2124 Al/SiC_p复合材料的动态变形行为及微结构效应

THE DEFORMATION BEHAVIOR AND MICROSTRUCTURE EFFECT OF 2124 Al/SiC p UNDER IMPACT LOADING 1)

研究了在动态压缩时２１２４Ａｌ／ＳｉＣｐ复合材料的变形行为与微结构效应．分析结果表明，对于给定材料，复合材料的流动应力主要取决于微结构尺度效应．若增强相尺寸，基体晶粒尺寸以及增强相间距三者大小相当，则复合材料的流动应力取决于增强相的分散程度和位错密度；若增强相尺寸及其间距大小相当，但比基体晶粒大得多，那复合材料的流动应力主要取决于增强相的分散度．微观观测发现在同样加载条件下，变形局部化更容易在含较小碳化硅颗粒的复合材料内形成；变形区内的微损伤几乎都是基体与粒子界面脱粘和粒子角点邻近的微裂纹．对于所研究的这类复合材料，弹性模量及应变硬化几乎不受增强颗粒尺寸影响．

An investigation has been carried out on the deformation and microstructure effect of 2124 Al/SiC p composites under dynamic compression. The experimental materials are 2124 Al alloy and its composites, reinforced with SiC particles of 3μm, 13μm and 37μm, the volume fractions of SiC particles is about 17%. One of the experimental results is that, in these composites, their flow stress varies with the SiC particle size under same loading condition, =21001/s. The further analysis show that the flow stress of these MMC p is related mainly to the microstructure scale effect. Particularly, the flow stress depends on the dispersion of reinforcements and the density of dislocation in the matrix if the reinforcement size, their distance and the size of matrix grain are almost equal to one another. The flow stress mainly depends on the dispersion of reinforcement if the matrix grain size is much smaller than that of reinforcements and their distance while the latter two are almost equal. This agrees with those of previous researches. Microscopic observations showed that, for the present materials, the localized deformation occurred more readily in the MMC p containing 3μm SiC particles, which is due to the plastic work of the present material during deformation. The microdamages occurred in these composites are almost exclusively the debonding in the interface between SiC particle and matrix and microcracks at corners of hard particles. Additionally, the Young's modulus and the strain hardening, in these materials, are not affected by SiC particle size.