Determination of interaction parameters in titanium alloys with vanadium, niobium and molybdenum

The paper describes the phase boundaries in the Ti-V, Ti-Nb, Ti-Mo systems. The systems under consideration are characterized by the positive interaction parameters, which determines their binodal decay trend. The binodal decay region is imaginary and located within the two-phase (α+β) region. In the Ti-V and Ti-Nb systems a binodal decay region might develop with a transition to the monotectoid reaction in case of a high impurity content in the alloys. The two-phase (α+β) region considerably expands as the temperature goes down, which results in the thermodynamic nonstability of β-solid solution below 400-500 deg C for the Ti-V and Ti-Nb systems and below 300 deg C for the Ti-Mo system practically within the whole concentration range. Solubility in α-Ti is of a retrograde nature. It reaches its peak at 500-600 deg C and decreases as the temperature goes down