Investigation of omega-phase in Ti–Mo alloys by high resolution electron microscopy, image processing and dark-field methods

Abstract
The microstructures of the omega phase in Ti-Mo alloy single crystals were investigated using high resolution electron microscopy (HREM), image processing and dark-field methods. By image processing, the assembly of linear defects which had been reported was revealed in the region of the superposition of two kinds of omega variant. The superpositions of these omega variants were observed in the dark-field images using two beams from each variant. HREM images of the particles corresponding to the omega phase, which is identified in the dark-field image, suggest that the omega phase is formed by atomic displacements in the four 〈111〉 directions as proposed by de Fontaine and Buck, and that omega phase particles grow parallel to the direction of atomic displacement.