【摘要】 通过半连续铸造的方法制备了Mg-xAl（x=9%,12%,15%）合金。采用XRD、OM和SEM分析研究了Al含量对铸态Mg-Al合金的组织结构变化的影响。同时,利用浸泡腐蚀实验和动电位电化学极化曲线研究了Mg-xAl合金的耐蚀行为。最后,通过SEM观察去除腐蚀产物后样品表面形貌,研究了其腐蚀机理。结果表明:3种合金材料的组织都是由α-Mg相和β-Mg₁₇Al₁₂相组成,而且β相含量随着Al含量的增多而增多。3种合金中随β相的增多,合金的耐腐蚀性能逐渐增强,即Mg-15%Al合金的耐腐蚀性能最好,Mg-9%Al的最差。铸态Mg-Al合金在3.5%NaCl溶液中浸泡72 h后,表面都可以形成氧化膜,随着Al含量增高,膜层的稳定性增强。更多还原

【Abstract】 Mg-xAl（x=9%, 12%, 15%, mass fraction） alloys were prepared by semi-continuous casting. The effects of Al contents on microstructure evolution of Mg-Al alloy were investigated using X-ray diffraction（XRD）, optical microscopy（OM） and scanning electron microscopy（SEM）. Meanwhile, the corrosion behaviors of the Mg-xAl alloys were studied by both hydrogen evolution and potentiodynamic polarization curves. Moreover, the corrosion mechanism of Mg-xAl alloys was also discussed based on the SEM corrosion morphologies of as-cast Mg-Al alloys after hydrogen evolution testing for 72 h in 3.5% NaCl without corrosion products. The results indicate that the microstructure of the three alloys is composed of α-Mg phase and β-Mg₁₇Al₁₂ phase. Moreover, the content of β phase increases with the increase of Al content. As a result, the corrosion resistance of the three alloys is enhanced with the increase of the β phase. The Mg-15%Al alloy has the best corrosion resistance, while Mg-9%Al has the worst. The oxide film forms on the surface of all the as-cast Mg-Al alloys after hydrogen evolution testing for 72 h in 3.5% NaCl. Furthermore, the stability of the film increases with the increase of Al content.更多还原