Heterogeneous nucleation mechanism of CaS and TiN on spinel combining DFT calculations and experiments

The characteristics of composite inclusions between atomic interfaces has been investigated by combining high-angle annular dark field (HAADF) with first-principles computations. The characteristics of the composite inclusions reveal a core of Ca2Al2O5, with CaS and TiN adhering to its surface. According to mismatch degree theory and SEM characterization, the nucleation rate increases with a decreasing degree of mismatch. Notably, the adhesion work of the Ca2Al2O5/CaS interface is greater than that of the Ca2Al2O5/TiN interface, demonstrating the stronger bond strength of the Ca2Al2O5/CaS interface. The prediction of the lowest interfacial energy shows that a stable interface can form between Ca2Al2O5 and MX. Hence, Ca2Al2O5 can be effectively utilized as a nucleation side for CaS (TiN). The present work provides valuable theoretical and technical information for knowledge-based design and prediction of composite inclusion regulation for structural steels, especially for marine engineering steels.