Evaluation of recycled materials from TA6V alloy machining chips consolidated by Fabrication Additive

Context : The TYREX project (Titanium recycled by grinding and shaped by new processes) aims to study and develop different ranges of powder production processes from chips and demonstrate their compatibility with the requirements of processes and applications. Even if today there are industrial sectors and projects relating to the treatment of short cycle waste in the industry (by melting), the recycling of machining chips of this type of alloy in the form of powders is much more complex and is not addressed. This project intends to deal more specifically with these points using the additive manufacturing technology SLM (Selective Laser Melting) as the technique for the final consolidation of recycled powders. Indeed, this technique is well mastered at LISL (partner laboratory) and allows to reduce the inventory of material required (recycled powders) for the manufacture.
In order to demonstrate the potential of the proposed solutions and their economic and scientific interest, we first propose to study the recycling of “clean” chips obtained by dry and / or cryogenic machining. Mecachrome will supply these chips and 2 recycling paths will be studied. The first will consist in grinding these shavings to transform them into powders. The second way will consist of making chip compacts which will be atomized later (compaction and atomization conditions to be defined and optimized). The powders obtained by these 2 routes will thus be used to produce specimens consolidated by SLM that will be characterized to judge the interest of the solutions proposed. In parallel, definition of optimal densification conditions by SLM will be carried out using commercial powders and will serve as a point of comparison. All the materials obtained will be widely characterized from a chemical, microstructural and mechanical point of view.
To support this work, we are offering a 6-month internship in order to carry out SLM consolidations and all of the characterizations. To this end, the powders and consolidated materials will be characterized by numerous local techniques (MO, microprobe, SEM, chemical analyzer). An initial assessment of the mechanical properties will be obtained by tensile tests of the materials produced.
Although this project is dedicated to TA6V alloy, the methodologies and solutions proposed will be transposable to other alloys with high added value.

LOCATION

CEA de Saclay, Département des Matériaux pour le Nucléaire, Service de Recherches de Métallurgie Appliquée

PROFILE

Master 2 ou 3ième année d’école d’ingénieur métallurgie / matériau

CONTACT

Cédric SAUDER (SRMA/LTMEx) – cedric.sauder@cea.fr ; Hicham MASKROT (SEARS/LISL) – hicham.maskrot@cea.fr

INFORMATION

Internship duration : 5-6 months
Beginning of intership : november 2020 or up to fébruary-March 2021
Payement : ~ range 700-1300 euros

6-months internship on the monitoring of reactive magnetron sputtering of complex concentrated alloys

Complex concentrated alloys (or CCA) and their compounds (oxides, nitrides, carbides…) have been gaining interest for a decade and infuse innovation in the metallurgy field. Academic players use two main synthesis routes, arc melting for bulk materials and physical vapor deposition (PVD) for thin films along with numerical predictive tools, thanks to their high-throughput capabilities that are required to explore the potential composition space of such materials. If many studies focus on the elaboration of thin films of CCA and their compounds deposited by PVD, and more specifically magnetron sputtering, there is still not a lot done on the understanding of fundamental phenomena during the deposition process and their influence on the characteristics and the performances of the coatings. This project proposes to investigate and evaluate several characterization techniques for the monitoring of the reactive deposition of CCA from an alloyed target that has already been studied for non-reactive deposition in CEA: (i) LIBS (Laser Induced Breakdown Spectroscopy) analysis to relatively trace elements in the coating and in the target, (ii) optical emission spectroscopy coupled with (iii) an ultra-high-speed camera to study the species in the plasma along with their dispersal between pulses, (iv) the measurement of the energy distribution of ionized species from the plasma and finally (v) the quantification of coating thicknesses and growth rates by PTR (PhotoThermal Radiometry).

This project is fully integrated into the industrial IMPACT Chair (Innovative Materials and Processes Accelerated through Computing Technologies) from INSTN (French National Institute for Nuclear science and Technology).

It is expected to be extended into a PhD project by September 2020.

LOCATION

Physico-Chemistry Department of CEA Saclay 91191 Gif-sur-Yvette

PROFILE

Master degree in Material Science and Engineering. An experience in thin film deposition would be appreciated, along with a recommendation from the head of studies and the last internship supervisor.

CONTACT

Alexandre MICHAU : alexandre.michau@cea.fr

Microstructural and interfacial characterization for protective thin films in extreme environments

The development and optimization of coatings towards their application are of major importance especially when the components they protect are exposed to aggressive media. Extreme environments impose strong constraints on the design of the film and its interface with the substrate. Moreover, various degradation mechanisms such as the ones we study (corrosion, high-temperature oxidation, abrasive wear and irradiation mainly) can have very different and local effects. As a result, refined coating solutions are under development and need to be characterized. Indeed, fine, accurate and multi-scale characterizations prior to and after ageing tests constitute the major comprehension and analysis tool. The coatings concerned are nanostructured films, high-entropy alloys, MAX-phase, metallic oxides and nanometric multilayers. Because they all include nanometer-scale characteristics (particles, layers or simply interface), they require high-resolution analyzes which is possible with Transmission Electron Microscopy (TEM). This internship will be dedicated to the TEM analysis of coated samples before and after their degradation in extreme environments.

LOCATION

NTU Singapore
School of Materials Science & Engineering
50 Nanyang Avenue, Singapore 639798

CONTACT

NTU: Dong ZHILI, ZLDong@ntu.edu.sg