Abstract
The aging behavior of a ternary Mg–15%Gd–6.4%Sc (mass%) alloy was examined by high-resolution transmission electron microscopy. During the first stage of age hardening of the alloy, a contrast corresponding to a precursor of the β″ phase was observed predominantly. The β″ and β′ phases coexist in the second stage of hardening, up to the point of maximum hardness. In the over-aging stage, the spheroidal contrast of the β′ phase became longer along the ⟨1\\bar100⟩Mg direction. The addition of Sc to the Mg-Gd alloys is useful to clarify the precipitation behavior and contribution of the β″ and β′ phases to age hardening, as indicated by the two stage in the early stage of aging.
