Sr对Mg-6Zn-2Al-2Ca合金显微组织的影响

The Effect of Sr Addition on the Microstructure of Mg-6Zn-2Al-2Ca Magnesium Alloy

采用扫描电镜、X射线衍射仪和光学显微镜研究了Mg-6Zn-2Al-2Ca-xSr (x = 0, 0.5, 1, 2, 3)合金随Sr的含量变化组织形貌的演化规律。实验结果表明:0.5%Sr可以抑制β-Mg17Al12相的形成;Sr的加入,具有增加Mg-6Zn-2Al-2Ca液态金属成分过冷的能力,使胞状组织向树枝状组织发展,枝晶组织随Sr含量的增加而得到细化。当Sr含量达到3%时,形成非枝晶状组织。当Sr含量超过2%时,组织中板块状Mg17Sr2相尺寸明显增大,对组织的演化规律进行了讨论。

The effect of Sr addition on microstructure evolution of Mg-6Zn-2Al-2Ca-xSr (x = 0.5, 1, 2, 3) alloys was investigated by using scanning electron microscope (SEM), X-ray diffraction (XRD) and optical microscope. The results show that the 0.5% Sr addition can restrain the formation of β-Mg17Al12 phase. The constitutional undercooling increases with Sr addition, which changes the structure from cellular to dendritic. The dendritic structure becomes more refinement with Sr addition. Furthermore non-dendritic structure is formed when Sr content is 3%. However, a paddle Mg17Sr2 structure was observed when Sr content is 2% and its size increases with Sr. The structure evolution of Mg-6Zn-2Al-2Ca alloy with Sr addition was discussed.