Characterisation of structural similarities of precipitates in Mg-Zn and Al-Zn-Mg alloys systems

Bendo, A.*; Maeda, Tomoyoshi*; Matsuda, Kenji*; Lervik, A.*; Holmestad, R.*; Marioara, C. D.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Toda, Hiroyuki*; Yamaguchi, Masatake   ; Ikeda, Kenichi*; Homma, Tomoyuki*

High angle annular dark field scanning transmission electron microscopy has been employed to observe precipitate structures in Al-Zn-Mg and Mg-Zn alloys. precipitate structures in Al-Zn-Mg are commonly formed by MgZn Penrose bricks, but also frequently observed to incorporate MgZn elongated hexagons via two different modes. Tilings of MgZn and MgZn building blocks in both in Mg-Zn and in Al-Zn-Mg alloys, create overall patterns which deviate from the chemical and structural configuration of solely monoclinic MgZn or MgZn unit cells. Precipitate morphologies were found to be correlated to their internal sub-unit cell arrangements, especially to MgZn elongated hexagons.