铸造SiCp／2024复合材料微观结构与强化机制的研究

研究了SiC体积分数分别为5,10,15和20%的2024Al基复合材料在峰值时效态下的微观结构和强化机制透射电镜观察和Vickers硬度测定表明:增强相的加入使复合材料基体中的位错密度升高,亚晶尺寸略有下降,但基体的硬度却无明显升高拉伸试验发现,弹性模量和加工硬化指数随SiC体积分数增加而显著提高,初始流变应力先下降后升高本文认为由增强相导致的应力集中和基体形变的高约束度是控制SiC_p/2024复合材料形变与强化的两个主要因素

MICROSTRUCTURE OF CAST SiC_p/2024 Al COMPOSITE AND ITS STRENGTHENING MECHANISM

Microstructure of the cast SiC_p/2024 Al composites, containing 5, 10, 15 and 20 v.-% SiC particles, under peak-aged state and the strengthening mechanism have been studied by TEM observation and Vickers hardness measurements. An increase of dislocation density in the matrix and slight reduction of subgrain size may be caused by the reinforcement, but the hardness of the matrix increases no more. Tensile tests show that the elastic modulus and work hardening index increase obviously, and the initial flow stress de- creases first and increases afterwards with the increase of volume fraction of SiC particles. It is believed that the stress concentration and the deformation constraint by the reinforcement are two main factors in control of the plastic deformation and strengthening of the SiC_p/2024 composite.