Methodology to characterize microsegregation

Alain Hazotte (1) , Jacques Lacaze (2)

1 LETAM - Laboratoire d'étude des textures et application aux matériaux
2 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux

Chemical microsegregation resulting from solidification of metallic alloys is most often characterised by EDS or WDS microanalysis using spot measurements located along a regular grid. Due to experimental limitations, the wave lengths of both dendrite arms and analysis grid are often of the same order of magnitude. Although this fact is generally eluded, it complicates the statistical analysis of the results, in particular when the objective is to validate a given solidification model or to prove the occurrence of solid state diffusion. This is first illustrated in the present work by means of experimental analysis performed on an Al alloy. The problem is then tackled using 2D simulations of more or less periodic solidification structures which are sub-sampled along periodic or random point distributions of different surface densities. Statistics tools are used to compare the resulting chemical distributions with the solidification model (Gulliver-Scheil model) injected in the simulation. This allows pointing out the limitations of classical statistical approach in that case, and finally to propose an optimum –at least less bad- procedure to characterise microsegregated structures.

Mots clés: Matériaux

Domaines: Matériaux

Alain Hazotte, Jacques Lacaze. Methodology to characterize microsegregation. Transactions of the Indian Institute of Metals, 2007, 60 (2), pp.267-271. ⟨hal-03477954⟩