Molecular dynamics simulation of interface dynamics during the fcc-bcc transformation of a martensitic nature

Abstract

The structural and dynamic properties of the interface during the fcc-bcc transformation in pure iron have been investigated by molecular dynamics simulations. An embedded atom method potential was used for the atomic interactions. Two interfaces, close to the Bain and Kurdjumov-Sachs orientation relations, have been examined during the fcc-to-bcc transformation. In each simulation the system was left to evolve freely at the imposed temperature. In a system with fully periodic boundaries no interface motion has been observed, whereas systems with at least one free boundary do show a mobile interface. After an incubation time, there is a very fast transformation from fcc to bcc, with interface velocities reaching values in the range of 200-700 m / s, depending on the interface orientation and on temperature. The characteristics of the transformation are of a martensitic nature, without this being imposed on the system. During the incubation time a complex interface structure is formed, which appears to be essential for the martensitic transformation. From the atomic displacements during the transformation, the occurrence of slip planes can be identified.

A Molecular Dynamics Study of Bidirectional Phase Transformation between bcc and fcc Iron

“…For example, Sinclair and Hoagland 14) examined the role of fault band intersections in the nucleation of martensite from austenite using the EAM potential fit by Ackland et al. 15) Bos and coworkers 16) estimated the interface velocity during the fccto-bcc phase transformation in pure iron in the range of 200-700 m/s using the Johnson-Oh potential. 17) In addition, we have investigated the kinetics of the fcc-bcc heterointerface during the fcc-to-bcc phase transformation with respect to ORs ranging from Nishiyama-Wasserman (N-W) OR 18,19) to Kurdjumow-Sachs (K-S) OR 20) using the Finnis-Sinclair potential 21) and revealed that there are two different propagation behaviors of the heterointerface: a planar propagation for the heterointerface with the N-W or near N-W ORs and a fast needlelike growth after initial planar growth for the heterointerface with the K-S or near K-S ORs.…”

Orientation Relationship in Fcc–Bcc Phase Transformation Kinetics of Iron: a Molecular Dynamics Study

“…Sinclair and Hoagland 21) examined the role of fault band intersections in the nucleation of martensite from austenite by MD simulation with the EAM potential. Bos et al performed kinetic MC 22) and MD 23) simulations to discuss the kinetics during phase transformation of iron from the fcc to the bcc phase. Nagano and Enomoto 24) calculated the interfacial energy between fcc and bcc iron with various orientations by MC calculation.…”

Faceted interfaces: a key feature to quantitative understanding of transformation morphology

“…However, the interfaces explored so far in kinetic simulations are not typical of those observed in experiments. [98][99][100][101][102][103] Therefore, we only concern ourselves here with calculations of interfacial energy by atomistic simulations. Before summarising the simulation results, several key issues that have substantial effects on the results, and that have not been paid sufficient attention in the past, will be discussed.…”

“…As a result of rapid advances in computing techniques, atomistic simulations have become a powerful tool for obtaining fundamental knowledge of interfaces, 92 and numerous results have been obtained both on the thermodynamics 86,87,[93][94][95][96][97] and the kinetics [98][99][100][101][102][103] of interfaces. However, the interfaces explored so far in kinetic simulations are not typical of those observed in experiments.…”