Role of excess atomic volume in crack growth in bcc iron

DS Kryzhevich and AVP Korchugano and K Zolnikov, RESULTS IN PHYSICS, 33, 105163 (2022).

DOI: 10.1016/j.rinp.2021.105163

A molecular dynamics simulation was performed to study the localization of regions with excess atomic volume in bcc iron single crystals with variously oriented incipient edge cracks under uniaxial tension at room temperature. It is found that a region with excess atomic volume is always formed at the crack tip. In the case of brittle crack growth, structural defects are not emitted from this region, and the crack grows due to bcc-fcc-bcc transformations in it. Ductile fracture is accompanied by the nucleation of various structural defects in the region with excess volume and by plastic zone formation. Bands of structural transformations, dislocations, and other defects emitted from this region carry away the excess volume and partially relax the structure around the crack.

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