Abstrakt
The shapes and orientations of lamellae of the hexagonal close-packed α phase in single crystals of the body-centred cubic β phase in a metastable β-Ti alloy (Timetal LCB) were investigated by synchrotron small-angle x-ray scattering. Several steps of thermal treatment with various annealing times and temperatures were employed.
The measured scattering data were fitted to a model of ellipsoidal lamellae of random sizes, and the mean lamella shapes and orientations of their axes with respect to the β-Ti matrix were determined from the fit. The number and relative volume of the lamellae were estimated from the integrated scattered intensity.
The elastic energy of the lamellae as well as the energy of defects at the α/β interface (misfit dislocations) were calculated from the parameters of the lamellae. The results provide information on the kinetics of the βRIGHTWARDS ARROWα transformation in metastable β-Ti alloys and allow assessing the degree of thermodynamic equilibrium of the final α/β composite.