【作者】 许林；

【导师】 杨湘杰；

【作者基本信息】 南昌大学 ， 机械设计及理论， 2005， 硕士

【摘要】 本文采用数值模拟方法研究了二元合金凝固过程中的组织演变,建立了耦合温度场、浓度场和相场的3DMicrosCA模型。从多个尺度对二元合金的凝固过程进行了模拟研究。这部分工作有助于深入理解凝固组织的形成,并为今后控制组织演变提供了理论基础。 本文主要包括以下内容: 1) 在对原有二维元胞自动机模型修改的基础上,向三维进行了扩展,结合直接差分法、蒙特卡罗方法和面向对象方法,构建3DMicrosCA模型。该模型详细阐述了三维元胞自动机模型的基本思想,为具体微观组织模拟建模提供理论和方法论上的支持。 2) 应用3DMicrosCA,耦合了温度场、浓度场方程,建立了3DMicrosCA-Solidification模型。该模型是金属凝固理论在3DMicrosCA模型中的实例化,有机集成了确定性模型和概率模型、宏观模型和微观元胞自动机模型。 3) 通过使用3DMicrosCA-Solidification模型,结合后处理软件进行三维组织形态的动态显示,建立了3DMicrosCA-Solidification模拟系统,实现了二元合金三维凝固微观组织演变过程的实时计算和可视化,为研究微观组织演变特性提供了一个虚拟实验室。 4) 采用一种不同的元胞自动机模型(Nastac模型)模拟了二维单个和多个晶粒的生长过程。 5) 针对二元合金(铝铜合金、铝硅合金)进行了一系列计算机试验,通过理论分析、与权威学者的模拟和实验结果比较检验了三维模型的正确性和适用条件。更多还原

【Abstract】 The dendritic evolution during solidification process of binary alloys is investigated by numerical simulation technique. A 3DMicrosCA model, considering coupled temperature field, concentration field and phase field, has been built to investigate the solidification process of binary alloys from different scales. This work helps to understand the solidification microstructure, and also provides a theoretical reference to control the morphology of microstructure.The paper includes the following five parts, which are:1) A 3DMicrosCA model, taking direct difference method, Monte Carlo method and Oriented-object method into account, is built on the basis of the previous 2D model. This model describes the general idea of 3D cellular automata, which is very supportive theoretically and methodologically for the microstructure modeling.2) Specifically, a 3DMicrosCA-Solidification model is built based on the above-mentioned 3DmicrosCA model. This model, with the application of a deterministic model and a stochastic model, and, a macro model and a micro model, is the instantiation of metal solidification theories.3) Based on this 3DMicrosCA-Solidification model and together with the post-processing software, a 3DMicrosCA-Solidification simulation software is developed to carry out the real-time calculation and visualization of 3D binary alloy microstructure solidification evolution and hence provide with a virtual laboratory for the study of microstructure solidification evolution.4) Another CA model (Nastac method) is used to simulate evolution process of single or multi dentrite in 2D.5) A series of computer simulation have been done to binary alloys. By theoretical analysis and, with the comparison to simulation and experimental results of authorative scholars, this 3DMicrosCA model under certain circumstances has been proved to be reliable and accurate.更多还原