Theoretical Tensile Deformation of SIGMA 13 Pyramidal Twin Grain Boundary in Alumina

摘要

First-principles grain boundary (GB) tensile deformation simulations were performed to investigate the atomic-scale mechanism of GB fracture of the SIGMA 13 pyramidal twin GB in alpha-Al_2O_3. It was found that the specific Al-O bond broke at the GB core in the early stage of tensile deformation. From chemical bonding analyses, the first breaking bond was the weakest bond in the GB core. However, when the catastrophic GB fracture started, initially strong Al-O bond broke. This indicates that local atomic bonds should determine the microscopic GB fracture behavior.