Anisotropic and temperature-dependent growth mechanism of S-phase precipitates in Al-Cu-Mg alloy in relation with GPB zones

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• 作者：Mei-jie YIN ; Jiang-hua CHEN ; ^{jhchen123@hnu.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Shuang-bao WANG ; Zi-ran LIU ; Li-mei CHA ; Shi-yun DUAN ; Cui-lan WU
• 关键词：aluminum alloy ; precipitation ; age hardening ; anisotropy ; crystal growth
• 刊名：Transactions of Nonferrous Metals Society of China
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：26
• 期：1
• 页码：1-11
• 全文大小：5130 K

文摘

By employing atomic-resolution imaging and first principles energy calculations, the growth behavior of S-phase precipitates in a high strength Al–Cu–Mg alloy was investigated. It is demonstrated that the nucleation and growth of the S-phase precipitate are rather anisotropic and temperature-dependent companying with low dimensional phase transformation. There are actually two types of Guinier–Preston (GP) zones that determine the formation mechanism of S-phase at high aging temperatures higher than 180 °C. One is the precursors of the S-phase itself, the other is the structural units or the precursors of the well-known Guinier–Preston–Bagaryatsky (GPB) zones. At high temperatures the later GPB zone units may form around S-phase precipitate and cease its growth in the width direction, leading to the formation of rod-like S-phase crystals; whereas at low temperatures the S-phase precipitates develop without the interference with GPB zones, resulting in S-phase precipitates with lath-like morphology.