Decomposition Processes of Metastable β Phase in Transition Titanium Alloys

The structural and phase transformations occurring during the decomposition of a metastable β‑solid solution upon aging in titanium alloys of transition class Ti–14Mo and VST3553 (Ti–3Al–5V–5Mo–3Cr) have been analyzed. The phases formed during aging, the morphology, and temperature ranges of their precipitation have been determined by structural analysis methods. The formation of an athermal ω‑phase during quenching and its subsequent dissolution during heating have been shown; the formation of a transient metastable O′′-phase, which is intermediate in the β → ωiso → α-transformation, has been established; and the precipitation of the O′′-phase has been recorded in the presence of an isothermal ω-phase in the structure.