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SUMMARY:IMX Colloquium - Martensite\, twins and math
DTSTART:20250303T131500
DTEND:20250303T141500
DTSTAMP:20260921T172003Z
UID:1406067e8a5ce5bf2905ce01b1ac4da54460c247303ee1b06dd64c8a
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Cyril Cayron\, Laboratory of Thermomechanical Metallurgy\,
  EPFL\nMetallurgists spend part of their time trying to modify the chemica
 l compositions and thermomechanical parameters of the alloys to improve th
 eir mechanical properties by forming complex microstructures. Understandin
 g these microstructures requires curiosity\, efforts and … math. Let me 
 give two examples. 1) Martensite forms complex intricate assemblies of lat
 hs or plates that can be very hard\, as in the steels used for sharp knive
 s\, or very soft\, as in shape memory alloys. Twenty years ago\, I underst
 ood that martensite variants can be defined from the parent and martensite
  symmetries by a mathematical structure called groupoid. The groupoid comp
 osition table is a kind of signature of the phase transformation\; it can 
 be used to reconstruct the parent grains from EBSD maps\, with many applic
 ations in metallurgy and beyond. 2) Deformation twinning is a lattice shea
 r deformation that may compete with usual dislocation plasticity at low te
 mperatures or high deformation rates\, or at room temperature in hexagonal
  alloys and TWIP steels. Four years ago\, I realized that a deep link exis
 ts between deformation twinning and three math problems: lattice reduction
 \, Bézout’s identity and integer relations. Thinking these problems in 
 terms of hyperplanar lattice shears allowed me to develop new algorithms t
 hat\, surprisingly\, showed better performances than the usual LLL and PLS
 Q methods implemented in Mathematica.\n\nBio: Dr Cyril Cayron is as senior
  scientist at EPFL in the Laboratory of Thermo Mechanical Metallurgy (LMTM
 ). His domains of research cover metallurgy\, microscopy and crystallograp
 hy. He earned his Ph.D in 2000 at EPFL in the Interdepartmental Center for
  Electron Microscopy (CIME) on the study by TEM of the interfacial reactio
 ns and precipitation in aluminum matrix composites. He worked for fourteen
  years at Commissariat à l’Energie Atomique et aux Energies Alternative
 s (CEA) in Grenoble\, France\, on projects aiming at developing or improvi
 ng materials for nuclear\, aerospace\, microelectronic\, photovoltaic\, hy
 drogen and Li-battery industries. He came back to EPFL in 2014 to join LMT
 M. Since then\, he has participated to the development of new alloys for w
 atch industries\, and helped the students in their works on additive manuf
 acturing. He is also in charge of the SEM Gemini microscope equipped with 
 STEM\, EDS and EBSD. He continues his research on martensite and twins tha
 nks to SNSF subsidies and some collaborations with other research groups.
LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201
STATUS:CONFIRMED
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