Crystal chemistry of the G-phase region in the Ti-Co-Al system

In order to establish site preference in the G-phases with Ti/Al substitution, the extensive range of the ternary solid solution for the G-phase in the Ti-Co-Al system has been investigated by X-ray powder/single crystal and neutron powder diffraction. A filled variant of the Th6Mn23 type (space group Fm3¯m) was confirmed for the Al-rich single-phase region, whereas a novel structure variant with space group F4¯3m was established for the Ti-rich side of the G-phase region. Precise atom site occupation has been established for both structure types throughout the full extension of the G-phase homogeneity region.