Materials Transactions Online

Materials Transactions, Vol.47 No.04 (2006) pp.1264-1267
© 2006 The Japan Institute of Metals

Precipitates with Peculiar Morphology Consisting of a Disk-Shaped Amorphous Core Sandwiched between 14H-Typed Long Period Stacking Order Crystals in a Melt-Quenched Mg98Cu1Y1 Alloy

Makoto Matsuura1, Kazuya Konno1, Mitsuhiko Yoshida1, Masahiko Nishijima2 and Kenji Hiraga2

1Miyagi National College of Technology, Natori 981-1239, Japan
2Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

The microstructure of a melt-quenched Mg98Cu1Y1 alloy has been studied by high-resolution transmission electron microscopy (HRTEM) and high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). We have found Cu- and Y-rich precipitates, which are uniformly dispersed in Mg-matrix grains. The precipitates are aligned parallel to the c-plane of the Mg-matrix crystal, and have the peculiar morphology consisting of a disk-shaped amorphous core sandwiched between 14H-typed long period stacking order (LPSO) crystals. A relatively stable supper-cooled liquid phase in an Mg-Cu-Y alloy system, and the formation and growth of the LPSO crystals from the amorphous phase are responsible for the peculiar morphology of the precipitates.

(Received 2005/12/22; Accepted 2006/3/9; Published 2006/4/15)

Keywords: high-resolution transmission electron microscopy, high-angle annular detector dark-field scanning transmission electron microscopy, magnesium-cupper-yttrium, precipitate, long period stacking order, amorphous

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