论文部分内容阅读
改进了模拟枝晶生长常用的二维元胞自动机和有限差分(CA-FD)模型,新模型引入扰动函数来控制二、三次枝晶的生长;在枝晶生长过程中,将溶质浓度明确地分为液相溶质浓度和固相溶质浓度两部分;并在溶质再分配与扩散过程中采用八邻位差分以减少网格形状导致溶质扩散的各向异性。模拟了Al-4%Cu二元合金过冷熔体中,单个和多个等轴晶沿不同择优方向生长及单方向和多方向柱状树枝晶竞争生长过程中的枝晶形貌、液相溶质浓度和固相溶质浓度分布情况。模拟结果表明:扰动的引入能够促使枝晶产生分支,并控制二、三次枝晶的生长速率;液/固相溶质计算模型能够准确地模拟出枝晶生长过程中液/固相溶质分布;此外改进后的模型实现了枝晶沿任意方向的竞争生长。
The two-dimensional cellular automata and finite difference (CA-FD) models which are commonly used to simulate dendritic growth are improved. The new model introduces a perturbation function to control the growth of second and third dendrites. In the process of dendrite growth, the concentration of solute Is divided into liquid solute concentration and solid solute concentration in two parts; and in the process of solute redistribution and diffusion using the eight-neighbor difference to reduce the grid shape resulting in solute diffusion anisotropy. In Al-4% Cu binary alloy supercooled melt, the growth of single and multiple equiaxed grains along different preferred directions and the dendritic morphology during the growth of unidirectional and multi-directional columnar dendrites were simulated. The liquid solutes Concentration and solid solute concentration distribution. The simulation results show that the introduction of perturbation can promote the branching of dendrite and control the growth rate of second and third dendrites. The liquid / solid solute calculation model can accurately simulate the liquid / solid solute distribution during dendrite growth. In addition The improved model realizes the competitive growth of dendrite in any direction.