Atomistic insight into the solid-solid phase transitions in iron nanotube: A molecular dynamics study
T Ruan and BJ Wang and Y Li and C Xu, MATERIALS TODAY COMMUNICATIONS, 29, 102833 (2021).
Molecular dynamics (MD) simulations are performed to investigate the austenitic and martensitic transitions in three iron (Fe) nanotubes (NTs) with 100(bcc) (NT1), 110(bcc) (NT2) and 111(bcc) (NT3) axial orientations, respectively. For all NTs studied, the inner and outer surface energies differ slightly and the surface morphologies are analyzed at atomic scale. In NT1, the body-centered cubic (bcc) to hexagonal close packed (hcp) transition is dominated rather than bcc to face-centered cubic (fcc) transition upon heating. The bcc to hcp transition follows the Burgers mechanism and the back transition upon cooling obeys the same pathway. In NT2, the austenitic transition follows the Pitsch mechanism and both the Pitsch and Bain mechanisms are observed during the martensitic transition. In NT3, the bcc <-> hcp and the bcc <-> fcc transitions follow the Burgers and Pitsch mechanisms, respectively. In all three cases studied, the nucleation positions of the austenitic and martensitic transitions are discussed referring to the local structures and energetics. Regarding the previous works, we summarize that the transition mechanism tends to be normal strain- controlled rather than shear strain-controlled with the surface-volume ratio increase.
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