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系统研究在相同冷却条件和成分控制条件下,不同Mg-Al-Si合金(AS11,AS21,AS41,AS61和AS91)的腐蚀行为。采用光学显微镜和扫描电子显微镜观察合金的显微组织。采用浸泡实验和动电位极化测试研究合金在3.5%NaCl溶液中的腐蚀行为。结果表明,添加2.0%Al(质量分数)的合金(AS21)抗腐蚀能力提高,而Al含量大于2.0%(AS41,AS61,AS91)时,合金的抗腐蚀能力降低。这是由于生成了β相作为阴极,以及β相和Mg_2Si相的粗化导致合金表面氧化膜的破裂后不连续。
The corrosion behavior of different Mg-Al-Si alloys (AS11, AS21, AS41, AS61 and AS91) was studied systematically under the same cooling and compositional control conditions. The microstructure of the alloy was observed by optical microscope and scanning electron microscope. The corrosion behavior of alloy in 3.5% NaCl solution was studied by immersion test and potentiodynamic polarization test. The results show that the corrosion resistance of AS21 with 2.0% Al increases, while the corrosion resistance decreases with the Al content of more than 2.0% (AS41, AS61, AS91). This is due to the formation of the β phase as the cathode, and the coarsening of the β phase and the Mg 2 Si phase leading to the discontinuity of the oxide film on the alloy surface after rupture.