Al-Si/SiC_p复合材料微观组织模拟及颗粒分布均匀性定量预测

MICROSTRUCTURE SIMULATION OF Al-Si/SiC_p COMPOSITES AND QUANTI-TATIVE ASSESSMENT OF PARTICLE DISTRIBUTION HOMOGENEITY

为研究颗粒偏聚现象进而准确预测复合材料最终性能,在搅拌铸造法制备SiC颗粒增强Al-Si复合材料的试验基础上,对复合材料的微观组织进行数值模拟研究。建立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(Cellul arautomaton)方法耦合有限差分法进行数值计算得到复合材料组织的形成过程。采用一种简便的颗粒均匀性定量分析方法从模拟和试验两个角度研究不同铸造方式、颗粒体积分数及冷却速度对复合材料微观组织以及颗粒分布的影响。模拟得到的复合材料颗粒分布及微观组织与试验结果吻合。

To study particle segregation phenomena and predict the final performance of particle reinforced metal matrix composite, the microstructure of SiC particle reinforced Al-Si composite made by stir casting is simulated based on the experiment. Two-dimensional models under normal solidification condition including macro heat transfer, nucleation, equiaxed dendrite growth and particle pushing aro established and composite microstructures are simulated by a modified cellular automaton method coupled with finite difference method. A simple method is applied for quantitatively analyzing the effects of different casting processes, particle volume fraction and cooling rate on composite microstructure and particle distribution from both experimental and simulated sides. The simulated results of particle distribution and microstructures of composite are in agreement with the experimental results.