Precipitation and Coarsening of a 718 Alloy

The Precipitation Module (TC-PRISMA) can be used to simulate co-precipitation and coarsening of precipitates, shown below using the TCS Ni-based Superalloys Database (TCNI) and TCS Ni-alloys Mobility Database (MOBNI) for 718-type alloys.

Read more about the Precipitation Module (TC-PRISMA) on our website. If you are in Thermo‑Calc, press F1 to search the help to learn about the available settings included with the Add-on Module.

As part of the simulation set up, these Precipitation Calculator settings are used in the calculation:

  • Cubic elastic properties in matrix phase
    • c11 =232.5 GPa
    • c12 = 136.6 GPa
    • c44 = 120 GPa
  • Interfacial energy
    • γ" 0.014 J/m2
    • γ' 0.14076-0.00012*T
  • Transformation strain
    • γ" : ε11 = ε22 = 0.00667
    • ε33 = 0.0286

Results of particle size are sensitive to the value of interfacial energy.

Calculated plate diameter/particle length of γ'' precipitates in 718 alloy compared with data in the literature.

Figure 1: Calculated plate diameter/particle length of γ'' precipitates in 718 alloy compared with data in the literature [1982Han; 1992Sun; 2008Dev]. Where "modified" indicates that literature data was doubled with the possibility that reported values are half the major axis, as noted by [2018Wu].

Mean γ' particle radius in 718-type alloy compared with data by Sundaraman et al. at 1023 K and Han et al. at 998 and 973 K.

Figure 2: Mean γ' particle radius in 718-type alloy compared with data by [199Sun] at 1023 K, and [1982Han] at 998 and 973 K.

Volume fraction of precipitates simulated for 718-type alloy at 1023 K for 200 hours for a composition based on Sundaraman et. al.

Figure 3: Volume fraction of precipitates simulated for 718-type alloy at 1023 K for 200 hours for a composition based on [1992Sun]. Note that time scale is logarithmic.

References

[1982Han] Y. Han, P. Deb, M. C. Chaturvedi, Coarsening behaviour of γ″- and γ′-particles in Inconel alloy 718, Met. Sci. 16(12), 555–562 (1982).

[1992Sun] M. Sundararaman, P. Mukhopadhyay, S. Banerjee, Some aspects of the precipitation of metastable intermetallic phases in INCONEL 718, Metall. Trans. A. 23, 2015–2028 (1992).

[2008Dev] A. Devaux, L. Nazé, R. Molins, A. Pineau, A. Organista, J. Y. Guédou, J. F. Uginet, P. Héritier, Gamma double prime precipitation kinetic in Alloy 718. Mater. Sci. Eng. A. 486, 117–122 (2008).

[2018Wu] K. Wu, Q. Chen, P. Mason, Simulation of Precipitation Kinetics with Non-Spherical Particles. J. Phase Equilibria Diffus. 39, 571–583 (2018).