Scientist at the MPIE

Dr. Paraskevas Kontis works as a postdoctoral researcher in the group “Atom Probe tomography” since 2016. He focuses on hydrogen embrit-tlement in engineering alloys, damage and crack initiation mechanisms in superalloys and the relationship between grain boundaries and me-chanical performance at elevated temperatures in superalloys. Thereby he uses atom probe tomography as a tool to understand deformation mechanisms at high performance materials, which allows to design strategies for the development of materials exhibiting enhanced performance.

Selected Publications:

1.
P. Kontis, D.M. Collins, A.J. Wilkinson, r.C. reed, D. raabe, B. Gault
Microstructural degradation of polycrystalline superalloys from oxidized carbides and implications on crack initiation.
Scripta Mater, 147, 59-63 (2018)
2.
P. Kontis, Z. Li, D.M. Collins, J. Cormier, D. raabe, B. Gault
The Effect of Chromium and Cobalt Segregation at Dislocations on Nickel-based Superalloys.
Scripta Mater, 145, 76-80 (2018)
3.
E. Chauvet, P. Kontis, E.A. Jägle, B. Gault, D. raabe, C. tassin, J.-J. Blandin, r. Dendievel, B. Vayre, s. Abed, G. Martin
Hot Cracking Mechanism Affecting a Nonweldable Ni-based Superalloy Produced by Selective Electron Beam Melting.
Acta Mat, 142, 82-94 (2018)

Dr.   Dirk   Ponge   is   head   of   the   group   “Alloy    Design    and    thermomechanical  Processing”.  His  group’s   mission   is   the  optimization  of properties   of   novel   complex  engineering  steels  through  a  detailed  characterization  and  interpretation of materials’ microstructures  and  through  advanced  ways  of    thermomechanical processing. Coupling alloy design strategies with processing enables to influence bulk phase  transformations, precipitates  and  grain  refinement  mechanisms. Application  fields  are  for  example medium  and  high  manganese  and  dual phase steels for lightweight automotive  design. The  group is  also  investigating  mechanisms  of  hydrogen  embrittlement  in  high  strength  alloys. the mission here is to create tailored   microstructures   providing   high strength but with a low sensitivity against hydrogen embrittlement. Before  joining  the  MPIE  in  2001,  Ponge  did  his  PhD  at  the  RWTH  Aachen in the field of dynamic recrystallization of Ni3Al.  After  that  he  was  head  of  the  materials  testing  department  at  the  schweißtechnische   Lehr- und Versuchsanstalt Nord in Hamburg where he also was involved in  training of welding engineers.

Selected Publications:

4.
A. Kwiatkowski da Silva, D. Ponge, Z. Peng, G. Inden, Y. lu, A. Breen, B. Gault, D. Raabe
Phase nucleation through confined spinodal fluctuations at crystal defects evidenced in Fe-Mn alloys
Nat Commun, 9(1), 1137, (2018)
5.
Z. Tarzimoghadam, D. Ponge, J. Klöwer, D. Raabe
Hydrogen-assisted failure in Ni-based superalloy 718 studied under in situ hydrogen charging: The role of localized de-formation in crack propagation.
Acta Mat, 128, 365-374 (2017)
6.
M.-M. wang, C.C. Tasan, D. Ponge, D. Raabe
Spectral TRIP enables ductile 1.1 GPa martensite
Acta Mat, 111, 262-272 (2016)
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