(华南理工大学机械工程学院， 广州 510641)
摘 要: 采用光学显微镜、 扫描和透射电子显微镜研究了含Ca、 Si镁合金的显微组织特征。 铸态下， 仅含Ca的镁合金主要由镁基体和晶界离异共晶组织(Mg+Mg2Ca)组成； 加入约0.5%(质量分数)Si后， 晶界离异共晶组织消失， 在晶界附近及晶内形成弥散分布的细小点状(球状)、 针状和粗块状CaMgSi相； 当含Si量较高(约1.0%)时， 出现中国字形(针状)的Mg2Si相。 固溶时效后， 只含Ca的镁合金中晶界处离异共晶组织消失， 代之以长大了的颗粒状Mg2Ca相； 而Mg-Ca-Si合金的固溶时效组织较铸态无明显变化。 对合金常温和高温短时拉伸性能也作了初步探讨。
关键字: 镁钙合金; Mg2Ca; CaMgSi; Mg2Si; 力学性能
（ College of Mechanical Engineering,
South China University of Technology, Guangzhou 510641, China）
Abstract: The microstructure of magnesium alloys containing Ca and Si were investigated using optical microscope, scanning electron microscope and transmission electron microscopes.The as-cast Mg-Ca alloy containing only Ca is composed of Mg matrix and divorced eutectic (Mg+Mg2Ca) formed along the grain boundaries. With about 0.5%Si (mass fraction) added to the Mg-Ca alloy to produce Mg-Ca-Si alloys, no grain boundary divorced eutectic is formed any more, instead, dispersive dot-like, needle-like or discrete lump-like CaMgSi compounds are formed at the grain boundaries and within the grains. When the Si content is further increased to about 1.0%, Chinese-character-like (needle like) Mg2Si compounds are formed in addition to the CaMgSi ones. After solution-ageing treatment, the divorced eutectic (Mg+Mg2Ca) along the grain boundaries of Mg-Ca alloy containing only Ca disappears, where the grown-up granular Mg2Ca was found instead, whereas no evident change of microstructure could be found in Mg-Ca-Si alloys. The room temperature tensile properties and elevated temperature transient tensile properties of alloys were also investigated.
Key words: Mg-Ca alloy; Mg2Ca; CaMgSi; Mg2Si; mechanical properties
