In Situ Investigation of Si-Poisoning Effect in Al-Cu-Si Alloys Inoculated by Al-5Ti-1B |
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Authors: | Yiwang Jia Dongfu Song Nan Zhou Kaihong Zheng Yanan Fu Da Shu |
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Affiliation: | 1.Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application, Institute of New Materials, Guangdong Academy of Sciences, Guangzhou, 510650, China;2.Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, China;3.Shanghai Key Lab of Advanced High-Temperature Materials and Precision Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China |
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Abstract: | In situ synchrotron X-radiography was carried out on Al-13Cu and Al-13Cu-7Si alloys with and without addition of Al-5Ti-1B master alloy. The effects of Si content on grain growth and the solute-suppressed nucleation zone (SSNZ) were quantitatively studied. The average grain size can be refined to 164 μm of Al-13Cu alloy inoculated by Al-5Ti-1B. After addition of 7% Si content, a large number of TiB2 sites in the melt lost the inoculating ability due to “Si poisoning.” The radius of the dendrite tip curvature of Al-13Cu is more than two times as large as that of Al-13Cu-7Si. The sharper tip is able to disperse the solute more effectively and thus grains can grow more rapidly. This causes that the dendrite arm growth rate with addition of 7% Si solute is about 2.6 times that of no Si addition. In addition, the solute enrichment in the SSNZ of Al-13Cu is faster, and the area change of SSNZ is slower than that of Al-13Cu-7Si. Thus more nucleation sites in the SSNZ cannot be activated with addition of Si. This study will shed light on the understanding of Si poisoning in casting Al-Cu-Si alloys. |
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Keywords: | Al-Si alloy Dendrite tip Si poisoning X-ray radiography Al-5Ti-1B |
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