Materials Transactions Online

Materials Transactions, Vol.58 No.02 (2017) pp.167-175
© 2016 The Japan Institute of Light Metals

Extra Electron Diffraction Spots Caused by Fine Precipitates Formed at the Early Stage of Aging in Al-Mg-X (X=Si, Ge, Zn)-Cu Alloys

Kenji Matsuda1, Akihiro Kawai2, Katsumi Watanabe2, Seungwon Lee1, Calin D. Marioara3, Sigurd Wenner4, Katsuhiko Nishimura1, Teiichiro Matsuzaki5, Norio Nunomura6, Tatsuo Sato7, Randi Holmestad4 and Susumu Ikeno1

1Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555, Japan
2Graduate School of Science and Engineering for Education, University of Toyama, Toyama 930-8555, Japan
3Department of Synthesis and Properties, SINTEF Materials and Chemistry, 7465 Trondheim, Norway
4Department of Physics, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway
5RIKEN Nishina Center for Accelerator Based Science, RIKEN, Wako 351-0198, Japan
6Information Technology Center, University of Toyama, Toyama 930-8555, Japan
7Tokyo Institute of Technology, Tokyo 152-8550, Japan

Age-hardenable Al-Mg-Si, Al-Mg-Ge, and Al-Zn-Mg alloys including Cu were investigated by transmission electron microscopy to understand extra diffraction spots that appear in their selected area electron diffraction patterns. These alloys containing Cu exhibit similar extra diffracted spots to each other with diffracted spots or streaks for Al matrix and major precipitates in each alloy. The extra spots cannot be confirmed in Cu-free alloys. The initial cluster, which is based on the β''-phase in the Al-Mg-Si alloy, is proposed to be MgSi(/Ge)Mg, CuMgSi(/Ge), AlCuMg, and AlZnMg, while the second clusters, which consist of three initial clusters including anti-phase boundary short-range order, are proposed for Cu-containing alloys.


(Received 2016/06/18; Accepted 2016/11/10; Published 2017/01/25)

Keywords: aluminum alloys, copper addition, electron diffraction pattern, clusters, precipitation

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