Effect of strontium on liquid structure of Al–Si hypoeutectic alloys using high-energy X-ray diffraction
Effect of strontium on liquid structure of Al–Si hypoeutectic alloys using high-energy X-ray diffraction
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DOI：
10.1016/j.actamat.2010.09.050
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发表时间：
2011
期刊：
影响因子：
9.4
通讯作者：
P. Srirangam;M. Kramer;S. Shankar
中科院分区：
文献类型：
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作者：
P. Srirangam;M. Kramer;S. Shankar
采用同步束流源进行高能x射线衍射实验，研究了锶对Al-Si亚共晶合金液态原子结构的影响。分别对Si含量为3、7、10和12.5（共晶）wt.%， Si含量为0和0.04wt的铝合金进行了高温液相衍射实验。在每种合金中添加Sr。此外，所有合金在不同熔体温度（5-220K）下的衍射数据均高于各自的液相温度。结果表明，添加0.04wt。在任意熔体温度下，% Sr的加入会导致合金的结构因子、对分布函数、径向分布函数、配位数和填充密度等液态结构参数发生显著变化。显著的观察结果是，对于任何特定的合金和温度，添加锶显著降低配位数和堆积密度。随着Sr的加入，合金的原子配位数和堆积密度随合金温度的降低和Si含量的降低而增大。这些结果与先前的知识相结合，使我们能够深入了解凝固相的成核环境，特别是Sr在延迟共晶Si相的聚类倾向（成核）中的作用。
High-energy X-ray diffraction experiments were performed using a synchrotron beam source to investigate the effect of strontium on the liquid atomic structure of Al–Si hypoeutectic alloys. The high-temperature liquid diffraction experiments were carried out on Al alloys with 3, 7, 10 and 12.5 (eutectic) wt.% Si, respectively, with 0 and 0.04wt.% addition of Sr to each of the alloys. Further, the diffraction data for all the alloys were obtained at various melt temperatures (5–220K) above the respective liquidus temperature. It was observed that the addition of 0.04wt.% Sr results in significant change in the liquid structure parameters, such as structure factor, pair distribution function, radial distribution function, coordination number and packing density, at any given melt temperature of the alloy. Salient observations were that, for any specific alloy and temperature, addition of Sr significantly decreases coordination number and packing density. Further, with the addition of Sr in the liquid alloy, the atomic coordination number and packing density increases with decreasing temperature and decreasing Si content of the alloy. The results coupled with prior knowledge have enabled an in-depth understanding of the nucleation environment of the solidifying phases, specifically the role of Sr in delaying the clustering tendencies (nucleation) of the eutectic Si phase.