A 12R long-period stacking-ordered structure in a Mg-Ni-Y alloy. Issue 12 (December 2018) - Liu, Cheng
Abstract: A hitherto unreported long-period stacking-ordered (LPSO) phase, designated 12R, was observed in a Mg80 Ni5 Y15 (at.%) alloy. Microstructure was investigated by electron diffraction and high-angle annular dark-field scanning transmission electron microscopy. Results show that the 12R has a trigonal lattice ( a = b = 1.112 nm, c = 3.126 nm, α = β = 90°, and γ = 120°). Unit cell of the 12R is consisted of three ABCA-type building blocks and each building block contains dominant Ni6 Y8 -type building clusters. A sound structural model is proposed based on relative positions of Ni6 Y8 clusters in neighboring building blocks.