(華南理工大學(xué)機(jī)械工程學(xué)院， 廣州 510641)
摘 要: 采用光學(xué)顯微鏡、 掃描和透射電子顯微鏡研究了含Ca、 Si鎂合金的顯微組織特征。 鑄態(tài)下， 僅含Ca的鎂合金主要由鎂基體和晶界離異共晶組織(Mg+Mg2Ca)組成； 加入約0.5%(質(zhì)量分?jǐn)?shù))Si后， 晶界離異共晶組織消失， 在晶界附近及晶內(nèi)形成彌散分布的細(xì)小點(diǎn)狀(球狀)、 針狀和粗塊狀CaMgSi相； 當(dāng)含Si量較高(約1.0%)時， 出現(xiàn)中國字形(針狀)的Mg2Si相。 固溶時效后， 只含Ca的鎂合金中晶界處離異共晶組織消失， 代之以長大了的顆粒狀Mg2Ca相； 而Mg-Ca-Si合金的固溶時效組織較鑄態(tài)無明顯變化。 對合金常溫和高溫短時拉伸性能也作了初步探討。
關(guān)鍵字: 鎂鈣合金; Mg2Ca; CaMgSi; Mg2Si; 力學(xué)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
