Phase-field analysis of volume-diffusion controlled shape-instabilities in metallic systems-I: 2-Dimensional plate-like structures

Shape-instabilities induced by the difference in curvature enables the morphological evolution of the microstructure despite the absence of any phase transformations. In this work, a thermodynamically-consistent phase-field approach is adopted to quantitatively capture the kinetics of this transformation in 2-dimensional plate-like structures. Analytical treatment of cylinderization, hitherto adhered in both theoretical and experimental studies, is revisited by relaxing the geometrical approximation and incorporating the dynamical nature of the curvature-driven driving force. Present works reveals that the cylinderization time for 'smooth' 2D-plates is proportional to (w/t(p))(1.52), where w/t(p) represents the aspect ratio of the plate. Furthermore, analytically ill-posed plates with sharp corners ('faceted' 2D-plates), wherein the principal curvatures are zero, is analyzed and proportionality of (w/t(p))(1.52) is identified. Owing to its sharp corners, an increase in the rate of transformation (approximate to 25%) is observed in faceted plates when compared to its smooth counterparts. (C) 2017 Elsevier B.V. All rights reserved.