Slip to twinning to slip transition in polycrystalline BCC-Fe: Effect of grain size

J Veerababu and A Nagesha and V Shankar, PHYSICA B-CONDENSED MATTER, 694, 416465 (2024).

DOI: 10.1016/j.physb.2024.416465

A slip-to-twinning-to-slip transition concerning grain size has not been reported in the literature on BCC-Fe so far. In the present investigation, we report slip-to-twinning and twinning-to-slip transitions at 8 nm and 20 nm grain sizes, respectively. For this purpose, we used molecular dynamics simulations to study < 110 > quasi-3D polycrystals of BCC-Fe with grain sizes ranging from 3 nm to 102 nm at 10 K. Hall-Petch and inverse HallPetch relations were obtained depending on the grain size. Grain boundaries (GBs) were converted to lower energy boundaries through twin-GB interactions. Nucleation of twin boundary through GB decomposition was observed even under the constraints of triple junctions. Various dislocation mechanisms were observed, like delayed slip transfer, slip absorption, dislocations from a twin boundary, and formation of debris/point defects/ tubular-type cylindrical rods from the gliding dislocations. Dislocation activity was observed to increase with increasing grain size. Luster and Morris parameter was used to understand dislocation-GB interactions. Intergranular fracture was observed.

Return to Publications page