Date 2016-03-15 

The Spring Semester Seminar

■ TopicCorrelative 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 relationships.

  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.