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Pascal Jacques
Professor
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Recent publications


research focuses on the physical and mechanical metallurgy of several engineering alloys: advanced high strength steels for automotive applications with also concerns about hydrogen embrittlement; new high strength metastable titanium alloys for aerospace applications; new thermoelectric or magnetocaloric Heusler compounds for energy harvesting or magnetic cooling; bioresorbable alloys for cardiovascular implants; high entropy alloys with improved toughness; new alloys with improved properties specifically designed for 3D printing.

Research group(s): IMAP

PhD and Post-doc researchers under my supervision:


DeltaT
Valentin Marchal-Marchant

obtained his degree in engineering in materials science from the Université catholique de Louvain in 2011. Then, he accomplished his PhD under the supervision of prof. Pascal Jacques, on the study of Physical Vapor Deposition of thick copper films on steel.

His research is now focused on the development of thermoelectric materials and thermoelectric generators for energy harvesting and passive electromechanical systems. It aims at using common and non-toxic materials to generate electrical power from thermal gradients. Nowadays, attention is put on large scale applications owing to more than 7 years of research about thermoelectric materials leaded in IMAP.

The big challenge of this topic is the development of new tools and equipments for material production and assembly, and specific characterization methods. Such a wide range of different tasks can only be achieved thanks to the versatility of technical and scientific expertises of the IMAP team members as well as Lacami support.



Laurine Choisez

The association of different plastic deformation modes (TRIP, TWIP) induces unmatched levels of mechanical properties in a new beta metastables titanium alloys family. A hardening beyond the theoretical limit is especially noticed, together with a uniform deformation 3 to 4 times higher than the one in a classic TA6V alloy and a yield stress superior of 30 percent to the one in a

TWIP alloy. A positive synergy is thought to exist between a high hardening and the damage resistance and toughness of such materials. My thesis will consist in the study of the damage resistance and the toughness of several beta metastables titanium alloys with different prevailing plastic deformation mechanisms in order to highlight the mechanism responsible of the post-necking deformation properties.


Locoted
Geoffrey Roy

Geoffrey holds a Master in Mechatronic Engineering (2010) and a PhD in Engineering (2015) from the Université catholique de Louvain where he works as a senior researcher at the Institute of Mechanics, Materials and Civil Engineering (iMMC).
Within the Division of Materials and Process Engineering (IMAP), his research is focused on the development of new thermoelectric materials and systems for a range of applications going from industrial waste heat recovery to autonomous powering of smart sensors. In his research, he pays particular attention to the development of new solutions that present improved both technical and economical profiles in order to facilitate the emergence of these solutions out of the lab.
This research is followed by several companies such as: Drever International, AGC Glass Europe, Carmeuse or Engie.


Aerostream and IAWATHA (additive manufacturing), LOCOTED (thermoelectrics)
Camille van der Rest

Camille van der Rest completed her PhD thesis on the optimisation of Heusler Fe2VAl-based thermoelectric compounds through innovative metallurgical processing in 2015. It was under the joint supervision of Prof. Pascal Jacques and Prof. Aude Simar. Her research topics now concern thermoelectric materials, additive manufacturing and friction stir processing technologies. Concerning thermoelectrics, the main objective is the development of low-cost, non-toxic, and powerful materials that could be used in large-scale industrial applications of heat recovery. In addition, she studies some fundamental aspects in order to improve the performances of such materials, i.e. ordering phenomena in off-stoichiometric Fe2VAl-based Heusler compounds. It is essential to make the link between (innovative) manufacturing processes, microstructures and the functional properties of these TE materials. Concerning additive manufacturing, the main contributions are on the characterisation and optimisation of the microstructures and the mechanical behaviour of Al parts obtained by Selective Laser Melting and the developpment of new materials for additive manufacturing. Again, the link between the process parameters and the final microstructure/properties is a key issue. Finally, Camille developed, together with Prof. Aude Simar and Prof. Pascal Jacques, a novel Friction Melt Bonding (FMB) process in order to weld aluminium alloys and steels. This process is still under development thanks to the collaboration with other researchers of IMAP.


Influence of defects on the life of biomedical implants
Maïté Croonenborghs

Implants are devices aiming to support, help, or even correct biological structures. However, with time, some of these implants show aging problems. The roots of these problems can have numerous explanations. In some cases, the body reacts to the presence of a foreign body, and this can lead to health risks. Sometimes, the material can show, with time, signs of weakness. Later on, these defects can lead to the failure of the implant.

