Diffusion among Multiple Regions
- Purpose: Learn to perform diffusion simulation at constant temperature for a diffusion sandwich with different phase structure but uniform composition through each region before diffusion;
- Module: PanDiffusion
- Database: FeCrNi.tdb
Calculation Method 1:
- From menu bar click Batch Calc-> Batch Run, select Example_#4.5.pbfx;
Calculation Method 2:
- Create a workspace and select the PanDiffusion module following Pandat User’s Guide 2.1;
- Load FeCrNi.tdb following the procedure in Pandat User’s Guide 3.2.1;
- Click on “PanDiffusion->Diffusion Simulation” and set up the calculation condition as shown in Figure 1. First click the blue “+” above Regions to add another region, Region_3. Select Region Composition Distribution as “Uniform”.
- Click on Region_1 and set the composition of the left region of the diffusion triple as 30Cr-10Fe-60Ni (at%). Select Fcc as the entered phase in “Select Phases” of “Settings for the Selected Region [Region_1]”.
- Click on Region_2 and set the composition of the middle region of the diffusion triple as 55Cr-40Fe-5Ni (at%), Select Bcc as the entered phase in “Select Phases” of “Settings for the Selected Region [Region_2]”.
- Click on Region_3 and set the composition of the right region of the diffusion triple as 10Cr-20Fe-70Ni (at%). Select Fcc as the entered phase in “Select Phases” of “Settings for the Selected Region [Region_3]”.
- The length of each region is set to be 100 um, and the number of grids (# of Grids) is the default value of 100.
- The Thermal History is holding the diffusion sandwich at 1000oC for 500 hours.
- In the setting shown in Figure 36.1, composition profiles at the initial and final stages, as well as that at 200 hour will be outputted. Click OK to perform calculations.
![](https://computherm.com/wp-content/uploads/2021/03/image178.png)
Figure 1. Setting of the simulation condition
Post Calculation Operation:
- The calculated plot is shown in Figure 2. Add text and change graph appearance following the procedure in Pandat User’s Guide 2.3.1;
![](https://computherm.com/wp-content/uploads/2021/03/plot_1-5.png)
Figure 2. Calculated composition profiles for the diffusion sandwich at 1000oC for 200h and 500h
Information obtained from this calculation:
- The three regions of the diffusion triple locate at different phase fields, the one in Bcc is sandwiched between two regions in the Fcc as shown in Figure 3;
- After holding the diffusion couple at 1000oC for 500 hours, composition profiles can be viewed at final stage (500h) and intermediate stage (200h). The phase boundaries are moved;
![](https://computherm.com/wp-content/uploads/2021/03/plot_2-6.png)
Figure 3. Isothermal section of Ni-Cr-Fe at 1000oC, the initial compositions of the left and right regions locate in the single Fcc phase field, while the middle region locates in the Bcc phase field