铝合金凝固组织CA-PF耦合模拟研究

发布时间：2018-03-28 16:36

本文选题：相场模型　切入点：CA-PF模型　出处：《南昌大学》2015年硕士论文

【摘要】：随着科学技术的飞速发展,计算机技术也在日益进步,这为我们的工程材料的数值模拟提供了发展平台。本文基于元胞自动机和相场两种数值模型的理论基础耦合了一种新型的CA-PF模型,并对比了该模型和其他两种模型的不同点。以相场模型为例,模拟了Al-4.5wt%Cu五晶粒分别在不同过冷度(△T=17.3K、△T=15.3K、△T=13.3K)和不同晶粒间距(Δx=21.21×10-6m、Δx=14.14×10-6m、Δx=7.07×10-6m)下的各晶粒的生长情况;以及对比了等温和非等温条件下中心晶粒的变化。结果表明:当过冷度△T=13.3K和晶粒间距Δx=7.07×10-6m时,中心晶粒最易形成近球晶;且同等条件下,非等温比等温情况更易促使中心晶粒形成近球晶。以新建立的CA-PF模型为基础,模拟了Al-4.5wt%Cu二元合金在等温情况下的枝晶生长形貌以及不同过冷度下枝晶的生长形貌差别。对比了新型CA-PF模型和PF模型、CA模型的形貌差别、计算时间效率以及界面扩散层的不同。结果表明:CA-PF模型符合枝晶生长理论,且当初始温度T0=912K时出现二次枝晶臂。对比三种模型得出,PF模型的枝晶最为粗大,CA模型的枝晶最细,CA-PF模型的枝晶形貌介于二者之间。时间效率对比中,CA模型所耗时间最少,PF耗费时间最多,CA-PF介于其中。而界面层则是PF的最为光滑精确,CA-PF的界面不及PF光滑。
[Abstract]:With the rapid development of science and technology, computer technology is also increasingly advanced, This provides a development platform for numerical simulation of engineering materials. In this paper, a new CA-PF model is coupled based on the theory of cellular automata and phase field. The differences between the model and the other two models are compared. Taking the phase field model as an example, the growth of Al-4.5wt%Cu five grains at different undercooling degrees (T _ (17. 3) K, T _ (15. 3) K) and grain spacing (螖 x ~ (21) 21 脳 10 ~ (-6) m, 螖 x ~ (14) 脳 10 ~ (-6) m, 螖 x ~ (7) 7 脳 10 ~ (-6) m) is simulated. The changes of central grains under isothermal and non-isothermal conditions are compared. The results show that the center grains are most likely to form near spherulites when the undercooling degree Tn13.3K and the grain spacing 螖 x = 7.07 脳 10 ~ (-6) m, and under the same conditions, Non-isothermal conditions are more likely than isothermal conditions to promote the formation of near-spherulite in central grains, which is based on the newly established CA-PF model. The dendritic growth morphology of Al-4.5wt%Cu binary alloy under isothermal condition and the dendritic growth morphology at different undercooling degree were simulated. The morphology of new CA-PF model and PF model were compared with those of CA model. The calculated time efficiency and the interfacial diffusion layer are different. The results show that the 1: CA-PF model accords with the dendritic growth theory. The secondary dendritic arm appeared at the initial temperature T0 / 912K. The dendrite morphology of CA model of PF model was found to be the thickest than that of CA model, and the dendrite morphology of CA-PF model was between the two. The time consuming of CA model was compared with that of CA model. And the interface layer is the most smooth and accurate of PF. The interface of CA-PF is not as smooth as PF.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG292

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