[SY-K5] Symposium K-5

[SY-K5] First-principles local energy analysis of grain boundary segregation of sp-elements on bcc Fe

^○Kazuma Ito^1,2, Somesh Kr. Bhattacharya³, Shingo Tanaka³, Masanori Kohyama³, Hideaki Sawada², Shigenobu Ogata¹ (1.Osaka University, Japan, 2.Nippon Steel & Sumitomo Metal Corporation, Japan, 3.National Institute of Advanced Industrial Science and Technology, Japan)

In polycrystalline materials, grain boundary segregation of impurity elements and alloying elements may have a great influence on the material properties. Particularly in steel materials, it is known that the sp-elements such as P and S segregate at the grain boundary, thereby remarkably lowering hot ductility and low temperature toughness. However, the microscopic mechanism of grain boundary segregation of these elements has not been fully clarified.

In this study, grain boundary segregation energies for sp-elements (Al,Si,P and S) in bcc Fe are calculated by first-principles calculations. Furthermore, to investigate the microscopic mechanism, the contribution of each physical origin to the grain boundary segregation energies is evaluated numerically by using first-principles local energy analysis. We will also discuss the relationship between the contribution of each physical origin and the geometric structure or the electronic state of the grain boundary.