论文部分内容阅读
采用粒径为1μm的SiC颗粒,用挤压铸造法制备出体积分数为45%的SiCP/2024Al复合材料,研究了位错对高体积分数SiCP/2024Al时效行为的影响。结果表明,复合材料中的高密度位错可以湮灭大量的淬火空位,这在一定程度上抑制了GP区的析出。但是,高密度位错的存在降低了其它析出相的热扩散激活能,促进了析出相形核;还能为原子的管道扩散提供通道,促进了溶质原子的扩散,加速析出相的长大,在宏观上表现为对时效行为的促进,使峰时效提前。高密度的位错为强烈依赖于位错等缺陷形核的θ′和S′相提供许多优先形核的场所,使复合材料中的形核密度增加,同时使析出相的尺寸减小,所以复合材料中的析出相呈现细小弥散的分布特点。
The SiCP / 2024Al composites with volume fraction of 45% were prepared by squeeze casting method and the effect of dislocation on the aging behavior of high volume fraction SiCP / 2024Al was studied. The results show that the high-density dislocations in the composite can annihilate a large number of quenching vacancies, which inhibits the precipitation of the GP zone to a certain extent. However, the existence of high-density dislocations reduces the thermal diffusion activation energy of other precipitates and promotes the nucleation of precipitates. It also provides a channel for diffusion of atoms and promotes the diffusion of solute atoms and accelerates the growth of precipitates. Macroscopically manifested as the promotion of aging behavior, so that the peak aging ahead of schedule. High-density dislocations provide sites of preferential nucleation for the θ ’and S’ phases, which strongly depend on the defect nucleation of dislocations and the like, so that the nucleation density in the composite increases while the size of the precipitated phase decreases The precipitates in the composites show the characteristics of small and diffuse distribution.