Phase field study of grain boundary effects on spinodal decomposition

✍ Scribed by H. Ramanarayan; T.A. Abinandanan

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 294 KB
• Volume: 51
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/s1359-6454(03)00301-x

✦ Synopsis

We have developed a phase field model of a polycrystalline alloy by combining the Cahn-Hilliard model [J Chem Phys 28 (1958) 258] with a model of polycrystals due to Fan and Chen [Acta Mater 45 (1997) 3297]. We have used this model to study grain boundary (GB) effects on spinodal decomposition (SD) in two-dimensional (2D) systems. In binary A-B systems with constant atomic mobility, when the GB-energy (g a ) of the A-rich a phase is lower than that (g b ) of the B-rich b phase, decomposition starts by enriching the GB with species A, setting off a composition wave that produces alternating a and b bands near the GB. Simultaneously, the grain interiors undergo normal SD. Thus, when decomposition ends, GB-bands coexist with grain interiors with spinodal microstructure. The number of GB bands is rationalized in terms of (g b Ϫg a ) and the rate of SD in the grain interior. Further, during decomposition, grain growth is effectively suppressed.