Atomistic simulation of martensitic transformations induced by deformation of α-Fe single crystal during the mode-I fracture

Deformation-induced martensitic transformations (DIMTs) have been widely observed in iron and ferroalloys under various mechanical loading conditions, thereby showing extreme scientific merits and engineering significance. Since deformations and fractures affect one another and reflect the relative movements of atoms, DIMTs often accompany fractures. In this work, molecular dynamics simulation was performed with a (010) [100] pre-cracked model to study DIMTs from an a-Fe single crystal during the mode-I fracture process. The observed DIMTs were verified using first-principle calculations. A crack tip tracking algorithm by scanning the nearby atoms is proposed, and the obtained critical stress intensity factor was proved to be close to the experimental results. Quasi-cleavage fracture happened with the nucleation and growth of the c (fcc) phase, which was transformed by activating the {121} h111i and {110} h111i shears near the crack tip. The layered e (hcp) phase was formed by stacking faults inside the c phase and was unstable by driving force analysis.

Automated summary

This study investigates deformation-induced martensitic transformations (DIMTs) in a-Fe single crystal during mode-I fracture process using molecular dynamics simulation and first-principle calculations. The formation of c (fcc) phase near the crack tip leads to quasi-cleavage fracture, which is verified to be close to experimental results. The results highlight the relationship between fractures and DIMTs in iron and ferroalloys under mechanical loading conditions.