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Diffusion Simulations

Diffusion Module (DICTRA)

Simulate diffusion-controlled reactions in multicomponent alloys using the Add-on Diffusion Module (DICTRA).

About the Diffusion Module (DICTRA)

The Diffusion Module (DICTRA) is an Add-on Module to Thermo-Calc that makes modeling multicomponent diffusion-controlled transformations simple and accessible. The Diffusion Module (DICTRA) is based on the numerical solution of the multicomponent diffusion equations and the CALPHAD approach.

Questions Diffusion Simulations Can Help You Answer

The Diffusion Module (DICTRA) is a general tool for making diffusion simulations, but some typical questions it can help you answer are:

  • How long of a holding time is required at a specific temperature to homogenize the as-cast microstructure?
  • How long of an annealing time is needed to dissolve precipitates of a given size?
  • How does the cooling or heating rate influence the amount of phases transformed?
  • What elemental profiles result post welding or other similar joining operations?
  • Will undesirable phases form when joining two dissimilar materials?

A screenshot of the Diffusion Module (DICTRA) showing the results of a moving phase boundary calculation for a Fe-C system.

The Diffusion Module (DICTRA) Allows You to Simulate:

  • Microsegregation during solidification
  • Homogenization of alloys
  • Growth/dissolution of secondary phases, such as carbides, nitrides, or intermetallic phases
  • Coarsening of precipitate phases
  • Allotropic phase transformations, such as austenite to ferrite transformations in steel, or hcp (alpha-Ti) to bcc (beta-Ti) in titanium alloys
  • Carburization, nitriding, and carbonitriding of high-temperature alloys and steels
  • Interdiffusion in compounds, such as coating systems, dissimilar joints, and so on
  • Post weld heat treatment (interdiffusion and related phase changes)
  • Sintering of cemented-carbides

Generic Models for Flexible Use

In order to allow diffusion 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.

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

Databases for Diffusion Simulations

The Diffusion Module (DICTRA) requires a mobility database in addition to the standard thermodynamic and properties database that is used with Thermo-Calc. The mobility database contains information about the atomic mobility of individual components in relevant phases. Each mobility database is developed to correspond to a specific thermodynamic and properties database.


The Diffusion Module (DICTRA) is available as an Add-on to a Thermo-Calc license. In order to run the Diffusion Module (DICTRA), it is necessary to have a license for Thermo-Calc, at least one thermodynamic and properties database, and at least one mobility database. If you are interested in purchasing a license for this Module, please contact us to discuss which license is right for you.

Learn More about the Diffusion Module (DICTRA)

Thermodynamic and Kinetic Simulations on Joining and Additive Manufacturing Processes for an ICME Framework

Thermo-Calc Modelling of as-cast Features and Its Influence on Final Mechanical Properties

A comprehensive tutorial that teaches about the role of diffusion in materials and how the Diffusion Module (DICTRA) can be applied to materials design and processing.

Microsegregation During Solidification

DICTRA – Background – Theory – Applications

A collection of videos demonstrating the capabilities of the Diffusion Module (DICTRA).

An experimental and theoretical study of duplex fcc+hcp cobalt based entropic alloys

Continuous Casting of High Carbon Steel: How Does Hard Cooling Influence Solidification, Micro – and Macro Segregation?

Retention of Delta Ferrite in the Heat-Affected Zone of Grade 91 Steel Dissimilar Metal Welds

Application of finite element, phase-field, and CALPHAD-based methods to additive manufacturing of Ni-based superalloys

Modeling Interdiffusion Processes in CMSX-10/Ni Diffusion Couple

An overview of the Diffusion Module (DICTRA)

A collection of references regarding the development of the Diffusion Module (DICTRA), kinetic models implemented in the software, some specific applications utilizing it, and more.

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