About the Diffusion Module (DICTRA)

The Diffusion Module (DICTRA) is an Add-on Module to Thermo‑Calc. It is used for simulation of diffusion controlled transformations in multicomponent systems. The simulation calculations are both time- and space-dependent. The Diffusion Module (DICTRA) is available in both Graphical Mode (as the Diffusion Calculator) and Console Mode (as the DICTRA module).

The Diffusion Module (DICTRA), which is often just referred to as DICTRA, is ideally suited to solve diffusion simulations that include a moving boundary (Stefan problems). The multicomponent diffusion equations in the various regions of a material are solved under the assumption that thermodynamic equilibrium holds locally at all phase interfaces. Simulations are one-dimensional and three different geometries can be performed: planar, cylindrical, and spherical.

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

In order to perform a simulation in the Diffusion Module, both a thermodynamic database and a kinetic database is needed. The thermodynamic database is a normal Thermo‑Calc database, whereas the kinetic database contains information about the atomic mobility of individual elements in various phases.

Using the Diffusion Module (DICTRA) you can solve a variety of problems, some of which are described in Types of Diffusion Simulations.