摘要
利用光学金相显微镜OM和XRD分析了加入微量Si的AZ91D合金显微组织和相组成,测试了合金室温拉伸力学性能和硬度,利用SEM分析了合金拉伸断口形貌。结果表明,加入一定量Si后AZ91D合金组织中形成汉字状Mg2Si相,富集于固液界面前沿,阻碍α-Mg基体的自由长大,从而细化合金铸态组织;汉字状Mg2Si相的存在导致合金力学性能的降低;AZ91D合金室温拉伸断口是以解理断裂为主的脆性断裂,加入Si后,断裂常发生于α-Mg基体和汉字状Mg2Si相间的界面处。
Microstructures and phase compositions of AZ91D alloys after adding trace Si was observed using OM and XRD, meanwhile their tensile properties and hardness at ambient temperature were tested. The fractographs of the alloys were investigated using SEM. The results show that Chinese script type Mg_2Si phase is formed in the microstructures of AZ91D alloys after adding a certain quantity of Si content, which is enriched in the front edge of the solid/liquid interface. Then the free growth of α-Mg matrix is hindered and as-cast microstructures are refined. The existence of the Chinese script type Mg_2Si phase can lead to the reduction of the mechanical properties of the alloys. The fractograph of AZ91D alloy is brittle fracture that is mainly composed of cleavage-type fracture, while the fracture occurs in the interface between α-Mg matrix and Chinese script type Mg_2Si phase after adding Si content.
出处
《材料工程》
EI
CAS
CSCD
北大核心
2004年第6期28-32,共5页
Journal of Materials Engineering
基金
国家自然科学基金资助项目 (50 2 71 0 54)
关键词
AZ91D镁合金
Si变质
显微组织
力学性能
AZ91D magnesium alloy
Si modification
microstructure
mechanical propertyies
