Diffusion module (DICTRA)

Software for accurate simulation of diffusion controlled reactions in multi-component alloy systems, which is based on numerical solution of the multi-component diffusion equations. Examples of cases that have been simulated using the Diffusion module (DICTRA) include:

  • Microsegregation during solidification
  • Homogenization of alloys
  • Growth/dissolution of carbides, nitrides and intermetallic phases
  • Coarsening of precipitate phases
  • Interdiffusion in compounds, e.g. coating systems
  • Austenite to ferrite transformations in steel
  • Carburization, nitriding and carbonitriding of high-temperature alloys and steels
  • Post weld heat treatment
  • Sintering of cemented-carbides

Linking fundamental models to critically assessed thermodynamic and kinetic data
In order to allow simulations to be performed with realistic conditions on alloys of practical importance, emphasis during the development of the Diffusion module (DICTRA) has been on linking fundamental models to critically assessed thermodynamic and kinetic data. As a result, the Diffusion module (DICTRA) is very general and it is primarily the access to thermodynamic and kinetic data that determines if a problem can be simulated or not. This is of course under the assumption that the problem in question is diffusion controlled and that all other basic model assumptions are met.

In order to perform a diffusion simulation, both a thermodynamic database and a kinetic database, also known as a mobility database, are needed. The thermodynamic database is the same as used by Thermo-Calc, whereas the kinetic database is an additional database that contains information about the atomic mobility of individual components in relevant phases. The kinetic databases are created through an assessment procedure similar to the one that is used for thermodynamic databases. 

It should also be emphasised that simulations are one-dimensional and that three different geometries, i.e. planar, cylindrical and spherical, can be used. This is sufficient to model many cases of interest. A cylindrical geometry may e.g. be used both for modelling of diffusion through a tube wall, as well as the dissolution of a rod-shaped precipitate.

The Diffusion module (DICTRA) includes several different modules for performing specialized tasks, e.g. retrieving data, performing a simulation, plotting the result. The user interface consists of a command line interface where commands are typed. The use of MACRO files makes it possible to save command sequences and repeat or modify them for different cases. Several examples of such MACRO files are provided with the installation.

The Diffusion module (DICTRA) requires Thermo-Calc for necessary thermodynamic calculations and is available as an add-on to a Thermo-Calc license.

12-months of free maintenance & support
When purchasing a license for the Diffusion module (DICTRA), 12-months of free maintenance & support are always included. After this period, it is our recommendation that you renew this subscription to keep receiving automatic updates of the software, as well as to be entitled to have access to our technical support.