In the case of permanent stent implants, the presence of a foreign body in the blood vessels can lead to restenosis or late thrombosis. This is why bioresorbable stents are nowadays developed. These stents should support the vessels during their healing period and dissolve in an inoffensive way afterward. Iron-based alloys are investigated for their appropriate mechanical properties but their degradation rate is too low. One investigated solution is to increase surface roughness to dissolve faster the implant. The effect of this roughness on the expansion process has not been analyzed for now.

The case of growth rods shows that the material itself can lead to implant failure. These rods are placed, during surgery, along the spine of scoliotic children. They aim to support the spine and help it to straighten back. However, fracture events occur in 36% of the patients. During the surgery, the rods are bent to fit the natural shape of the spine. The tools employed for this process can introduce some indentation marks on the surface of the rods and decrease their fatigue lifetime.

From these case studies, it is observed that the completion of an implant (i.e. stent implantation process) or its lifetime (i.e. growth rod failure) can be affected by its surface state. This research will therefore focus on the imperfection sensitiveness of such devices. Various kinds of defects are introduced at the sample surface. To understand the influence of these defects on the mechanical properties, these samples are tested and compared.



Antoine Hilhorst

High entropy alloys (HEAs) are a new family of metallic alloys. In contrast to conventional alloys, HEAs have multiple principal elements e.g. the equiatomic "Cantor" alloy CrMnFeCoNi. Alloys in this range of chemical composition have gathered attention only recently. From what was observed in conventional alloys, it was expected that HEAs microstructure be composed of several intermetallic phases but some systems are surprisingly single phase solid solution. Moreover, such single-phase alloys have excellent mechanical properties. For instance, CrMnFeCoNi possess a large fracture toughness, which increases with decreasing temperature, putting this alloy on par with the current best alloys used for cryogenic applications. As such, the objective of the thesis is to understand the underlying mechanisms responsible for the observed macroscopic behavior of such alloys.


The thesis aims to answer several questions such as: What are the mechanisms responsible for the increase in ductility, strength, and fracture toughness with decreasing temperature? What high-throughput methodology would be able to screen the vast range of possible chemical composition of HEAs for high performance alloys?


To understand the deformation mechanisms, several HEAs will be fully characterized from casting to mechanical testing. For the fracture toughness measurements, the essential work of fracture method will be employed as it is best suited for ductile thin sheets than compact tests. Diffusion multiples will be explored as a possible high-throughput method, as the presence of composition gradients allows the simultaneous characterization of a range of composition by techniques such as EDX, EBSD and nano-indentation.


A microCT-based approach for high-resolution characterization of biodegradable metallic intravascular stent materials
Lisa Leyssens

The goal of my research project is to assess different potential biodegradable metallic intravascular stent materials using high-resolution 3D microfocus X-ray computed tomography (microCT). In a first step, the optimization of microCT and contrast-enhanced microCT (CECT) for the characterization of the 3D microstructure of different blood vessels is performed (aorta, femoral artery, vena cava). Then, this technique is applied to study the degradation behaviour of potential materials for biodegradable metallic intravascular stents. Structural properties are investigated. They are critical because they will influence the mechanical and in vivo behaviour of the stents. The materials (in the shape of wires) are screened to analyze the corrosion and surface changes, before and after immersion tests (in vitro part) and before and after implantation in rat arteries to additionally study interactions between the tissue (artery) and the metal (in vivo part).


Analysis of hydrogen uptake mechanisms in Al-Si coated high strength steels during hot stamping process
Mohamed Krid


Analysis and understanding of the damage and fracture mechanisms in advanced high strength steels for automotive applications
Thibaut Heremans

The environmental challenge the world is facing today is driving car manufacturers to limit their vehicule weight in order to reduce their fuel consumption. As a consequence, steels with higher specific strength performances are being constantly developed, while insuring that proper ductility and toughness levels are retained to allow for forming operations and passengers safety. Lately, the so-called "third generation" of advanced high strength steels (AHSS) has emerged, among which one finds the Quenching & Partioning (Q&P) steels. These Q&P steels demonstrate an excellent combination of ultimate tensile strength (UTS = 1500 MPa) and adequate ductility (TE = 18%). Nevertheless, their fracture properties and the underlying mechanisms are still not fully understood and start raising concerns as the strength levels of these steels increase. Indeed, recent studies have highlighted a shift in failure mechanism, from ductile to brittle, depending on the loading conditions. Although often left behind strength and elongation, toughness issues constitute essential stakes not only for ever more demanding applications but also for forming processes during which edge cracking is a key concern. The objective of my research project is to investigate the failure properties of these Q&P steels in order to understand how microstructural and micromechanical parameters influence the competition between three possible mechanisms : ductile flat, ductile slant and brittle intergranular.


