采用Cellular Automaton法模拟铝合金的微观组织

Microstructure Simulation of Al Alloy with Cellular Automaton Method

采用 Cellular Automaton微观模型 ,并与宏观的传热计算相结合 ,对砂型铸造铝合金铸件的凝固组织形成进行了模拟。在模拟过程中 ,采用连续形核的方法处理液态金属的异质形核现象。通过高斯分布函数描述形核质点密度随温度的分布关系 ,在给定过冷度时对分布函数求积分可得该时刻的形核密度。晶粒生长模型则考虑枝晶尖端生长动力学和择优生长方向〈1 0 0〉晶向。模拟计算结果表明 ,在冷却速度不变的情况下 ,随着形核分布参数ΔTN 增加 ,所得到的晶粒尺寸增大。

Microstructure simulation of aluminum alloy casting was carried out by Cellular Automaton model. Continuous nucleation model was used to describe heterogeneous nucleation of the liquid metal. Gauss distribution function was employed to describe the relation between the density of nucleation sites and the temperature and was integrated to get the grain density at a given undercooling. Dendrite tip growth kinetics and preferential 〈100〉 crystallographic orientation were also taken into account. Therefore not only the stochastic nature of nucleation process but also the deterministic of dendrite growth was considered in the calculation. Simulation results showed that the obtained grain size increases with the increasing of average nucleate undercooling Δ T N . The modeling results were analyzed mathematically.