Abstract
The structure of a Ti-3wt%Fe alloy quenched from the β-phase has been examined mainly by means of transmission electron microscopy. The quenched specimen is hard and very brittle. From the results of optical microscopy and X-ray diffraction, the structure is found to be very fine and to have a large number of lattice defects. Electron microscopy reveals that the structure consists of acicular grains of about 1∼2 μ in length and about 1/5 μ in width. Therefore, the electron diffraction analysis is difficult in most cases. However, from the results of the solvable diffraction patterns it is confirmed that there are two types of martensite : one is close-packed hexagonal and the other is face-centred cubic with internal twins on {111}. The latter is a newly found phase which cannot be directly deduced from the equilibrium phase diagram in the Ti-Fe system. The retained β-phase is also present in the quenched alloy.
