Transformations with inhomogeneous nucleation and growth velocity

The major part of solid-state transformations modeling has concentrated on transformations taking place from a homogeneous matrix. Nonetheless, there are situations in which one finds an inhomogeneous matrix. An example is the recrystallization of metals subjected to an inhomogeneous deformation. If the recrystallization takes place in the regions where the stored energy of cold work is high, one has both a higher number of nuclei and faster growth velocity than in the region where the stored energy is low. In this work, we conduct computer simulations of transformations of a matrix possessing inhomogeneous nucleation and growth. We compare the computer simulations with an analytical solution that considers at the same time both the variation of the number of nuclei and the velocity. These results are compared with results obtained when only inhomogeneous nucleation is considered, whereas the velocity is kept constant throughout the matrix. For the number of nuclei and velocity gradients used here the main simulation results were: a) the inhomogeneous velocity does have a substantial effect on the transformation kinetics and microstructural evolution, b) the inhomogeneous distribution of nuclei has a more significant impact on the microstructure than an inhomogeneous distribution of velocity.