Morphology evolution of -phase in Al-Mg-Si alloys during aging treatment

Ahmed, A.*; Uttarasak, K.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Toda, Hiroyuki*; Yamaguchi, Masatake   ; Tsuru, Tomohito   ; Ikeno, Susumu*; Matsuda, Kenji*

This study aims to clarify the growth process of the-phase in Al-Mg-Si alloys from the point of view of morphology evolution. For this research, the -phase orientation relationship, shape, growth process, misfit value, and interfacial condition between the -phase and Al matrix were investigated using high-resolution transmission electron microscopy (HR-TEM), focus ion beam (FIB), and optical microscope (OM). Results include the identification of {111} facets at the edges of the -phase, as well as the proposal of two new three-dimensional shapes for the -phase. We purposed the morphology evolution during the growth process of MgSi crystal and calculated the misfit to understand the unstable (111) facet has a higher misfit value as compared to the (001) and (011) facets. Our observations provide how they influence the behavior of MgSi crystals.