Nanoscale Nucleation of TixOy Inclusions in Ti-Containing Steel
摘要
Reducing the particle size of TixOy is a viable method for optimizing the performance of Ti-containing steel. The size of TixOy inclusions is strongly dependent on the behavior of their nucleation in steel. Through DFT-based computational simulations, further research on the nucleation mechanism of TixOy at the nanoscale in Ti-containing steel is conducted in this study. A nano-TixOy model was constructed for the purpose of exploring the homogeneous nucleation mechanism, while an interfacial model of Ti2O3–Al2O3 was used to investigate the heterogeneous nucleation mechanism. The results show that the values of the critical radius and ΔG for the nucleation of TixOy decrease as the supersaturation ratios of [O] and [Ti] increase, and they increase as the temperature increases. Under identical temperature and supersaturation conditions, the ΔG and critical radius pertaining to the heterogeneous nucleation of Ti2O3 are lower than those pertaining to homogeneous nucleation, and the heterogeneous nucleation rate for Ti2O3 is notably higher than the rate of homogeneous nucleation. In addition, the competitive nucleation mechanism of Ti2O3, Ti3O5 and TiO2 in molten steel is discussed, and the sequence of TixOy nucleation is suggested to be as follows: Ti3O5 → Ti2O3 → TiO2. The ΔG values required for the nucleation of TixOy increase in the order of Ti3O5 < Ti2O3 < TiO2 at the same content of [pct Ti] and [pct O]. The nucleation rates of Ti2O3 and Ti3O5 tend to decrease with decreasing degree of supersaturation and increasing temperature, whereas the nucleation rates of TiO2 decrease slightly with decreasing supersaturation ratio.
Graphical Abstract