New insights into the morphological stability of eutectic and peritectic coupled growth

Both eutectic and peritectic alloys exhibit three-phase equilibria and are used in diverse practical applications ranging from casting and welding to growing superconducting crystals. In-situ composites formed by the diffusively coupled growth of two solid phases are ubiquitous in eutectic solidification. This growth, however, is generally only stable over a finite range of eutectic spacing. The addition of a dilute ternary impurity can destabilize the interface and produce coarse two-phase cellular structures. Whether coupled growth is theoretically possible in peritectic alloys has been a question for over 40 years. This article reviews the current status of phase-field modeling of polyphase solidification in eutectic and peritectic alloys. Also discussed are new findings from both simulations and experiments that shed new light on the similarities and differences between the morphological stability of eutectic and peritectic coupled growth.