Influence of morphological instability on grain boundary trajectory during directional solidification. (15th August 2019)

• Record Type: Journal Article
• Authors: Ghosh, Supriyo; Karma, Alain; Plapp, Mathis; Akamatsu, Silvère; Bottin-Rousseau, Sabine; Faivre, Gabriel
• Is Part Of: Acta materialia. Volume 175(2019)
• Page Start: 214
• Page End: 221
• Publication Date: 2019-08-15
• Subjects: Solidification -- Morphological stability -- Grain boundaries -- Phase-field simulations -- In situ experiments; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.04.054
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The interplay between the diffusion-controlled dynamics of a solidification front and the trajectory of a grain boundary groove at the solid-liquid interface is studied by means of thin-sample directional solidification experiments of a transparent alloy, and by numerical simulations with the phase-field method in two dimensions. We find that low-angle grain boundaries (subboundaries) with an anisotropic interfacial free energy grow tilted at an angle θ t with respect to the temperature gradient axis. θ t remains essentially equal to its value imposed at equilibrium as long as the solidification velocity V remains low. When V increases and approaches the cellular instability threshold, θ t decreases, and eventually vanishes when a steady-state cellular morphology forms. The absence of mobility of the subboundary in the solid is key to this transition. These findings are in good agreement with a recent linear-stability analysis of the problem.