过冷熔体近球晶组织形成机理的相场模拟  

Phase-field of Simulation Formation Mechanism of Near Spherulite Microstructure in Undercooled Melt

作　　者：吕星[1,2] 杨湘杰[1,2] 桂云鹏[2,3] 郭洪民[2,3] 

机构地区：[1]南昌大学机电工程学院,江西南昌330031 [2]江西省高性能精确成形重点实验室,江西南昌330031 [3]南昌大学材料科学与工程学院,江西南昌330031

出　　处：《热加工工艺》2015年第7期88-91,97,共5页Hot Working Technology

基　　金：高校博士点专项科研基金项目(20113601110008);江西省自然科学基金重点项目(20133ACB21003);江西省自然科学基金项目(20122BAB206021);江西省青年科学家资助计划项目(20122BCB23001);国家自然科学基金项目(11364301)

摘　　要：以二元合金相场模型为基础,建立了耦合溶质场的相场模型,采用有限差分法对控制方程进行数值求解,模拟了Al-Cu二元合金在等温凝固时晶粒的生长过程。研究了过冷度和晶粒间距对晶粒生长行为的影响,分析了溶质扩散对晶粒生长长度和生长速率的影响。结果表明:在低的过冷度和小的晶粒间距下,晶粒趋于球形生长;而在高的过冷度或大的晶粒间距下,晶粒趋于树枝状生长。在高晶粒密度和缓慢冷却条件下,晶粒周围浓度场的相互叠加使得晶粒生长界面前沿的溶质分布更均匀,有利于晶粒呈球形生长,球晶可以在液相中直接形成。A phase-field model coupling with solute field was established based on binary phase-field model. A finite difference numerical method was used to solve the control equations, simulate the spherulitic growth in A1-Cu binary alloy under isothermal solidification. The effects of undercooling and distance on the near spherulite growth were studied, and the effects of solute diffusion on the growth length and growth rate were analyzed. The results indicate that it tends to be spherulitic growth when the grains have lower undercooling degree and higher grain density; on the contrary, it tends to be dendritic growth when increasing undercooling degree and grain spacing. With the condition of high grain density and slow cooling, the overlapping diffusion field from adjacent growing crystals can induce the solute distribution more uniform, promote the globular growth ofgra!ns. The spherulites can be formed directly in the liquid phase.

关 键 词：二元合金 相场法 近球晶生长 过冷度 晶粒间距 

分 类 号：TG292[金属学及工艺—铸造] TG244.3