PhD opportunities

Analysis of the phase transformation and damage coupling in anisothermal conditions by the phase field method: case of thermal cycling in diffusion coatings.

Thesis proposal

Area of expertiseMechanics
Doctoral SchoolSystems Engineering, Materials, Mechanics, Energy
SupervisorM. Vincent MAUREL
Co-supervisorM. Kais AMMAR
Research unitCentre of materials
ContactMAUREL Vincent
Starting dateOctober 1st 2020
Keywordsphase transformation, phase field, diffusion coating, phase morphology, mechanic/diffusion/damage coupling, oxidation
AbstractFor high temperature application (eg thermal barrier coatings), diffusion coatings are often used to protect Ni based superalloys from detrimental effect of high temperature exposure. Complex phase transformations occur in these coatings as a function of applied thermo-mechanical loadings [1]. To account for strong coupling between mechanical loading, thermal loading paths and microstructure, modeling phase transformation could not only be based on diffusion analysis [2]. For instance, oxide spallation could strongly modify oxidation and diffusion, and subsequently phase transformation kinetic.
Phase field analysis, are straightforward to model mechanic-oxidation coupling [3]. This could offer solution for a global scheme of strong mechanic/diffusion/damage coupling analysis.

Experimental results for diffusion coatings show the complexity of phase morphology and their strong evolution during anisothermal loading. Phase field approach is promising to account for both phase morphology and kinetic of transformation modeling. The proposed analysis will integrate several elements (and their own potential), phase field for oxidation description and a direct coupling to mechanical field (for elasto-visco-plastic and damage behavior).

The aim of the project is to answer scientific challenges:
improving the robustness of strong mechanical/phase transformation coupling for complex cases (multicomponent and multiphased materials, anisothermal loading, non-linear mechanical behavior)
building of an interface between phase field model and thermodynamic database
optimizing the computation time (including remeshing, model reduction...)
understanding of phase transformation/thermo-mechanical loading coupling observed in diffusion coatings for anisothermal loading
The project will sequentially address the following key-points:
state-of-the-art for coupling model
phase transformation model by CALPHAD method, accounting for real composition; sensistivity analysis and model reduction for diffusion coefficient;
phase transformation model by phase-field approach for anisothermal loading;
application to diffusion coating case: coupling damage to phase field analysis.
ProfileTo be admitted to a doctorate, the candidate must hold a national master's degree or another diploma conferring the master's degree (engineering diploma, equivalent foreign diploma, etc.), following a course of training establishing his research aptitude.
Applicants will be selected after interview before a jury assessing their research aptitude and the adequacy of their training and knowledge with the proposed thesis subject. Strong scientific knowledge, a first research experience (internship 4 months minimum), a strong motivation for research, a good level in English will be required (minimum B2).
The application must include:
a motivation letter including the candidate's professional project
a detailed curriculum vitae mentioning studies, research internships carried out, diplomas with date obtained, professional experience, research axes envisaged
a transcript of marks from the previous course (engineer and / or master cycle)
one or more letters of recommendation ...
a certificate of English level.
for a non-French speaking student, an A2 / B1 level in French (European standard) is recommended when entering a doctorate
for students who do not hold a national research masters diploma, all documents attesting to the students qualifications in research training (research internship certificates with summary of the dissertation, recommendations, publications, etc.)
a copy of identity card or passport

The documents in pdf format must be sent to no later than June 8.

FundingConcours pour un contrat doctoral
Partnership2 sujets parmi les 5 sujets ci-dessous seront slectionns aprs concours sur audition des candidats :
Analyse du couplage transformation de phase et endommagement en conditions anisothermes par la mthode des champs de phase: cas du cyclage thermique dans les revtements de diffusion.
Encadrement Kas Ammar, Vincent Maurel, Samuel Forest
Effet du procd sur la microstructure et les proprits de lacier inoxydable 316L labor par fabrication additive
Encadrement : Sylvain Dpinoy, Jrme Crpin
Vers une nouvelle gnration de poudres pour la projection cold spray: enrobage de particules de polymres par des particules mtalliques ou d'oxydes mtalliques.
Encadrement : Jean-Franois Hochepied, Francesco Delloro
Effets polycristallins sur l'interaction entre dformation et endommagement : mesures 4D et calculs EF de micro/structures
Encadrement: Thilo Morgeneyer, Henry Proudhon
Etude multi-chelles des mcanismes thermo-mcaniques du frottement.
Encadrement : Vladislav Yastrebov, Cristian Ovalle