Molecular Dynamic Simulation of Kinetics of fcc–bcc Heterointerface in Phase Transformation of Iron and Carbon Steel

Abstract

The kinetics of fcc–bcc heterointerface with typical orientation relationships (ORs) during phase transformation of iron and carbon steels is investigated by molecular dynamics simulations. The heterointerface with the Nishiyama–Wasserman (N–W) OR immediately propagates downward keeping parallel to the initial interface. On the other hand, the incubation time appears before the rapid growth of the needle–like bcc phase at the heterointerface with the Kurdjumov–Sachs (K–S) OR. The transformation rate decreases with increasing carbon concentration at both the interfaces with N–W and K–S ORs. Moreover, analyses of mean square displacement revealed that carbon atoms are constrained by surrounding iron atoms and therefore no carbon diffusion occurs during the phase transformation of carbon steels, which can be regarded as a diffusionless phase transformation.