Tip splitting instability of cellular interface morphology in directional solidification is analyzed based on the bias field method proposed recently by Glicksman. The physical mechanism of tip instability is explaine...Tip splitting instability of cellular interface morphology in directional solidification is analyzed based on the bias field method proposed recently by Glicksman. The physical mechanism of tip instability is explained by analyzing the interface potential, the tangential energy flux, and the normal energy flux. A rigorous criterion for tip-splitting instability is established analytically, i.e., the ratio of the cellular tip radius to the cellular width α 〉3/2/π≈ 0.3899, which is in good agreement with simulation results. This study also reveals that the cellular tip splitting instability is attributable to weak Gibbs–Thomson energy acting on the interface.展开更多
The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been st...The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been studied with the B-S phase field model. Simulated results reproduced the morphology transitions of deep cell to shallow cell and shallow cell to plane front. The primary cellular spacing, depth of groove and effective solute redistribution coefficient for different V and G are compared. The absolute stability under high pulling speed and high temperature gradient has also been predicted, which is in agreement with the Mullins-Sekerka (M-S) stability theory.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2011CB610401)the National Natural Science Foundation of China(Grant No.51371151)the Free Research Fund of State Key Laboratory of Solidification Processing,China(Grant No.100-QP-2014)
文摘Tip splitting instability of cellular interface morphology in directional solidification is analyzed based on the bias field method proposed recently by Glicksman. The physical mechanism of tip instability is explained by analyzing the interface potential, the tangential energy flux, and the normal energy flux. A rigorous criterion for tip-splitting instability is established analytically, i.e., the ratio of the cellular tip radius to the cellular width α 〉3/2/π≈ 0.3899, which is in good agreement with simulation results. This study also reveals that the cellular tip splitting instability is attributable to weak Gibbs–Thomson energy acting on the interface.
基金Supported by the National Natural Science Foundation of China (Grant No. 50401013)
文摘The influences of pulling speed V and temperature gradient G on morphology evolution, concentration distribution, solute trapping and interface stability during directional solidification of binary alloys have been studied with the B-S phase field model. Simulated results reproduced the morphology transitions of deep cell to shallow cell and shallow cell to plane front. The primary cellular spacing, depth of groove and effective solute redistribution coefficient for different V and G are compared. The absolute stability under high pulling speed and high temperature gradient has also been predicted, which is in agreement with the Mullins-Sekerka (M-S) stability theory.
