Solidification Behavior and Microstructure of Al-7Si Alloys with Individual and Combined Additions of Sr and Yb

被引：13
作者：
Dong, Zhou [1 ]
Hu, Zhi [1 ,2 ]
Yan, Hong [1 ,2 ]
Xie, Hecong [1 ]
Li, Xiao [1 ]
机构：
[1] Nanchang Univ, Inst Adv Forming, Nanchang 330031, Jiangxi, Peoples R China
[2] Key Lab Light Alloy Preparat & Proc Nanchang City, Nanchang 330031, Jiangxi, Peoples R China
来源：
ADVANCES IN MATERIALS SCIENCE AND ENGINEERING | 2019年 / 2019卷
基金：
中国国家自然科学基金;
关键词：
AL-SI ALLOYS; MECHANICAL-PROPERTIES; EUTECTIC SILICON; 1ST-PRINCIPLES; GROWTH;
D O I：
10.1155/2019/9750526
中图分类号：
T [工业技术];
学科分类号：
08 ;
摘要：
The effects of individual and combined additions of Sr and Yb on the solidification behavior and microstructure of Al-7Si alloys were investigated using thermal analysis, optical microscopy, and scanning electron microscopy. The results showed that the nucleation temperature, minimum temperature, and growth temperature of eutectic solidification were lower than those of the unmodified alloys, and eutectic recalescence at 2 degrees C in the Yb- and (Sr+Yb)-modified alloys was observed. The decrease in the nucleation temperature and an increase in recalescence obviously refined the eutectic Si morphology of the Sr-, Yb-, and (Sr+Yb)-modified alloys from a coarse plate-like structure to a fine fibrous structure. Moreover, the three-dimensional microstructure of eutectic Si in the (Sr+Yb)-modified alloy showed the finer fibrous structure, which was mainly attributed to formation of the Al2Si2Yb phase. The formation enthalpy of Al2Si2Yb was lower than that of Al-(Si)-Sr in the (Sr+Yb)-modified alloy, thus suppressing the formation of the Al2Si2Sr intermetallic compound. The more effective Sr together with Yb further improved the modification effect of eutectic silicon.
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页数：10
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