Diffusion Simulations (DICTRA)
Combining the TCS High Entropy Alloys Database (TCHEA) with its compatible TCS High Entropy Alloy Mobility Database (MOBHEA), the elemental diffusion and diffusion control phase transformation can be simulated using the Diffusion Calculator, which is part of the Add-on Diffusion Module (DICTRA) in Thermo‑Calc.
Read more about the Diffusion Module (DICTRA) on our website. There is also a Getting Started with the Diffusion Module (DICTRA) page available. If you are in Thermo‑Calc, press F1 to search the help to learn about the available settings included with the Add-on Module.
Interdiffusion of FCC HEAs
This example shows the simulation of interdiffusion in the diffusion couple of two FCC HEAs namely Co30Cr20Fe25Ni10Mn15 and Co10Cr20Fe15Ni30Mn25 (at %) in comparison with experimental information from [2017Ver].
Figure 1: A Diffusion Module (DICTRA) simulated concentration profile of FCC HEA diffusion couple annealed at 1000 °C for 100 hours. Experimental data from [2017Ver].
Interdiffusion of BCC HEAs
In this example, the simulations were performed at a temperature of 1373 K annealed after 64800 s, where the composition of the diffusion couple is Ti-0.222Nb-0.078Ta/Ti-0.144Nb-0.069Ta-0.058Zr (unit: mole fraction) with a BCC_A2 phase.
Figure 2: Simulated concentration profiles of diffusion couple Ti-0.222Nb-0.078Ta/Ti-0.144Nb-0.069Ta-0.058Zr with BCC_A2 phase annealed after 64800 s at 1373 K compared with the experimental data [2019Che].
Kinetics of Fe/Ti Diffusion Couples
The simulations were performed using the homogenization model available with the Diffusion Module (DICTRA). The concentration profiles of Fe in the diffusion couple Fe/Ti at a temperature of 1273 K are annealed after 1 h.
Figure 3: Simulated concentration profiles of Fe in the diffusion couple Fe/Ti annealed after 1 h at 1273 K compared with experimental data [2021Sal].
References
[2017Ver] V. Verma, A. Tripathi, K. N. Kulkarni, On Interdiffusion in FeNiCoCrMn High Entropy Alloy. J. Phase Equilibria Diffus. 38, 445–456 (2017).
[2019Che] W. Chen, L. Zhang, Experimental Investigations on the Quaternary Interdiffusion Coefficients, Young’s Modulus and Hardness in bcc Ti-Nb-Ta-Zr Quaternary Alloys. J. Phase Equilibria Diffus. 40, 138–147 (2019).
[2021Sal] A. Salmasi, S. J. Graham, I. Galbraith, A. D. Graves, M. Jackson, S. Norgren, D. Guan, H. Larsson, L. Höglund, Mobilities of Ti and Fe in disordered TiFe-BCC assessed from new experimental data. Calphad. 74, 102300 (2021).