Formation Processes of the α + α 2 Structure in Model Pseudo-α-Titanium Alloys

—The effect of the initial structures of titanium alloys containing 10 wt % aluminum and additionally alloyed with molybdenum, niobium, zirconium, and/or tin, which are formed by quenching from various phase regions, on the structure formation in the course of prolonged isothermal annealing at 650°С is studied. It is shown that, in alloys quenched from temperatures corresponding to the β region to form the α' martensite, the decomposition of the martensite and formation of the α-, α 2 -, and β-phases mixture within initial martensite plates occur. In this case, the formation of the α 2 phase is realized via the nucleation and growth mechanism. In the alloys quenched from temperatures corresponding to the two-phase region, the spinodal decomposition occurs within the primary α-phase crystallites, and the α + α 2 structure characterized by a great amount of antiphase boundaries forms.