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Precipitation of (Si2−xAlx)Hf in an Al–Si–Mg–Hf Alloy

Published online by Cambridge University Press:  20 June 2017

Xueli Wang
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
Zhiqiang Xie
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
Huilan Huang
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
Zhihong Jia*
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
Guang Yang
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi’an Jiaotong University, Xi’an 710049, China
Lin Gu
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Qing Liu
College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China
*Corresponding author.
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The morphology, composition, and structure of precipitates in an Al–Si–Mg–Hf alloy after heat treatment at 560°C for 20 h were studied by means of Cs-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy (HRTEM), and first-principle calculations. Precipitates with three kinds of morphologies were observed. The rectangular and square precipitates were predominantly (Si2−xAlx)Hf phases, while the nanobelt-like precipitate is the Si2Hf phase. First-principle calculations were used to show that the Si6 and Si8 sites were the most favorable sites for Al incorporation in the orthorhombic Si2Hf phase.

Materials Science Applications
© Microscopy Society of America 2017 

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