Rare-earth (RE) elements (Ce and Y) addition on modification effect and corrosion behavior of the Mg-0.8%Si alloy were investigated in the present work. Their correlation was also discussed. The results indicated that both Ce and Y could effectively modify the eutectic Mg2Si phase in the Mg-0.8%Si alloy. The coarse Chinese script type eutectic Mg2Si phase was refined to rod or punctiform shape. The modification effect of Y was better than that of Ce. Si-RE-rich phases were formed in the RE-modified Mg-0.8%Si alloy. Both Ce and Y elements could improve the corrosion resistance. Y showed better effect than Ce. “Barrier effect” and “passive cathodic effect” were the main reasons for the improvement of corrosion resistance. After being modified by 0.5%Y, the corrosion rate in immersion test and the corrosion current density of the Mg-0.8%Si alloy decreased from 6.68 mg/cm2·h to 0.44 mg/cm2·h and from 145.1 μA/cm2 to 33.8 μA/cm2, respectively. Good modification effect exhibited good corrosion resistance due to the barrier effect of the film formed by Mg2Si phases and corrosion products.

Subject
Corrosion resistant alloys, Corrosion currents, Corrosion rate, Metal surfaces, Magnesium alloys, Density, Corrosion products, Sodium chloride solution, Corrosion behavior, Film formation, Immersion, Corrosion resistance, Elements
Keywords:
corrosion behavior, eutectic Mg2Si phase, Mg-0.8%Si, modification
© 2019, NACE International
2019
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