Formation of Intermediate Phases in Decomposition of Metastable B-Phase in Titanium Alloys of Transition Class

The process of precipitation of transition phases in quenched alloys Ti – 14% Mo and VST3553 is studied under aging at from 300 to 500°C. X-ray diffraction phase analysis and transmission electron microscopy are used to detect the presence of a metastable O″-phase in the alloys quenched from the β-range. The morphology of the precipitated particles and the kinetics of formation of the O″-phase are determined. It is shown that phases O′ and/or O″ are continuously associated with precipitation of phase ω and are transition phases up to the temperature of formation of the α-phase, i.e., 500°C.