An atomistic perspective into the fracture behaviour of Fe-bicrystal

S.S. Pezeshki, M. Silani, M.S. Talaei and S. Ziaei-Rad

Molecular Simulation, Volume 246, Issue 13, July 2020, Pages 966-974

ABSTRACT

The interaction between the crack and the grain boundary has been investigated by molecular dynamics simulation. The focus of this research is to study fracture resistance of grain boundary in a three-dimensional pre-cracked Fe-bicrystal. The fracture resistance of Σ5 < 100> {013} symmetric tilt grain boundary (STGB) has been compared with Σ5 < 100> {012} STGB in terms of crack length-time curve, temperature per time diagram, and the stress–strain curve to understand the detailed mechanism of fracture in Fe-bicrystal. Crack delay time at the grain boundary is proposed as a parameter for comparing the fracture resistance of grain boundaries. The results show that the crack delay time at the grain boundary is inversely related to the grain boundary energy. Hence, crack delay time for Σ5{013} STGB with 986 mj/m2 energy is more than Σ5{012} STGB with 1098 mj/m2 energy. The findings show that Σ5{013} STGB resists more than Σ5{012} STGB against crack propagation. The required stress, which is needed to overcome the grain boundary resistance and cause the crack penetration to the adjacent grain, has been calculated by using stress–strain curve. Modified BCC defect analysis algorithm and centrosymmetry parameter are also employed to analyze propagated defects and their interaction with the grain boundary.

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