A publication by Q. Chen et al., in the December issue of the Journal of Materials Engineering and Performance presents a model using TC-PRISMA that correctly predicts the chemical and thermal conditions for mono- and bimodal distributions of M7C3 precipitates in Fe-Cr-C alloy and γ’ precipitates in Ni-Al-Cr alloy, further demonstrating the program’s value for designing alloy chemistry and heat treatment.
The paper, Modeling Precipitation Kinetics During Heat Treatment with Calphad-Based Tools, shows that simulations made in TC-PRISMA are in reasonably good agreement with experimental data.
TC-PRISMA was developed by Thermo-Calc Software to treat concurrent nucleation, growth/dissolution and coarsening under arbitrary heat treatment conditions in multi-component and multi-phase systems. The program relies on the Langer-Schwartz theory and the Kampmann-Wagner numerical approach, and is the newest software package developed by Thermo-Calc Software.
Sophisticated precipitation reaction models combined with well-developed CALPHAD databases provide an efficient way to tailor precipitate microstructures that maximize strengthening via the optimization of alloy chemistries and heat treatment schedules. The success of the CALPHAD approach relies on the capability to provide fundamental phase equilibrium and phase transformation information in materials of industrial relevance taking into consideration composition and temperature variation. The newly developed TC-PRISMA program is described. The effect of growth modes, alloy chemistries, and cooling profiles on the formation of multimodal microstructures has been examined in order to understand the underlying thermodynamics and kinetics. Practical issues that are critical to the accuracy and applicability of the current simulations, such as modifications that overcome mean field approximations, compatibility between CALPHAD databases, and selections of key parameters (particularly interfacial energy and nucleation site densities), are also addressed.