibrous or dot-like. The modification mechanism might be related to the decrease of the interfacial tension between Mg2Si phase and AI liquid and the composition supercooling is caused by the segregation of Nd in the front of the solid/liquid interface of Mg2Si during the solidification.

关 键 词：Mg2Si/Al复合材料 ND 变质 初生和共晶Mg2Si 

分 类 号：TB333[一般工业技术—材料科学与工程]