Trends in grain-boundary segregation
The project aims at building simplified models of the bonding which governs the segregation of light elements at and cohesion of grain boundaries in steel.
The project is divided into three major parts. First DFT studies will be performed to elucidate the influence of C on elastic properties of bcc iron. Such studies have already been performed at ICAMS for H in bcc-iron and results will contribute to a larger database of calculated elastic properties which will serve as input for scale bridging models.The second part concerns the stability of light elements at grain boundaries and will be performed using DFT. Specifically C at selected low angle grain boundaries in bcc iron will be studied and phenomenological trends will be extracted. These results will form the base of the third part of the project, which concerns modelling the obtained results. By simplifying the electronic structure models of the segregation of transition metals and p-valent atoms at grain boundaries will be obtained. These models should explain the observed trends in terms of simple chemical concepts such as atomic volume, electron count, frontier orbital symmetry and electro-negativities. Furthermore, they should form the basis of quantitative O(N) methods, allowing for large scale simulation of steels and pd-alloys.