溶质梯度系数对二元合金枝晶生长的影响

Influence of solute gradient in the dendritic growth of binary alloy

为了准确描述金属凝固过程中的微观特性,用相场法模拟流场下二元合金的枝晶形貌.结合C.W.Lan提出的耦合流场的相场模型,在溶质场中加入溶质梯度项,研究溶质梯度系数对合金非等温凝固过程中枝晶生长及溶质截留效应的影响.结果表明:随着溶质梯度系数的增大,上游尖端半径和尖端速率都逐渐增大,固相中的溶质浓度显著提高,溶质截留效应更加明显.另外,此模型的计算结果与Oseen-Ivantsov理论符合较好.

In order to describe the microscopic characteristics of metal solidification accurately, this article simulated the dendrite morphology with the phase-field method. Solute gradient was introduced into the equation of solute field based on the phase-field model offered by C. W. Lan. The dendrite growth and solute trapping for a binary alloy during non-isothermal solidification were investigated with various solute gradient coefficients. The results indicate that the tip radius and the tip velocity become larger with thin,increment of Solute gradient coefficient, the concentration in solid phase increases significantly, and the phenomenon of solute trapping becomes conspicuous. Moreover, the results agree well with Oseen-Ivantsov theory .