Deformation-induced phase transformation and twinning in Fe and Fe-C alloys

Y Yang and H Zhang and XQ Ou and J Gu and M Song, MATERIALS SCIENCE AND TECHNOLOGY, 37, 1246-1256 (2021).

DOI: 10.1080/02670836.2021.1992948

The phase transformations and twinning in a nano-sized face-centred cubic (FCC) crystal of iron with different carbon contents are studied by molecular dynamic (MD) simulations. The simulation cells are stretched uniaxially along the 100(FCC) direction. It is found that the FCC matrix transforms into the body-centred cubic (BCC) phase following the Nishiyama-Wassermann orientation relationship (OR). Then, the 'BCC <-> hexagonal close-packed (HCP)' and 'BCC <-> FCC' transformations occur following different variants of the Burgers OR and the Pitsch OR, respectively. The 112(BCC) twins form between two neighbouring BCC grains. Additionally, the carbon atoms can destabilise the BCC phase, inhibit the phase transformation and pin phase interfaces, leading to tiny BCC twins.

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