The codes were developed for predicting kinetics of austenite-ferrite phase transformations in low-alloyed steels under various conditions of heat treatments. This model takes into account both nucleation and interface migration. The nucleation is calculated according to continuous nucleation theory. The interface migration is computed by deriving interface velocity that meets the Gibbs energy balance (GEB) beteween chemical driving force and energy dissipations due to interface friction and trans-diffusion of substitutional elements inside the interface. The latter is normally termed as solute drag. Since an analytical solution for calculating the solute drag is proposed, the computation speed has been increased significantly compared to the conventional approach. New features of this model are its efficient algorithm to compute energy dissipation by solute drag, its capabilities of predicting the microstructural state for spatially resolved grains and the minimal adjustment of modelling parameters. The codes were a result of a follow-up research to Haixing Fang's PhD thesis supervised by Dr.ir. N.H. van Dijk and Prof.dr.ir. S. van der Zwaag at Delft University of Technology.

• Austenite-ferrite phase transformations during continuous cooling, isothermal holding and thermal cycling in the two-phase region
• Nucleation and interface migrates isotropically
• Potential nucleation sites are grain corners but they can also be at grain edges, boundaries or a mixture of them
• Gibbs energy balance between chemical driving force and energy dissipations due to interface friction and solute drag

• Install the Multi-Parametric Toolbox 3 (mpt3): https://www.mpt3.org/ into the same folder, for generating Voronoi cells to represent austenite grains.
• Make sure that 'Optimization toolbox' and 'Symbolic Math toolbox' are included in your own Matlab package. These toolboxes should be included by default. All codes have been tested executable with Matlab 2014b or above.

Just run ferrite_3d_model_voronoin_PBC_ND_CNT_GEB.m.
But, remember to first set up the chemical compositions, heat treatment parameters and include thermodynamic data (which can be parameterized first with Thermo-Calc software) in SimulCond.m.

Within this file, set the variable CyclicFlag for different thermal routes:

• 1-thermal cycling;
  
• 0-isothermal holding;
  
• -1-continuous cooling.
  

The variable fsite defines the fraction of different types of potential nucleation sites: grain corners, edges or boundaries. Only nucleation at grain corners is allowed by default.

The codes can run on a linux cluster by running the bash file FeCMn_3D_GEB.pbs.

This package is free to use, ditribute and adapt, but no warranty and liability to any kinds of simulation results.
See the LICENSE for license rights and limitations (GNU General Public License v3.0).

H. Fang, S. van der Zwaag & N.H. van Dijk (2021). A novel 3D mixed-mode multigrain model with efficient implementation of solute drag applied to austenite-ferrite phase transformations in Fe-C-Mn alloys, Acta Materialia, 116897.
Please cite our paper if you use or get inspired by our code or algorithm.