Transformation Pathway upon Heating of Metastable β Titanium Alloy Ti-15Mo Investigated by Neutron Diffraction.

A transformation pathway during thermal treatment of metastable beta Ti-15Mo alloy was investigated by in situ neutron diffraction. The evolution of individual phases alpha, beta, and omega was investigated during linear heating with two heating rates of 1.9 degrees C/min and 5 degrees C/min and during aging at 450 degrees C. The results showed that with a sufficient heating rate (5 degrees C/min in this case), the w phase dissolves before the alpha phase forms. On the other hand, for the slower heating rate of 1.9 degrees C/min, a small temperature interval of the coexistence of the alpha and omega phases was detected. Volume fractions and lattice parameters of all phases were also determined.