The time–temperature-transformation diagram of this alloy was determined. It exhibited differing precipitation sequences at low, medium and high temperatures. Low-temperature aging at <523K brings about coherent β′-phase precipitation to a α-Mg solid solution, resulting in increase in strength of the alloys. However, aging at medium and high temperatures >623K led to strengthening of the Mg–Zn–Gd alloy, owing to the formation of profuse stacking faults and 14H long period stacking ordered structure from the supersaturated α-Mg matrix, respectively.

Formation of 14H Long Period Stacking Ordered Structure and Profuse Stacking Faults in Mg-Zn-Gd Alloys during Isothermal Aging at High Temperature. M.Yamasaki, M.Sasaki, M.Nishijima, K.Hiraga, Y.Kawamura: Acta Materialia, 2007, 55[20], 6798-805