One Phase Examples

Homogenization of a binary Fe-Ni alloy: Linear concentration profile

Simple homogenization of a binary Fe-Ni alloy. It is assumed there is initially a linear Ni-concentration profile.

Homogenization of a binary Fe-Ni alloy

• Example exa2a Step Profile: Simple homogenization of a binary Fe-Ni alloy. A Ni rich and a Ni lean alloy are put together and initially there is a step profile.
• Example exa2b Time Integration: This example is identical to a2a but instead it uses implicit time integration instead of the trapezoidal method for solving the PDEs.

Uphill diffusion in an Fe-Si-C alloy

This is an example to simulate uphill diffusion in a ternary single phase austenite matrix due to the classical Darken experiment published by Darken, 1949 [1949Dar].  

In this example, two pieces of austenite (3.80 wt%Si, 0.49 wt%C) and (0.05 wt%Si, 0.45 wt%C) are put together and are subsequently annealed at 1050 C for 13 days. As both pieces are austenite they must be entered into the same region. This is done by individually giving the compositions of Si and C in each grid point. These data are then stored to file.

This example uses the TCFE and MOBFE databases. These licenses are required to run the example.

Carburization of binary Fe-C alloy: Comparison to an analytical erf solution

This is a simple binary simulation with one single phase region. The numerical simulation is compared with an analytical erf-solution. A special database is created (erf.tdb) where the diffusion coefficient is set to a concentration independent value.

Carburization of a binary Fe-0.15 wt% C alloy

A mixture of 40% N2 and 60% cracked methanol is used as carrier gas. The carburizing "carbon potential" in the gas is 0.85 wt% and a surface reaction controls the flux of C at the surface.

Diffusion through a tube wall

A simple example of diffusion through a tube wall. The tube material is an Fe-0.6%Mn-0.7%Si-0.05%C alloy. On the inside wall a carbon activity of 0.9 is maintained whereas on the outside the C-activity is very low. This example demonstrates the use of the command SET-FIRST-INTERFACE as well as the use of MIXED boundary conditions.

This example uses the TCFE and MOBFE databases. These licenses are required to run the example.

A modified version of this example is also available in Graphical Mode as example D_06. For Graphical Mode you do not need a Diffusion Module (DICTRA) license. You can open the example from Thermo‑Calc when in Graphical Mode (File → Examples Files → Diffusion Module).

Homogenization heat treatment

The initial segregation profile is created from a Scheil calculation (see macro create_initial_profile.TCM). The command INPUT_SCHEIL_PROFILE in the DICTRA monitor performs most of the setup. Only time and temperature must be entered after the INPUT_SCHEIL_PROFILE command is executed.

[1949Dar] L. S. Darken, Diffusion of Carbon in Austenite with a Discontinuity in Composition. Trans. Am. Soc. Met. AIME 180, 430–438 (1949).