Development and charactrisation of a Fe2VAl-based transverse thermoelectric module built by additive manufacturing
Mathieu Delcroix

The aim of my thesis is to study and optimise an innovative alternative to classical thermoelectric generators according to different aspects : geometry, materials and manufacturing processes. More specifically, it consists in implementing and optimising a Fe2VAl-based transverse thermoelectric generator with an optimize internal topology built by multimaterial additive manufacturing. The main scientific issues that will dictate the experimental approaches and the modelling steps consist in : (i) understanding the transverse thermoelectric effect and its experimental study coupled with a topological optimisation (since existing studies are mainly theoretical only); (ii) the analyse of the microstructural characteristics resulting from the additive manufacturing on the electrical and thermal properties of the Fe2VAl compound (what has not been done so far), but also of the other compounds that are needed in case of multimaterial additive manufacturing; (iii) optimising the characteristics of a functional transverse thermoelectrical generator in function of the operating conditions.


Additive manufacturing of beta-metastable titanium alloys
Marion Coffigniez

High resistance to both damage nucleation and void coalescence has been observed in beta-metastable titanium alloys presenting both transformation-induced plasticity and twinning-induced plasticity effects. These alloys could therefore be particularly suitable for additive manufacturing since their extremely high ductility is not impacted by the presence of defects induced by the Selective Laser Melting (SLM) process. However, in the case of the Ti12Mo previously studied at IMAP, the SLM process induces the formation of omega precipitates that embrittle the as-built samples. The idea of this project is thus to work on alloy design to keep the TRIP/TWIP effects but to avoid the precipitation of the omega phase during the SLM process.


Analysis and understanding of the defect tolerance of beta metastable titanium alloy for an effective additive manufacturing
Sarah Dethier

For several decades, the field of aeronautics has been constantly seeking to lighten structures, while maintaining adequate mechanical properties. Up until now, the structures produced by additive manufacturing present a reduction in properties compared to forged materials, in particular in the case of titanium alloys, essentially due to the formation of defects during manufacturing. More recently, new beta metastable titanium alloys have been developped, offering better mechanical performance thanks to the activation of martensitic
transformation (TRIP) and mechanical twinning (TWIP). The objective of my thesis is to investigate the different microstructural and mechanical mechanisms responsible for the excellent toughness and resistance to damage of the Ti-12 wt% Mo titanium alloy. Model samples with variable porosity proportions will be processedin order to study the influence of porosities with controlled characteristics on the mechanisms involved and the resulting properties. My study will therefore make it possible to determine the tolerance to defects of this type of alloy in order to guarantee adequate properties regardless of the regularity of the implementation process, in particular by additive manufacturing.



Romain Gautier



Recent publications

See complete list of publications

Journal Articles


1. Ding, Lipeng; Idrissi, Hosni; Hilhorst, Antoine; Jacques, Pascal. Potential TRIP/TWIP coupled effects in equiatomic CrCoNi medium-entropy alloy. In: Acta Materialia, Vol. 234, p. 118049 (2022). doi:10.1016/j.actamat.2022.118049. http://hdl.handle.net/2078.1/261142

2. Pardoen, Thomas; Hilhorst, Antoine; Jacques, Pascal. Optimisation of the essential work of fracture method for characterization of the fracture resistance of metallic sheets. In: Engineering Fracture Mechanics, Vol. 268, p. 108442 (2022). doi:10.1016/j.engfracmech.2022.108442. http://hdl.handle.net/2078.1/260090

