A HREM study of domain structures in the H phase coexisting with the s^' phase in a nickel-based alloy

Parallel and rotation domains occur abundantly in the newly discovered H phase, always found coexisting with a s^' phase, of a nickel-based alloy. The domain structures have been studied in detail by means of high resolution electron microscopy. All variants of domain boundary studied are coherent and a narrow band of s^' can always be identified at the boundary as a transition structure between two H domains. This is discussed from the viewpoint of tetrahedral close-packed structures in general and cloee structural relationship between H and s^' in particular.