Dendritic tip selection during solidification of alloys:Insights from phase-field simulations

【摘要】 The effect of undercooling AT and the interface energy anisotropy parameter ε₄ on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys.It was found that the tip radius p increases and the tip shape amplitude coefficient A₄ decreases with the increase of the fitting range for all cases.The dendrite tip shape selection parameter σ^* decreases and then stabilizes with the increase of the fitting range,and σ^*increases with the increase of ε₄.The relationship between σ^* and ε₄ follows a power-law function σ^* ∝ ε₄^α,and α is independent of ΔT but dependent on the fitting range.Numerical results demonstrate that the predicted σ^* is consistent with the curve of microscopic solvability theory（MST） for ε₄ <0.02,and σ^* obtained from our phase-field simulations is sensitive to the undercooling when ε₄ is fixed.更多还原

【Abstract】 The effect of undercooling AT and the interface energy anisotropy parameter ε₄ on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys.It was found that the tip radius p increases and the tip shape amplitude coefficient A₄ decreases with the increase of the fitting range for all cases.The dendrite tip shape selection parameter σ^* decreases and then stabilizes with the increase of the fitting range,and σ^*increases with the increase of ε₄.The relationship between σ^* and ε₄ follows a power-law function σ^* ∝ ε₄^α,and α is independent of ΔT but dependent on the fitting range.Numerical results demonstrate that the predicted σ^* is consistent with the curve of microscopic solvability theory（MST） for ε₄ <0.02,and σ^* obtained from our phase-field simulations is sensitive to the undercooling when ε₄ is fixed.更多还原