3. Feng, Tao; Zhou, Hao; Xiao, Lirong; Jacques, Pascal; Ying, Huiqiang; Lai, Qingquan; Pardoen, Thomas; Yang, Huiqin; Lan, Si; You, Zesheng; Kou, Zongde; Lu, Qi; Wei, Yuntao. Transformation plasticity in high strength, ductile ultrafine-grained FeMn alloy processed by heavy ausforming. In: International Journal of Plasticity, Vol. 148, p. 103151 (2022). doi:10.1016/j.ijplas.2021.103151. http://hdl.handle.net/2078.1/254505

4. Kashiwar, Ankush; Ding, Lipeng; Idrissi, Hosni; Jacques, Pascal; Marteleur, Matthieu; Choisez,Laurine. Shear banding-activated dynamic recrystallization and phase transformation during quasi-static loading of β-metastable Ti – 12 wt % Mo alloy. In: Acta Materialia, Vol. 235, p. 118088 (2022). http://hdl.handle.net/2078.1/262011

5. van der Rest, Camille; Jacques, Pascal; Simar, Aude; Poncelet, Olivier; Dancette, Sylvain; Adrien, J.; Marteleur, Matthieu; Rigo, O. Critical assessment of the impact of process parameters on vertical roughness and hardness of thin walls of AlSi10Mg processed by laser powder bed fusion. In: Additive Manufacturing, Vol. 38, p. 101801 (2021). doi:10.1016/j.addma.2020.101801. http://hdl.handle.net/2078.1/240724

6. Jacques, Pascal; Pardoen, Thomas; Ismail, Karim; Perlade, Astrid. Outstanding cracking resistance of fibrous dual phase steels. In: Acta Materialia, Vol. 207, p. 116700 (2021). doi:10.1016/j.actamat.2021.116700. http://hdl.handle.net/2078.1/242882

7. Irda, Nadia; Ribesse, Arnaud; Jacques, Pascal; Croonenborghs, Maïté; Pardoen, Thomas; Ismail, Karim; Mousny, Maryline; Miladi, Lotfi. Fracture mechanisms in Ti and Co–Cr growing rods and impact on clinical practice. In: Journal of the Mechanical Behavior of Biomedical Materials, Vol. 121, p. 104620 (2021). doi:10.1016/j.jmbbm.2021.104620. http://hdl.handle.net/2078.1/248140

8. Zuo, X.; Hilhorst, Antoine; Moelans, N.; Miotti Bettanini, Alvise; Jacques, Pascal. Influence of 5 at.%Al-Additions on the FCC to BCC Phase Transformation in CrFeNi Concentrated Alloys. In: Journal of Phase Equilibria and Diffusion, Vol. 42, p. 794-813 (2021). doi:10.1007/s11669-021-00924-7. http://hdl.handle.net/2078.1/251421

9. Hilhorst, Antoine; Jacques, Pascal. Diffusion Multiples as a Tool to Efficiently Explore the Composition Space of High Entropy Alloys. In: Journal of Phase Equilibria and Diffusion, Vol. online (2021). doi:10.1007/s11669-021-00902-z. http://hdl.handle.net/2078.1/250263

10. Gorsse, S.; Jacques, Pascal; Hautier, Geoffroy; Bokas, Georgios; Chen, Wei; Hilhorst, Antoine. Unveiling the thermodynamic driving forces for high entropy alloys formation through big data ab initio analysis. In: Scripta Materialia, Vol. 202, p. 114000 (2021). doi:10.1016/j.scriptamat.2021.114000. http://hdl.handle.net/2078.1/246724


Patents


1. Simar, Aude; van der Rest, Camille; Jacques, Pascal. Method for Welding at least two layers. http://hdl.handle.net/2078.1/135184 http://hdl.handle.net/2078.1/135184

2. van der Rest, Camille; Roy, Geoffrey; Jacques, Pascal; Simar, Aude; Matagne, Ernest; Shmitz, Alain. Thermoelectric conversion module and method for making it. http://hdl.handle.net/2078.1/135212 http://hdl.handle.net/2078.1/135212


Conference Papers


1. Marchal-Marchant, Valentin; van der Rest, Camille; Jacques, Pascal; Roy, Geoffrey; Poncelet, Olivier. Low-cost Heusler-based Thermoelectric Materials and Systems for Energy Harvesting. 2021 xxx. http://hdl.handle.net/2078.1/258314

2. van der Rest, Camille; Roy, Geoffrey; Jacques, Pascal. Optimisation des propriétés thermoélectriques du Fe2VAl en couches minces obtenues par co-pulvérisation. 2021 xxx. http://hdl.handle.net/2078.1/258313

