Probing fundamental deformation mechanisms and trends during decohesion across random high angle grain boundaries

Abstract

The influence of grain boundaries (GBs) on the mechanical behavior and deformation of crystalline materials is well documented. Specifically, intergranular failure within the microstructure often is due to GB fracture or decohesion under load. By analyzing the incipient failure response of individual GBs (e.g., decohesion), as a function of GB character, a more fundamental understanding of microstructure failure can be uncovered. Accordingly, this work leverages atomistic modeling and simulations of GBs in Al to ascertain the governing role of GB character on decohesion behavior. A range of GB characters are studied by using a newly developed GB structure database to develop trends and identify fundamental decohesion behaviors using macroscopic GB descriptors (e.g., energy, misorientation, and excess volume). However, we find that no clear correlations exist between GB decohesion and these descriptors, indicating that the origins of decohesion are missed by GB descriptors that ignore the underlying spectrum of atomic environments that compose a GB. Our results further indicate that GB decohesion behavior may be driven by atomic environments and/or dynamics specific to individual GBs, potentially independent of the macroscopic descriptions of GBs commonly employed for identification and model development.