Modelling of phase transformation kinetics in Ti alloys – Isothermal treatments

We have developed a model which is able to describe the formation of high temperature microstructures in beta metastable titanium alloys. It is based on the classical theory of nucleation, and on growth laws obtained by assuming that the processes are controlled by the diffusion of the alloying chemical species only. Two morphologies are described: grain boundary allotriomorphs, and Widmanstatten plates gathered in colonies growing from the allotriomorphs. Moreover, a statistical description of the nucleation conditions on beta grain boundaries has been introduced in order to obtain the global kinetics of the transformation. The model predictions proved to be in good agreement with experimental results.