Simulation Of Precipitate Evolution Research Articles

Simulation of precipitates evolution in multiphase multicomponent systems with consideration of nucleation

A numerical method of simulation of precipitates evolution in multiphase multicomponent systems is suggested. This method is based on the mean field approximation for the description of evolution of the pre-existing particles and on the classical theory of nucleation for calculation of the rate of formation of new nucleation centres. It takes into account the polydispersity of precipitate ensembles and can be used on all the stages of precipitates evolution, namely, nucleation, growth, dissolution, coarsening and transition stages between the growth or dissolution and coarsening. The application of this method is demonstrated by an example of precipitates evolution in low-carbon steels doped with Ti, Nb and V.

Simulation of Precipitates Evolution in Steels with V and Nb at Annealing

Based on the mean field approximation, a model has been worked out for the description of evolution of carbonitride precipitate ensemble with various composition in steels at the stages of their growth, dissolution and coarsening. Based on the numerical realization of this model, the calculations of growth and dissolution kinetics of carbonitrides in a Fe-Nb-V-C-N system have been carried out.

Simulation of precipitate evolution in Fe–25 Co– 15 Mo with Si addition based on computational thermodynamics

Abstract Multi-component nucleation theory is applied to decipher the precipitate evolution of solution-treated and quenched Fe–25Co–15Mo (mass%) with Si addition during continuous heating and isothermal aging. For computer simulation of the nucleation and growth kinetics of precipitates, we optimize thermodynamic model parameters of the Fe–Co–Mo system with experimental data and enthalpies of formation of ternary ferrite phase determined by density functional theory analysis. Si-solubility in the precipitation-hardening μ-phase is considered in the thermodynamic modeling. The body-centered cubic (bcc) ferrite phase reveals a metastable miscibility gap between Fe- and Mo-rich phase below 1033 K. Based on thermodynamic modeling of the Fe–Co–Mo system, it is shown that the alloy Fe–25Co–15Mo is located outside the spinodal region, which is in contrast to some previous work on this system. Thermo-kinetic simulations, which are validated on experimental data from atom probe tomography, propose that during aging, the first microstructures form by means of nucleation and growth of metastable bcc-precipitates before the formation of rhombohedral μ-phase. For the thermokinetic analysis, we evaluate and utilize theoretically predicted nucleus compositions of bcc-precipitates from the minimum nucleation barrier concept.

Thermodynamics-Integrated Simulation of Precipitate Evolution in Al-Mg-Si-Alloys

Metastable precipitates govern the mechanical properties of hardenable Al-alloys. A computational precipitation simulation approach is presented that is based on a combination of compiled and assessed thermodynamic and diffusion data with predictive physical models. Predictive precipitation kinetics simulation delivers approximations of thermodynamic properties that would otherwise require time-consuming computational techniques based on density functional theory. Coupling of thermodynamics with thermo-kinetic simulation of hardenable Al-alloys Al-Mg-Si 6016 is presented.

Numerical Simulation of Precipitates Evolution in Iron-Based Alloys

Approaches used for simulation of precipitates evolution in multicomponent systems are analyzed in brief. Simulation of precipitates growth and dissolution in such systems, simulation of a polydisperse particle ensemble evolution at different stages and possibilities of taking into account nucleation during precipitates growth from a supersaturated solid solution are considered by an example of iron-carbon alloys. The problems to be solved are formulated.

Simulation of Precipitates Evolution in Steels

The model describing the behavior of precipitates of variable composition at heat treatment is suggested. The specific feature of this model is that it enables to take into account the effect of diffusion inside the particles on the kinetics of the process. The application of this model is demonstrated by the example of vanadium carbonitrides V(C,N) evolution in austenite at heat treatment of vanadium-containing steels. The necessity to take into account the diffusion modification of carbonitride composition is considered. Examples of particles composition evolution at heat treatment are demonstrated.

Numerical simulation of carbide and nitride precipitate evolution in steels

A numerical method of simulation of carbide and nitride precipitates evolution in steels at isothermal annealing is described. This method is based on the mean field approximation and consideration of precipitates evolution in field cells. Not only the growth and dissolution of the particles present, but also the nucleation of the new ones is taken into account. This method enables to simulate the precipitates evolution at all the stages beginning from the nucleation and up to the stationary coarsening. The results of kinetic calculations of vanadium carbides evolution in steels for different initial particle size distributions are presented and analyzed. Numerische Simulation der Bildung von Karbid- und Nitrid-Ausscheidungen in Stahlen Eine numerische Methode zur Simulation der Bildung von Karbid- und Nitrid-Ausscheidungen in Stahlen bei isothermen Gluhung wird beschrieben. Diese Methode beruht auf der Mean-Field-Naherung und der Berucksichtigung der Ausscheidungsbildung in Feldzellen. Nicht nur das Wachstum und die Auflosung der Partikel, sondern auch die Vereinigung neuer Partikel wird berucksichtigt. Diese Methode erlaubt die Simulation der Ausscheidungsbildung auf allen Ebenen, beginnend von der Keimbildung bis hin zur stationaren Vergroberung. Die Ergebnisse der kinetischen Berechnungen der Vanadium-Karbid-Bildung in Stahlen fur unterschiedliche Anfangsverteilungen der Partikel werden dargestellt und analysiert.