Phase field simulation of the columnar dendritic growth and microsegregation in a binary alloy

• 作 者: 李俊杰 王锦程 杨根仓
• 机 构: State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,
• 出 处: Chinese Physics B
• 发表日期: 2008年09期
• 关键词: columnar solidification coarsen isothermal continuously solute analysed spacing

This paper applies a phase field model for polycrystalline solidification in binary alloys to simulate the formation and growth of the columnar dendritic array under the isothermal and constant cooling conditions.The solidification process and microsegregation in the mushy zone are analysed in detail.It is shown that under the isothermal condition solidification will stop after the formation of the mushy zone,but dendritic coarsening will progress continuously,which results in the decrease of the total interface area.Under the constant cooling condition the mushy zone will solidify and coarsen simultaneously.For the constant cooling solidification,microsegregation predicted by a modified BrodyFlemings model is compared with the simulation results.It is found that the Fourier number which characterizes microsegregation is different for regions with different microstructures.Dendritic coarsening and the larger area of interface should account for the enhanced Fourier number in the region with well developed second dendritic arms.

This paper applies a phase field model for polycrystalline solidification in binary alloys to simulate the formation and growth of the columnar dendritic array under the isothermal and constant cooling conditions. The solidification process and microsegregation in the mushy zone are analyzed in detail. It is shown that under the isothermal condition solidification will stop after the formation of the mushy zone, but dendritic coarsening will progress continuously, which results in the decrease of the total interface area. Under the constant cooling condition the mushy zone will solidify and coarsen simultaneously. For the Constant cooling solidification, microsegregation predicted by a modified Brody Fleming model is compared with the simulation results. It is found that the Fourier number which characterizes microsegregation is different for regions with different microstructures. Dendritic coarsening and the larger area of ​​interface should account for the enhanced Fourier number in the region with well developed second dendritic arms.