Asymmetric interfacial energies in tilted lamellar Mo–Si–Ti structures: a multi-phase-field study analysis of material characteristics

In this study, a multi-phase-field model based on the grand chemical potential framework is employed to investigate the growth behavior of lamellar structures in the Mo–Si–Ti ternary system. The interfacial energy between the liquid and solid phases is identified as a key parameter governing three distinct growth modes: (g$_i$) regular growth, (g$_{ii}$) tilted growth, and (g$_{iii}$) unstable growth. To examine the influence of solid–liquid interfacial energy on lamellar morphology, we focus on the four-phase reaction: L + Mo(Ti)$_3$Si → Ti(Mo)$_5$Si$_3$ + β(Mo,Si,Ti), which occurs during isothermal solidification. The transition to tilted growth is analyzed by simulating variations in solid–liquid interfacial energy, lamellar spacing, melt supersaturation, and the emergence of oscillatory morphologies. The orientation angle, a key characteristic of tilted growth, is shown to be highly sensitive to changes in interfacial energy. At lower interfacial energy values, a symmetric and regular lamellar morphology is observed. However, as the interfacial energy increases, asymmetric redistribution of the solute and capillarity-driven deviations arise, leading to tilted or unstable growth modes. ... mehrThis parametric study provides fundamental insight into the mechanisms that govern the orientation angle on the solidification front, highlighting the interplay between capillarity and diffusion-controlled dynamics at triple junctions. In particular, the novelty of this work lies in the observation of pronounced tilt angles in a system with isotropic interfacial energies. Furthermore, the relationship between orientation angle and interfacial energy established through phase-field modeling offers a potential framework for addressing experimental challenges in elucidating the role of interfacial energies in tilted lamellar morphologies.