Atomistic study of inelastic deformation in aluminium grain boundary fractures

Abstract

The plastic work of fracture in a deformable solid has been believed to be related to only the ideal brittle fracture energy. However, additional factors affecting the plastic work must also exist because the plastic work is a path function. In the present work, first-principles calculations and molecular dynamics simulations of tensile tests were performed on Σ3(1 1)[1 1 0] and Σ11(1 3)[1 1 0] symmetric tilt aluminium grain boundaries, where the grain boundary energy of the Σ11(1 3) grain boundary is higher than that of the Σ3(1 1)[1 1 0] gain boundary. The calculations showed that, although the ideal brittle fracture energy for the Σ11(1 3) grain boundary was almost the same as that for the Σ3(1 1) grain boundary, the plastic work for the former was larger than that for the latter, resulting in a larger fracture energy for the Σ11(1 3) grain boundary. Local inelastic deformation occurred around the atoms with high internal energy at the grain boundary for the Σ11(1 3) grain boundary. It is therefore suggested that the plastic work is a function of both the grain boundary energy and the ideal brittle fracture energy.

Keywords:

• First-principles calculation of tensile tests
• fracture
• deformation
• grain boundaries: aluminium
• molecular dynamics simulations

Acknowledgements

N. M. acknowledges support from a Grant-in-Aid for JSPS Fellows.