Phase Field Crystal Modeling of Grain Boundary Mechanics – Focus on Abnormal Grain Growth

Abnormal grain growth (AGG) occurs during the heat treatment of polycrystals as certain crystallites undergo an extreme increase in size at the expense of their neighbors. In some cases, AGG is facilitated by the pinning of grain boundaries by second-phase particles, a process called Zener Pinning (ZP). Although of considerable technological importance, there is still no consensus regarding the mechanisms underlying AGG/ZP, and existing data are conflicting. The project will exploit the recent developments in numerical modeling of crystal microstructures offered by the phase field crystal (PFC) method. The PFC method places itself between the scales reached by atomistic simulations and those of standard mesoscale models (such as phase fields) by providing atomistic spatial resolution at time scales that are relevant for AGG/ZP. In addition, as spatial averaging of the atomic scale is avoided, the PFC method naturally provides an accurate description of features such as grain boundaries, crystal orientations, dislocations and other lattice defects. The numerical model will be used to identify how pinning particles influence the selective abnormal growth of individual grains and will yield fundamental insights into the interplay between AGG and ZP that is responsible for dramatic changes in microstructure. The proposed investigations will also shed new light on the individual nature of AGG and ZP, each of which is an important metallurgical phenomenon in its own right.

Project

The 5-year project is funded by the Swedish Science Council.

PhD student: Kevin Hult Blixt, Division of Solid Mechanics, Lund University.