The Spring Semester Seminar
high-resolution characterization for understanding and knowledge-based design
of advanced materials
■ Speaker : Prof. Pyuck-Pa Choi (Dept. of Materials Science and Engineering, KAIST)
■ Date & Time : March 15 (Tue), 16:00
■ Venue : KAIST Applied Engineering B/D(W1), Multimedia Lecture Hall (1st Floor)
■ Abstract : Atom Probe Tomography (APT) is a high-resolution
characterization method that enables three-dimensional elemental mapping with
near-atomic resolution. Therefore, APT is highly useful for characterizing
advanced materials and for understanding their structure-property
This presentation gives an overview of the APT-related research done
by the author. The materials systems which will be presented are advanced
high-strength steels and nanostructured materials for various applications.
These materials can undergo complex changes during synthesis and processing,
and it will be discussed how local chemical changes such as nano-precipitation,
segregation to internal interfaces and elemental partitioning across phase
boundaries can significantly affect the material properties. Furthermore, we
will emphasize the importance of correlating APT data with theoretical
predictions, for instance made by ab-initio density functional theory, and with
other experimental techniques such as transmission electron microscopy (TEM).
It will be shown that information gathered from these different techniques can
serve as a basis of a knowledge-based rather than empirical approach of
designing advanced materials.
Finally, we will present a new methodology for coupling chemical and
crystallographic analyses at the atomic-scale, using joint APT / TEM nano-beam
diffraction analyses on identical samples. This method has been used for
quantifying solute segregation to grain boundaries in a nanocrystalline steel
as a function of grain boundary character and misorientation.