Phase-field modeling of the discontinuous precipitation reaction

✍ Scribed by Lynda Amirouche; Mathis Plapp

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 306 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.09.015

✦ Synopsis

A multi-phase-field model for the description of the discontinuous precipitation reaction is formulated which takes into account surface diffusion along grain boundaries and interfaces as well as volume diffusion. Simulations reveal that the structure and steady-state growth velocity of spatially periodic precipitation fronts depend strongly on the relative magnitudes of the diffusion coefficients. Steadystate solutions always exist for a range of interlamellar spacings that is limited by a fold singularity for low spacings, and by the onset of tip-splitting or oscillatory instabilities for large spacings. A detailed analysis of the simulation data reveals that the hypothesis of local equilibrium at interfaces, used in previous theories, is not valid for the typical conditions of discontinuous precipitation.