3. Simar, Aude; Sapanathan, Thaneshan; Ryelandt, Sophie; Miotti Bettanini, Alvise; Jacques, Pascal. Segregation of alloying elements on the hot tear formation in friction melt bonding of Al/steel joints. 2021 xxx. http://hdl.handle.net/2078.1/244593

4. Santos Macias, Juan Guillermo; van der Rest, Camille; Jacques, Pascal; Zhao, Lv; Marteleur, Matthieu; Simar, Aude. Enhancement of the mechanical behavior of SLM AlSi10Mg by optimized thermomechanical postprocessing routes. In: THERMEC‘2021 – Book of Abstracts, 2021, p. 701 (#1390) xxx. http://hdl.handle.net/2078.1/244611

5. Ding, Lipeng; Jon M. Molina-Aldareguia; Jacques, Pascal; Simar, Aude; Idrissi, Hosni; Sapanathan, Thaneshan; Ilchat Sabirov; Miotti Bettanini, Alvise; Miguel A. Monclús; Peikang Xia. On the formation of modified intermetallics at an Al/Fe interface via segregated Si. 2020 xxx. http://hdl.handle.net/2078.1/235844

6. Norberto Jimenez-Mena; Jacques, Pascal; Simar, Aude; Sandra Cabeza; Thilo Pirling; ‪Jean-Marie Drezet; Sapanathan, Thaneshan. Residual stress measurement in dissimilar metal joints using neutron diffraction. 2020 xxx. http://hdl.handle.net/2078.1/238545

7. Marchal-Marchant, Valentin; van der Rest, Camille; Roy, Geoffrey; Jacques, Pascal; Erauw, Jean-Pierre; Dupont, Vedi; Poncelet, Olivier. Optimisation des conditions de brasage pour le développement de modules thermoélectriques basés sur le composé Heusler Fe2VAl. 2020 xxx. http://hdl.handle.net/2078.1/238589

8. Jacques, Pascal; Croonenborghs, Maïté. Iron-based biodegradable stents: impact of surface roughness on mechanical properties. 2019 xxx. http://hdl.handle.net/2078.1/218882

9. Jacques, Pascal; Verhaegen, Carole; Leyssens, Lisa; Kerckhofs, Greet; Horman, Sandrine. Optimization of contrast-enhanced micro-CT for characterization of the in vivo behavior of biodegradable metallic intravascular stents. 2019 xxx. http://hdl.handle.net/2078.1/219156

10. Jimenez-Mena, Norberto; Jacques, Pascal; Simar, Aude; Sapanathan, Thaneshan; Drezet, Jean-Marie; Cabeza, Sandra; Pirling, Thilo. Residual stresses in Al6061/DP600 welds produced by a process derived from Friction Stir Welding. 2019 xxx. http://hdl.handle.net/2078.1/219667


Book Chapters


1. Jacques, Pascal. Phase transformations in transformation induced plasticity (TRIP)-assisted multiphase steels. In: Phase transformations in steels. Volume 2: Diffusionless transformations, high strength steels, modelling and advanced analytical techniques , Woodhead Publishing: Cambridge, UK, 2012, p. 213-246. 978-1-84569-971-0. xxx xxx. doi:10.1533/9780857096111.2.213. http://hdl.handle.net/2078.1/122798

2. Furnemont, Quentin; Conlon, K.; Godet, Stéphane; Jacques, Pascal. Micromechanical characterisation and modelling of TRIP-assisted multiphase steels. In: Annual report 2003 NRC-CNRC , xxx, 2003, p. 42-43. xxx xxx. http://hdl.handle.net/2078.1/74933

3. Jacques, Pascal. Transformation-induced plasticity in Steels. In: Thermodynamics, Microstructures and Plasticity , xxx, 2003, p. 241-250. xxx xxx. http://hdl.handle.net/2078.1/74934


Dissertations


1. Jacques, Pascal. On the control of the interactions between phase transformations and mechanical properties in finely-grained multiphase alloys, a way for sustainable development in materials science, 2007-09-03. http://hdl.handle.net/2078.1/5190

2. Jacques, Pascal. On the physics and mechanics of phase transformations in TRIP-assisted multiphase steels, prom. : Delannay, Francis, 1999-02-02. http://hdl.handle.net/2078.1/20871