microstructural evolution

Université Côte d'Azur and CEMEF Mines ParisTech, in the French Riviera, currently have a Ph.D. position in computational geomechanics.

The goal of the project is to study the microstructural evolutions that take place on rocks of the lithosphere by using full field numerical simulations. The idea is to directly account for the physical mechanisms responsible for the microstructural evolution of the rocks and that are thought to be at the origin of strain localization and might help us to understand the origin of tectonic plates.

A typical two phase microstructure consists of a topologically continuous `matrix' phase in which islands of `precipitate' phase are embedded. Usually, the matrix phase is also the majority phase in terms of volume fraction. However, sometimes this relationship between the volume fraction and topology is reversed, and this reversal is known as phase inversion. Such a phase inversion can be driven by an elastic moduli mismatch in two-phase solid systems. In this paper (submitted to Philosophical magazine), we show phase inversion, and the effect of the elastic moduli mismatch and elastic anisotropy on such inversion.

During solid-solid phase transformations elastic stresses arise due to a difference in lattice parameters between the constituent phases. These stresses have a strong influence on the resultant microstructure and its evolution; more specifically, if there be externally applied stresses, the interaction between the applied and the transformation stresses can lead to rafting.