On the orientation dependence of grain boundary triple line energy in Cu

Abstract Triple lines are the lines of intersection of three interfaces, either external interfaces or internal interfaces of a bulk material. They have been recognized as important microstructural features with specific kinetic and thermodynamic properties. Utilizing atomic force microscopy, the line tensions, i.e. the energy of grain boundary-free surface triple lines and grain boundary triple junctions for different crystallographic systems in copper were determined. The line tension of grain boundary triple junctions in copper was found to be positive and of the order of 10−9 J m−1. Junctions including low energy boundaries, twin boundaries and low angle boundaries revealed a substantially lower line tension than triple junctions comprised only of random high angle boundaries. A simple model based on a constant grain boundary energy density is proposed to account for the orientation dependence of triple line energy.