PhD opportunities

[DOCTORAL CONTRACT] Effect of crystalline defects on chromium diffusion in NiCr alloys at low temperatures

Thesis proposal

Area of expertiseMaterials science and engineering
Doctoral SchoolSystems Engineering, Materials, Mechanics, Energy
SupervisorMme Cécilie DUHAMEL
Research unitCentre of materials
ContactDUHAMEL Cécilie
Starting dateOctober 1st 2021
KeywordsDiffusion, grain boundaries, Plasticity, NiCr alloys
AbstractDue to their good oxidation resistance and good mechanical properties, Ni-Cr-based alloys are widely used in many industrial domains over a wide temperature range from 300 °C for nuclear components to more than 1000 °C for aeronautic applications. When exposed to an oxidizing atmosphere, these materials may be selectively oxidized, i.e. a thin layer of chromium oxide may form at their surface, conferring them a protection to oxidation. The selective oxidation of chromium may lead to the formation of a chromium-depleted zone in the metallic substrate underneath the metal/oxide interface, the extent of which results from a balance between chromium diffusion in the alloy and oxidation kinetics. Stress-induced plastic deformation might modify the overall oxidation kinetics and the chromium depletion profile. However, a reliable quantitative description of this phenomenon is still an issue. To get insight into plasticity-diffusion relationship in Ni-Cr alloys, the aim of the PhD project is to extend previously developed methodology to investigate the effect of plastic deformation on bulk and grain boundary diffusion in model binary Ni-Cr alloys in a temperature range including low temperatures where the bulk diffusion cannot be easily measured (350-700 °C). To be able to study both bulk and grain boundary diffusion of Cr in Ni-Cr alloys, concentration profiles of chromium diffusion will be measured by a combination of two methods to get reliable data: secondary ion mass spectrometry (SIMS) using stable isotopes for bulk diffusion and the radiotracer technique for grain boundary diffusion in the framework of close collaborations established with Université de Versailles-St Quentin and Université de Münster (Germany), respectively.
Profilethe candidate must hold a national master's degree or another degree conferring the grade of master (engineering degree, equivalent foreign degree...), at the end of a training course establishing his/her aptitude for research.

Prerequisite (specific skills for this thesis):
Solid background in metallurgy, rigour, attitude to experimental work.

The application file must include
- a letter of motivation to pursue a doctoral program on the targeted thesis topic and including the candidate's professional project
- a detailed curriculum vitae mentioning the candidate's studies, research internships, diplomas with dates obtained, professional experience, and planned research areas
- a transcript of grades from previous studies (engineering and/or master)
- one or more letters of recommendation...
- a certificate of English level.
- for non-French speaking students, a level A2/B1 in French (European reference system) is recommended for entry into the doctoral program
- for students who do not hold a national research master's degree, all documents attesting to the student's qualifications in terms of training through research (attestations of research internships with a summary of the thesis, recommendations, publications, etc.)
- a copy of identity card or passport

The documents in pdf format must be sent before May 05, 2021 to
FundingConcours pour un contrat doctoral