The influences of the mechanical equilibrium among interfacial tensions at triple junction on the morphological evolution of eutectic lamella

In this work, the influence of the mechanical equilibrium among interfacial tensions at three-phase triple junctions on the morphological evolution of growing eutectic lamella was quantitatively investigated through the phase-field simulations. We found that, when eutectic lamella grows at the steady-state, the orientations of the three interfacial tensions under mechanical equilibrium state are highly coincident with the tangent lines of the contour of the corresponding interfacial morphologies at the three phases’ triple junction. It is argued that the eutectic lamellar growth is unable to reach the steady state when the interfacial tensions fail to achieve mechanical equilibrium at the triple junctions. Moreover, a strong dependence of interfacial morphology on the state of the mechanical equilibrium between interfacial tensions is determined, and quantified through the change of lamella spacing and local curvature radius of lamella with the interfacial tensions. Furthermore, the underlying mechanism about the effects of mechanical equilibrium state on eutectic morphological evolution is also explained. We conclude that the final steady-state of eutectic growth is determined by the complex interplay among solute diffusion, eutectic morphology and the mechanical equilibrium of interfacial tensions.