用颗粒推移模型模拟Al-Si／SiC_p复合材料微观组织

MICROSTRUCTURE SIMULATION OF Al-Si/SiC_p COMPOSITES WITH PARTICLE PUSHING MODEL

对搅拌铸造法制备SiC颗粒(SiCp)增强Al-7．0％Si(质量分数)复合材料的微观组织形成过程进行了模拟研究,建立 了常规凝固条件下相应的宏观传热、等轴枝晶形核生长以及颗粒推移的二维计算模型,采用一种改进的CA(cellular automaton) 方法与有限差分法耦合进行数值计算,研究了不同铸造方式对复合材料微观组织以及颗粒分布的影响．为了验证模拟结果,浇注了 阶梯形金属型和砂型试样．结果表明,模拟得到的复合材料颗粒分布及微观组织与实验结果吻合良好．

The microstructure of SiC particle reinforced Al-7.0%Si （mass fraction） composite prepared by stir casting was simulated by a modified cellular automaton method coupled with finite difference method and two-dimensional models under normal solidification condition including macro heat transfer, nucleation, equiaxed dendrite growth and particle pushing. The effects of different casting processes on composite microstructure and particle distribution were analyzed. The simulated results can clearly show the evolution of the microstructure of composite and particle clustering phenomena caused by particle pushing. The simulated results are in good agreement with the experimental results. Grain size is smaller and particle distribution is more uniform for metal mould casting than sand mould casting.