Modification of eutectic Si and the microstructure in an Al-7Si alloy with barium addition
Modification of eutectic Si and the microstructure in an Al-7Si alloy with barium addition
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DOI：
10.1016/j.msea.2018.05.010
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发表时间：
2018-06
期刊：
影响因子：
6.4
通讯作者：
Jinsong Rao;Jin Zhang;Ruxue Liu;Jiang Zheng;D. Yin
中科院分区：
文献类型：
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作者：
Jinsong Rao;Jin Zhang;Ruxue Liu;Jiang Zheng;D. Yin
添加钡（Ba）的效果(0,0.05,0.15,0.5 wt。研究了pct对Al-7Si合金显微组织和力学性能的影响。采用差示扫描量热法分析了共晶Si的成核行为。用透射电镜研究了共晶硅的生长机理。结果表明，加入0.15 wt。pct Ba使共晶Si的形貌由粗片状变为细纤维状，显著提高了合金的抗拉强度和伸长率。Ba添加量(≥0.15 wt。pct)诱导粗块状含Ba相（即Al2Si2Ba相）的形成和孔隙率的增加，从而对塑性产生不利影响。热分析表明，Ba的加入抑制了共晶Si的成核，这是由于ba3p2相的形成。在含Ba合金中观察到明显的高密度Si孪晶，为杂质诱导孪晶生长机制提供了实验支持。
The effect of Barium (Ba) addition (0, 0.05, 0.15, 0.5 wt. pct) on the microstructure and mechanical properties of an Al-7Si alloy was studied. Differential scanning calorimetry was employed to analyze the nucleation behavior of eutectic Si. Transmission electron microscopy was used to clarify growth mechanism of eutectic Si. The result indicates that the addition of 0.15 wt. pct Ba modifies the morphology of eutectic Si from coarse flake-like to fine fibrous, which dramatically improves the ultimate tensile strength and elongation. However, Ba addition (≥ 0.15 wt. pct) induces the formation of coarse blocky Ba containing phase (i.e. Al2Si2Ba phase) and porosity increment, and resultantly has a deleterious effect on the ductility. Thermal analysis reveals that Ba addition suppresses the nucleation of eutectic Si due to the formation of Ba3P2phase. Significant multiply Si twins with high density was observed in the Ba containing alloy, which provides an experimentally support to the impurity-induced twinning growth mechanism.