采用粉末冶金方法制备体积分数为35%的SiCp/2024 Al复合材料.利用高分辨透射电镜对复合材料中 SiCp与Al基体、析出相与Al基体之间的界面微结构进行表征,采用拉伸弹性模量和布氏硬度测试对界面状况进行评估.结果表明,所得复合材料中SiC与Al的界面整体状况良好.复合材料中SiC/Al界面分为3种类型:大部分干净界面、少量轻微反应型界面以及极少量的非晶层界面.在干净界面中,SiC和Al的结合机制为紧密原子匹配形成的半共格界面,且 SiC 和 Al 无固定或择优的取向关系.在轻微反应型界面中,MgAl2O4尖晶石与 SiC和Al均形成半共格界面,作为中间媒介很好地连接SiC和Al.复合材料经510 °C固溶2 h再在190 °C时效9 h后,许多圆盘状纳米析出相和棒针状纳米析出相弥散分布于基体中,且与基体的界面为错配度较小的半共格界面.此时,复合材料的布氏硬度达到峰值.%35% SiCp/2024 Al (volume fraction) composite was prepared by powder metallurgy method. The microstructures of SiCp/Al interfaces and precipitate phase/Al interfaces were characterized by HRTEM, and the interface conditions were evaluated by tensile modules of elasticity and Brinell hardness measurement. The results show that the overall SiCp/Al interface condition in this experiment is good and three kinds of SiCp/Al interfaces are present in the composites, which includevast majority of clean planer interfaces, few slight reaction interfaces and tiny amorphous interfaces. The combination mechanism of SiC and Al in the clean planer interface is the formation of a semi-coherent interface by closely matching of atoms and there are no fixed or preferential crystallographic orientation relationships between SiC and Al. MgAl2O4 spinel particles act as an intermediate to form semi-coherent interface with SiC and Al respectively at the slight reaction interfaces. When the composite is aged at 190 °C for 9 h after being solution-treated at 510 °C for 2 h, numerous discoid-shaped and needle-shaped nanosized precipitates dispersively exist in the composite and are semi-coherent of low mismatch with Al matrix. The Brinell hardness of composites arrives peak value at this time.
展开▼
