Deakin-INSA Lyon Cotutelle - Optimisation of microstructure and mechanical properties of high entropy alloys

This is a doctoral cotutelle project between Deakin University (Australia) and National Institute of Applied Sciences of Lyon (INSA Lyon) (France) under the AUFRANDE Program.

The successful candidate will sign a 36-month employment contract with the National Institute of Applied Sciences (INSA) of Lyon and be enrolled as a PhD candidate at both INSA Lyon (France) and Deakin University (Australia) and spend up to 12 months of the total period of the program at Deakin University  (Australia).

International mobility is a core feature of the program. Besides a residential year in Australia, the successful candidate will be part of a cohort of 64 PhD fellows and will participate in regular events where they will share common experiences and build a sustainable community, laying a strong foundation for long-term impact on future collaborations and careers.

There are three projects of which one will be funded;

Project 1 - Significance of model approximations for yield strength predictions of high entropy FCC alloys

Background: 
High entropy alloys (HEAs) are an exciting relatively new concept in metallurgy: multiple chemical elements at high concentrations are mixed, leading sometimes to single phase crystalline materials. Several single-phase FCC HEAs have shown impressive yield strength, due to solute strengthening, and the vast composition range of this class of materials opens many possibilities for the design of alloys with superior mechanical properties. Since their discovery, important theories have emerged to predict the composition, strain-rate and temperature dependence of their yield strength. Key ingredients to such models are dislocation/solute interactions, dislocation properties and dislocation line tension, and can be obtained either from empirical potential calculations, ab initio calculations, or from experimental data, depending on the levels of simplifications of the theories (mean/full field approach, elastic theory approximations, sum rules, etc.). How these approximations impact predictions remains elusive, which can be a problem for alloy design.

Aim: 
This PhD project will aim at quantifying the consequences of model inadequacies in identifying interesting alloy compositions, and then propose new methodologies for accurate predictions of FCC HEAs yield strength

Project 2 - Atomistic comprehensive insights on the dislocation properties of refractory BCC High Entropy Alloys

Background:
Within the active field of high entropy alloys (HEAs), the refractory subclasses of alloys are complex substitutional solid solutions made of nearly equal proportions of up to 5-6 refractory elements and have a BCC structure. They have received considerable attention due to their potential for high temperature applications: they exhibit a very high yield strength up to elevated temperatures - thus competing/superseding Ni-based superalloys, and some of them also have a significant ductility at room temperature. However, there is a lack of fundamental knowledge of the dislocation properties in refractory high-entropy alloys (RHEAs), and as a function of alloy composition, even though such properties dictate the exact nature of the mechanisms responsible for the plasticity in these complex materials.

Aim:
The PhD student will develop ad hoc interatomic potentials to systematically investigate the links between composition, dislocation/solute properties, and plasticity mechanisms at the atomic scale. Once these links are established, the student will be able to identify the relevant physical assumptions to be used in the development of mesoscale models of RHEAs yield strength (currently a highly controversial topic in the literature). This will also help to provide guidance for alloy design of RHEAs.

Project 3 - On the use of precipitation to strengthen High Entropy alloys

Background:
High entropy alloys are an exciting relatively new concept in alloy design. Rather than taking one element and adding small amounts of others to it, high entropy alloys comprise nearly equal parts of up to five or so elements. Interest in this field was initially focused on single phase solid solution materials. More recently, however, the use of hardening precipitation – such as the one in steels or other convention alloys – has been considered to achieve better mechanical strength, leading for example to the so-called high entropy superalloys, that involve complex ordered/disordered phases.

Aim:
This PhD will explore such a strengthening route by adding some specific alloying elements in small quantities to model medium entropy alloys, and by carrying out some heat treatments to involve the precipitation. The newly formed phases will be characterized in detail and their influence on the mechanical properties will be measured. The modeling of the precipitation kinetics will also be performed by physically-based models.

Applications close 11:59pm, Wednesday 27 August  2024

This scholarship is co-funded by Marie Skłodowska-Curie Actions (MSCA), Horizon Europe, European Union;  National Institute of Applied Sciences of Lyon (INSA Lyon) and Deakin University.

INSA Lyon offers a 36 months full-time work contract (with the option to extend up to a maximum of 42 months) incurring a 2 month probation period and a 35 hour working week.

The benefits include:

• Gross annual salary €28,800
• A Tuition Fee Waiver at both PhD awarding institutions
• Yearly travel allowance to cover flights and accommodation for participating in AUFRANDE events
• €10,000 allowance to cover flights and living expenses for up to 12 months in Australia (which may be taken in several blocks over the period of the employment term as best suits the needs of the researcher).
• 25 days paid holiday leave
• Sick leave and parental leave (112 days maternity and 28 days paternal).

To be eligible you must meet all the minimum eligibility criteria by the application closing date:

• must have not yet been awarded a doctoral degree. Researchers who have successfully defended their doctoral thesis but who have not yet formally been awarded the doctoral degree will not be considered eligible to apply.
• have not resided or carried out your main activity (e.g. work or studies) in France for more than 12 months in the 3 years immediately before the application closing date. Time spent as part of a procedure for obtaining refugee status under the Geneva Convention (1951 Refugee Convention and the 1967 Protocol), compulsory national service and/or short stays such as holidays are not taken into account.
• have not be already permanently employed by the chosen research host at the time of the application closing date.
• must meet the academic criteria for admission to the doctoral programs at both the French and the Australian enrolling universities.
• must be able to C1 level of English (Common European Framework of Reference for Languages in both speaking and in writing).
• be able to physically locate to both National Institute of Applied Sciences of Lyon (France) and Deakin University (Australia)

More information on INSA Lyon's requirements:

For more information, please view: National Institute of Applied Sciences of Lyon (France)

More information on Deakin University’s requirements:

Applicants must have completed a research project in a related area including a thesis which is equivalent to at least 25% of a year’s full-time study with achievement of a grade for the project equivalent to a Deakin grade of 80% or equivalent.  For more information, please view: Research applications | Deakin