Mobility of the austenite–ferrite interface under various states of loading

Abstract

The massive austenite–ferrite phase transformation was simulated on an atomic scale for various states of loading: uniaxial, planar and hydrostatic. The simulated system involved the lateral growth of a two-dimensional ferrite seed at the ferrite–austenite phase boundary for a variable number of vacancies at the interface. The atomistic simulation was based on the application of a recently developed multi-lattice kinetic Monte Carlo method. The effects of the different states of loading and of the vacancy concentration at the interface were discussed in terms of their impact on the necessary local rearrangement of austenite atoms to unblock unoccupied ferrite–lattice sites. It followed that the net outcome of the effects of additional free volume and of vacancy pinning strongly depends on the state of loading.

Keywords:

• phase transformations
• kinetics
• atomistic simulations
• Monte Carlo
• ferrite growth
• transformations in a state of stress

Notes

One of the authors (MB) would like to thank the German Research Foundation (DFG) for financial support of the project within the Cluster of Excellence in Simulation Technology (EXC 310/1) at the University of Stuttgart.

1 In this work a difference is considered to be significant if the null hypothesis [24] can be rejected with more than 95% confidence.

2 The planar number density is the number of atoms within a one atomic layer thick plane divided by the area of that plane.