Phase transformation kinetics during continuous heating of a beta-quenched Ti-10V-2Fe-3Al alloy

摘要

The effect of heating rate on the phase transformation kinetics of a Ti-10V-2Fe-3Al metastable beta titanium alloy quenched from the beta field is investigated by fast in situ high energy synchrotron X-ray diffraction and differential scanning calorimetry. The initial microstructure is formed by alpha aEuro(3) martensite and fine omega(ath) particles distributed in the retained beta-phase matrix. The phase transformation sequence varies with the heating rate as revealed by analysis of the continuous evolution of crystallographic relationships between phases. At low temperatures an athermal reversion of alpha aEuro(3) martensite into beta takes place. This reversion occurs to a larger extent with increasing heating rate. On the other hand, diffusion-driven precipitation and growth of the omega phase is observed for lower heating rates accompanying the reverse martensitic transformation. Furthermore, the results show that the stable alpha phase can form through three different paths: (a) from the omega phase, (b) from alpha aEuro(3) martensite, and (c) from the beta phase.