2007 Volume 48 Issue 5 Pages 954-959
Precipitation sequence of the Mg-8.3 mass%Gd-3.7 mass%Y-0.76 mass%Zr alloy at 423 K was investigated by high resolution transmission electron microscopy (HRTEM). After heat treatment of the solution and quenching, the aging treatment was performed for 1024 h at 423 K. In the specimen aged at 423 K for 64 h monolayers on the {1\\bar100}Mg planes composed of Gd and Y atoms, β″ phase with D019 structure and β′ phase with base centered orthorhombic structure already co-existed. The β″ phase is likely created via growth of monolayers composed of Gd and Y atoms on {1\\bar100}Mg planes. Co-existence of the monolayers on {1\\bar100}Mg planes and β″ and β′ phases continued up to 1024 h of aging at 423 K when the specimen reaches its maximum hardness. Both the β″ and β′ phases grew along the ⟨11\\bar20⟩Mg direction, while along the ⟨1\\bar100⟩Mg direction only grow of the β′ phase has been observed.
