D019-Mg3In stable structure in Mg-In alloy

In this study, Mg-3.0 wt% In binary alloys were solution treated at 420 degrees C and aging treated at 200 degrees C. To understand clearly the microstructural characteristics, the alloys were characterized by atomic-scale high angle annular dark field scanning transmission electron microscopy. It is found that a hitherto unreported D0(19)-Mg3In order structure is formed in alpha-Mg matrix. With a hexagonal lattice (a approximate to 0.641 nm and c approximate to 0. 521 nm), the D0(19)-Mg3In structure is relatively stable and fully coherent with alpha-Mg matrix. Solid solution indium atoms have four categories of optional positions of Mg-sublattice, leading to the formation and co-existence of four sets of D0(19)-Mg3In structures in a-Mg matrix. With aging time prolonged, a high concentration of D0(19)-Mg3In structures results in several combined configurations of two or more sets of D0(19)-Mg3In structures in Mg-In binary alloy. (C) 2020 Published by Elsevier B.V.