复合添加Yb和Ca对Mg-6Zn合金组织的影响.pdfVIP

学兔兔 铸 造 Sep．2010 · 886 · FOUNDRY VoI．59 NO．9 复合添)311Yb~ilCa对Mg一6Zn合金组织的影响 秦 兵，于文斌，李坊平，李春梅 (西南大学材料科学与工程学院，重庆 400715) 摘要：利用OM、SEM、EDS、XRD及DSC等测试方法研究了复合添加Yb和Ca对Mg一6Zn合金组织的影响。结果表明： Mg-6Zn一0．2Ca合金铸态组织主要由仪一Mg、Mg7Zn 、MgZn2及MgZn等相组成，合金组织有被Ca细化趋势；复合添加微量 Ca和Yb后，枝晶组织呈 “花瓣”状，并随Yb含量增加， “花瓣”状组织明显增多，其晶粒稍有细化；经固溶处理 (T4)后，Mg．6Zn一0．2Ca-xYb =0、】、1．5)合金组织由铸态时枝晶转变成等轴晶，与Mg．6Zn．0．2Ca合金相比，含Yb合 金晶粒有明显粗化现象；Mg．6Zn．0．2Ca一1．5Yb合金中含有稳定的三元Mg—Zn—Yb化合物，初步认定该化合物中Zn、Yb的 原子比在4～6之间。 关键词：镁合金；钙；镱；Mg．Zn；显微组织 中图分类号：TG146．2+2 文献标识码：A 文章编号：1001—4977(2010)09—0886—05 Effects of Yb and Ca Additions on Microstructure of Mg一6Zn Alloys QIN Bing，YU Wen—bin，LI Fang—ping，LI Chun—mei (School of Materials Science and Engineering，Southwest University，Chongqing 40071 5，China) Abstract： The investigation was carried out to study the effects of Yb and Ca additions on micrOstructure of the Mg一6Zn alloys by opticaI microscopy。scanning electron microscopy．energy dispersive spectrometer．X—ray diffraction analysis and simultaneous thermaI analysis．The results show that as—cast micrOstructure Of Mg一6Zn一0．2Ca alloy mainly consists of oc．Mg，Mg7Zn 31 MgZn2 and MgZn phase，and tends to be grain—refined tendency by trace Ca addition；after the combined additions of Ca and Yb lO the Mg一6Zn alloy．dendrite structure present peta1 1ike shape jncreases obviously with increasing of Yb content，moreover，the grain of the alloys are refined slightly．After T4 treatment，the microstructure of Mg一6Zn．0．2Ca．xYb(x=0，1，1．5)alloys changes from dendrite crystal to equiaxed grain．Grain coarsening exists in the Mg．6Zn一0．2Ca alloy with Yb addition after T4，which