Features of the interaction of cracks with inclined grain boundaries in Al during brittle fracture

The propagation of cracks in Al bicrystals with inclined grain boundaries under uniaxial tension has been studied in the laboratory of computer-aided design of materials based on molecular dynamics simulation. It was revealed that the propagation of a crack is always preceded by an abrupt increase in the atomic volume in the region of its tip due to the formation of a nanopore. The beginning of crack propagation or the resumption of its movement after stopping is always accompanied by a fairly rapid drop in the atomic volume at its tip. It has been shown that a crack can cause significant grain boundary migration. The magnitude of grain boundary migration increases with decreasing grain misorientation angle. It was found that inclined grain boundaries with misorientation angles greater than 20 degrees completely block the passage of a crack into an adjacent grain. At smaller inclination angles, the crack temporarily stops at the grain boundary. The duration of its stop increases with increasing angle of inclination.

Drawing. Fragment of the structure of samples with grain misorientation angles of 20° (a), 40° (b) at strains of 6.43 and 5.74%, respectively. Green, red, gray and violet show atoms with fcc symmetry of the nearest environment, hcp symmetry of the nearest environment, with indeterminate symmetry and atoms through which the grain boundary has migrated, respectively.

The work was carried out within the framework of the state assignment of the Institute of Physical Problems and Problems of the Siberian Branch of the Russian Academy of Sciences (project FWRW-2021-0002).

The results were published in the journal Nanoscience and Technology: An International Journal  (IF 1.3, Q3).

Kryzhevich D.S., Korchuganov A.V., Zolnikov K.P. Crack interaction with tilt grain boundaries in brittle fracture of aluminum // Nanoscience and Technology: An International Journal. - 2023. - V. 14(4). - P. 87-95.
https://doi.org/10.1615/NanoSciTechnolIntJ.2023047562