PhD opportunities

4D Characterization of the Relationship between Microstructure, Deformation Mechanisms, and Fatigue Cracking of a Nickel-Based Superalloy

Thesis proposal

Area of expertiseMécanique
Doctoral SchoolISMME - Ingénierie des Systèmes, Matériaux, Mécanique, Énergétique
SupervisorPROUDHON Henry
Research unitCentre des Matériaux
KeywordsFatigue, Tomography, 4D Characterization, Microstructure, Nickel-based Superalloy
AbstractThe fatigue life of metallic materials can vary by several orders of magnitude under identical loading conditions. This dispersion is mainly attributed to the microstructural variability of the material. Indeed, fatigue results from the microscopic accumulation of plasticity, which depends on the morphology and grain orientation of the material. Currently, fatigue life models only qualitatively reproduce this dispersion. A major obstacle in modeling this phenomenon is the lack of experimental data capable of quantitatively describing the evolution of deformation and damage at the microstructural level.

The proposed thesis, in collaboration with the Center for Materials (Mines Paris), aims to quantitatively relate intragranular deformation measurements to fatigue crack initiation and propagation in polycrystalline materials. It will rely on the development of innovative fatigue tests, imaged in-situ in 3D using recent advances in synchrotron X-ray diffraction tomography (DCT, 3D-XRD, topotomography). This 4D testing protocol (in-situ 3D characterization) will allow for simultaneous characterization of microstructure, microscopic plastic/elastic deformations, and fatigue crack initiation and propagation in nickel-based superalloy samples, with sub-micron resolution. These tests, conducted at the ESRF synchrotron, will be coupled with a study of fatigue behavior using conventional and micromechanical tests (in-situ scanning electron microscopy), to enhance the understanding of fatigue phenomena.

The overall results of this research will shed light on the mechanisms of fatigue crack propagation in the material and identify measurable quantities linked to microscopic deformation mechanisms that are quantitatively correlated with crack initiation and/or propagation. This thesis will contribute to enhancing the understanding of fatigue at the microstructural scale and support the development of quantitatively predictive fatigue models that take into account the influence of microstructure.
ProfileEngineer and / or Master of Science - Good level of general and scientific culture. Good level of knowledge of French (B2 level in french is required) and English. (B2 level in english is required) Good analytical, synthesis, innovation and communication skills. Qualities of adaptability and creativity. Teaching skills. Motivation for research activity. Coherent professional project.

Prerequisite (specific skills for this thesis):

Applicants should supply the following :
• a detailed resume
• a copy of the identity card or passport
• a covering letter explaining the applicant's motivation for the position
• detailed exam results
• two references : the name and contact details of at least two people who could be contacted
• to provide an appreciation of the candidate
• Your notes of M1, M2
• level of English equivalent TOEIC
to be sent to
FundingFinancement par crédits ANR