Highly ordered 10H-type long-period stacking order phase in a Mg–Zn–Y ternary alloy

A highly ordered long-period stacking order (LPSO) structure of 10H-type is found to form in Mg75Zn10Y15 (at.%) alloys annealed at 773 K, with a remarkably developed in-plane long-range order of Zn/Y atoms. The degree of order of the present 10H-LPSO Mg–Zn–Y phase is similar to that of the Mg–Al–Gd alloys, the structural characteristics of which are described according to order/disorder-type intermetallic polytypes. The measured composition Mg77.2Zn9.7Y13.1 appears to be precisely consistent with an ideal stoichiometry of the 10H-Mg23Zn3Y4 (Mg76.7Zn10Y13.3) phase.