Effect of C on the martensitic transformation in Fe-C alloys in the presence of pre-existing defects

Effect of C on the martensitic transformation in Fe-C alloys in the presence of pre-existing defects: A molecular dynamics study

Karewar, S.V. (TU Delft (OLD) MSE-3)
Sietsma, J. (TU Delft Materials Science and Engineering; TU Delft (OLD) MSE-3)
Santofimia, Maria Jesus (TU Delft (OLD) MSE-3)

Materials Science and Engineering

2019

Molecular dynamics simulations are used to investigate the atomic effects of carbon (C) addition in Fe on the martensitic phase transformation in the presence of pre-existing defects such as stacking faults and twin boundaries. The pre-existing defect structures in Fe-C alloys have the same effect on the atomistic mechanisms of martensitic transformation as in pure Fe. However, C addition decreases the martensitic transformation temperature. This effect is captured by characterizing three parameters at the atomic level: atomic shear stresses, atomic energy, and total energy as a function of temperature for face-centered-cubic (fcc) and body-centered-cubic (bcc) phases. The thermodynamic effect of fcc phase stabilization by C addition is revealed by the atomic energy at a particular temperature and total energy as a function of temperature. The barrier for fcc-to-bcc transformation is revealed by analysis of atomic shear stresses. The analysis indicates that addition of C increases the atomic shear stresses for atomic displacements during martensitic transformation, which in turn decreases the martensitic transformation temperature.

Fe-C alloys
Martensitic transformations
Molecular dynamics
Stacking faults
Twin boundary

http://resolver.tudelft.nl/uuid:1afd8221-0a05-40ca-9963-4310c85fbd5c

https://doi.org/10.3390/cryst9020099

2073-4352

Crystals, 9 (2)

Institutional Repository

journal article

© 2019 S.V. Karewar, J. Sietsma, Maria Jesus Santofimia