ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 26    No. 1    January 2016

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Anisotropic and temperature-dependent growth mechanism ofS-phase precipitates in Al-Cu-Mg alloy in relation with GPB zones
Mei-jie YIN, Jiang-hua CHEN, Shuang-bao WANG, Zi-ran LIU, Li-mei CHA, Shi-yun DUAN, Cui-lan WU
(College of Materials Science and Engineering, Hunan University, Changsha 410082, China)
Abstract: By employing atomic-resolution imaging and first principles energy calculations, the growthbehavior of S-phase precipitates in a high strength Al-Cu-Mg alloy was investigated. It is demonstrated that the nucleation and growth of theS-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.
Key words: aluminum alloy; precipitation; age hardening; anisotropy; crystal growth
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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