过冷熔体中枝晶生长的相场法数值模拟

利用相场法模拟了过冷纯金属熔体中的枝晶生长过程,研究了各向导性、界面动力学、热扩散和界面能对枝晶生长的影响.结果表明,热噪声可以促发侧向分支的形成,但不影响枝晶尖端的稳态行为;随着各向异性的增加,枝晶尖端生长速度增加,尖端半径减小;当界面动力学系数减小及在界面动力学系数小于1的条件下热扩散系数减小时,枝晶尖端生长速度随之减小,而尖端半径相应增大;界面能趋于增大枝晶尺度并保持界面在扰动下的稳定,界面能越大,形成侧向分支的趋势越小 关键词： 过冷 枝晶生长 相场法 数值模拟

NUMERICAL SIMULATION OF DENDRITIC GROWTH IN UNDERCOOLED MELT USING PHASE-FIELD APPROACH

Using the phase-field approach, the dendritic growth in the undercooled pure metal melt is simulated, and the dependence of dendritic growth upon the anisotropy,interfacial kinetics,thermal diffusivity and surface energy is investigated.The calculated results indicate that the heat noise can trigger the growth of side-branches;however this dose not influence the selection of the tip operating state.The dimensionless tip velocity increases and the tip radius decreases with the increase of anisotropy. Correspondently,the dimensionless tip velocity decreases and tip radius increases when the interfacial kinetics or thermal diffusivity (when the interface kinetic coeffiecient is less than 1) inreases. The surface energy tends to increase the size of dendrite and keeps the stability of interface under the disturbance of heat noise.The greater the surface energy,the weaker the tendency to form side-branches.