9 / 24
allied
academies
May 20-21, 2019 | Vienna, Austria
Biomaterials and Nanomaterials &
Materials Physics and Materials Science
2
nd
International Conference on
Page 22
Journal of Materials Science and Nanotechnology | Volume 3
I
n several applications functionally oriented materials are
exposed to extreme conditions. Large steam turbines
are e.g. exposed to high temperatures. The higher the
temperature of the hot temperature reservoir, the better
is the efficiency factor and the lower is the CO
2
emission
caused by the process. Line pipe steels as another example
have to withstand high temperatures during welding. It
is essential that the microstructures of these materials
consist of fine, homogeneously distributed grains. Only
then, the materials will have the desired mechanical
properties. However, grain growth cannot be completely
avoided at elevated temperatures. A possible strategy to
retard grain growth to a certain extent is to micro alloy
the steels with niobium and titanium. Niobium carbides
and titanium nitrides nucleate at the grain boundaries
and can effectively pin the grain boundaries. However,
this phenomenon is only effective below a certain critical
temperature. Normal grain growth is revealed below the
critical temperature and abnormal grain growth above this
temperature by an in-situ high temperature laser scanning
confocal microscope. The kinetics of the motion of triple
junctions and of whole grain arrangements is simulated
based on the use of local constitutive equations. Not only
distinct specific energies and mobilities can be assigned
to the grain boundaries, but also finite mobilities can be
assigned to the triple junctions. Thereby it is possible to
interpret the results of the in-situ experiments in order
to better understand the dissipative processes that occur
during grain growth at elevated temperatures in micro
alloyed steels.
Speaker Biography
Ernst Gamsjager has completed his PhD in 2002 and worked as a
post doc with professor Militzer at the University of British Columbia,
Canada and professor Fratzl, Max Planck Institute of Biomaterials,
Germany. He obtained the Masing Memorial Award of the German
Society of Materials Science in 2007. Since 2010, he works as an
associate professor at University of Leoben, Austria. He has published
around 50 papers in reputed journals, is member of the editorial board
of “Metals” and is very active in reviewing manuscripts. He is member
of the management committee of the Cost action CA15102 “Solutions
for critical raw materials under extreme conditions”.
e:
ernst.gamsjaeger@unileoben.ac.atNotes:
Ernst Gamsjager
1
Jiri Svoboda
2
1
University of Leoben, Austria
2
Institute of Physics of Materials, Czech Republic
Kinetics of grain arrangements controlled by grain boundary and
triple junction migration-experiments and modeling