Sr对Mg-5Sn-5Zn铸造镁合金组织的影响

Effect of strontium on the microstructure of as-cast Mg-5Sn-5Zn alloy

通过光学显微镜、扫描电镜和X射线衍射仪研究了Mg-5Sn-5Zn-xSr(x=0,0.5,1,2)4种铸造镁合金的显微组织和相组成.结果表明:在Mg-5Sn-5Zn合金中加入质量分数为0.5%～2%的Sr元素后,不但能够缩小α-Mg枝晶间距,而且还能形成三元相MgSnSr.随着Sr含量的增加,在晶界析出的Mg2Sn相减少,晶内的MgSnSr相增加。合金中的MgZn相与Mg2Sn相依附在一起,大多数的MgZn相以α-Mg+MgZn相的共晶方式存在.

The microstructures and phase constituent of as-cast Mg-5Sn-5Zn-xSr（x = 0,0.5,1,2） alloys were analyzed by the optical microscopy（OM）,the scanning electron microscope（SEM） and the X-ray diffraction （XRD）.The results indicate that an addition of 0.5%～2%（mass fraction） Sr to the Mg-5Zn-5Sn alloy not only refines the dendrite arm spacing of α-Mg but also results in the formation of MgSnSr phases.Furthermore,it was found that the Sr increment results in the Mg2Sn phase decreases and MgSnSr phase increases.While the MgZn phase attached to the Mg2Sn phase exists in the form of α-Mg ＋ MgZn eutectic structure.