Density of composite materials: the case of cast irons

CDD 12 mois, rémunéré

CIRIMAT, Toulouse

Personnes à contacter par le candidat

Jacques Lacaze jacques.lacaze@toulouse-inp.fr -
Moukrane Dehmas moukrane.dehmas@toulouse-inp.fr

DATE DE DÉBUT SOUHAITÉ

02/01/2023

DATE LIMITE DE CANDIDATURE

14/10/2022

TÉLÉCHARGEZ L’OFFRE

The proposed study will focus on the evolution with temperature of the solid state density of different cast irons. It will be carried out mainly using two experiment devices, X-rays diffraction in temperature and dilatometry:

  • X-rays diffraction will allow to measure the mean lattice parameters and the volume fraction of each phase at solid state and will lead to the determination of the theoretical specific volumes of the phases and thus of the theoretical density of the materials. Particular attention will be paid to the crystalline quality of graphite and the effect of chemical heterogeneities (microsegregations) in the matrix.
  • Dilatometry will allow to directly evaluate the density of the materials as a function of temperature. The comparison with theoretical values will highlight the effect of microstructural defects such as microporosities and decohesion at the graphite/matrix interface. The effect of the eutectoid transformation of the matrix (from high temperature austenite to low temperature ferrite) will be studied.

In parallel, a proposal for in-situ synchrotron radiation experiments will be submitted and will thus complete the results of the laboratory tests. According to his/her own interests, the post-doc will then be able to direct the work towards one or more of the following aspects in relation with the shape of graphite:

  • the interfacing of the dilatometer with electrical resistivity monitoring to better characterize interface decohesions;
  • the application of fast cooling tests to characterize the conditions of eutectoid transformation under conditions of competition between the stable and metastable phase diagrams;
  • the modeling of the microstructure resulting from the eutectoid transformation.