X-ray Fluorescence Holography for a Ti-Nb Binary Alloy Consisting of the Martensite, Austenite and Omega Phase

摘要

The local atomic structure near an Nb atom in a Ti-20 at.% Nb alloy single crystal, which consists of the beta, alpha '' and omega Ti phases, was investigated by means of X-ray fluorescence holography (XFH). The atomic images were reconstructed in the vicinity of an Nb atom, which is one of the typical beta stabilizing elements in beta Ti alloys. Most atoms in the beta Ti primary phase were reconstructed clearly. The atoms in the alpha '' Ti martensite phase could not be reconstructed, because the alpha '' Ti martensite has the crystal structure with low symmetry. Some atoms in the omega Ti fine precipitates were reconstructed successfully, although the amount of the omega Ti phase was much smaller than that of the beta phase. An Nb atom and its first nearest neighbors tend to keep the BCC structure even upon the omega Ti phase formation.