Time: 2:00 p.m.
Place: IC 02-718
Marcel Sluiter, Delft University of Technology, Delft, The Netherlands
Cluster expansions have proven a very useful tool to model thermodynamics and kinetics of substitutional alloys in metallic, ionic, and even covalently bonded systems.Cluster expansions are usually derived at via the structure inversion method in which the energies, or other relevant property, of a set of structures on a fixed underlying parent lattice are used to obtain expansion coefficients that pertain to clusters of sites on the parent lattice. The practical issues that arise for binary alloys, which structures and especially which clusters are required for an adequate description of the energy, become much more daunting when dealing with multicomponent alloys. The reason is that the number of candidate clusters in a cluster expansion increases exponentially with the number of components. Several methods for dealing with the increasing complexity of cluster selection will be presented for multicomponent aluminum alloys. This makes it possible to model the earliest stages of precipitation in alloys with realistic compositions.