IMX Seminar Series - Nucleation of diffusion controlled phase transformations in the solid state, beyond or beside classical nucleation theory ?

First order phase transformations in metallic alloys may occur in a number of ways, depending if the composition is conserved or changed, and depending on the mechanisms of structural transformations from one crystallography to another. When the transformation is diffusion controlled, it may occur by the amplification of concentration fluctuation (spinodal decomposition), or by nucleation and growth of the new phase. The classical nucleation theory, developed initially for liquids and solids, have been adapted to solid state transformations in pure metal and binary alloys. In alloys having more than three elements, where the diffusion coefficients may differ by orders of magnitude, the situation is more complex, both for the growth mechanisms, but also for the nucleation mechanisms. Recent experimental observations and simple calculation show the necessity to revisit classical nucleation theory in this context.

Bio: Yves Bréchet is a member of the French Academy of Sciences.
As a specialist in materials science, he got interested both on microstructural evolution in metals and alloys, and on their consequences on mechanical properties, plasticity and fracture. Involved both in fundamental issues such as plastic instabilities and kinetics of phase transformations, he also worked closely with M.F. Ashby on materials selection methods and development of tailored “architecture materials”. In these fields he has authored or co authored 5 books and more than 600 publications.
Professor during more than 30 years in Grenoble University (1988-2012) , he also held the annual chair «  Innovation » in  college de France ( 2012-2013), and is now res, a research professor in Monash University (Australia) and adjunct professor at McMaster University (Canada). He is currently Scientific director of Saint Gobain compagny, a worldwide Materials industry which is more than 350 years old.
He has held the position of «  Haut Commissaire à l’énergie atomique » ( 2012-2018) which is the scientific advisor of the french government for energy related questions.