Effect of pre-existing defects in the parent fcc phase on atomistic mechanisms during the martensitic transformation in pure Fe

Effect of pre-existing defects in the parent fcc phase on atomistic mechanisms during the martensitic transformation in pure Fe: A molecular dynamics study

Karewar, S.V. (TU Delft (OLD) MSE-3)
Sietsma, J. (TU Delft (OLD) MSE-3)
Santofimia, Maria Jesus (TU Delft (OLD) MSE-3)

2018

Molecular dynamics (MD) simulations are used to study the effect of different defect configurations and their arrangements in the parent fcc phase on atomistic mechanisms during the martensitic transformation mechanisms in pure Fe. The defect configurations considered are stacking faults (SF) and twin boundaries (TB) in single crystal fcc. Three arrangements of these defect structures are considered: parallel TB, intersecting SF, and intersecting SF and TB. Each of these defect configurations affect the transformation mechanisms and transformation temperatures. Parallel TB are the lowest-barrier sites for the atomic shear and thus accelerate the transformation process. The fcc phase with parallel TB follows the Nishiyama-Wasserman (NW) martensitic transformation mechanism. On the other hand, intersecting SF impede the atomic shear and thus retard the transformation. The atomistic transformation mechanism in this case first follows the hcp to bcc Burgers path and then the fcc to bcc Olson-Cohen model. The intersecting SF and TB result in a combined effect of both the previous cases. The simulation results show the occurrence of different atomistic mechanisms during martensitic transformation depending on the type of defects present in the parent fcc phase.

Atomistic mechanisms
Martensitic transformations
Molecular dynamics
Stacking faults
Twin boundary

http://resolver.tudelft.nl/uuid:5e4a60a7-286f-4391-9952-18451cad6bcc

https://doi.org/10.1016/j.actamat.2017.09.049

2018-03-30

1359-6454

Acta Materialia, 142, 71-81

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

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© 2018 S.V. Karewar, J. Sietsma, Maria Jesus Santofimia