Mg-10Gd-2Y-0.5Zr（GW102K） microcrystalline（MC） film with grain size about 300 to 400 nm was fabricated on a glass substrate by magnetron sputtering technique.The corrosion behavior of GW102K MC film and GW102K target alloy in 0.2 mol/L Na_2O_4 solution was investigated by polarization curves and electrochemical impedance spectrum（EIS）.The polarization measurement results showed that the cathodic process was accelerated and the anodic process was decelerated of MC film in comparison with GW102K target alloy.The analysis of EIS measurement revealed that the transition resistance and film resistance were decreased.The corrosion resistance of MC film was decreased at open circuit potential.Large amount of grain boundaries existed in the MC film,which therefore might facilitate the diffusion process of adsorption hydrogen in the MC film.The hydrides could form on the surface of MC film.As a result the cathode process for the MC film was accelerated.It also followed that the microcristallization process might facilitate the anodic dissolution process of metal,which then induced formation of corrosion products on the surface of MC film,and the later might play certain role in inhibiting the further dissolution of metals.
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