INVESTIGATION OF INITIAL STRUCTURES OF AGED OMEGA-PHASE CRYSTALS IN BETA-TITANIUM ALLOYS USING HIGH-RESOLUTION ELECTRON-MICROSCOPY

In order to clarify the beta-->omega phase transformation mechanism in beta-titanium alloys, an investigation of the atomic structure of Ti- Mo alloys at early stages of aging was carried out using high resoluti on electron microscopy (HREM), in situ HREM, and image-processing meth ods. The initial structure of omega-phase crystals was observed as a l ine structure of bright spots in the [111] directions with 0.28 nm spa cing. The formation of the line structure was also observed with in-si tu HREM. The appearance of the line structure was confirmed by an imag e contrast simulation method. (C) 1997 Elsevier Science Ltd.