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采用真空热压烧结工艺在580℃下制备了35%(体积分数)SiCp/2024铝基复合材料,利用扫描电镜(SEM)、透射电镜(TEM)、能谱(EDS)、高分辨透射电镜(HRTEM)对复合材料热处理过程中微观组织进行了表征,研究了热压烧结后复合材料的析出相的微观结构以及析出相在热处理过程的演变规律。结果表明,热压烧结后复合材料中存在许多粗大析出相颗粒,包括Al4Cu9,Al2Cu,Al18Mg3Mn2,Al5Cu6Mg2和Al7Cu2Fe。随着固溶温度的提高,粗大析出相颗粒逐渐回溶到Al基体中,当固溶温度达到510℃时,粗大析出相颗粒几乎全部回溶到基体中,但还存在少量的难溶相。复合材料经510℃固溶2 h+190℃时效9 h后,除了少量的难溶相,许多圆盘状纳米析出相Al2Cu和棒针状纳米析出相Al2Cu Mg弥散分布于基体中且与基体的界面为错配度较小的半共格界面,圆盘状纳米析出相的直径为50~200 nm,棒针状纳米析出相长度为100~150 nm。
A 35% (volume fraction) SiCp / 2024 aluminum matrix composite was prepared by vacuum hot pressing at 580 ℃. The microstructures of SiCp / 2024 aluminum matrix composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and high resolution transmission electron microscopy HRTEM) was used to characterize the microstructure of the composite during the heat treatment. The microstructure of the precipitated phase and the evolution of the precipitated phase during the heat treatment were investigated. The results show that there are many coarse precipitates in the composite after hot-pressing, including Al4Cu9, Al2Cu, Al18Mg3Mn2, Al5Cu6Mg2 and Al7Cu2Fe. With the increase of solution temperature, coarse precipitated phase particles gradually dissolved back into the Al matrix. When the solid solution temperature reached 510 ℃, almost all of the coarse precipitated particles were dissolved back into the matrix, but a small amount of insoluble phase existed. After being solution-treated at 510 ℃ for 2 h and aged at 190 ℃ for 9 h, many disk-shaped nano-precipitates Al2Cu and rod-shaped nano-precipitates Al2Cu Mg diffusely dispersed in the matrix with the interface of the matrix For the mismatched half-coherent interface, the diameter of disc-shaped nano-precipitates is 50-200 nm and the length of bar-like nano-precipitates is 100-150 nm.