Effect of Zn/Gd Ratio on Phase Constitutions in Mg-Zn-Gd Alloys

Abstract

This paper discusses the influence of Zn/Gd ratio on the phase constitutions of as-cast Mg-Zn-Gd alloys in the Mg-rich corner within the range of 0.5-3.0 at.% for Zn content and 0.5-3.0 at.% for Gd content. The critical Zn/Gd ratio for the formation of icosahedral quasicrystal phase (I phase) and long period stacking ordered (LPSO) structure in the Mg-Zn-Gd system has been confirmed. LPSO structure and (Mg,Zn) 3 Gd phase are formed in Mg-Zn-Gd alloys in the range of Zn/Gd ratio ≤1.0. However, only (Mg,Zn) 3 Gd phase is observed in the alloys in the range of 1.0 <1.5. And if Zn/Gd ratio is ≥1.5, I phase and (Mg,Zn) 3 Gd phase in the alloys begin to form gradually.