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Thermodynamic equilibria in the Al-Ti-C ternary system are considered as applied to synthesizing titanium carbides in an aluminum medium using the CALPHAD method. A set of calculated isothermal sections of the corresponding state diagram is obtained. Using the results of the thermodynamic analysis of the system, a physically substantiated semi-empirical mathematical computer model was developed that describes the kinetics of TiC synthesis processes in the aluminum medium for the Al-TiC two-phase equilibrium region. Based on the simulation results, it was found that with increased aluminum content in the system, the exothermic burst during TiC synthesis is characterized by lower temperatures and becomes more diffuse in time. The dependence of the dispersity of titanium carbide particles on the aluminum content in the mixture is nonlinear. An increase in the aluminum content slows down the growth of TiC particles. It is shown for the Ti-Al-C system that there is a certain threshold value of the aluminum content (about 30-40%), the excess of which leads to a noticeable dispersion of the sizes of the synthesized titanium carbide grains, which makes it possible to obtain submicron TiC particles. The results obtained are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

A mathematical physical based semi-empirical model and a corresponding computer program are developed for describing recrystallization process and carbonitrides particles precipitation in deformed austenite. The model is suitable for alloyed steels of a wide range of compositions. The model allows calculating a thermodynamic equilibrium for carbonitride excess phases with solid solution, the kinetics of their nucleation and growth, and their effect on recovery and recrystallization. A detailed description is given for each aspect of the model and its physical nature. Verification of the simulation results with the experimental data taken from published sources confirms the sufficient reliability of the proposed computer model for evaluative calculations. The model's features are demonstrated by an example that simulates influence of Nb content on recristallization, recovery and nucleation, growth and Ostwald ripping of Nb and Ti carbonitride particles. The simulation shows and numerically predicts the effect of slowing down recrystallization and recovery with increasing in Nb content. That attests significance of the effect of dispersed carbonitrides on recrystallization and recovery. The simulation theoretically predicts an intensification of Ti(C, N) particles precipitation and growth with an increase in the Nb concentration. As another result, it is an increasing the dispersion and number of Nb(C, N) particles with an increase in the Nb concentration owing to more rapid transition to the Ostwald ripening stage, which is characterized by much more slowly average particle size growth than from a supersaturated solid solution. [ABSTRACT FROM AUTHOR]

A mathematical physical-based semi-empirical model and a corresponding computer program are developed for describing recrystallization process and carbonitrides particles precipitation in deformed austenite. The model is suitable for alloyed steels of a wide range of compositions. The model allows calculate a thermodynamic equilibrium for excess carbonitride phases with solid solution, the kinetics of their nucleation and growth, and their effect on recovery and recrystallization. A detailed description is given for each aspect of the model and its physical nature. Verification of the simulation results with the experimental data from published sources confirms the sufficient reliability of the proposed computer model for evaluative calculations. The model's features are demonstrated by an example that simulates influence of Nb content on recristallization, recovery and nucleation, growth and Ostwald ripening of Nb and Ti carbonitride particles. The simulation shows and allows numerically evaluate the effect of slowing down recrystallization and recovery with increasing in Nb content. This indicates a significant effect of dispersed carbonitrides on recrystallization and recovery. The simulation theoretically predicts an intensification of Ti(C, N) particles precipitation and growth with an increase in the Nb concentration. Another result is an increase of dispersion and number of Nb(C, N) particles with an increase in the Nb concentration owing to more rapid transition to the Ostwald ripening stage, which is characterized by much more slowly average particle size growth than from a supersaturated solid solution. [ABSTRACT FROM AUTHOR]