利用SEM、EDX、XRD等分析技术分析3种不同Al添加量的镁合金的显微组织和相结构，经实验室模拟金属大气腐蚀实验后观察其腐蚀形貌。结果表明，随着Al含量的增加，Mg-Al合金中β相（Mg17Al12 ）的数量明显增加；不存在β相的镁合金表面腐蚀产物较少，基体腐蚀较浅，存在β相的镁合金表面腐蚀产物较多，基体出现较深的腐蚀坑；β相数量与分布的不同是镁合金腐蚀形貌产生差异的主要原因。
Microstructure and phase constituent of magnesium-aluminum alloys adding different aluminum content (3.4mass%, 9.3mass%, and 20.7mass%)were investigated utilizing the scanning electron microscopy (SEM) equipped with energy-dispersive analysis of x-ray (EDAX) and X-ray diffraction (XRD).The influence of microstructure on the corrosion morphologies was observed after corrosion tests in laboratory simulated atmosphere. The results indicated that magnesium-aluminum alloys with different aluminum content in the atmospheric environment had different corrosion behavior due to amount and distribution of the βphase (Mg17Al12). Mg-3Al alloy was single-phase alloy,while Mg-9Al alloy and Mg-21Al alloy were two-phase alloys. There were more βphase in Mg-21Al alloy than in Mg-9Al alloy because of its higher aluminum content. Mg-3Al alloy exhibited better atmospheric corrosion resistance than Mg-9Al alloy and Mg-21Al alloy. There were fewer corrosion products on the surfaces of Mg-3Al specimens, while severe corrosion was found to take place in both Mg-9Al alloy and Mg-21Al alloy due to the presence of the β phase in them.More specifically , it was discovered that due to the absence of the couple-actuation of βphase ,the corrosion of single -phase alloy Mg-3Al may be attributed solely to the pitting caused by high concentration of Cl- near the NaCl deposits however, with Mg-9Al alloy and Mg-21Al alloy, a more important factor for corrosion is the presence of β phase. under couple-actuation of the negative of β phase, αphase causes a corrosion along the depth extent.
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